SEC Filing | Adicet Bio

View:

424B5

The information in this preliminary prospectus supplement and the accompanying prospectus, relating to an effective registration statement under the Securities Act of 1933, as amended, is not complete and may be changed. A registration statement relating to these securities has been declared effective by the Securities and Exchange Commission. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities and we are not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted..

Filed Pursuant to Rule 424(b)(5)
Registration No. 333-229499

SUBJECT TO COMPLETION, DATED SEPTEMBER 21, 2020

PRELIMINARY PROSPECTUS SUPPLEMENT

(To Prospectus dated February 1, 2019)

4,500,000 Shares

LOGO

Common Stock

We are offering 4,500,000 shares of our common stock. Our common stock is listed on the Nasdaq Global Market under the symbol “ACET.” On September 18, 2020, the last reported sale price of our common stock was $21.40 per share.

We are an “emerging growth company” as defined by the Jumpstart Our Business Startups Act of 2012 and, as such, we have elected to comply with certain reduced public company reporting requirements for this prospectus supplement, the accompanying prospectus and future filings.

Investing in our common stock involves a high degree of risk. Please read “Risk Factors ” beginning on page S-10 of this prospectus supplement and in the documents incorporated by reference into this prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.


	Per Share	Total
Public offering price	$	$
Underwriting discounts and commissions (1)	$	$
Proceeds to Adicet Bio, Inc., before expenses	$	$

(1)

We have agreed to reimburse the underwriters for certain expenses. See “Underwriting.”

We have granted the underwriters an option for a period of 30 days to purchase up to an additional 675,000 shares of our common stock at the public offering price, less the underwriting discount. Delivery of the shares of common stock is expected to be made on or about , 2020.

Joint Book-Running Managers


BofA Securities		Jefferies		SVB Leerink

Lead Manager

Wedbush PacGrow

The date of this prospectus supplement is , 2020.

TABLE OF CONTENTS


	Page
PROSPECTUS SUPPLEMENT

ABOUT THIS PROSPECTUS SUPPLEMENT		S-i
CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS		S-iii
PROSPECTUS SUPPLEMENT SUMMARY		S-1
RISK FACTORS		S-10
USE OF PROCEEDS		S-21
DIVIDEND POLICY		S-22
DILUTION		S-23
UNDERWRITING		S-32
CONCURRENT PRIVATE PLACEMENT		S-39
LEGAL MATTERS		S-40
EXPERTS		S-40
WHERE YOU CAN FIND ADDITIONAL INFORMATION		S-40
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE		S-40

PROSPECTUS

ABOUT THIS PROSPECTUS		1
RISK FACTORS		2
CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS		3
THE COMPANY		5
USE OF PROCEEDS		8
SECURITIES WE MAY OFFER OR THAT A SELLING STOCKHOLDER MAY OFFER		8
DESCRIPTION OF CAPITAL STOCK		9
DESCRIPTION OF DEBT SECURITIES		14
DESCRIPTION OF WARRANTS		29
DESCRIPTION OF UNITS		30
SELLING STOCKHOLDERS		34
PLAN OF DISTRIBUTION		36
LEGAL MATTERS		39
EXPERTS		39
WHERE YOU CAN FIND MORE INFORMATION		39
INCORPORATION BY REFERENCE		39

ABOUT THIS PROSPECTUS SUPPLEMENT

This document is part of the registration statement that we filed with the Securities and Exchange Commission, or the SEC, using a “shelf” registration process and consists of two parts. The first part is this prospectus supplement, including the documents incorporated by reference, which describes the specific terms of this offering. The second part, the accompanying prospectus dated February 12, 2019, included in our registration statement on Form S-3 (File No. 333-229499) including the documents incorporated by reference, gives more general information, some of which may not apply to this offering. Generally, when we refer to the “prospectus,” we are referring to both parts combined. This prospectus supplement and any related free writing prospectus we authorize for use in connection with this offering may add to, update or change information in the accompanying prospectus and the documents incorporated by reference into this prospectus supplement or the accompanying prospectus.

If information in this prospectus supplement is inconsistent with the accompanying prospectus or with any document incorporated by reference that was filed with the SEC before the date of this prospectus supplement, you should rely on this prospectus supplement. This prospectus supplement, the accompanying prospectus, the documents incorporated by reference into each and any free writing prospectus we authorize for use in connection with this offering include important information about us, the common stock and other information should you consider before investing in the common stock. See “Incorporation of Certain Information by Reference.”

We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference herein were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties and covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

We take no responsibility for, and can provide no assurances as to the reliability of, any information that is in addition to or different from that contained or incorporated by reference in this prospectus supplement and the accompanying prospectus. We are not offering to sell these securities in any jurisdiction where the offer or sale is not permitted. You should not assume that the information contained or incorporated by reference in this prospectus supplement or the accompanying prospectus is accurate as of any date other than as of the date of this prospectus supplement or the accompanying prospectus, as the case may be, or in the case of the documents incorporated by reference, the date of such documents regardless of the time of delivery of this prospectus supplement and the accompanying prospectus or any sale of our securities. Our business, financial condition, liquidity, results of operations and prospects may have changed since those dates.

Unless the context otherwise requires, references in this prospectus supplement to “Adicet,” the “Company,” the “combined company” “we,” “our” or “us” refer to Adicet Bio, Inc. (formerly known as resTORbio, Inc.) and its subsidiaries; references to “Adicet” refer to the Company following the completion of the Merger (defined below); references to “resTORbio” refer to the Company prior to the completion of the Merger; references to “Former Adicet” refer to Adicet Bio, Inc., a privately held corporation prior to the completion of the Merger; and references to “Adicet Sub” refer to Adicet Therapeutics, Inc., the Company’s wholly owned subsidiary following the Merger. See “Prospectus Supplement Summary—Company Information.”

We use various trademarks and trade names in our business, including without limitation our corporate name and logo. This prospectus supplement, the accompanying prospectus and the information incorporated herein and therein by reference contain references to trademarks, service marks and trade names owned by us or other companies. Solely for convenience, trademarks, service marks and trade names referred to in this

S-i

prospectus supplement, the accompanying prospectus and the information incorporated herein and therein, including logos, artwork, and other visual displays, may appear without the ^® or ^™ symbols, but such references are not intended to indicate, in any way, that we will not assert, to the fullest extent under applicable law, our rights or the rights of the applicable licensor to these trademarks, service marks and trade names. We do not intend our use or display of other companies’ trade names, service marks or trademarks to imply a relationship with, or endorsement or sponsorship of us by, any other companies. All trademarks, service marks and trade names included or incorporated by reference into this prospectus supplement, the accompanying prospectus or any related free writing prospectus are the property of their respective owners.

S-ii

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement, the accompanying prospectus and the information incorporated by reference herein and therein contain and any free writing prospects we authorize for use in connection with this offering may contain forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. Any statements about our expectations, plans, objectives, assumptions or future events or performance are not historical facts and may be forward-looking. These statements are often, but are not always, made through the use of words or phrases such as “may,” “will,” “could,” “should,” “expects,” “intends,” “plans,” “anticipates,” “believes,” “estimates,” “predicts,” “projects,” “potential,” “continue,” and similar expressions, or the negative of these terms, or similar expressions. Accordingly, these statements involve estimates, assumptions, risks and uncertainties which could cause actual results to differ materially from those expressed in them. We believe that it is important to communicate our future expectations to our investors. However, there may be events in the future that we are not able to accurately predict or control and that may cause our actual results to differ materially from the expectations we describe in our forward-looking statements.

This prospectus supplement, the accompanying prospectus, and the information incorporated by reference herein and therein contain, and any free writing prospects we authorize for use in connection with this offering may contain, forward-looking statements that are based on our management’s belief and assumptions and on information currently available to our management. These statements relate to future events or our future financial performance, and involve known and unknown risks, uncertainties and other factors that may cause our actual results, levels of activity, performance or achievements to be materially different from any future results, levels of activity, performance or achievements expressed or implied by these forward-looking statements. Forward-looking statements include, but are not limited to, statements about:

•

the anticipated timing of our submission of investigational new drug applications, or INDs, or equivalent regulatory filings and initiation of future clinical trials for ADI-001 in Non-Hodgkin’s Lymphoma, or NHL, including the anticipated results;

•

the anticipated timing of our submission of INDs or equivalent regulatory filings and initiation of future clinical trials for ADI-002 in solid tumors, including the timing the anticipated results;

•

the impacts of the current COVID-19 pandemic on our continuing operations, clinical development plans, including the timing of initiation and completion of studies or trials, financial forecasts and expectations, and other matters related to our business and operations;

•

the timing of and our ability to obtain and maintain regulatory approvals for our product candidates;

•

the rate and degree of acceptance and clinical utility of any products for which we receive regulatory approval;

•

our commercialization, marketing and manufacturing capabilities and strategy;

•

our intellectual property position and strategy;

•

our ability to identify additional product candidates with significant commercial potential;

•

our plans to enter into collaborations for the development and commercialization of product candidates;

•

the potential benefits of any future collaboration;

S-iii

•

our ability to contract with third-party suppliers and manufacturers and their ability to perform adequately;

•

the success of competing therapies that are or may become available;

•

our ability to retain the continued service of our key professionals and to identify, hire, and retain additional qualified professionals;

•

our financial performance;

•

our expectations related to the use of cash, cash equivalents and marketable securities;

•

our estimates regarding expenses, future revenue, capital requirements and needs for additional financing;

•

our ability to remediate the material weaknesses in internal control over financial reporting and to maintain effective internal control over financial reporting;

•

our expectations regarding the time during which we will be an emerging growth company under the Jumpstart our Business Startups Act of 2012, or the JOBS Act;

•

our expected uses of the net proceeds from this offering and the concurrent private placement;

•

developments relating to our competitors and our industry; and

•

the impact of government laws and regulations.

These forward-looking statements are neither promises nor guarantees of future performance due to a variety of risks and uncertainties, many of which are beyond our control, which could cause actual results to differ materially from those indicated by these forward-looking statements, including, without limitation, the risk factors and cautionary statements described in other documents that we file from time to time with the SEC, specifically under “Item 1A: Risk Factors” and elsewhere in our most recent Annual Report on Form 10-K, and under similar headings in subsequent Quarterly Reports on Form 10-Q, or Current Reports on Form 8-K, and the section of the prospectus supplement titled “Risk Factors.”

You should read this prospectus supplement, the accompanying prospectus, and the information incorporated by reference herein and therein, completely and with the understanding that our actual future results may be materially different from what we expect. The forward-looking statements in this prospectus supplement and the documents we incorporate by reference herein represent our views as of their respective dates. We anticipate that subsequent events and developments will cause our views to change. However, while we may elect to update these forward-looking statements at some point in the future, we have no current intention of doing so except to the extent required by applicable law. You should, therefore, not rely on these forward-looking statements as representing our views as of any date subsequent to the date of this prospectus supplement.

S-iv

PROSPECTUS SUPPLEMENT SUMMARY

This summary highlights certain information about us, this offering and the concurrent private placement and selected information contained elsewhere or incorporated by reference in this prospectus supplement and the accompanying prospectus. This summary is not complete and does not contain all the information that you should consider before making your investment decision. You should read this entire prospectus supplement and the accompanying prospectus carefully, especially the risks of investing in our securities discussed under “Risk Factors” beginning on page S-10 of this prospectus supplement, along with our financial statements and related notes and the other information incorporated by reference into this prospectus supplement and the accompanying prospectus and any free writing prospectus we authorize for use in connection with this offering, before making an investment decision. This prospectus supplement may add to, update or change information in the accompanying prospectus.

Overview

We are a biotechnology company that is advancing a new generation of chimeric antigen receptor (CAR)-modified-T cell therapy candidates in oncology and other indications. Our approach is based on gamma delta T cells, an immune cell population that we believe has potentially significant advantages over alpha beta T cells, which are the basis of standard CAR-T cell therapies. We are developing proprietary processes for engineering and manufacturing product candidates based on gamma delta T cells from the blood of healthy donors, resulting in high yields of cells with efficacious tumor-killing activity in preclinical studies. The potential to administer product candidates based on gamma delta T cells to patients without inducing a graft versus host immune response could mean that our products can potentially be produced as “off-the-shelf” therapies. This is in contrast to products based on alpha beta T cells, which either must be manufactured for each patient from his or her own T cells, or require significant gene editing to manufacture if the T cells are derived from donors that are unrelated to the patient. Based on what we believe is the unique potential of these cells and associated modifications, we are initially developing product candidates in oncology, both for hematological malignancies and for solid tumors. Due to certain unique properties of gamma delta T cells, we believe that our product candidates can be developed to have an inherent capacity to recognize and kill circulating tumor cells and to infiltrate and kill solid tumors. We intend to file an IND with the United States, or U.S., Food and Drug Administration, or FDA, in the second half of 2020 for ADI-001, our lead product candidate, in NHL. We intend to initiate a clinical trial and treat the first patient with ADI-001 in the first half of 2021. We expect initial clinical results from this trial in 2021. We intend to file an IND with the FDA in 2021 for ADI-002, our first solid tumor product candidate.

Gamma delta T cells have unique attributes that we believe make them especially well-suited to be used for cancer therapy. Approximately 95% of T cells in circulation are so-called alpha beta T cells, named after the proteins that make up the cells’ T cell receptor, or TCR. Gamma delta T cells, along with a few other cell types, make up the remaining 1% to 5% of all T cells. Distinct among immune cell populations, therapeutic candidates derived from gamma delta T cells have the following potential attributes:

•

can be used “off-the-shelf” after being expanded from healthy donors;

•

are actively cytotoxic to tumor cells;

•

can replicate in an appropriate and measured way after manufacture;

•

can locate in tissues and recognize and attack cancerous cells;

•

can have their specificity for tumor cells enhanced further by the addition of a CAR;

S-1

•

express both T cell and natural killer, or NK, cell receptors, facilitating both adaptive and innate antitumor immune responses; and

•

can be manufactured in large numbers to facilitate the treatment of many patients and to avoid the cumbersome nature and expense of isolating T cells from each patient.

By contrast, approved CAR-T cell therapies, as well as the majority of CAR-T cell therapies in clinical development, are based on a different population of T cells known as alpha beta T cells, which have the ability to attack healthy tissues if those cells are not immunologically matched to the patient. For this reason, the majority of alpha-beta-T-cell-derived CAR-T cell products are custom-generated from cells isolated from each patient. Gamma delta T cells, by contrast, do not in principle require immunological matching to be potentially administered as a part of a therapy, and therefore cells isolated from healthy donors have the potential to be administered to any patient. This enables cell therapy product candidates based on gamma delta T cells to be manufactured in bulk and developed as off-the-shelf products. In animal models and early clinical trials, gamma delta T cells have largely not expanded in healthy tissues, indicating that they may be associated with a lower risk of life-threatening immune responses.

ADI-001 is a gamma delta T-cell product candidate into which we introduced a CAR that is designed to specifically recognize CD20, a highly expressed surface protein found on the majority of NHLs. We are developing a highly efficient and robust process to activate, engineer and manufacture product candidates derived from peripheral blood cells of healthy donors. We are developing processes that can produce these cells in bulk under conditions that are designed to meet current Good Manufacturing Practices requirements, or cGMP, to generate an inventory of cell product that is readily available to patients on demand at clinical sites. Gamma delta T cells engineered with anti-CD20 CAR have shown highly potent antitumor activity in preclinical models, which could lead to effective long-term control of tumor growth. We believe that ADI-001 has the potential to benefit patients that have NHL while also providing clinical validation of our gamma delta T-cell platform technology. We anticipate filing an IND with the FDA in the second half of 2020 and initiating clinical development of ADI-001 in the first half of 2021.

In addition to potentially providing access to immunocellular therapies to a broader set of patients with hematological malignancies, we believe that our technology is well-positioned to potentially bring these therapies to patients with solid tumors. ADI-002 is a gamma delta T cell product candidate containing a CAR directed against Glypican-3, or GPC3, a tumor antigen that is highly expressed in hepatocellular carcinoma, or HCC, and other tumors such as gastric cancer and squamous cell carcinoma of the lung. ADI-002 has shown dose-dependent antitumor activity in animal models. We intend to file an IND with the FDA in 2021 for ADI-002.

Our solid tumor efforts are further complemented by our proprietary T cell receptor-like-antibody, or TCRL, platform technology, a monoclonal antibody technology which enables the generation of CARs that are designed to recognize tumor antigens inside tumor cells, also known as intracellular proteins. We believe that the ability to selectively bind to tumor antigens derived specifically from intracellular proteins is a critical advantage to immunocellular therapy due to the scarcity of tumor-specific surface antigens on solid tumors. Our approach to generating CARs for some product candidates is designed to take advantage of this potential ability.

S-2

Pipeline

LOGO

We have a pipeline of wholly owned product candidates. As part of a five-year collaboration between us and Regeneron Pharmaceuticals, Inc., or Regeneron, pursuant to an agreement signed in 2016, Regeneron has the option to obtain development and commercial rights for a certain number of product candidates, and we have an option to participate in the development and commercialization of these potential products or are entitled to royalty payments by Regeneron. Immunocellular therapy product candidates developed and commercialized by us under our agreement with Regeneron will be subject to payment of royalties to Regeneron. To date, Regeneron has not exercised an option on any of our candidates. Our pipeline of additional product candidates includes ADI-00x, for which the company expects to file an IND for solid tumor indications in 2022, and an IND for solid tumor and hematological indications in 2023.

Strategies

Our objective is to be the leading biotechnology company developing oncology and other therapies based on CAR-modified gamma delta T cells. Our strategy to achieve this is as follows:

•

Target clinical development, regulatory approval and commercialization of ADI-001, our lead product candidate. We intend to achieve two key objectives with the development program for ADI-001:

•

Bring a meaningful product to patients by developing ADI-001 in NHL and demonstrating its safety and efficacy; and

•

Validate the gamma delta T cell platform, showing both safety and efficacy of a product candidate designed from that platform, to enable rapid application to additional potential oncology indications.

To achieve these objectives, we hope to demonstrate in our clinical trials efficacy and safety results that are similar to or better than the currently approved autologous (manufactured from the patient’s own cells) alpha-

S-3

beta based T-cell therapies in similar patient populations of NHL while making the product available off the shelf.

•

Advance ADI-002 into clinical development. ADI-002, our lead solid tumor product candidate, is currently undergoing preclinical studies. We intend to file an IND with the FDA in 2021 for ADI-002. Our goal is to develop ADI-002, both in monotherapy and in combination with standard of care agents, in a number of solid tumors that express high levels of GPC3.

•

Continue to innovate and invest in the gamma delta T cell platform and pipeline. We expect to continue to develop product candidates in oncology based on the gamma delta T cell platform, using either previously validated antigens, or those that we identify and target using our TCRL technology. We may utilize additional genetic engineering and editing technologies to further improve our products for greater cell persistence, which may lead to greater efficacy. A key strength of our gamma delta T cell therapy platform lies in our ability to target antigens of both known and unknown potential, and devote our clinical development resources to those antigens that show the most promise in preclinical in vivo analyses and early human trials.

•

Expand and protect our intellectual property. We will continue to aggressively protect the gamma delta T cell production methodology we have developed as well as specific product candidates based on proprietary antigen-binding domains.

•

Potential for outpatient administration. While we expect that the initial subjects treated with gamma delta T cell-based therapy candidates in clinical studies will be hospitalized for a minimum of 24 hours for observation after infusion, favorable tolerability results may allow administration of such therapies in an outpatient setting. This would represent a significant competitive advantage for gamma delta T cell-based therapies as compared to existing approved CAR-T cell therapies.

Concurrent Private Placement

The consummation of the concurrent private placement will be contingent upon the closing of this offering. However, the consummation of this offering is not contingent on the consummation of the concurrent private placement.

Company Information

Prior to September 15, 2020, we were a clinical-stage biopharmaceutical company known as resTORbio, Inc. (“resTORbio”) that had historically focused on developing innovative medicines that target the biology of aging, to prevent or treat age-related diseases with the potential to extend healthy lifespan. resTORbio was originally incorporated under the laws of the State of Delaware in July 2016 and commenced research and development operations in March 2017.

On September 15, 2020, we completed our business combination whereby a wholly-owned subsidiary of resTORbio, Inc. merged with and into Adicet Bio, Inc., with Adicet Bio, Inc. surviving as a wholly-owned subsidiary of resTORbio and changing its name to Adicet Therapeutics, Inc. (the “Merger”). In connection with the completion of the Merger, resTORbio was renamed Adicet Bio, Inc., or Adicet Bio.

S-4

Immediately prior to the effective time of the Merger, resTORbio effected a reverse stock split of its common stock at a ratio of 1-for-7 (the “Reverse Stock Split”). At the effective time of the Merger, each outstanding share of Former Adicet’s capital stock was converted into the right to receive 0.1240 (the “Exchange Ratio”) shares of resTORbio common stock.

We have offices in Menlo Park, CA, and Boston, MA, located at 200 Constitution Dr, Menlo Park, CA 94025, and 500 Boylston Street, 13^th Floor, Boston, MA 02116. Our principal executive offices are located at 500 Boylston Street, 13^th Floor, Boston, MA 02116. Our telephone number is (857) 315-5528. Our website is located at www.adicetbio.com. Our website and the information contained on, or that can be accessed through, the website will not be deemed to be incorporated by reference in, and are not considered part of, this prospectus supplement. You should not rely on any such information in making your decision whether to purchase our common stock. Our common stock trades on the Nasdaq Global Market under the symbol “ACET”.

Implications of Being an Emerging Growth Company and a Smaller Reporting Company

We qualify as an “emerging growth company” as defined in Section 2(a) of the Securities Act, as modified by the JOBS Act. We are also a “smaller reporting company” as defined in the Exchange Act. As an emerging growth company and as a smaller reporting company we may take advantage of specified reduced disclosure and other requirements that are otherwise applicable, in general, to public companies that are not emerging growth companies. These provisions include:

•

only two years of audited financial statements in addition to any required unaudited interim financial statements with correspondingly reduced “Management’s Discussion and Analysis of Financial Condition and Results of Operations” disclosure;

•

reduced disclosure about our executive compensation arrangements;

•

exemption from the non-binding stockholder advisory votes on executive compensation or golden parachute arrangements;

•

exemption from the auditor attestation requirement in the assessment of our internal control over financial reporting; and

•

delayed adoption of new or revised financial accounting standards until they would apply to private companies and from compliance with any new requirements adopted by the Public Company Accounting Oversight Board, or PCAOB, requiring mandatory audit firm rotation.

We will remain an emerging growth company until the earlier of (1) December 31, 2023 or (2) the last day of the fiscal year (a) in which we have total annual gross revenue of at least $1.07 billion, or (b) in which we are deemed to be a large accelerated filer, which means the market value of our common stock that is held by non-affiliates exceeds $700 million as of the prior June 30th, or (3) the date on which we have issued more than $1.0 billion in non-convertible debt during the prior three year period. References in this prospectus supplement and the accompanying prospectus to “emerging growth company” shall have the meaning ascribed to it in the JOBS Act.

We will continue to be a smaller reporting company if the Company has (i) less than $250 million in market value of its shares held by non-affiliates as of the last business day of its second fiscal quarter or (ii) less than $100 million of annual revenues in its most recent fiscal year completed before the last business day of its second fiscal quarter and a market value of its shares held by non-affiliates of less than $700 million as of the last business day of its second fiscal quarter.

S-5

We may choose to take advantage of some but not all of these exemptions. We have taken advantage of reduced reporting requirements in this prospectus supplement. Accordingly, the information contained herein may be different from the information you receive from other public companies in which you hold stock. We have elected to avail ourselves of the exemption for the delayed adoption of certain accounting standards and, therefore, are not subject to the same new or revised accounting standards as other public companies that are not emerging growth companies.

S-6

THE OFFERING

Common stock offered by us

4,500,000 shares (or 5,175,000 shares if the underwriters exercise their option to purchase additional shares in full).

Concurrent private placement

Certain of our existing investors have agreed to purchase from us, concurrently with this offering in a private placement, $15.0 million of shares of our common stock at a price per share equal to the public offering price, or 700,934 shares, based on an assumed public offering price of $21.40 per share (the last reported sale price of our common stock on the Nasdaq Global Market on September 18, 2020). We will receive the full proceeds from the sale and will not pay any underwriting discounts or commissions with respect to the shares of common stock that are sold in the private placement. The sale of these shares of common stock to such investors will not be registered under the Securities Act. We refer to the private placement of these shares as the concurrent private placement. The closing of this offering is not conditioned upon the closing of the concurrent private placement.

Option to purchase additional shares of common stock

We have granted the underwriters an option exercisable for 30 days from the date of this prospectus supplement to purchase up to 675,000 additional shares from us.

Common stock to be outstanding immediately after this offering and the concurrent private placement

24,790,762 shares (or 25,465,762 shares if the underwriters exercise in full their option to purchase additional shares), assuming sales of 4,500,000 shares of our common stock in this offering and the concurrent private placement at an offering price of $21.40 per share (the last reported sale price of our common stock on the Nasdaq Global Market on September 18, 2020). The actual number of shares issued will vary depending on the sales price in this offering.

Use of proceeds

We estimate that the net proceeds to us from this offering, after deducting the estimated underwriting discounts and commissions and estimated offering expenses payable by us, will be approximately $89.8 million (or approximately $103.4 million if the underwriters exercise their option to purchase additional shares of common stock in full). Our proceeds from the concurrent private placement will be $15.0 million. We currently intend to use the net proceeds from this offering and the concurrent private placement, together with our cash, cash equivalents and investments, primarily to fund activities related to our internal discovery research, other pipeline candidates and to fund the continued development of our gamma delta T cell platform; the external costs for the development of ADI-001 through the completion of a Phase 1 dose expansion study for ADI-001 in NHL; the external costs for the development of ADI-002 through the completion of a Phase 1 dose finding study for ADI-002 in solid

S-7

tumors; and the remainder, if any, to fund working capital and other general corporate purposes, which may include funding for the hiring of additional personnel, capital expenditures and the costs of operating as a public company. See “Use of Proceeds” on page S-21 of this prospectus supplement.

Risk factors

Investing in our common stock involves significant risks. See “Risk Factors” on page S-10 of this prospectus supplement and under similar headings in the documents incorporated by reference into this prospectus supplement for a discussion of the factors you should carefully consider before deciding to invest in our common stock.

Nasdaq Global Market symbol

“ACET”

The number of shares of our common stock to be outstanding immediately after this offering and the concurrent private placement as shown above is based on 19,589,828 shares outstanding as of September 15, 2020. This number of shares excludes the following:

•

1,564,156 shares of common stock issuable upon the exercise of stock options outstanding as of September 15, 2020 at a weighted-average exercise price of $4.36 per share;

•

226,193 shares of common stock issuable upon the exercise of stock warrants at an exercise price of $11.32 per share;

•

2,686,141 shares of common stock reserved for future issuance under our 2018 Stock Option and Incentive Plan, or 2018 Plan;

•

900,415 shares of common stock for the future issuance under our 2015 Stock Incentive Plan, or 2015 Plan; and

•

131,432 shares of common stock reserved for the future issuance under our 2018 Employee Stock Purchase Plan, or 2018 ESPP.

To the extent that any of these options are exercised, new options are issued under our equity incentive plans and subsequently exercised, or we issue additional shares of common stock in the future, there will be further dilution to the investors participating in this offering.

Unless otherwise indicated, all information in this prospectus supplement assumes that the underwriters do not exercise their option to purchase up to 675,000 of additional shares of our common stock. Except as otherwise indicated, all share and per share amounts included in this prospectus supplement reflect the issuance of shares of common stock in the Merger and the Reverse Stock Split and assume no exercise of outstanding stock options or warrants as described above.

S-8

Former Adicet Bio Loss Per Share

On September 15, 2020, the Company completed the Merger pursuant to the Agreement and Plan of Merger, dated as of April 28, 2020, as amended or restated from time to time, by and among resTORbio, Former Adicet and Project Oasis Merger Sub, Inc. (the “Merger Agreement”). The transaction was accounted for as a reverse acquisition in accordance with accounting principles generally accepted in the United States, or GAAP, and therefore, Former Adicet was deemed to be the accounting acquirer for financial reporting purposes. As a result, after the completion of the Merger, the historical financial statements of Former Adicet became the historical financial statements of the combined company. In connection with the Merger, each outstanding share of Former Adicet capital stock was then converted into the right to receive 0.1240 (the “Exchange Ratio”) shares of resTORbio common stock. The following table presents the historical loss per share information of Former Adicet after giving effect to the Exchange Ratio.


	Six-months ended June 30, 2020		Six-months ended June 30, 2019		Year-ended December 31, 2019		Year-ended December 31, 2018
(in thousands, except share and per share data)
Net loss	$	(12,941)	$	(6,782)	$	(28,138)	$	(9,299)
Weighted average shares of Former Adicet, used in computing net loss per share attributable to common stockholders, as originally reported, basic and diluted		17,502,411		17,139,657		17,249,656		15,701,158
Net loss per share, as originally reported, basic and diluted	$	(0.74)	$	(0.40)	$	(1.63)	$	(0.59)
Exchange Ratio		0.1240		0.1240		0.1240		0.1240
Weighted average shares of Former Adicet outstanding immediately prior to the closing of the Merger, as effected for the Exchange Ratio		2,170,299		2,125,317		2,138,957		1,946,944
Net loss per share, as effected for the Exchange Ratio, basic and diluted	$	(5.96)	$	(3.19)	$	(13.16)	$	(4.78)

S-9

RISK FACTORS

Investing in our common stock involves a high degree of risk. You should carefully consider the risk factors described below and the risk factors incorporated by reference to our Annual Report on Form 10-K for the period ended December 31, 2019, and any subsequent Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q or Current Reports on Form 8-K we file after the date of this prospectus supplement, and all other information contained or incorporated by reference into this prospectus supplement and the accompanying prospectus, including our financial statements and the related notes, as updated by our subsequent filings under the Exchange Act and in any free writing prospectus that we have authorized for use in connection with this offering before acquiring any of our common stock. These risks could have a material and adverse impact on our business, results of operations, financial condition and growth prospects, which may cause the trading price of our common stock to decline and you could lose all or part of your investment. The risks discussed below also include forward-looking statements and our actual results may differ substantially from those discussed in these forward-looking statements. See “Cautionary Note Regarding Forward-Looking Statements.”

Risks Related to This Offering and Our Common Stock

The price of our common stock historically has been volatile, which may affect the price at which you could sell any shares of our common stock.

The market price for our common stock historically has been highly volatile and could continue to be subject to wide fluctuations in response to various factors. The market price for our common stock has varied between a high price of $10.44 on September 16, 2019 and a low price of $0.87 on March 18, 2020 in the twelve-month period ending on September 15, 2020. This volatility may affect the price at which you could sell the shares of our common stock, and the sale of substantial amounts of our common stock could adversely affect the price of our common stock. Our stock price is likely to continue to be volatile and subject to significant price and volume fluctuations in response to market and other factors, including:

•

the success of competing products or technologies;

•

results of preclinical studies or clinical trials of our product candidates or those of our competitors;

•

developments or disputes concerning patent applications, issued patents or other proprietary rights;

•

results from, and any delays in, research and development efforts, planned clinical trials for the combined company’s product candidates, or any other future product candidates, including potential delays due to the COVID-19 pandemic, and the results of trials of competitors or those of other companies in the combined company’s market sector;

•

regulatory or legal developments in the U.S. and other countries;

•

the recruitment or departure of key personnel;

•

the level of expenses related to any of our product candidates or clinical development programs;

•

the results of our efforts to discover, develop, acquire or in-license additional product candidates or products;

•

actual or anticipated changes in estimates as to financial results, development timelines or recommendations by securities analysts;

S-10

•

variations in our financial results or the financial results of companies that are perceived to be similar to us;

•

sales of a substantial number of shares of our common stock in the public market, or the perception in the market that the holders of a large number of shares intend to sell shares;

•

changes in the structure of healthcare payment systems;

•

market conditions in the pharmaceutical and biotechnology sectors;

•

general economic, industry and market conditions; and

•

the other factors described in this “Risk Factors” section.

In addition, companies trading in the stock market in general, and the Nasdaq Global Market in particular, have experienced extreme price and volume fluctuations that have often been unrelated or disproportionate to the operating performance of these companies. Broad market and industry factors may negatively affect the market price of our common stock, regardless of our actual operating performance. In the past, following periods of volatility in the market, securities class-action litigation has often been instituted against companies. Such litigation, if instituted against us, could result in substantial costs and diversion of management’s attention and resources, which could materially and adversely affect our business, financial condition, results of operations and growth prospects.

We have broad discretion in the use of the net proceeds from this offering and the concurrent private placement and may invest or spend the proceeds in ways with which you do not agree and in ways that may not yield a return on your investment.

Although we currently intend to use the net proceeds from this offering and the concurrent private placement in the manner described in the section titled “Use of Proceeds” in this prospectus supplement, our management will have broad discretion in the application of the net proceeds from this offering and the concurrent private placement and could spend the proceeds in ways that do not improve our results of operations or enhance the value of our common stock. You will not have the opportunity to influence our decisions on how to use the net proceeds from this offering and the concurrent private placement. The failure by our management to apply these funds effectively could result in financial losses that could harm our business, cause the price of our common stock to decline and delay the development of our product candidates. Pending their use, we may invest the net proceeds from this offering and the concurrent private placement in a manner that does not produce income or that loses value.

You will experience immediate and substantial dilution.

The offering price per share in this offering and the concurrent private placement will exceed the net tangible book value per share of our common stock outstanding prior at the time of sale. Assuming that an aggregate of 5,200,934 shares of our common stock are sold at a price of $21.40 per share (the last reported sale price of our common stock on the Nasdaq Global Market on September 18, 2020) for aggregate net proceeds of $104.8 million, after deducting underwriting discounts and commissions and offering expenses payable by us, investors in this offering would experience immediate dilution of $12.74 per share, representing the difference between our pro forma as-adjusted net tangible book value per share as of June 30, 2020, after giving effect to the Merger, this offering and the concurrent private placement.

In addition, we have a significant number of stock options outstanding. The exercise of any of these outstanding options could result in further dilution. Further, because we expect we will need to raise additional capital to fund our future activities, we may in the future sell substantial amounts of common stock or securities convertible into or exchangeable for common stock. Future issuances of common stock or common stock-related securities, together with the exercise of outstanding stock options, if any, may result in further dilution. For additional information on the dilution that you will experience immediately after this offering and the concurrent private placement, see the section titled “Dilution.”

S-11

Future sales and issuances of our common stock or rights to purchase common stock, including pursuant to our equity incentive plans, could result in additional dilution of the percentage ownership of our stockholders and could cause our stock price to fall.

Additional capital will be needed in the future to continue our planned operations. To the extent we raise additional capital by issuing equity securities, our stockholders may experience substantial dilution. We may sell common stock, convertible securities or other equity securities in one or more transactions at prices and in a manner we determine from time to time. If we sell common stock, convertible securities or other equity securities in more than one transaction, investors may be materially diluted by subsequent sales. These sales may also result in material dilution to our existing stockholders, and new investors could gain rights superior to our existing stockholders.

In addition, sales of a substantial number of shares of our outstanding common stock in the public market could occur at any time. These sales, or the perception in the market that the holders of a large number of shares of common stock intend to sell shares, could reduce the market price of our common stock. Significant portions of these shares are held by a relatively small number of stockholders. Sales by our stockholders of a substantial number of shares, or the expectation that such sales may occur, could significantly reduce the market price of our common stock.

Our principal stockholders and management own a significant percentage of our stock and will be able to exert significant control over matters subject to stockholder approval.

As of September 15, 2020, our executive officers, directors, five percent or greater stockholders and their affiliates beneficially own approximately 58.9% of our outstanding voting stock. These stockholders will have the ability to influence us through their ownership positions. These stockholders may be able to determine all matters requiring stockholder approval. For example, these stockholders, acting together, may be able to control elections of directors or approval of any Merger, sale of assets, or other major corporate transaction. This may prevent or discourage unsolicited acquisition proposals or offers for our common stock that you may believe are in your best interest as one of our stockholders.

Sales of a substantial number of shares of our common stock in the public market could cause our stock price to fall.

Sales of a substantial number of shares of our common stock in the public market or the perception that these sales might occur could depress the market price of our common stock and could impair our ability to raise capital through the sale of additional equity securities. We are unable to predict the effect that such sales may have on the prevailing market price of our common stock. In addition, the sale of substantial amounts of our common stock could adversely impact its price. As of September 15, 2020, we had outstanding 19,589,828 shares of our common stock and options to purchase 1,564,156 shares of our common stock. The sale or the availability for sale of a large number of shares of our common stock in the public market could cause the price of our common stock to decline.

If securities or industry analysts do not publish research, or publish inaccurate or unfavorable research, about our business, our stock price and trading volume could decline.

The trading market for our common stock will depend, in part, on the research and reports that securities or industry analysts publish about us or our business. Securities and industry analysts may not publish an adequate amount of research on us, which may negatively impact the trading price for our stock. In addition, if one or more of the analysts who cover us downgrade our stock or publish inaccurate or unfavorable research about our business, our stock price would likely decline. Further, if our operating results fail to meet the forecasts

S-12

of analysts, our stock price would likely decline. If one or more of these analysts cease coverage of us or fail to publish reports on us regularly, demand for our stock could decrease, which might cause our stock price and trading volume to decline.

Because we do not anticipate paying any cash dividends on our capital stock in the foreseeable future, capital appreciation, if any, will be your sole source of gain.

We have never declared or paid cash dividends on our capital stock. We currently intend to retain all of our future earnings, if any, to finance the growth and development of our business. In addition, the terms of any future debt agreements may preclude us from paying dividends. As a result, capital appreciation, if any, of our common stock will be your sole source of gain for the foreseeable future.

We are an “emerging growth company,” and the reduced disclosure requirements applicable to emerging growth companies may make our common stock less attractive to investors.

We are an “emerging growth company,” as defined in JOBS Act. For so long as we remain an emerging growth company, we are permitted and intend to rely on exemptions from certain disclosure requirements that are applicable to other public companies that are not emerging growth companies. These exemptions include not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act of 2002, or the Sarbanes Oxley Act, not being required to comply with any requirement that may be adopted by the PCAOB regarding mandatory audit firm rotation or a supplement to the auditor’s report providing additional information about the audit and the financial statements, reduced disclosure obligations regarding executive compensation and exemptions from the requirements of holding a nonbinding advisory vote on executive compensation and shareholder approval of any golden parachute payments not previously approved. We cannot predict whether investors will find our common stock less attractive if we rely on these exemptions. If some investors find our common stock less attractive as a result, there may be a less active trading market for our common stock and our stock price may be reduced or more volatile.

In addition, the JOBS Act also provides that an “emerging growth company” can take advantage of an extended transition period for complying with new or revised accounting standards. Adicet has elected to take advantage of this extended transition period under the JOBS Act. As a result, Adicet’s operating results and financial statements may not be comparable to the operating results and financial statements of other companies who have adopted the new or revised accounting standards. It is possible that some investors will find Adicet’s common stock less attractive as a result, which may result in a less active trading market for Adicet’s common stock and higher volatility in Adicet’s stock price.

The market price of our common stock may be adversely affected by market conditions affecting the stock markets in general, including price and trading fluctuations on the Nasdaq Global Market.

Market conditions may result in volatility in the level of, and fluctuations in, market prices of stocks generally and, in turn, our common stock and sales of substantial amounts of our common stock in the market, in each case being unrelated or disproportionate to changes in our operating performance. Concerns over global stability and economic conditions in the U.S. and abroad have contributed to the extreme volatility of the markets, which may have an effect on the market price of our common stock.

Our ability to utilize our net operating loss, or NOL, carryforwards and certain other tax attributes may be limited.

Our ability to utilize our NOL carryforwards to offset potential future taxable income and related income taxes that would otherwise be due is dependent upon our generation of future taxable income before the expiration dates of the NOL carryforwards, and we cannot predict with certainty when, or whether, we will generate sufficient taxable income to use all of our NOL carryforwards.

S-13

Under Sections 382 and 383 of the Internal Revenue Code of 1986, as amended, or the Code, if a corporation undergoes an “ownership change,” generally defined as a greater than 50 percentage point change (by value) in its equity ownership by certain stockholders over a three-year period, the corporation’s ability to use its pre-change NOL carryforwards and other pre-change tax attributes (such as research and development tax credits) to offset its post-change income or taxes may be limited.

Adicet may have experienced ownership changes in the past, and resTORbio has experienced ownership changes in the past, including as a result of the Merger. The combined company may experience ownership changes in the future (some of which may be outside our control), including as a result of this offering. As a result, if we earn net taxable income, our ability to use our pre-change NOL carryforwards and other tax attributes to offset U.S. federal taxable income may be subject to limitations under Sections 382 and 383 of the Code, which could potentially result in increased future tax liability to us. In addition, at the state level, our NOL carryforwards may also be impaired or limited, which could increase the amount of state taxes owed in future taxable periods.

U.S. federal income tax reform could adversely affect our business and financial condition.

The rules dealing with U.S. federal, state, and local income taxation are constantly under review through the legislative process and by the Internal Revenue Service and the U.S. Treasury Department. Changes to tax laws (which changes may have retroactive application) could adversely affect us or holders of our common stock. In recent years, many such changes have been made and changes are likely to continue to occur in the future. For example, the Tax Cuts and Jobs Act, or the TCJA, was enacted in 2017 and significantly reformed the Internal Revenue Code of 1986, as amended. The TCJA, among other things, contains significant changes to corporate and individual taxation, some of which could adversely impact an investment in our common stock. Additionally, on March 27, 2020, President Trump signed into law the Coronavirus Aid, Relief and Economic Security Act, or the CARES Act, which included certain changes in tax law intended to stimulate the U.S. economy in light of the COVID-19 outbreak, including temporary beneficial changes to the treatment of NOLs, interest deductibility limitations and payroll tax matters. Future changes in tax laws could have a material adverse effect on our business, cash flow, financial condition or results of operations. We urge investors to consult with their legal and tax advisers regarding the implications of potential changes in tax laws on an investment in our common stock.

Tax authorities may disagree with our positions and conclusions regarding certain tax positions, resulting in unanticipated costs, taxes or non-realization of expected benefits.

A tax authority may disagree with tax positions that we have taken, which could result in increased tax liabilities. For example, a tax authority could challenge our allocation of income by tax jurisdiction and the amounts paid between our affiliated companies pursuant to our intercompany arrangements and transfer pricing policies, including amounts paid with respect to transfers of intellectual property and our intellectual property development. Such an assertion, if successful, could increase our expected tax liability in one or more jurisdictions. A tax authority may take the position that material income tax liabilities, interest and penalties are payable by us, in which case, we expect that we might contest such assessment. Contesting such an assessment may be lengthy and costly and if we were unsuccessful in disputing the assessment, the implications could increase our anticipated effective tax rate, where applicable.

Risks Related to the Combined Company

The market price of the combined company’s common stock is expected to be volatile and may drop following the Merger.

The market price of the combined company’s common stock is likely to be volatile following the Merger. The combined company’s stock price could be subject to wide fluctuations in response to a variety of factors including the following:

•

results from, and any delays in, research and development efforts, planned clinical trials for the combined company’s product candidates, or any other future product candidates, including

S-14

potential delays due to the COVID-19 pandemic, and the results of trials of competitors or those of other companies in the combined company’s market sector;

•

potential delays and disruptions in the manufacture and supply of experimental drug product for pre-clinical and clinical studies;

•

any delay in filing an IND, Investigational Device Exemption or new drug application (“NDA”) for any of the combined company’s product candidates and any adverse development or perceived adverse development with respect to the FDA’s review of that NDA;

•

significant lawsuits, including patent or stockholder litigation;

•

inability to obtain additional funding;

•

failure to successfully develop and commercialize the combined company’s product candidates;

•

changes in laws or regulations applicable to the combined company’s product candidates;

•

inability to obtain adequate product supply for the combined company’s product candidates, or the inability to do so at acceptable prices;

•

unanticipated serious safety concerns related to any of the combined company’s product candidates;

•

adverse regulatory decisions;

•

introduction of new products or technologies by the combined company’s competitors;

•

failure to meet or exceed drug development or financial projections the combined company provides to the public;

•

failure to meet or exceed the estimates and projections of the investment community;

•

the perception of the biopharmaceutical industry by the public, legislatures, regulators and the investment community;

•

announcements of significant acquisitions, strategic partnerships, joint ventures or capital commitments by the combined company or the combined company’s competitors;

•

disputes or other developments relating to proprietary rights, including patents, litigation matters and the combined company’s ability to obtain patent protection for the combined company’s licensed and owned technologies;

•

additions or departures of key scientific or management personnel;

•

changes in the market valuations of similar companies;

•

general economic and market conditions and overall fluctuations in the U.S. equity market;

•

sales of the combined company’s common stock by the combined company or its stockholders in the future; and

•

trading volume of the combined company’s common stock.

S-15

In addition, the stock market, in general, and small biopharmaceutical companies, in particular, have experienced extreme price and volume fluctuations that have often been unrelated or disproportionate to the operating performance of these companies. Broad market and industry factors may negatively affect the market price of the combined company’s common stock, regardless of the combined company’s actual operating performance. Further, a decline in the financial markets and related factors beyond the combined company’s control may cause the combined company’s stock price to decline rapidly and unexpectedly.

The combined company will need to raise additional financing in the future to fund its operations, which may not be available to it on favorable terms or at all.

The combined company will require substantial additional funds to conduct the costly and time-consuming clinical efficacy trials necessary to pursue regulatory approval of each potential product candidate and to continue the development of ADI-001 and ADI-002. The combined company’s future capital requirements will depend upon a number of factors, including: the number and timing of future product candidates in the pipeline; progress with and results from preclinical testing and clinical trials; the ability to manufacture sufficient drug supplies to complete preclinical and clinical trials; the costs involved in preparing, filing, acquiring, prosecuting, maintaining and enforcing patent and other intellectual property claims; and the time and costs involved in obtaining regulatory approvals and favorable reimbursement or formulary acceptance. Raising additional capital may be costly or difficult to obtain and could significantly dilute stockholders’ ownership interests or inhibit the combined company’s ability to achieve its business objectives. If the combined company raises additional funds through public or private equity offerings, the terms of these securities may include liquidation or other preferences that adversely the rights of its common stockholders. Further, to the extent that the combined company raises additional capital through the sale of common stock or securities convertible or exchangeable into common stock, its stockholder’s ownership interest in the combined company will be diluted. In addition, any debt financing may subject the combined company to fixed payment obligations and covenants limiting or restricting its ability to take specific actions, such as incurring additional debt, making capital expenditures or declaring dividends. If the combined company raises additional capital through marketing and distribution arrangements or other collaborations, strategic alliances or licensing arrangements with third parties, the combined company may have to relinquish certain valuable intellectual property or other rights to its product candidates, technologies, future revenue streams or research programs or grant licenses on terms that may not be favorable to it. Even if the combined company were to obtain sufficient funding, there can be no assurance that it will be available on terms acceptable to the combined company or its stockholders.

The combined company will incur costs and demands upon management as a result of complying with the laws and regulations affecting public companies.

The combined company will incur significant legal, accounting, and other expenses Adicet did not incur as a private company, including costs associated with public company reporting requirements. The combined company will also incur costs associated with corporate governance requirements, including requirements under the Sarbanes-Oxley Act, as well as new rules implemented by the SEC and Nasdaq. These rules and regulations are expected to increase the combined company’s legal and financial compliance costs and to make some activities more time-consuming and costly. For example, the combined company’s management team consists partially of the executive officers of Adicet prior to the Merger, some of whom may not have previously managed and operated a public company. These executive officers and other personnel will need to devote substantial time to gaining expertise regarding operations as a public company and compliance with applicable laws and regulations. These rules and regulations may also make it difficult and expensive for the combined company to obtain directors and officers liability insurance. As a result, it may be more difficult for the combined company to attract and retain qualified individuals to serve on the combined company’s board of directors or as executive officers of the combined company, which may adversely affect investor confidence in the combined company and could cause the combined company’s business or stock price to suffer. Further, the combined company may need to add additional experience and personnel to support its public company operations. The loss of any existing personnel in these areas or the combined company’s inability to achieve or manage such

S-16

expansion effectively may result in weaknesses in its infrastructure and the combined company’s business, financial condition and results of operations may be materially adversely affected.

Anti-takeover provisions in the combined company charter documents and under Delaware law could make an acquisition of the combined company more difficult and may prevent attempts by the combined company stockholders to replace or remove the combined company management.

Provisions in the combined company’s certificate of incorporation and bylaws may delay or prevent an acquisition or a change in management. These provisions include a classified board of directors, a prohibition on actions by written consent of the combined company’s stockholders and the ability of the board of directors to issue preferred stock without stockholder approval. In addition, because the combined company is incorporated in Delaware, it is governed by the provisions of Section 203 of the Delaware General Corporation Law, which prohibits stockholders owning in excess of 15% of the outstanding combined company voting stock from merging or combining with the combined company. Although Adicet believes these provisions collectively will provide for an opportunity to receive higher bids by requiring potential acquirers to negotiate with the combined company’s board of directors, they would apply even if the offer may be considered beneficial by some stockholders. In addition, these provisions may frustrate or prevent any attempts by the combined company’s stockholders to replace or remove then current management by making it more difficult for stockholders to replace members of the board of directors, which is responsible for appointing the members of management.

Adicet does not anticipate that it will pay any cash dividends in the foreseeable future.

Adicet will retain its future earnings to fund the development and growth of the combined company’s business. As a result, capital appreciation, if any, of the common stock of Adicet will be your sole source of gain, if any, for the foreseeable future.

An active trading market for Adicet’s common stock may not develop and its stockholders may not be able to resell their shares of common stock for a profit, if at all.

Prior to the Merger, there had been no public market for Adicet’s capital stock. Although resTORbio’s common stock was listed on Nasdaq, and Adicet’s common stock is listed on Nasdaq, an active trading market for the combined company’s shares of common stock may never develop or be sustained. The price that the combined company’s shares trade at immediately after the Merger may not necessarily reflect the price at which investors in the market will be willing to buy and sell the shares on a sustained basis. The lack of an active market may impair your ability to sell your shares at the time you wish to sell them or at a price that you consider reasonable. An inactive market may also impair the combined company’s ability to raise capital by selling shares and may impair the combined company’s ability to acquire other businesses or technologies using the combined company’s shares as consideration, which, in turn, could materially adversely affect the combined company’s business.

If equity research analysts do not publish research or reports, or publish unfavorable research or reports, about the combined company, its business or its market, its stock price and trading volume could decline.

The trading market for the combined company’s common stock will be influenced by the research and reports that equity research analysts publish about it and its business. Equity research analysts may elect not to provide research coverage of the combined company’s common stock after the completion of this offering and the concurrent private placement, and such lack of research coverage may adversely affect the market price of its common stock. In the event it does have equity research analyst coverage, the combined company will not have any control over the analysts or the content and opinions included in their reports. The price of the combined company’s common stock could decline if one or more equity research analysts downgrade its stock or issue other unfavorable commentary or research. If one or more equity research analysts ceases coverage of the combined company or fails to publish reports on it regularly, demand for its common stock could decrease, which in turn could cause its stock price or trading volume to decline.

S-17

The Funding Transaction may not be completed.

In order to fund the research and development programs and working capital requirements described elsewhere in this prospectus supplement and to enhance the overall capitalization of Adicet, the parties entered into a funding agreement (the “Funding Agreement”) simultaneously with the signing of the Merger Agreement with certain current investors of Adicet, pursuant to which such investors committed to fund up to an aggregate of $15.0 million (the “Funding Amount”) into an escrow account at or prior the time of completion of the Merger (the “Funding Transaction”). If a concurrent private placement in connection with a private placement or public offering of our common stock for aggregate gross proceeds (including the Funding Amount) to the Company of at least $30.0 million (a “Qualified Financing”) does not occur within 12 months of the effective time of the Merger, the escrowed cash will be returned to the investors party to the Funding Agreement. The combined company cannot predict whether it will be successful in consummating a Qualified Financing. Accordingly, there can be no guarantee that the Qualified Financing will occur at all or within the time period required under the Funding Agreement and that the combined company will receive the escrowed funds pursuant to the terms of the Funding Agreement. See “Concurrent Private Placement.”

The combined company will have broad discretion in the use of proceeds released to it from the escrow under the Funding Agreement, if any, and may invest or spend any such proceeds in ways with which you do not agree and in ways that may not increase the value of your investment.

The combined company will have broad discretion over the use of proceeds released to it from the escrow under the Funding Agreement, if any. Its stockholders may not agree with the combined company’s decisions, and its use of the proceeds may not yield any return on its stockholders’ investments. The combined company’s failure to apply such net proceeds effectively could compromise its ability to pursue its growth strategy and the combined company might not be able to yield a significant return, if any, on its investment of these net proceeds. The combined company’s stockholders will not have the opportunity to influence its decisions on how to use such net proceeds.

The combined company’s failure to meet the continued listing requirements of the Nasdaq could result in a delisting of the combined company’s common stock.

If the combined company fails to satisfy the continued listing requirements of the Nasdaq, such as the corporate governance requirements or the minimum closing bid price requirement, Nasdaq may take steps to delist the combined company’s common stock. Such a delisting would likely have a negative effect on the price of the combined company’s common stock and would impair your ability to sell or purchase the combined company’s common stock when you wish to do so. In the event of a delisting, the combined company can provide no assurance that any action taken by the combined company to restore compliance with listing requirements would allow the combined company’s common stock to become listed again, stabilize the market price or improve the liquidity of the combined company’s common stock, prevent the combined company’s common stock from dropping below the Nasdaq minimum bid price requirement or prevent future non-compliance with Nasdaq’s listing requirements.

Future sales of shares by existing stockholders could cause the combined company’s stock price to decline.

If existing stockholders of Adicet sell, or indicate an intention to sell, substantial amounts of the combined company’s common stock in the public market after legal restrictions on resale discussed in this prospectus supplement lapse, the trading price of the common stock of the combined company could decline. Adicet is unable to predict the effect that sales may have on the prevailing market price of the combined company’s common stock.

S-18

The combined company’s internal control over financial reporting may not meet the standards required by Section 404 of the Sarbanes-Oxley Act, and failure to achieve and maintain effective internal control over financial reporting in accordance with Section 404 of the Sarbanes-Oxley Act, could have a material adverse effect on the combined company’s business and share price.

As a privately held company, Adicet was not required to evaluate its internal control over financial reporting in a manner that meets the standards of publicly traded companies required by Section 404 of the Sarbanes-Oxley Act. Commencing with the combined company’s Annual Report on Form 10-K for this fiscal year, the combined company’s management will be required to report on the effectiveness of the combined company’s internal control over financial reporting. The rules governing the standards that must be met for the combined company’s management to assess the combined company’s internal control over financial reporting are complex and require significant documentation, testing and possible remediation.

The existence of the Contingent Value Rights Agreement, or the CVR Agreement, may result in the combined company spending funds, time and resources outside of its core focus.

In connection with the Merger, resTORbio entered into the CVR Agreement, pursuant to which each holder of resTORbio common stock as of immediately prior to the effective time of the Merger was entitled to one contingent value right, or CVR, issued by resTORbio, subject to and in accordance with the terms and conditions of the CVR Agreement, for each share of resTORbio common stock held by such holder. Each CVR will entitle the holder of the CVR to receive net proceeds of the commercialization, if any, received from a third party commercial partner of RTB101 for a COVID-19-related indication, with clinical data expected by the first quarter of 2021. The combined company is obligated to use commercially reasonable efforts (as such term is defined in the CVR Agreement) with respect to developing, seeking regulatory approval for and commercializing RTB101 for a COVID-19-related indication, which will result in the combined company spending funds, time and resources to comply with the terms of the CVR Agreement. Further, pursuant to the terms of the CVR Agreement, the holders of resTORbio common stock as of immediately prior to the Merger, rather than the holders of the combined company’s common stock, are the primary recipients of any net proceeds of the commercialization, if any, received from a third-party commercial partner of RTB101 for a COVID-19-related indication. Absent such CVR Agreement, the combined company could have allocated such funds, time and resources to its core programs and the foregoing, and could be a distraction to the combined company’s management and employees. As a result, the combined company’s operations and financial condition may be adversely affected.

The combined company’s executive officers, directors and principal stockholders, if they choose to act together, will continue to control or significantly influence all matters submitted to stockholders for approval.

The combined company’s executive officers, directors and greater than 5% stockholders, in the aggregate, own approximately 46.1% of combined company’s outstanding common stock (assuming no exercise of outstanding options). As a result, such persons or their appointees to the combined company’s board of directors, acting together, will have the ability to control or significantly influence all matters submitted to the combined company’s board of directors or stockholders for approval, including the appointment of the combined company’s management, the election and removal of directors and approval of any significant transaction, as well as the combined company’s management and business affairs. This concentration of ownership may have the effect of delaying, deferring or preventing a change in control, impeding a Merger, consolidation, takeover or other business combination involving the combined company, or discouraging a potential acquiror from making a tender offer or otherwise attempting to obtain control of the combined company’s business, even if such a transaction would benefit other stockholders.

The combined company could be subject to securities class action litigation.

In the past, securities class action litigation has often been brought against a company following a decline in the market price of its securities. This risk is especially relevant for the combined company, because

S-19

biotechnology and pharmaceutical companies have experienced significant stock price volatility in recent years. If the combined company faces such litigation, it could result in substantial costs and a diversion of management’s attention and resources, which could harm the combined company’s business.

The integration of the management team and operations of Adicet and resTORbio may be more difficult, costly or time-consuming than expected.

The success of the Merger will depend, in part, on the combined company’s ability to successfully combine and integrate the management team and operations of Adicet and resTORbio into the combined company. There are a large number of processes, policies, procedures, operations, technologies and systems that must be integrated, including purchasing, accounting and finance, sales, payroll, pricing, revenue management, marketing and benefits. A number of factors could affect the combined company’s ability to successfully combine the two companies management teams and operations, including the following:

•

the potential for unexpected costs, delays and challenges that may arise in integrating the management team and operations of the two companies;

•

any departures of key employees in connection with the Merger;

•

the combined company’s ability to retain key employees and maintain relationships;

•

the combined company’s ability to integrate the finance and public company support operations of the Boston office with the clinical and research operations in California; and

•

diversion of management’s attention and resources during integration efforts.

If the combined company is unable to successfully integrate the management team and operations of the two companies, the combined company’s business, financial condition and results of operations may be materially adversely affected.

S-20

USE OF PROCEEDS

We estimate that the net proceeds from this offering and the concurrent private placement will be approximately $104.8 million at an assumed public offering price of $21.40 (the last reported sale price of our common stock on the Nasdaq Global Market on September 18, 2020), or approximately $118.4 million if the underwriters exercise in full their option to purchase additional shares of our common stock, after deducting estimated underwriting discounts and commissions and estimated offering expenses. We currently intend to use the net proceeds of this offering and the concurrent private placement, together with our cash, cash equivalents and investments, for the following purposes:

•

approximately $75.2 million to fund our internal discovery research, other pipeline candidates and to fund the continued development of our gamma delta T cell platform;

•

approximately $16.8 million to fund the external costs for the development of ADI-001 through the completion of a Phase 1 dose expansion study for ADI-001 in NHL;

•

approximately $12.8 million to fund the external costs for the development of ADI-002 through the completion of a Phase 1 dose finding study for ADI-002 in solid tumors; and

•

the remainder, if any, to fund working capital and other general corporate purposes, which may include funding for the hiring of additional personnel, capital expenditures and the costs of operating as a public company.

Certain of our existing investors have agreed to purchase from us, concurrently with this offering in a private placement, $15.0 million of shares of our common stock at a price per share equal to the public offering price. Our proceeds from the concurrent private placement will be $15.0 million. See “Concurrent Private Placement.”

We have not entered into any agreements or commitments with respect to any acquisitions or investments at this time.

Based on our current plans, we believe our existing cash, cash equivalents and marketable securities, together with the net proceeds from this offering and the concurrent private placement, will be sufficient to fund our operating expenses and capital expenditure requirements through the first half of 2023. Our expected use of net proceeds from this offering and the concurrent private placement represents our current intentions based upon our present plans and business condition. As of the date of this prospectus supplement, we cannot predict with certainty all of the particular uses for the net proceeds to be received upon the completion of this offering and the concurrent private placement or the amounts that we will actually spend on the uses set forth above. The amounts and timing of our actual expenditures may vary significantly depending upon numerous factors, including the progress of our development efforts, the status of and results from the ongoing clinical trials or any clinical trials we may commence in the future, and the scope and results of our regulatory activities. We may temporarily invest the net proceeds in a variety of capital preservation instruments, including investment grade, interest bearing instruments and U.S. government securities, until they are used for their stated purpose. We have not determined the amount of net proceeds to be used specifically for such purposes. As a result, management will retain broad discretion over the allocation of net proceeds.

S-21

DIVIDEND POLICY

We have never declared or paid cash dividends on our capital stock. We intend to retain all of our future earnings, if any, to finance the growth and development of our business. We do not intend to pay cash dividends to our stockholders in the foreseeable future.

S-22

DILUTION

If you invest in our common stock in this offering, your ownership interest will be diluted to the extent of the difference between the public offering price per share of our common stock in this offering and the pro forma as adjusted net tangible book value per share of our common stock immediately after this offering and the concurrent private placement.

Our pro forma net tangible book value as of June 30, 2020 was approximately $107.1 million, or approximately $5.56 per share of common stock. See Exhibit 99.7 on Form 8-K that we filed with the SEC on September 16, 2020 for details on the calculations of pro forma amounts. Our pro forma, as adjusted, net tangible book value per share represents the amount of total tangible assets, excluding goodwill and in-process research and development, less total liabilities, divided by the number of shares of our common stock outstanding as of June 30, 2020, after giving effect to the Merger and the reverse stock split.

Dilution in net tangible book value per share to new investors participating in this offering represents the difference between the amount per share paid by purchasers in this offering and the pro forma as adjusted net tangible book value per share of our common stock immediately after giving effect to this offering and the concurrent private placement. After giving further effect to (i) the assumed sale of 4,500,000 shares of our common stock at an assumed offering price of $21.40 per share (the last reported sale price of our common stock on the Nasdaq Global Market on September 18, 2020), and after deducting estimated underwriting discounts and commissions and estimated offering expenses payable by us, and (ii) the issuance and sale by us in the concurrent private placement of shares of common stock to certain of our investors, our pro forma, as adjusted, net tangible book value as of June 30, 2020 would have been approximately $107.1 million, or approximately $5.56 per share of common stock. This represents an immediate increase in net tangible book value of $3.10 per share of common stock to our existing stockholders and an immediate dilution in net tangible book value of $8.66 per share of common stock to investors participating in this offering at the assumed offering price.

Dilution per share to new investors is determined by subtracting pro forma as adjusted net tangible book value per share after this offering and the concurrent private placement from the assumed public offering price per share paid by new investors. The following table illustrates this per share dilution:


Assumed offering price per share			$	21.40
Pro forma net tangible book value per share as of June 30, 2020	$	5.56
Increase in net tangible book value per share attributable to new investors attributable to this offering and the concurrent private placement	$	3.10

Pro forma as adjusted net tangible book value per share as of June 30, 2020, after giving effect to this offering and the concurrent private placement			$	8.66

Dilution in net tangible book value per share to new investors participating in this offering			$	12.74

An increase of $1.00 per share in the price at which the shares are sold from the assumed offering price of $21.40 per share shown in the table above, assuming all of our common stock in the aggregate amount of approximately $104.8 million is sold at that price, would result in an increase to our adjusted net tangible book value per share after the offering and the concurrent private placement to $8.74, and an increase in the dilution in net tangible book value per share to new investors in this offering and the concurrent private placement to $13.66, after deducting underwriting discounts and commissions payable by us. A decrease of $1.00 per share in the price at which the shares are sold from the assumed offering price of $21.40 per share shown in the table above, assuming all of our common stock in the aggregate amount of approximately $104.8 million is sold at that price, would result in a decrease to our adjusted net tangible book value per share after the offering and the concurrent private placement to $8.57 and a decrease in the dilution in net tangible book value per share to new

S-23

investors in this offering to $11.83, after deducting underwriting discounts and commissions payable by us. This information is supplied for illustrative purposes only, and will be adjusted based on the actual offering prices, the actual number of shares that we offer and sell in this offering and the concurrent private placement and other terms of each sale of shares in this offering.

The information above assumes that the underwriters do not exercise their option to purchase additional shares. If the underwriters exercise in full their option to purchase an assumed 675,000 additional shares of common stock at an assumed public offering price of $21.40 per share, the pro forma as adjusted net tangible book value after this offering and the concurrent private placement would be $8.96 per share, representing an increase in net tangible book value of $3.40 per share to existing stockholders and immediate dilution in net tangible book value of $12.44 per share to investors purchasing our common stock in this offering at the public offering price.

The information above and in the foregoing table is based on 19,275,574 shares of our common stock outstanding as of June 30, 2020, pro-forma, as adjusted, assuming the reverse stock split and excludes:

•

1,564,156 shares of common stock issuable upon the exercise of stock options outstanding as of September 15, 2020 at a weighted-average exercise price of $4.36 per share;

•

226,193 shares of common stock issuable upon the exercise of stock warrants assumed in the Merger at an exercise price of $11.32 per share;

•

2,686,141 shares of common stock reserved for future issuance under our 2018 Plan;

•

900,415 shares of common stock for the future issuance under our 2015 Plan; and

•

131,432 shares of common stock reserved for the future issuance under our 2018 ESPP.

In addition, we may choose to raise additional capital in the future through the sale of equity or convertible debt securities due to market conditions or strategic considerations, even if we believe we have sufficient funds for our current or future operating plans. To the extent that any of our outstanding options are exercised; new options are issued under our equity incentive plans; or we issue additional shares of common stock or other equity or convertible debt securities in the future, there will be further dilution to investors participating in this offering.

S-24

MATERIAL U.S. FEDERAL INCOME TAX CONSIDERATIONS FOR NON-U.S. HOLDERS

The following discussion is a summary of the material U.S. federal income tax considerations for non-U.S. holders (as defined below) with respect to their ownership and disposition of shares of our common stock issued pursuant to this offering. For purposes of this discussion, a non-U.S. holder means a beneficial owner of our common stock that is for U.S. federal income tax purposes:

•

a non-resident alien individual;

•

a foreign corporation or any other foreign organization taxable as a corporation for U.S. federal income tax purposes; or

•

a foreign estate or trust, the income of which is not subject to U.S. federal income tax on a net income basis.

This discussion does not address the tax treatment of partnerships or other entities or arrangements that are treated as partnerships or other pass-through entities for U.S. federal income tax purposes or persons that hold their common stock through partnerships or other pass-through entities. A partner in a partnership or other pass-through entity that will hold our common stock should consult his, her or its tax advisor regarding the tax consequences of acquiring, holding and disposing of our common stock through a partnership or other pass-through entity, as applicable. This summary does not apply to any shares acquired in the concurrent private placement.

This discussion is based on current provisions of the U.S. Internal Revenue Code of 1986, as amended, or the Code, existing and proposed U.S. Treasury regulations promulgated thereunder, current administrative rulings and judicial decisions, all as in effect as of the date of this prospectus supplement and all of which are subject to change or to differing interpretation, possibly with retroactive effect. Any such change or differing interpretation could alter the tax consequences to non-U.S. holders described in this prospectus supplement. There can be no assurance that the Internal Revenue Service, or the IRS, will not challenge one or more of the tax consequences described herein. We assume in this discussion that a non-U.S. holder holds shares of our common stock as a capital asset within the meaning of Section 1221 of the Code, which is generally property held for investment.

This discussion does not address all aspects of U.S. federal income taxation that may be relevant to a particular non-U.S. holder in light of that non-U.S. holder’s individual circumstances nor does it address any U.S. state, local or non-U.S. tax consideration, the alternative minimum tax, the rules regarding qualified small business stock within the meaning of Section 1202 of the Code, the Medicare tax on net investment income or any other aspect of any U.S. federal tax other than income taxes. This discussion also does not consider any specific facts or circumstances that may apply to a non-U.S. holder and does not address the special tax rules applicable to particular non-U.S. holders, such as:

•

insurance companies;

•

tax-exempt or governmental organizations;

•

financial institutions;

•

brokers or dealers in securities;

•

regulated investment companies;

•

pension plans;

S-25

•

“controlled foreign corporations,” “passive foreign investment companies,” and corporations that accumulate earnings to avoid U.S. federal income tax;

•

“qualified foreign pension funds” as defined in Section 897(I)(2) of the Code and entities all of the interests of which are held by qualified foreign pension funds;

•

persons that have a functional currency other than the U.S. dollar;

•

persons deemed to sell our common stock under the constructive sale provisions of the Code;

•

persons that hold our common stock as part of a straddle, hedge, conversion transaction, synthetic security or other integrated investment;

•

persons subject to special tax accounting rules as a result of any item of gross income with respect to our common stock being taken into account in an applicable financial statement;

•

persons who hold or receive our common stock pursuant to the exercise of any employee stock option or otherwise as compensation; and

•

certain U.S. expatriates.

This discussion is for general information only and is not tax advice. Accordingly, all prospective non-U.S. holders of our common stock should consult their tax advisors with respect to the U.S. federal, state, local and non-U.S. tax consequences of the purchase, ownership and disposition of our common stock.

Distributions on Our Common Stock

As described in the “Dividend Policy” section above, we do not anticipate paying any cash dividends on our capital stock in the foreseeable future. Distributions, if any, on our common stock will constitute dividends for U.S. federal income tax purposes to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. If a distribution exceeds our current and accumulated earnings and profits, the excess will be treated as a tax-free return of the non-U.S. holder’s investment, up to such holder’s tax basis in the common stock. Any remaining excess will be treated as capital gain, subject to the tax treatment described below in “Gain on Sale or Other Taxable Disposition of Our Common Stock.” Any such distributions will also be subject to the discussions below under the sections titled “Backup Withholding and Information Reporting” and “FATCA.”

Subject to the discussion in the following two paragraphs in this section, dividends paid to a non-U.S. holder generally will be subject to withholding of U.S. federal income tax at a 30% rate or such reduced rate specified by an applicable income tax treaty between the United States and such holder’s country of residence. Dividends that are treated as effectively connected with a trade or business conducted by a non-U.S. holder within the United States and, if an applicable income tax treaty so provides, that are attributable to a permanent establishment or a fixed base maintained by the non-U.S. holder within the United States, are generally exempt from the 30% withholding tax if the non-U.S. holder satisfies applicable certification and disclosure requirements. However, such U.S. effectively connected income, net of specified deductions and credits, is taxed at the same graduated U.S. federal income tax rates applicable to United States persons (as defined in the Code). Any U.S. effectively connected income received by a non-U.S. holder that is a corporation may also, under certain circumstances, be subject to an additional “branch profits tax” at a 30% rate or such reduced rate specified by an applicable income tax treaty between the United States and such holder’s country of residence.

S-26

A non-U.S. holder of our common stock who claims the benefit of an applicable income tax treaty between the United States and such holder’s country of residence generally will be required to provide a properly executed IRS Form W-8BEN or W-8BEN-E (or successor form) to the applicable withholding agent and satisfy applicable certification and other requirements. Non-U.S. holders are urged to consult their tax advisors regarding their entitlement to benefits under a relevant income tax treaty. A non-U.S. holder that is eligible for a reduced rate of U.S. withholding tax under an income tax treaty may obtain a refund or credit of any excess amounts withheld by timely filing a U.S. tax return with the IRS.

Gain on Sale or Other Taxable Disposition of Our Common Stock

Subject to the discussions below under “Backup Withholding and Information Reporting” and “FATCA,” a non-U.S. holder will not be subject to any U.S. federal income or withholding tax on any gain realized upon such holder’s sale or other taxable disposition of shares of our common stock unless:

•

the gain is effectively connected with the non-U.S. holder’s conduct of a U.S. trade or business and, if an applicable income tax treaty so provides, is attributable to a permanent establishment or a fixed base maintained by such non-U.S. holder in the United States, in which case the non-U.S. holder generally will be taxed on a net income basis at the graduated U.S. federal income tax rates applicable to United States persons (as defined in the Code) and, if the non-U.S. holder is a foreign corporation, the branch profits tax described above in “Distributions on Our Common Stock” also may apply;

•

the non-U.S. holder is a nonresident alien individual who is present in the United States for 183 days or more in the taxable year of the disposition and certain other conditions are met, in which case the non-U.S. holder will be subject to a 30% tax (or such lower rate as may be specified by an applicable income tax treaty between the United States and such holder’s country of residence) on the net gain derived from the disposition, which may be offset by certain U.S. source capital losses of the non-U.S. holder, if any (even though the individual is not considered a resident of the United States), provided that the non-U.S. holder has timely filed U.S. federal income tax returns with respect to such losses; or

•

we are, or have been, at any time during the five-year period preceding such sale or other taxable disposition (or the non-U.S. holder’s holding period, if shorter) a U.S. real property holding corporation, unless our common stock is regularly traded on an established securities market and the non-U.S. holder has held no more than 5% of our outstanding common stock, directly or indirectly, actually or constructively, at any time during the shorter of the 5-year period ending on the date of the disposition or the period that the non-U.S. holder held our common stock. Generally, a corporation is a U.S. real property holding corporation only if the fair market value of its U.S. real property interests equals or exceeds 50% of the sum of the fair market value of its worldwide real property interests plus its other assets used or held for use in a trade or business. Although there can be no assurance, we do not believe that we are, or have been, a U.S. real property holding corporation, or that we are likely to become one in the future. No assurance can be provided that our common stock will be regularly traded on an established securities market for purposes of the rules described above.

Backup Withholding and Information Reporting

We must report annually to the IRS and to each non-U.S. holder the gross amount of the distributions on our common stock paid to such holder and the tax withheld, if any, with respect to such distributions. Non-U.S. holders may have to comply with specific certification procedures to establish that the holder is not a United States person (as defined in Section 7701(a)(30) of the Code) in order to avoid backup withholding at the applicable rate with respect to dividends on our common stock. Dividends paid to non-U.S. holders subject to

S-27

withholding of U.S. federal income tax, as described above in “Distributions on Our Common Stock,” generally will be exempt from U.S. backup withholding.

Information reporting and backup withholding will generally apply to the proceeds of a disposition of our common stock by a non-U.S. holder effected by or through the U.S. office of any broker, U.S. or foreign, unless the holder certifies its status as a non-U.S. holder and satisfies certain other requirements, or otherwise establishes an exemption. Generally, information reporting and backup withholding will not apply to a payment of disposition proceeds to a non-U.S. holder where the transaction is effected outside the United States through a non-U.S. office of a broker. However, for information reporting purposes, dispositions effected through a non-U.S. office of a broker with substantial U.S. ownership or operations generally will be treated in a manner similar to dispositions effected through a U.S. office of a broker.

Non-U.S. holders should consult their tax advisors regarding the application of the information reporting and backup withholding rules to them. Copies of information returns may be made available to the tax authorities of the country in which the non-U.S. holder resides or is incorporated under the provisions of a specific treaty or agreement. Backup withholding is not an additional tax. Any amounts withheld under the backup withholding rules from a payment to a non-U.S. holder can be refunded or credited against the non-U.S. holder’s U.S. federal income tax liability, if any, provided that an appropriate claim is filed with the IRS in a timely manner.

FATCA

The Foreign Account Tax Compliance Act, or FATCA, generally imposes a U.S. federal withholding tax at a rate of 30% on payments of dividends on, or subject to the discussion of certain proposed U.S. Treasury regulations below, gross proceeds from the sale or other disposition of, our common stock paid to a foreign entity unless (i) if the foreign entity is a “foreign financial institution,” such foreign entity undertakes certain due diligence, reporting, withholding, and certification obligations, (ii) if the foreign entity is not a “foreign financial institution,” such foreign entity identifies certain of its U.S. investors, if any, or (iii) the foreign entity is otherwise exempt under FATCA. However, proposed regulations, if finalized in their present form, would eliminate the federal withholding tax of 30% of the gross proceeds of a sale or other disposition of our common stock. Taxpayers (including withholding agents) may generally rely on the proposed regulations until final regulations are issued. Under certain circumstances, a non-U.S. holder may be eligible for refunds or credits of this withholding tax. An intergovernmental agreement between the United States and an applicable foreign country may modify the requirements described in this paragraph. Non-U.S. holders should consult their tax advisors regarding the possible implications of this legislation on their investment in our common stock and the entities through which they hold our common stock, including, without limitation, the process and deadlines for meeting the applicable requirements to prevent the imposition of the 30% withholding tax under FATCA.

The preceding discussion of U.S. federal income tax considerations is for general information only. It is not tax advice. Each prospective investor should consult its tax advisor regarding the particular U.S. federal, state and local and non-U.S. tax consequences of purchasing, holding and disposing of our common stock, including the consequences of any proposed change in applicable laws.

S-28

DESCRIPTION OF CAPITAL STOCK

The following description of our common stock and preferred stock summarizes the material terms and provisions of the common stock that we may offer under this prospectus supplement. The following description of our capital stock does not purport to be complete and is subject to, and qualified in its entirety by, our amended and restated certificate of incorporation and restated bylaws and by applicable law. The terms of our common stock and preferred stock may also be affected by Delaware law.

Authorized Capital Stock

Our authorized capital stock consists of 150,000,000 shares of common stock, par value $0.0001 per share, and 10,000,000 shares of preferred stock, par value $0.0001 per share, all of which shares of preferred stock are undesignated.

As of September 15, 2020, 19,589,828 shares of our common stock were outstanding and held by 58 stockholders of record.

Common Stock

The holders of our common stock are entitled to one vote for each share held on all matters submitted to a vote of the stockholders. The holders of our common stock do not have any cumulative voting rights. Holders of our common stock are entitled to receive ratably any dividends declared by our board of directors out of funds legally available for that purpose, subject to any preferential dividend rights of any outstanding preferred stock. Our common stock has no preemptive rights, conversion rights or other subscription rights or redemption or sinking fund provisions.

In the event of our liquidation, dissolution or winding up, holders of our common stock will be entitled to share ratably in all assets remaining after payment of all debts and other liabilities and any liquidation preference of any outstanding preferred stock. All outstanding shares are fully paid and nonassessable.

When we issue shares of common stock under this prospectus supplement, the shares will fully be paid and nonassessable and will not have, or be subject to, any preemptive or similar rights.

Undesignated Preferred Stock

Our board of directors is authorized to issue up to 10,000,000 shares of undesignated preferred stock in one or more series without stockholder approval. Our board of directors may determine the rights, preferences, privileges and restrictions, including voting rights, dividend rights, conversion rights, redemption privileges and liquidation preferences, of each series of preferred stock. The purpose of authorizing our board of directors to issue preferred stock in one or more series and determine the number of shares in the series and its rights and preferences is to eliminate delays associated with a stockholder vote on specific issuances. Examples of rights and preferences that the board of directors may fix are:

•

dividend rights;

•

conversion rights;

•

voting rights;

•

terms of redemption;

•

liquidation preference;

S-29

•

sinking fund terms; and

•

the number of shares constituting, or the designation of, such series, any or all of which may be greater than the rights of common stock.

The existence of authorized but unissued shares of undesignated preferred stock may enable our board of directors to discourage an attempt to obtain control of us by means of a merger, tender offer, proxy contest or otherwise. For example, if in the due exercise of its fiduciary obligations, our board of directors were to determine that a takeover proposal is not in the best interests of us or our stockholders, our board of directors could cause shares of preferred stock to be issued without stockholder approval in one or more private offerings or other transactions that might dilute the voting or other rights of the proposed acquirer, stockholder or stockholder group. The rights of holders of our common stock described above, will be subject to, and may be adversely affected by, the rights of any preferred stock that we may designate and issue in the future. The issuance of shares of undesignated preferred stock could decrease the amount of earnings and assets available for distribution to holders of shares of common stock. The issuance may also adversely affect the rights and powers, including voting rights, of these holders and may have the effect of delaying, deterring or preventing a change in control of us.

Registration Rights

Pursuant to the terms of our investors’ rights agreement entered into in November 2017 (the “Investors’ Rights Agreement”), certain of our stockholders are entitled to rights with respect to the registration of their shares under the Securities Act until the earliest of (a) January 2023, (b) the date on which such holder ceases to hold registrable securities, or (c) such holder’s registrable securities could be sold without any restriction on volume or manner of sale on any three-month period under Rule 144 or any successor rule, as described below. We refer to these shares collectively as registrable securities.

Demand Registration Rights

Certain holders of our common stock are entitled to demand registration rights. Under the terms of the Investors’ Rights Agreement, we will be required, upon the written request of the holders of at least 20% of our outstanding registrable securities, as defined in the Investors’ Rights Agreement, to file a registration statement with respect to at least 40% of the registrable securities and use commercially reasonable efforts to effect the registration of all or a portion of their registrable securities for public resale so long as the total amount of registrable shares requested to be registered has an anticipated aggregate offering price to the public, net of selling expenses, of at least $15.0 million. We are required to effect only two registrations pursuant to this provision of the Investors’ Rights Agreement.

Short-Form Registration Rights

The holders of at least 10% of our outstanding registrable securities can request that we register all or part of their shares on Form S-3 if we are eligible to file a registration statement on Form S-3 and if the aggregate offering price, net of selling expenses, is at least $10.0 million. We are required to effect only two registrations in any twelve month period pursuant to the Investors’ Rights Agreement. The right to have such shares registered on Form S-3 is further subject to other specified conditions and limitations.

Piggyback Registration Rights

Pursuant to the investors’ rights agreement, if we register any of our securities either for our own account or for the account of other security holders, the holders of these shares are entitled to include their shares in the registration. Subject to certain exceptions contained in the Investors’ Rights Agreement, we and the underwriters may limit the number of shares included in the underwritten offering to the number of shares which we and the underwriters determine in our sole discretion will not jeopardize the success of the offering.

S-30

Indemnification

Our Investors’ Rights Agreement contains customary cross-indemnification provisions, under which we are obligated to indemnify holders of registrable securities in the event of material misstatements or omissions in the registration statement attributable to us, and they are obligated to indemnify us for material misstatements or omissions attributable to them.

S-31

UNDERWRITING

We are offering the shares of common stock described in this prospectus supplement through a number of underwriters.

BofA Securities, Inc., Jefferies LLC and SVB Leerink LLC are acting as representatives of the underwriters. We have entered into an underwriting agreement with the underwriters. Subject to the terms and conditions of the underwriting agreement, we have agreed to sell to the underwriters, and each underwriter has severally agreed to purchase, at the public offering price less the underwriting discounts and commissions set forth on the cover page of this prospectus supplement, the number of shares of common stock listed next to its name in the following table:


Name	Number of Shares
BofA Securities, Inc.
Jefferies LLC
SVB Leerink LLC
Wedbush Securities Inc.

Total		4,500,000

The underwriters are committed to purchase all the common shares offered by us if they purchase any shares. The underwriting agreement also provides that if an underwriter defaults, the purchase commitments of non-defaulting underwriters may also be increased or the offering may be terminated.

The underwriters propose to offer the common shares directly to the public at the public offering price set forth on the cover page of this prospectus supplement and to certain dealers at that price less a concession not in excess of $ per share. After the offering of the shares to the public, the offering price and other selling terms may be changed by the underwriters. Sales of shares made outside of the United States may be made by affiliates of the underwriters.

The underwriters have an option to buy up to 675,000 additional shares of common stock from us. The underwriters have 30 days from the date of this prospectus supplement to exercise this option to purchase additional shares. If any shares are purchased with this option to purchase additional shares, the underwriters will purchase shares in approximately the same proportion as shown in the table above. If any additional shares of common stock are purchased, the underwriters will offer the additional shares on the same terms as those on which the shares are being offered.

The underwriting fee is equal to the public offering price per share of common stock less the amount paid by the underwriters to us per share of common stock. The underwriting fee is $ per share. The following table shows the per share and total underwriting discounts and commissions to be paid to the underwriters assuming both no exercise and full exercise of the underwriters’ option to purchase additional shares.


	Without option to purchase additional shares exercise	With full option to purchase additional shares exercise
Per Share	$	$
Total	$	$

We estimate that the total expenses of this offering, including registration, filing and listing fees, printing fees and legal and accounting expenses, but excluding the underwriting discounts and commissions, will be approximately $750,000. We have agreed to reimburse the underwriters in an amount of up to $30,000 for certain expenses incurred in connection with this offering.

S-32

A prospectus in electronic format may be made available on the web sites maintained by one or more underwriters, or selling group members, if any, participating in the offering. The underwriters may agree to allocate a number of shares to underwriters and selling group members for sale to their online brokerage account holders. Internet distributions will be allocated by the representatives to underwriters and selling group members that may make Internet distributions on the same basis as other allocations.

We, our executive officers and directors and our other existing security holders have agreed, subject to certain exceptions, not to sell or transfer any common stock or securities convertible into, exchangeable for, exercisable for, or repayable with common stock, for 90 days after the date hereof without first obtaining the written consent of the representatives. Specifically, we and these other persons have agreed, with certain limited exceptions, not to directly or indirectly:

•

offer, pledge, sell or contract to sell any common stock;

•

sell any option or contract to purchase any common stock;

•

purchase any option or contract to sell any common stock;

•

grant any option, right or warrant for the sale of any common stock;

•

lend or otherwise dispose of or transfer any common stock;

•

request or demand that we file a registration statement related to the common stock; or

•

enter into any swap or other agreement that transfers, in whole or in part, the economic consequence of ownership of any common stock whether any such swap or transaction is to be settled by delivery of shares or other securities, in cash or otherwise.

This lock-up provision applies to common stock and to securities convertible into or exchangeable or exercisable for or repayable with common stock. It also applies to common stock owned now or acquired later by the person executing the agreement or for which the person executing the agreement later acquires the power of disposition.

We have agreed to indemnify the underwriters against certain liabilities, including liabilities under the Securities Act.

Our common stock is listed on the Nasdaq Global Market under the symbol “ACET.”

In connection with this offering, the underwriters may engage in stabilizing transactions, which involves making bids for, purchasing and selling shares of common stock in the open market for the purpose of preventing or retarding a decline in the market price of the common stock while this offering is in progress. These stabilizing transactions may include making short sales of the common stock, which involves the sale by the underwriters of a greater number of shares of common stock than they are required to purchase in this offering, and purchasing shares of common stock on the open market to cover positions created by short sales. Short sales may be “covered” shorts, which are short positions in an amount not greater than the underwriters’ option to purchase additional shares referred to above, or may be “naked” shorts, which are short positions in excess of that amount. The underwriters may close out any covered short position either by exercising their option to purchase additional shares, in whole or in part, or by purchasing shares in the open market. In making this determination, the underwriters will consider, among other things, the price of shares available for purchase in the open market compared to the price at which the underwriters may purchase shares through the option to purchase additional shares. A naked short position is more likely to be created if the underwriters are concerned that there may be downward pressure on the price of the common stock in the open market that could adversely affect investors who purchase in this offering. To the extent that the underwriters create a naked short position, they will purchase shares in the open market to cover the position.

S-33

The underwriters have advised us that, pursuant to Regulation M of the Securities Act, they may also engage in other activities that stabilize, maintain or otherwise affect the price of the common stock, including the imposition of penalty bids. This means that if the representatives of the underwriters purchase common stock in the open market in stabilizing transactions or to cover short sales, the representatives can require the underwriters that sold those shares as part of this offering to repay the underwriting discount received by them.

These activities may have the effect of raising or maintaining the market price of the common stock or preventing or retarding a decline in the market price of the common stock, and, as a result, the price of the common stock may be higher than the price that otherwise might exist in the open market. If the underwriters commence these activities, they may discontinue them at any time. The underwriters may carry out these transactions on the Nasdaq Global Market, in the over-the-counter market or otherwise.

In addition, in connection with this offering certain of the underwriters (and selling group members) may engage in passive market making transactions in our common stock on the Nasdaq Global Market prior to the pricing and completion of this offering. Passive market making consists of displaying bids on the Nasdaq Global Market no higher than the bid prices of independent market makers and making purchases at prices no higher than these independent bids and effected in response to order flow. Net purchases by a passive market maker on each day are generally limited to a specified percentage of the passive market maker’s average daily trading volume in the common stock during a specified period and must be discontinued when such limit is reached. Passive market making may cause the price of our common stock to be higher than the price that otherwise would exist in the open market in the absence of these transactions. If passive market making is commenced, it may be discontinued at any time.

Other than in the United States, no action has been taken by us or the underwriters that would permit a public offering of the securities offered by this prospectus supplement in any jurisdiction where action for that purpose is required. The securities offered by this prospectus supplement may not be offered or sold, directly or indirectly, nor may this prospectus supplement or any other offering material or advertisements in connection with the offer and sale of any such securities be distributed or published in any jurisdiction, except under circumstances that will result in compliance with the applicable rules and regulations of that jurisdiction. Persons into whose possession this prospectus supplement comes are advised to inform themselves about and to observe any restrictions relating to the offering and the distribution of this prospectus supplement. This prospectus supplement does not constitute an offer to sell or a solicitation of an offer to buy any securities offered by this prospectus supplement in any jurisdiction in which such an offer or a solicitation is unlawful.

Certain of the underwriters and their affiliates have provided in the past to us and our affiliates and may provide from time to time in the future certain commercial banking, financial advisory, investment banking and other services for us and such affiliates in the ordinary course of their business, for which they have received and may continue to receive customary fees and commissions. In addition, from time to time, certain of the underwriters and their affiliates may effect transactions for their own account or the account of customers, and hold on behalf of themselves or their customers, long or short positions in our debt or equity securities or loans, and may do so in the future.

Notice to Prospective Investors in Australia

No placement document, prospectus, product disclosure statement or other disclosure document has been lodged with the Australian Securities and Investments Commission (“ASIC”), in relation to the offering. This prospectus supplement does not constitute a prospectus, product disclosure statement or other disclosure document under the Corporations Act 2001 (the “Corporations Act”), and does not purport to include the information required for a prospectus, product disclosure statement or other disclosure document under the Corporations Act.

Any offer in Australia of the shares may only be made to persons (the “Exempt Investors”) who are “sophisticated investors” (within the meaning of section 708(8) of the Corporations Act), “professional

S-34

investors” (within the meaning of section 708(11) of the Corporations Act) or otherwise pursuant to one or more exemptions contained in section 708 of the Corporations Act so that it is lawful to offer the shares without disclosure to investors under Chapter 6D of the Corporations Act.

The shares applied for by Exempt Investors in Australia must not be offered for sale in Australia in the period of 12 months after the date of allotment under the offering, except in circumstances where disclosure to investors under Chapter 6D of the Corporations Act would not be required pursuant to an exemption under section 708 of the Corporations Act or otherwise or where the offer is pursuant to a disclosure document which complies with Chapter 6D of the Corporations Act. Any person acquiring shares must observe such Australian on-sale restrictions.

This prospectus supplement contains general information only and does not take account of the investment objectives, financial situation or particular needs of any particular person. It does not contain any securities recommendations or financial product advice. Before making an investment decision, investors need to consider whether the information in this prospectus supplement is appropriate to their needs, objectives and circumstances, and, if necessary, seek expert advice on those matters.

Notice to Prospective Investors in Canada

The securities may be sold only to purchasers purchasing, or deemed to be purchasing, as principal that are accredited investors, as defined in National Instrument 45-106 Prospectus Exemptions or subsection 73.3(1) of the Securities Act (Ontario), and are permitted clients, as defined in National Instrument 31-103 Registration Requirements, Exemptions and Ongoing Registrant Obligations. Any resale of the securities must be made in accordance with an exemption from, or in a transaction not subject to, the prospectus requirements of applicable securities laws.

Securities legislation in certain provinces or territories of Canada may provide a purchaser with remedies for rescission or damages if this prospectus supplement (including any amendment thereto) contains a misrepresentation, provided that the remedies for rescission or damages are exercised by the purchaser within the time limit prescribed by the securities legislation of the purchaser’s province or territory. The purchaser should refer to any applicable provisions of the securities legislation of the purchaser’s province or territory for particulars of these rights or consult with a legal advisor.

Pursuant to section 3A.3 (or, in the case of securities issued or guaranteed by the government of a non-Canadian jurisdiction, section 3A.4) of National Instrument 33-105 Underwriting Conflicts (NI 33-105), the underwriters are not required to comply with the disclosure requirements of NI 33-105 regarding underwriter conflicts of interest in connection with this offering.

Notice to Prospective Investors in the Dubai International Financial Centre

This prospectus supplement relates to an Exempt Offer in accordance with the Offered Securities Rules of the Dubai Financial Services Authority (“DFSA”). This prospectus supplement is intended for distribution only to persons of a type specified in the Offered Securities Rules of the DFSA. It must not be delivered to, or relied on by, any other person. The DFSA has no responsibility for reviewing or verifying any documents in connection with Exempt Offers. The DFSA has not approved this prospectus supplement nor taken steps to verify the information set forth herein and has no responsibility for the prospectus supplement. The shares to which this prospectus supplement relates may be illiquid and/or subject to restrictions on their resale. Prospective purchasers of the shares offered should conduct their own due diligence on the shares. If you do not understand the contents of this prospectus supplement you should consult an authorized financial advisor.

Notice to Prospective Investors in the European Economic Area and the United Kingdom

In relation to each Member State of the European Economic Area and the United Kingdom (each a “Relevant State”), no shares have been offered or will be offered pursuant to the offering to the public in that

S-35

Relevant State prior to the publication of a prospectus in relation to the Shares which has been approved by the competent authority in that Relevant State or, where appropriate, approved in another Relevant State and notified to the competent authority in that Relevant State, all in accordance with the Prospectus Regulation), except that offers of shares may be made to the public in that Relevant State at any time under the following exemptions under the Prospectus Regulation

(a)

to any legal entity which is a qualified investor as defined under the Prospectus Regulation;

(b)

to fewer than 150 natural or legal persons (other than qualified investors as defined under the Prospectus Regulation), subject to obtaining the prior consent of the underwriters for any such offer; or

(c)

in any other circumstances falling within Article 1(4) of the Prospectus Regulation,

provided that no such offer of shares shall require the Issuer or any Manager to publish a prospectus pursuant to Article 3 of the Prospectus Regulation or supplement a prospectus pursuant to Article 23 of the Prospectus Regulation.

Each person in a Relevant State who initially acquires any shares or to whom any offer is made will be deemed to have represented, acknowledged and agreed to and with the Company and the underwriters that it is a qualified investor within the meaning of the Prospectus Regulation.

In the case of any shares being offered to a financial intermediary as that term is used in Article 5(1) of the Prospectus Regulation, each such financial intermediary will be deemed to have represented, acknowledged and agreed that the shares acquired by it in the offer have not been acquired on a non-discretionary basis on behalf of, nor have they been acquired with a view to their offer or resale to, persons in circumstances which may give rise to an offer to the public other than their offer or resale in a Relevant State to qualified investors, in circumstances in which the prior consent of the underwriters has been obtained to each such proposed offer or resale.

The Company, the underwriters and their affiliates will rely upon the truth and accuracy of the foregoing representations, acknowledgements and agreements.

For the purposes of this provision, the expression an “offer to the public” in relation to any shares in any Relevant State means the communication in any form and by any means of sufficient information on the terms of the offer and any shares to be offered so as to enable an investor to decide to purchase or subscribe for any shares, and the expression “Prospectus Regulation” means Regulation (EU) 2017/1129.

References to the Prospectus Regulation includes, in relation to the UK, the Prospectus Regulation as it forms part of UK domestic law by virtue of the European Union (Withdrawal) Act 2018.

The above selling restriction is in addition to any other selling restrictions set out below.

Notice to Prospective Investors in the United Kingdom

This document is for distribution only to persons who (i) have professional experience in matters relating to investments and who qualify as investment professionals within the meaning of Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005 (as amended, the “Financial Promotion Order”), (ii) are persons falling within Article 49(2)(a) to (d) (“high net worth companies, unincorporated associations etc.”) of the Financial Promotion Order, (iii) are outside the United Kingdom, or (iv) are persons to whom an invitation or inducement to engage in investment activity (within the meaning of Section 21 of the Financial Services and Markets Act 2000, as amended (“FSMA”)) in connection with the issue

S-36

or sale of any securities may otherwise lawfully be communicated or caused to be communicated (all such persons together being referred to as “relevant persons”). This document is directed only at relevant persons and must not be acted on or relied on by persons who are not relevant persons. Any investment or investment activity to which this document relates is available only to relevant persons and will be engaged in only with relevant persons.

Notice to Prospective Investors in Hong Kong

The securities have not been offered or sold and will not be offered or sold in Hong Kong, by means of any document, other than (a) to “professional investors” as defined in the Securities and Futures Ordinance (Cap. 571) of Hong Kong and any rules made under that Ordinance; or (b) in other circumstances which do not result in the document being a “prospectus” as defined in the Companies Ordinance (Cap. 32) of Hong Kong or which do not constitute an offer to the public within the meaning of that Ordinance. No advertisement, invitation or document relating to the securities has been or may be issued or has been or may be in the possession of any person for the purposes of issue, whether in Hong Kong or elsewhere, which is directed at, or the contents of which are likely to be accessed or read by, the public of Hong Kong (except if permitted to do so under the securities laws of Hong Kong) other than with respect to securities which are or are intended to be disposed of only to persons outside Hong Kong or only to “professional investors” as defined in the Securities and Futures Ordinance and any rules made under that Ordinance.

Notice to Prospective Investors in Switzerland

The shares may not be publicly offered in Switzerland and will not be listed on the SIX Swiss Exchange (“SIX”) or on any other stock exchange or regulated trading facility in Switzerland. This document has been prepared without regard to the disclosure standards for issuance prospectuses under art. 652a or art. 1156 of the Swiss Code of Obligations or the disclosure standards for listing prospectuses under art. 27 ff. of the SIX Listing Rules or the listing rules of any other stock exchange or regulated trading facility in Switzerland. Neither this document nor any other offering or marketing material relating to the shares or the offering may be publicly distributed or otherwise made publicly available in Switzerland.

Neither this document nor any other offering or marketing material relating to the offering, the Company, the shares have been or will be filed with or approved by any Swiss regulatory authority. In particular, this document will not be filed with, and the offer of shares will not be supervised by, the Swiss Financial Market Supervisory Authority FINMA (“FINMA”), and the offer of shares has not been and will not be authorized under the Swiss Federal Act on Collective Investment Schemes (“CISA”). The investor protection afforded to acquirers of interests in collective investment schemes under the CISA does not extend to acquirers of shares.

Notice to Prospective Investors in Japan

The securities have not been and will not be registered under the Financial Instruments and Exchange Law of Japan (Law No. 25 of 1948, as amended) and, accordingly, will not be offered or sold, directly or indirectly, in Japan, or for the benefit of any Japanese Person or to others for re-offering or resale, directly or indirectly, in Japan or to any Japanese Person, except in compliance with all applicable laws, regulations and ministerial guidelines promulgated by relevant Japanese governmental or regulatory authorities in effect at the relevant time. For the purposes of this paragraph, “Japanese Person” shall mean any person resident in Japan, including any corporation or other entity organized under the laws of Japan.

Notice to Prospective Investors in Singapore

This prospectus supplement has not been registered as a prospectus supplement with the Monetary Authority of Singapore. Accordingly, the securities were not offered or sold or caused to be made the subject of an invitation for subscription or purchase and will not be offered or sold or caused to be made the subject of an

S-37

invitation for subscription or purchase, and this prospectus supplement or any other document or material in connection with the offer or sale, or invitation for subscription or purchase, of the securities, has not been circulated or distributed, nor will it be circulated or distributed, whether directly or indirectly, to any person in Singapore other than (i) to an institutional investor (as defined in Section 4A of the Securities and Futures Act (Chapter 289) of Singapore, as modified or amended from time to time (the “SFA”)) pursuant to Section 274 of the SFA, (ii) to a relevant person (as defined in Section 275(2) of the SFA) pursuant to Section 275(1) of the SFA, or any person pursuant to Section 275(1A) of the SFA, and in accordance with the conditions specified in Section 275 of the SFA, or (iii) otherwise pursuant to, and in accordance with the conditions of, any other applicable provision of the SFA.

Where the securities are subscribed or purchased under Section 275 of the SFA by a relevant person which is:

(a)

a corporation (which is not an accredited investor (as defined in Section 4A of the SFA)) the sole business of which is to hold investments and the entire share capital of which is owned by one or more individuals, each of whom is an accredited investor; or

(b)

a trust (where the trustee is not an accredited investor) whose sole purpose is to hold investments and each beneficiary of the trust is an individual who is an accredited investor,

or securities-based derivatives contracts (each term as defined in Section 2(1) of the SFA) of that corporation or the beneficiaries’ rights and interest (howsoever described) in that trust shall not be transferred within six months after that corporation or that trust has acquired the securities pursuant to an offer made under Section 275 of the SFA except:

(a)

to an institutional investor or to a relevant person, or to any person arising from an offer referred to in Section 275(1A) or Section 276(4)(i)(B) of the SFA;

(b)

where no consideration is or will be given for the transfer;

(c)

where the transfer is by operation of law; or

(d)

as specified in Section 276(7) of the SFA.

S-38

CONCURRENT PRIVATE PLACEMENT

In September 2020, we entered into a Funding Agreement with certain of our investors (referred to as the “Investors”), pursuant to which the Investors have agreed to fund the Funding Amount into an escrow account, which will be used to subscribe for shares of our common stock in a concurrent private placement in connection with this offering, on the same economic conditions (including the price per share) and similar other terms and conditions as the shares being sold in this offering. If we fail to consummate the offering within twelve months of September 15, 2020 or certain other events occur, the Funding Amount will be distributed back to the Investors.

Pursuant to the Funding Agreement, we intend to enter into a stock purchase agreement with the Investors (the “Subscription Agreement”), which requires the Investors to purchase from us, concurrently with this offering in a private placement, $15.0 million of shares of our common stock at a price per share equal to the public offering price, subject to the terms and conditions set forth in the Subscription Agreement. The sale of these shares will not be registered under the Securities Act. The concurrent private placement is subject to certain closing conditions. We will receive the full proceeds from the sale and will not pay any underwriting discounts or commissions with respect to the shares of common stock that are sold in the concurrent private placement. The closing of this offering is not conditioned on the closing of the concurrent private placement.

S-39

LEGAL MATTERS

Certain legal matters relating to the shares of common stock offered hereby will be passed upon for us by Goodwin Procter LLP, Boston, Massachusetts. Certain legal matters in connection with this offering will be passed upon for the underwriters by Latham & Watkins LLP.

EXPERTS

The consolidated financial statements of resTORbio, Inc. as of December 31, 2019 and 2018, and for each of the years in the three-year period ended December 31, 2019, have been incorporated by reference herein and in the registration statement in reliance upon the report of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing.

The audited historical financial statements of Adicet Bio, Inc. included in Exhibit 99.5 of Adicet Bio, Inc.’s Current Report on Form 8-K dated September 16, 2020 have been so incorporated in reliance on the report (which contains an explanatory paragraph relating to Adicet Bio, Inc.’s ability to continue as a going concern as described in Note 1 to the financial statements) of PricewaterhouseCoopers LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

WHERE YOU CAN FIND ADDITIONAL INFORMATION

We have filed with the SEC a registration statement on Form S-3 under the Securities Act with respect to the shares of common stock offered by this prospectus supplement. This prospectus supplement does not contain all the information set forth in the registration statement and its exhibits and schedules, portions of which have been omitted as permitted by the rules and regulations of the SEC. You should read the registration statement and its exhibits and schedules carefully for provisions that may be important to you.

We file annual, quarterly and current reports, proxy statements and other information with the SEC. The SEC also maintains a website at www.sec.gov that contains periodic and current reports, proxy and information statements, and other information regarding registrants that are filed electronically with the SEC.

These documents are also available, free of charge, through the Investors section of our website, which is located at www.adicetbio.com. Information contained on our website is not incorporated by reference into this prospectus supplement or the accompanying prospectus and you should not consider information on our website to be part of this prospectus supplement or the accompanying prospectus.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to incorporate by reference the information and reports we file with it into our registration statement of which this prospectus supplement is a part, which means that we can disclose important information to you by referring you to these documents. The information incorporated by reference is an important part of this prospectus supplement, and information that we file later with the SEC will automatically update and supersede the information already incorporated by reference. Any statement contained in a previously filed document incorporated by reference will be deemed to be modified or superseded for purposes of this prospectus supplement to the extent that a statement contained in this prospectus supplement modifies or replaces that statement.

We incorporate by reference our documents listed below and any future filings made by us with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act, between the date of this prospectus supplement and the termination of the offering of the securities described in this prospectus supplement. We are not, however, incorporating by reference any documents or portions thereof, whether specifically listed below or filed in the

S-40

future, that are not deemed “filed” with the SEC, including any information furnished pursuant to Items 2.02 or 7.01 of Form 8-K or related exhibits furnished pursuant to Item 9.01 of Form 8-K:

•

our Annual Report on Form 10-K for the year ended December 31, 2019, filed with the SEC on March 12, 2020;

•

The information specifically incorporated by reference into our Annual Report on Form 10-K for the year ended December 31, 2019 from our definitive proxy statement on Schedule 14A (other than information furnished rather than filed), which was filed with the SEC on April 30, 2020;

•

our Quarterly Reports on Form 10-Q for the quarters ended March 31, 2020 and June 30, 2020, filed with the SEC on May 7, 2020 and July 30, 2020, respectively;

•

our Current Reports on Form 8-K filed with the SEC on April 3, 2020, April 29, 2020, April 30, 2020, May 28, 2020, June 2, 2020, June 5, 2020, June 23, 2020, July 7, 2020, July 28, 2020, September 15, 2020, September 16, 2020 and September 18, 2020 (in each case, except for information contained therein which is furnished rather than filed); and

•

the description of our common stock contained in our registration statement on Form 8-A filed with the SEC on January 22, 2018 (File No. 001-28259) under Section 12(b) of the Exchange Act, including any amendments or reports filed for the purpose of updating such description.

You may request a copy of these filings, and any exhibits we have specifically incorporated by reference as an exhibit in this prospectus supplement, at no cost by writing us at the following address: Investor Relations Department, Adicet Bio, Inc., 500 Boylston Street, 13^th Floor, Boston, MA 02116, telephone (857) 315-5528.

You may also access these documents, free of charge on the SEC’s website at www.sec.gov or on our website at www.adicetbio.com. The information contained on, or that can be accessed through, our website does not constitute part of this prospectus supplement, and the reference to our website address is included in this prospectus supplement as an inactive textual reference only.

S-41

PROSPECTUS

LOGO

$175,000,000

Common Stock

Preferred Stock

Debt Securities

Warrants

Units

12,445,646 Shares of Common Stock

Offered by Selling Stockholders

We may from time to time issue, in one or more series or classes, up to $175,000,000 in aggregate principal amount of our common stock, preferred stock, debt securities, warrants and/or units.

In addition, selling stockholders named in this prospectus may from time to time offer and sell up to an aggregate of 12,445,646 shares of our common stock in one or more offerings, subject to market conditions and prices, liquidity objectives and other investment considerations. We will not receive any of the proceeds from the sale of our common stock by the selling stockholders. We have borne and will continue to bear the costs relating to registration of these shares.

We may offer these securities separately or together in units. Each time we sell securities described herein, and in certain cases where one or more selling stockholders sell securities pursuant to this prospectus, we or the selling stockholders, as applicable, will provide prospective investors with a supplement to this prospectus that will specify the terms of the securities being offered. We may sell these securities to or through underwriters and also to other purchasers or through agents. We will set forth the names of any underwriters or agents, and any fees, conversions, or discount arrangements, in the accompanying prospectus supplement. We may not sell any securities under this prospectus without delivery of the applicable prospectus supplement. You should read this document and any prospectus supplement or amendment carefully before you invest in our securities.

Our common stock is listed on The Nasdaq Global Select Market under the symbol “TORC.” On January 31, 2019, the closing price for our common stock, as reported on The Nasdaq Global Select Market, was $8.88 per share. Our principal executive offices are located at 500 Boylston Street, 12^th Floor, Boston, Massachusetts 02116.

Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties described under the heading “Risk Factors” contained in this prospectus beginning on page 2 and any applicable prospectus supplement, and under similar headings in the other documents that are incorporated by reference into this prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this Prospectus is February 12, 2019

TABLE OF CONTENTS


	Page
About this Prospectus		1
Risk Factors		2
Cautionary Statement Regarding Forward-Looking Statements		3
The Company		5
Use of Proceeds		8
Securities We May Offer or That a Selling Stockholder May Offer		8
Description of Capital Stock		9
Description of Debt Securities		14
Description of Warrants		29
Description of Units		30
Selling Stockholders		34
Plan of Distribution		36
Legal Matters		39
Experts		39
Where You Can Find More Information		39
Incorporation by Reference		39

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission, or the SEC, using a “shelf” registration process. Under this shelf registration process, we may from time to time sell any combination of the securities described in this prospectus in one or more offerings for an aggregate initial offering price of up to $175,000,000. In addition, the selling stockholders may from time to time sell up to an aggregate amount of 12,445,646, shares of our common stock in one or more offerings, subject to market conditions and prices, liquidity objectives and other investment considerations.

This prospectus provides you with a general description of the securities we or the selling stockholders may offer. Each time we sell securities described herein, and in certain cases where one or more selling stockholders sell securities pursuant to this prospectus, we or the selling stockholders, as applicable, will provide one or more prospectus supplements that will contain specific information about the terms of the offering. The prospectus supplement may also add, update or change information contained in this prospectus. You should read both this prospectus and the accompanying prospectus supplement together with the additional information described under the heading “Where You Can Find More Information” beginning on page of this prospectus.

You should rely only on the information contained in or incorporated by reference in this prospectus, any accompanying prospectus supplement or in any related free writing prospectus filed by us with the SEC. We have not authorized anyone to provide you with different information. This prospectus and the accompanying prospectus supplement do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the securities described in the accompanying prospectus supplement or an offer to sell or the solicitation of an offer to buy such securities in any circumstances in which such offer or solicitation is unlawful. You should assume that the information appearing in this prospectus, any prospectus supplement, the documents incorporated by reference and any related free writing prospectus is accurate only as of their respective dates. Our business, financial condition, results of operations and prospects may have changed materially since those dates.

Unless the context otherwise indicates, references in this prospectus to “resTORbio”, “we”, “our”, “us” and “the Company” refer, collectively, to resTORbio, Inc. and, where appropriate, our subsidiary.

RISK FACTORS

Investing in our securities involves a high degree of risk. You should carefully consider the risks referenced below and described in the documents incorporated by reference in this prospectus and any applicable prospectus supplement, as well as other information we include or incorporate by reference into this prospectus and any applicable prospectus supplement, before making an investment decision. Our business, financial condition or results of operations could be materially adversely affected by the materialization of any of these risks. The trading price of our securities could decline due to the materialization of any of these risks, and you may lose all or part of your investment. This prospectus and the documents incorporated herein by reference also contain forward-looking statements that involve risks and uncertainties. Actual results could differ materially from those anticipated in these forward-looking statements as a result of certain factors, including the risks described below and in the documents incorporated herein by reference, including (i) our Annual Report on Form 10-K for the fiscal year ended December 31, 2017, as amended, which is on file with the SEC and is incorporated herein by reference, (ii) our Quarterly Reports on Form 10-Q for the quarters ended March 31, 2018, June 30, 2018 and September 30, 2018, which are on file with the SEC and are incorporated herein by reference and (iii) other documents we file with the SEC that are deemed incorporated by reference into this prospectus.

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, including the documents that we incorporate by reference, contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act. Any statements about our expectations, beliefs, plans, objectives, assumptions or future events or performance are not historical facts and may be forward-looking. These statements are often, but are not always, made through the use of words or phrases such as “may,” “will,” “could,” “should,” “expects,” “intends,” “plans,” “anticipates,” “believes,” “estimates,” “predicts,” “projects,” “potential,” “continue,” and similar expressions, or the negative of these terms, or similar expressions. Accordingly, these statements involve estimates, assumptions, risks and uncertainties which could cause actual results to differ materially from those expressed in them. Any forward-looking statements are qualified in their entirety by reference to the factors discussed throughout this prospectus, and in particular those factors referenced in the section “Risk Factors.”

This prospectus contains forward-looking statements that are based on our management’s belief and assumptions and on information currently available to our management. These statements relate to future events or our future financial performance, and involve known and unknown risks, uncertainties and other factors that may cause our actual results, levels of activity, performance or achievements to be materially different from any future results, levels of activity, performance or achievements expressed or implied by these forward-looking statements. Forward-looking statements include, but are not limited to, statements about:

•

our plans to develop and commercialize RTB101 alone or in combination with rapalogs, such as everolimus or sirolimus, and other product candidates for the targeted indications and patient populations, including the therapeutic potential and clinical benefits thereof;

•

our ongoing and future clinical trials for RTB101 alone or in combination with rapalogs, such as everolimus or sirolimus, whether conducted by us or by any future collaborators, including the timing of initiation of these trials and of the anticipated results;

•

the timing of and our ability to obtain and maintain regulatory approvals for our product candidates;

•

the rate and degree of market acceptance and clinical utility of any products for which we receive regulatory approval;

•

our commercialization, marketing and manufacturing capabilities and strategy;

•

our intellectual property position and strategy;

•

our ability to identify additional product candidates with significant commercial potential;

•

our plans to enter into collaborations for the development and commercialization of product candidates;

•

the potential benefits of any future collaboration;

•

our expectations related to the use of cash, cash equivalents and marketable securities;

•

our estimates regarding expenses, future revenue, capital requirements and needs for additional financing;

•

our expectations regarding the time during which we will be an emerging growth company under the Jumpstart Our Business Startups Act of 2012, as amended, or the JOBS Act;

•

our expected uses of the net proceeds from any offering of our securities;

•

developments relating to our competitors and our industry; and

•

the impact of government laws and regulations.

This prospectus and the documents incorporated by reference also contain estimates, projections and other information concerning our industry, our business, and the markets for certain diseases, including data regarding the estimated size of those markets, and the incidence and prevalence of certain medical conditions. Information that is based on estimates, forecasts, projections, market research or similar methodologies is inherently subject to uncertainties and actual events or circumstances may differ materially from events and circumstances reflected in this information. Unless otherwise expressly stated, we obtained this industry, business, market and other data from reports, research surveys, studies and similar data prepared by market research firms and other third parties, industry, medical and general publications, government data and similar sources.

You should read this prospectus and the documents that we incorporate by reference in this prospectus completely and with the understanding that our actual future results may be materially different from what we expect. The forward-looking statements in this prospectus and the documents we incorporate by reference herein represent our views as of their respective dates. We anticipate that subsequent events and developments will cause our views to change. However, while we may elect to update these forward-looking statements at some point in the future, we have no current intention of doing so except to the extent required by applicable law. You should, therefore, not rely on these forward-looking statements as representing our views as of any date subsequent to the date of this prospectus.

THE COMPANY

We are a clinical-stage biopharmaceutical company developing a new class of innovative medicines that target the biology of aging to prevent or treat age-related diseases with the potential to extend healthy lifespan. Our lead program is selectively targeting the target of rapamycin complex 1, or TORC1, an evolutionarily conserved pathway that contributes to the decline in function of multiple organ systems. Our lead product candidate, RTB101, is an oral, selective, and potent inhibitor of TORC1. RTB101 inhibits the phosphorylation of multiple targets downstream of TORC1. Inhibition of TORC1 has been observed to extend lifespan and healthspan in aging preclinical species and to enhance immune, neurologic and cardiac functions, suggesting potential benefits in several aging-related diseases. We licensed the worldwide rights to our TORC1 program, including RTB101 alone or in combination with rapalogs, such as everolimus, sirolimus, or other mTOR inhibitors, from Novartis International Pharmaceutical Ltd. in March 2017.

The decline in immune function that occurs during aging, or immunosenescence, increases susceptibility to a variety of diseases, including respiratory tract infections, or RTIs, that significantly contribute to morbidity and mortality in the elderly. Our initial focus is on the development of RTB101 as a first-in-class immunotherapy designed to improve immune function and thereby reduce the incidence of RTIs in the elderly regardless of the causative pathogen. Our TORC1 immunotherapy approach is supported by two randomized, placebo-controlled Phase 2a and Phase 2b clinical trials enrolling more than 900 elderly subjects that provided statistically significant and clinically meaningful results. In 2018, we reported results from our exploratory dose-ranging randomized, placebo-controlled Phase 2b clinical trial in 652 elderly patients at increased risk of RTI-associated morbidity and mortality defined as aged 85 and over, or 65-84 with one or more of comorbidities including: asthma, chronic obstructive pulmonary disease, or COPD, type 2 diabetes mellitus, or T2DM, or current smoker. The results from this trial demonstrated a statistically significant and clinically meaningful 30.6% reduction in the percentage of patients with one or more laboratory-confirmed RTIs, the primary endpoint of the trial, in the RTB101 10 mg once daily cohort compared to the placebo cohort. Prespecified analyses of the patient populations enrolled in the trial demonstrated (i) a statistically significant 52.1% reduction in percentage of patients with severe laboratory-confirmed RTI symptoms in the RTB101 10 mg once daily cohort compared to the placebo cohort, (ii) a statistically significant 66.7%, 68.9%, and 25.3% reduction in the prespecified endpoint of percentage patients 85 and older, 65 and older with asthma and 65 and older with T2DM, respectively, with one or more laboratory-confirmed RTIs in the RTB101 10 mg once daily cohort compared to the placebo cohort, and (iii) no reduction in the incidence of laboratory-confirmed RTIs in patients who were current smokers or with COPD in the RTB101 10 mg once daily cohort compared to the placebo cohort. The lack of efficacy observed in current smokers and patients with COPD is consistent with nonclinical data suggesting that mTOR inhibition exacerbates cigarette smoke-induced lung inflammation in COPD. The combination of RTB101+everolimus did not meet the primary endpoint suggesting that less TORC1 inhibition with RTB101 10 mg once daily may be more beneficial for reducing the incidence of RTIs in high risk elderly patients. We believe the collective results from our Phase 2a and Phase 2b clinical trials enrolling more than 900 elderly subjects suggest that RTB101 10 mg once daily may improve the function of the aging immune system and reduce the incidence of laboratory-confirmed RTIs in elderly patients. In our planned Phase 3 studies, we may enroll elderly subjects 65 and older, excluding current smokers and COPD patients.

Additional positive results from prespecified analyses for any infection and urinary tract infections, or UTIs, from our Phase 2b trial demonstrated (i) a statistically significant 23.6% reduction in the percentage of patients with any infection in the RTB101 10 mg once daily cohort compared to the placebo cohort, (ii) a statistically significant 74.6% reduction in the percentage of patients with one or more UTIs in the RTB101 10 mg twice daily cohort and (iii) a 34.4% reduction in the percentage of patients with one or more UTIs in the RTB101 10 mg once daily cohort. If not otherwise specified, we used a nominal 5% or lower p-value (p < 0.05) to define statistical significance for the clinical trials and data presented in this prospectus.

As of January 31, 2019, one family in this patent portfolio covering compositions of matter has 44 issuances in 33 countries, and is pending in six. Our issued patents and pending applications with respect to RTB101 are

expected to expire in 2031 or 2032, depending on eligibility for patent term extension or supplementary protection. Additional pending applications are expected to expire between 2034 and 2037, exclusive of possible patent term adjustments or extensions.

Recent scientific findings, including those published in the scientific journals Cell, Nature and Science, suggest that aging and aging-related conditions, such as immunosenescence, may be attributable not only to random cellular wear and tear, but also to specific intra-cellular signaling pathways, including the mTOR pathway. mTOR is a protein kinase that signals via two multiprotein complexes, known as TORC1 and TORC2. TORC1 inhibition has been observed to prolong lifespan, improve immune, neurologic, and cardiac function, decrease adiposity, and delay the onset of aging-related diseases in multiple animal studies. Specifically, with respect to improved immune function, TORC1 inhibition was observed in preclinical and clinical studies to rejuvenate blood, or hematopoietic stem cell function, increase infection-fighting white blood cell production, enhance rapid and independent of antigen, or innate immunity, and enhance antibody-mediated, or adaptive immunity. On the other hand, TORC2 inhibition has been observed to decrease lifespan in preclinical studies and cause unwanted side effects of hyperlipidemia and hyperglycemia in certain animals and humans. Therefore, based on these observations and data from more than 900 patients enrolled in the Phase 2a and Phase 2b clinical trials, we believe our TORC1 program has the potential to improve the function of several aging organ systems such as immune system function and counteract immunosenescence in the elderly.

The reduced ability of elderly patients to effectively detect and fight infections is most commonly manifested in their susceptibility to RTIs and the negative effects such infections have on their overall health. RTIs are the second leading cause of hospitalization in people age 85 and over, and the fourth leading cause in people age 65 and over, contributing to high healthcare burdens and costs for the elderly population and the healthcare system that are three to five times higher than for the younger population. Furthermore, antibiotics, which are ineffective against viruses, are often prescribed indiscriminately to treat RTIs, which may cause side effects related to antibiotic use and contribute to the growing global problem of antibiotic resistance. As the elderly represent the fastest growing population in the world, we believe there is significant unmet medical need for innovative therapeutic options for reducing the incidence of RTIs by improving the function of the aging immune system.

We believe our approach to addressing RTIs in the elderly possesses several clinical and commercial advantages. Our TORC1 program offers an immunotherapy approach that has the potential to address a broad range of viral and bacterial pathogens. Statistically significant and clinically meaningful reductions in RTI incidence were observed in the Phase 2a and Phase 2b clinical trials with RTB101. We believe the risk-to-benefit ratio of our program observed in clinical studies to date would be well-suited to the elderly due to the following observations: our oral product candidates were well-tolerated in elderly subjects and none of the participants in the active treatment arms experienced a serious adverse event that was related to the study drug, and the doses being investigated in our Phase 2b clinical trial were 60 to 240 times lower than maximum tolerated doses established in prior clinical trials for other indications. Based on communications during a high-level policy meeting with the U.S. Food and Drug Administration, we believe a reduction in the incidence of RTIs has the potential to be a clinically relevant endpoint. Based on the results from our Phase 2b clinical trial with respect to reduction in RTI incidence, we plan to conduct pivotal clinical trials and to seek regulatory approval for commercialization of RTB101 in the United States, Europe and Japan. In some markets, we may collaborate with third parties for the development and commercialization of our product candidates.

Our management team includes Chen Schor, our co-founder who serves as our President and Chief Executive Officer, and Joan Mannick, M.D., our co-founder who serves as our Chief Medical Officer, Meredith Manning, who serves as our Chief Commercial Officer, and additional veterans in drug development and discovery with executive experience in leading global pharmaceutical companies. Dr. Mannick led the TORC1 clinical program at Novartis Institutes for Biomedical Research, Inc. prior to our in-licensing of the program. We are supported by investors that include both private equity venture capital funds and public healthcare investment funds.

We qualify as an “emerging growth company” as defined in the JOBS Act. As an emerging growth company, we may take advantage of specified reduced disclosure and other requirements that are otherwise applicable generally to public companies. We would cease to be an emerging growth company on the date that is the earliest of: (i) the last day of the fiscal year in which we have total annual gross revenues of $1.07 billion or more; (ii) December 31, 2023; (iii) the date on which we have issued more than $1 billion in nonconvertible debt during the previous three years; or (iv) the date on which we are deemed to be a large accelerated filer under the rules of the SEC.

We were incorporated under the laws of the state of Delaware in July 2016 under the name resTORbio, Inc. Our principal executive offices are located at 500 Boylston Street, 12^th Floor, Boston, MA 02116. Our telephone number is (857) 315-5521, and our website is located at www.restorbio.com. No portion of our website is incorporated by reference into this prospectus. We do not incorporate the information on or accessible through our website into this prospectus, and you should not consider any information on, or that can be accessed through, our website as part of this prospectus. Our common stock trades on The Nasdaq Global Select Market under the symbol “TORC”.

We use various trademarks and trade names in our business, including without limitation our corporate name and logo. All other trademarks or trade names referred to in this prospectus are the property of their respective owners. Solely for convenience, the trademarks and trade names in this prospectus may be referred to without the ^® and ™ symbols, but such references should not be construed as any indicator that their respective owners will not assert, to the fullest extent under applicable law, their rights thereto.

USE OF PROCEEDS

We intend to use the net proceeds from the sale of any securities offered under this prospectus for general corporate purposes unless otherwise indicated in the applicable prospectus supplement. General corporate purposes may include research and development costs, including the conduct of one or more clinical trials and process development and manufacturing of our product candidates, potential strategic acquisitions of complementary businesses, services or technologies, expansion of our technology infrastructure and capabilities, working capital, capital expenditures and other general corporate purposes. We may temporarily invest the net proceeds in a variety of capital preservation instruments, including investment grade, interest bearing instruments and U.S. government securities, until they are used for their stated purpose. We have not determined the amount of net proceeds to be used specifically for such purposes. As a result, management will retain broad discretion over the allocation of net proceeds. We will not receive any proceeds from the sale of shares of our common stock by the selling stockholders.

SECURITIES WE MAY OFFER OR THAT A SELLING STOCKHOLDER MAY OFFER

This prospectus contains summary descriptions of the securities we may offer from time to time. These summary descriptions are not meant to be complete descriptions of each security. The particular terms of any security will be described in the applicable prospectus supplement. In addition, the selling stockholders may sell from time to time up to an aggregate of 12,445,646 shares of our common stock in one or more offerings, subject to market conditions and prices, liquidity objectives and other investment considerations. This prospectus provides you with a general description of the securities we and the selling stockholders may offer. Each time we sell securities described herein, and in certain cases where one or more selling stockholders sell securities pursuant to this prospectus, we or the selling stockholders, as applicable, will provide prospective investors with a supplement to this prospectus that will contain specific information about the terms of that offering, including the specific amounts, prices and terms of the securities offered.

We or the selling stockholders may sell the securities to or through underwriters, dealers or agents, directly to purchasers or through a combination of any of these methods of sale or as otherwise set forth below under “Plan of Distribution.” We and the selling stockholders, as well as any agents acting on our or their behalf, reserve the sole right to accept and to reject in whole or in part any proposed purchase of securities. Any prospectus supplement will set forth the names of any underwriters, dealers, agents or other entities involved in the sale of securities described in that prospectus supplement and any applicable fee, commission or discount arrangements with them.

DESCRIPTION OF CAPITAL STOCK

The following description of our common stock and preferred stock, together with the additional information we include in any applicable prospectus supplements, summarizes the material terms and provisions of the common stock and preferred stock that we may offer under this prospectus. The following description of our capital stock does not purport to be complete and is subject to, and qualified in its entirety by, our certificate of incorporation and bylaws, which are exhibits to the registration statement of which this prospectus forms a part, and by applicable law. The terms of our common stock and preferred stock may also be affected by Delaware law.

Authorized Capital Stock

As of January 31, 2019, 28,055,344 shares of our common stock were outstanding and held by 7 stockholders of record.

Common Stock

When we issue shares of common stock under this prospectus, the shares will fully be paid and nonassessable and will not have, or be subject to, any preemptive or similar rights.

Undesignated Preferred Stock

Our certificate of incorporation provides for 10,000,000 authorized shares of preferred stock. Our board of directors may determine the rights, preferences, privileges and restrictions, including voting rights, dividend rights, conversion rights, redemption privileges and liquidation preferences, of each series of preferred stock. These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and the number of shares constituting, or the designation of, such series, any or all of which may be greater than the rights of common stock. The issuance of our preferred stock could adversely affect the voting power of holders of common stock and the likelihood that such holders will receive dividend payments and payments upon our liquidation. The purpose of authorizing our board of directors to issue preferred stock in one or more series and determine the number of shares in the series and its rights and preferences is to eliminate delays associated with a stockholder vote on specific issuances. In addition, the issuance of preferred stock could have the effect of delaying, deferring or preventing a change in control of our company or other corporate action. When we issue shares of preferred stock under this prospectus, the shares will fully be paid and nonassessable and will not be subject to any preemptive or similar rights.

The existence of authorized but unissued shares of preferred stock may enable our board of directors to discourage an attempt to obtain control of us by means of a merger, tender offer, proxy contest or otherwise. For

example, if in the due exercise of its fiduciary obligations, our board of directors were to determine that a takeover proposal is not in the best interests of our stockholders, our board of directors could cause shares of preferred stock to be issued without stockholder approval in one or more private offerings or other transactions that might dilute the voting or other rights of the proposed acquirer or insurgent stockholder or stockholder group. In this regard, our certificate of incorporation grants our board of directors broad power to establish the rights and preferences of authorized and unissued shares of preferred stock. The issuance of shares of preferred stock could decrease the amount of earnings and assets available for distribution to holders of shares of common stock. The issuance may also adversely affect the rights and powers, including voting rights, of these holders and may have the effect of delaying, deterring or preventing a change in control of us.

Registration Rights

Pursuant to the terms of our investors’ rights agreement entered into in November 2017, certain of our stockholders are entitled to rights with respect to the registration of their shares under the Securities Act until the earliest of (a) January 2023, (b) the date on which such holder ceases to hold registrable securities, or (c) such holder’s registrable securities could be sold without any restriction on volume or manner of sale on any three-month period under Rule 144 or any successor rule, as described below. We refer to these shares collectively as registrable securities.

Demand Registration Rights

The holders of 14,466,883 shares of our common stock, including the 12,445,646 shares of common stock to be registered pursuant to this Registration Statement, are entitled to demand registration rights. Under the terms of the investors’ rights agreement, we will be required, upon the written request of the holders of at least 20% of our outstanding registrable securities, as defined in the investors’ rights agreement, to file a registration statement with respect to at least 40% of the registrable securities and use commercially reasonable efforts to effect the registration of all or a portion of their registrable securities for public resale so long as the total amount of registrable shares requested to be registered has an anticipated aggregate offering price to the public, net of selling expenses, of at least $15.0 million. We are required to effect only two registrations pursuant to this provision of the investors’ rights agreement.

Short-Form Registration Rights

The holders of at least 10% of our outstanding registrable securities can request that we register all or part of their shares on Form S-3 if we are eligible to file a registration statement on Form S-3 and if the aggregate offering price, net of selling expenses, is at least $10.0 million. We are required to effect only two registrations in any twelve month period pursuant to the investors’ rights agreement. The right to have such shares registered on Form S-3 is further subject to other specified conditions and limitations.

Piggyback Registration Rights

Pursuant to the investors’ rights agreement, if we register any of our securities either for our own account or for the account of other security holders, the holders of these shares are entitled to include their shares in the registration. Subject to certain exceptions contained in the investors’ rights agreement, we and the underwriters may limit the number of shares included in the underwritten offering to the number of shares which we and the underwriters determine in our sole discretion will not jeopardize the success of the offering.

Indemnification

Our investors’ rights agreement contains customary cross-indemnification provisions, under which we are obligated to indemnify holders of registrable securities in the event of material misstatements or omissions in the registration statement attributable to us, and they are obligated to indemnify us for material misstatements or omissions attributable to them.

Expiration of Registration Rights

The demand registration rights and short form registration rights granted under the investors’ rights agreement will terminate on the earliest of (a) January 2023, (b) the date on which such holder ceases to hold registrable securities, or (c) such holder’s registrable securities could be sold without any restriction on volume or manner of sale on any three-month period under Rule 144 or any successor rule, as described below.

Anti-Takeover Effects of our Certificate of Incorporation and Bylaws and Delaware Law

Our certificate of incorporation and bylaws include a number of provisions that may have the effect of delaying, deferring or preventing another party from acquiring control of us and encouraging persons considering unsolicited tender offers or other unilateral takeover proposals to negotiate with our board of directors rather than pursue non-negotiated takeover attempts. These provisions include the items described below.

Board Composition and Filling Vacancies

Our certificate of incorporation provides for the division of our board of directors into three classes serving staggered three-year terms, with one class being elected each year. Our certificate of incorporation also provides that directors may be removed only for cause and then only by the affirmative vote of the holders of two-thirds or more of the shares then entitled to vote at an election of directors. Furthermore, any vacancy on our board of directors, however occurring, including a vacancy resulting from an increase in the size of our board, may only be filled by the affirmative vote of a majority of our directors then in office even if less than a quorum. The classification of directors, together with the limitations on removal of directors and treatment of vacancies, has the effect of making it more difficult for stockholders to change the composition of our board of directors.

No Written Consent of Stockholders

Our certificate of incorporation provides that all stockholder actions are required to be taken by a vote of the stockholders at an annual or special meeting, and that stockholders may not take any action by written consent in lieu of a meeting. This limit may lengthen the amount of time required to take stockholder actions and would prevent the amendment of our bylaws or removal of directors by our stockholders without holding a meeting of stockholders.

Meetings of Stockholders

Our certificate of incorporation and bylaws provide that only a majority of the members of our board of directors then in office may call special meetings of stockholders and only those matters set forth in the notice of the special meeting may be considered or acted upon at a special meeting of stockholders. Our bylaws limit the business that may be conducted at an annual meeting of stockholders to those matters properly brought before the meeting.

Advance Notice Requirements

Our bylaws establish advance notice procedures with regard to stockholder proposals relating to the nomination of candidates for election as directors or new business to be brought before meetings of our stockholders. These procedures provide that notice of stockholder proposals must be timely given in writing to our corporate secretary prior to the meeting at which the action is to be taken. Generally, to be timely, notice must be received at our principal executive offices not less than 90 days nor more than 120 days prior to the first anniversary date of the annual meeting for the preceding year. Our bylaws specify the requirements as to form and content of all stockholders’ notices. These requirements may preclude stockholders from bringing matters before the stockholders at an annual or special meeting.

Amendment to Certificate of Incorporation and Bylaws

Any amendment of our certificate of incorporation must first be approved by a majority of our board of directors, and if required by law or our certificate of incorporation, must thereafter be approved by a majority of the outstanding shares entitled to vote on the amendment and a majority of the outstanding shares of each class entitled to vote thereon as a class, except that the amendment of the provisions relating to stockholder action, board composition, limitation of liability and the amendment of our bylaws and certificate of incorporation must be approved by not less than two-thirds of the outstanding shares entitled to vote on the amendment, and not less than two-thirds of the outstanding shares of each class entitled to vote thereon as a class. Our bylaws may be amended by the affirmative vote of a majority of the directors then in office, subject to any limitations set forth in the bylaws; and may also be amended by the affirmative vote of a majority of the outstanding shares entitled to vote on the amendment, or, if our board of directors recommends that the stockholders approve the amendment, by the affirmative vote of the majority of the outstanding shares entitled to vote on the amendment, in each case voting together as a single class.

Choice of Forum

Our certificate of incorporation provides that, unless we consent in writing to the selection of an alternative form, the Court of Chancery of the State of Delaware will be the sole and exclusive forum for: (1) any derivative action or proceeding brought on our behalf; (2) any action asserting a claim of breach of a fiduciary duty or other wrongdoing by any of our directors, officers, employees or agents to us or our stockholders; (3) any action asserting a claim against us arising pursuant to any provision of the General Corporation Law of the State of Delaware or our certificate of incorporation or bylaws; or (4) any action asserting a claim governed by the internal affairs doctrine. Our certificate of incorporation also provides that any person or entity purchasing or otherwise acquiring any interest in shares of our capital stock will be deemed to have notice of and to have consented to this choice of forum provision. It is possible that a court of law could rule that the choice of forum provision contained in our restated certificate of incorporation is inapplicable or unenforceable if it is challenged in a proceeding or otherwise.

Section 203 of the Delaware General Corporation Law

We are subject to the provisions of Section 203 of the Delaware General Corporation Law. In general, Section 203 prohibits a publicly held Delaware corporation from engaging in a “business combination” with an “interested stockholder” for a three-year period following the time that this stockholder becomes an interested stockholder, unless the business combination is approved in a prescribed manner. Under Section 203, a business combination between a corporation and an interested stockholder is prohibited unless it satisfies one of the following conditions:

•

before the stockholder became interested, our board of directors approved either the business combination or the transaction which resulted in the stockholder becoming an interested stockholder;

•

upon consummation of the transaction which resulted in the stockholder becoming an interested stockholder, the interested stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction commenced, excluding for purposes of determining the voting stock outstanding, shares owned by persons who are directors and also officers, and employee stock plans, in some instances, but not the outstanding voting stock owned by the interested stockholder; or

•

at or after the time the stockholder became interested, the business combination was approved by our board of directors and authorized at an annual or special meeting of the stockholders by the affirmative vote of at least two-thirds of the outstanding voting stock which is not owned by the interested stockholder.

Section 203 defines a business combination to include:

•

any merger or consolidation involving the corporation and the interested stockholder;

•

any sale, transfer, lease, pledge or other disposition involving the interested stockholder of 10% or more of the assets of the corporation;

•

subject to exceptions, any transaction that results in the issuance or transfer by the corporation of any stock of the corporation to the interested stockholder;

•

subject to exceptions, any transaction involving the corporation that has the effect of increasing the proportionate share of the stock of any class or series of the corporation beneficially owned by the interested stockholder; and

•

the receipt by the interested stockholder of the benefit of any loans, advances, guarantees, pledges or other financial benefits provided by or through the corporation.

In general, Section 203 defines an interested stockholder as any entity or person beneficially owning 15% or more of the outstanding voting stock of the corporation and any entity or person affiliated with or controlling or controlled by the entity or person.

Nasdaq Global Select Market Listing

Our common stock is listed on The Nasdaq Global Select Market under the symbol “TORC.”

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Computershare Trust Company, N.A. The transfer agent and registrar’s address is 250 Royall Street, Canton, Massachusetts 02021, and its telephone number is (800) 962-4284.

DESCRIPTION OF DEBT SECURITIES

The paragraphs below describe the general terms and provisions of the debt securities we may issue. When we offer to sell a particular series of debt securities, we will describe the specific terms of the securities in a supplement to this prospectus, including any additional covenants or changes to existing covenants relating to such series. The prospectus supplement also will indicate whether the general terms and provisions described in this prospectus apply to a particular series of debt securities. You should read the actual indenture if you do not fully understand a term or the way we use it in this prospectus.

We may offer senior or subordinated debt securities. Each series of debt securities may have different terms. The senior debt securities will be issued under one or more senior indentures, dated as of a date prior to such issuance, between us and the trustee identified in the applicable prospectus supplement, as amended or supplemented from time to time. We will refer to any such indenture throughout this prospectus as the “senior indenture.” Any subordinated debt securities will be issued under one or more separate indentures, dated as of a date prior to such issuance, between us and the trustee identified in the applicable prospectus supplement, as amended or supplemented from time to time. We will refer to any such indenture throughout this prospectus as the “subordinated indenture” and to the trustee under the senior or subordinated indenture as the “trustee.” The senior indenture and the subordinated indenture are sometimes collectively referred to in this prospectus as the “indentures.” The indentures will be subject to and governed by the Trust Indenture Act of 1939, as amended. We included copies of the forms of the indentures as exhibits to our registration statement and they are incorporated into this prospectus by reference.

If we issue debt securities at a discount from their principal amount, then, for purposes of calculating the aggregate initial offering price of the offered securities issued under this prospectus, we will include only the initial offering price of the debt securities and not the principal amount of the debt securities.

We have summarized below the material provisions of the indentures and the debt securities, or indicated which material provisions will be described in the related prospectus supplement. The prospectus supplement relating to any particular securities offered will describe the specific terms of the securities, which may be in addition to or different from the general terms summarized in this prospectus. Because the summary in this prospectus and in any prospectus supplement does not contain all of the information that you may find useful, you should read the documents relating to the securities that are described in this prospectus or in any applicable prospectus supplement. Please read “Where You Can Find More Information” to find out how you can obtain a copy of those documents. Except as otherwise indicated, the terms of the indentures are identical. As used under this caption, the term “debt securities” includes the debt securities being offered by this prospectus and all other debt securities issued by us under the indentures.

General

The indentures:

•

do not limit the amount of debt securities that we may issue;

•

allow us to issue debt securities in one or more series;

•

do not require us to issue all of the debt securities of a series at the same time;

•

allow us to reopen a series to issue additional debt securities without the consent of the holders of the debt securities of such series; and

•

provide that the debt securities will be unsecured, except as may be set forth in the applicable prospectus supplement.

Unless we give you different information in the applicable prospectus supplement, the senior debt securities will be unsubordinated obligations and will rank equally with all of our other senior unsecured and unsubordinated

indebtedness. Payments on the subordinated debt securities will be subordinated to the prior payment in full of all of our senior indebtedness, as described under “Description of Debt Securities—Subordination” and in the applicable prospectus supplement.

Each indenture provides that we may, but need not, designate more than one trustee under an indenture. Any trustee under an indenture may resign or be removed and a successor trustee may be appointed to act with respect to the series of debt securities administered by the resigning or removed trustee. If two or more persons are acting as trustee with respect to different series of debt securities, each trustee shall be a trustee of a trust under the applicable indenture separate and apart from the trust administered by any other trustee. Except as otherwise indicated in this prospectus, any action described in this prospectus to be taken by each trustee may be taken by each trustee with respect to, and only with respect to, the one or more series of debt securities for which it is trustee under the applicable indenture.

The prospectus supplement for each offering will provide the following terms, where applicable:

•

the title of the debt securities and whether they are senior or subordinated;

•

the aggregate principal amount of the debt securities being offered, the aggregate principal amount of the debt securities outstanding as of the most recent practicable date and any limit on their aggregate principal amount, including the aggregate principal amount of debt securities authorized;

•

the price at which the debt securities will be issued, expressed as a percentage of the principal and, if other than the principal amount thereof, the portion of the principal amount thereof payable upon declaration of acceleration of the maturity thereof or, if applicable, the portion of the principal amount of such debt securities that is convertible into common stock or other securities of ours or the method by which any such portion shall be determined;

•

if convertible, the terms on which such debt securities are convertible, including the initial conversion price or rate and the conversion period and any applicable limitations on the ownership or transferability of common stock or other securities of ours received on conversion;

•

the date or dates, or the method for determining the date or dates, on which the principal of the debt securities will be payable;

•

the fixed or variable interest rate or rates of the debt securities, or the method by which the interest rate or rates is determined;

•

the date or dates, or the method for determining the date or dates, from which interest will accrue;

•

the dates on which interest will be payable;

•

the record dates for interest payment dates, or the method by which such dates will be determined;

•

the persons to whom interest will be payable;

•

the basis upon which interest will be calculated if other than that of a 360-day year of twelve 30-day months;

•

any make-whole amount, which is the amount in addition to principal and interest that is required to be paid to the holder of a debt security as a result of any optional redemption or accelerated payment of such debt security, or the method for determining the make-whole amount;

•

the place or places where the principal of, and any premium or make-whole amount, and interest on, the debt securities will be payable;

•

where the debt securities may be surrendered for registration of transfer or conversion or exchange;

•

where notices or demands to or upon us in respect of the debt securities and the applicable indenture may be served;

•

the times, prices and other terms and conditions upon which we may redeem the debt securities;

•

any obligation we have to redeem, repay or purchase the debt securities pursuant to any sinking fund or analogous provision or at the option of holders of the debt securities, and the times and prices at which we must redeem, repay or purchase the debt securities as a result of such obligation;

•

the currency or currencies in which the debt securities are denominated and payable if other than United States dollars, which may be a foreign currency or units of two or more foreign currencies or a composite currency or currencies and the terms and conditions relating thereto, and the manner of determining the equivalent of such foreign currency in United States dollars;

•

whether the principal of, and any premium or make-whole amount, or interest on, the debt securities of the series are to be payable, at our election or at the election of a holder, in a currency or currencies other than that in which the debt securities are denominated or stated to be payable, and other related terms and conditions;

•

whether the amount of payments of principal of, and any premium or make-whole amount, or interest on, the debt securities may be determined according to an index, formula or other method and how such amounts will be determined;

•

whether the debt securities will be in registered form, bearer form, or both, and (i) if in registered form, the person to whom any interest shall be payable, if other than the person in whose name the security is registered at the close of business on the regular record date for such interest, or (ii) if in bearer form, the manner in which, or the person to whom, any interest on the security shall be payable if otherwise than upon presentation and surrender upon maturity;

•

any restrictions applicable to the offer, sale or delivery of securities in bearer form and the terms upon which securities in bearer form of the series may be exchanged for securities in registered form of the series and vice versa, if permitted by applicable laws and regulations;

•

whether any debt securities of the series are to be issuable initially in temporary global form and whether any debt securities of the series are to be issuable in permanent global form with or without coupons and, if so, whether beneficial owners of interests in any such permanent global security may, or shall be required to, exchange their interests for other debt securities of the series, and the manner in which interest shall be paid;

•

the identity of the depositary for securities in registered form, if such series are to be issuable as a global security;

•

the date as of which any debt securities in bearer form or in temporary global form shall be dated if other than the original issuance date of the first security of the series to be issued;

•

the applicability, if any, of the defeasance and covenant defeasance provisions described in this prospectus or in the applicable indenture;

•

whether and under what circumstances we will pay any additional amounts on the debt securities in respect of any tax, assessment or governmental charge and, if so, whether we will have the option to redeem the debt securities in lieu of making such a payment;

•

whether and under what circumstances the debt securities being offered are convertible into common stock or other securities of ours, as the case may be, including the conversion price or rate and the manner or calculation thereof;

•

the circumstances, if any, specified in the applicable prospectus supplement, under which beneficial owners of interests in the global security may obtain definitive debt securities and the manner in which payments on a permanent global debt security will be made if any debt securities are issuable in temporary or permanent global form;

•

any provisions granting special rights to holders of securities upon the occurrence of such events as specified in the applicable prospectus supplement;

•

if the debt securities of such series are to be issuable in definitive form only upon receipt of certain certificates or other documents or satisfaction of other conditions, then the form and/or terms of such certificates, documents or conditions;

•

the name of the applicable trustee and the nature of any material relationship with us or any of our affiliates, and the percentage of debt securities of the class necessary to require the trustee to take action;

•

any deletions from, modifications of or additions to our events of default or covenants with regard to such debt securities and any change in the right of any trustee or any of the holders to declare the principal amount of any of such debt securities due and payable;

•

applicable CUSIP numbers; and

•

any other terms of such debt securities not inconsistent with the provisions of the applicable indenture.

We may issue debt securities that provide for less than the entire principal amount thereof to be payable upon declaration of acceleration of the maturity of the debt securities. We refer to any such debt securities throughout this prospectus as “original issue discount securities.” The applicable prospectus supplement will describe the United States federal income tax consequences and other relevant considerations applicable to original issue discount securities.

We also may issue indexed debt securities. Payments of principal of, and premium and interest on, indexed debt securities are determined with reference to the rate of exchange between the currency or currency unit in which the debt security is denominated and any other currency or currency unit specified by us, to the relationship between two or more currencies or currency units or by other similar methods or formulas specified in the prospectus supplement.

Except as described under “Merger, Consolidation or Sale of Assets” or as may be set forth in any prospectus supplement, the debt securities will not contain any provisions that (i) would limit our ability to incur indebtedness or (ii) would afford holders of debt securities protection in the event of (a) a highly leveraged or similar transaction involving us, or (b) a change of control or reorganization, restructuring, merger or similar transaction involving us that may adversely affect the holders of the debt securities. In the future, we may enter into transactions, such as the sale of all or substantially all of our assets or a merger or consolidation, that may have an adverse effect on our ability to service our indebtedness, including the debt securities, by, among other things, substantially reducing or eliminating our assets.

Our governing instruments do not define the term “substantially all” as it relates to the sale of assets. Additionally, Delaware cases interpreting the term “substantially all” rely upon the facts and circumstances of each particular case. Consequently, to determine whether a sale of “substantially all” of our assets has occurred, a holder of debt securities must review the financial and other information that we have disclosed to the public.

We will provide you with more information in the applicable prospectus supplement regarding any deletions, modifications, or additions to the events of default or covenants that are described below, including any addition of a covenant or other provision providing event risk or similar protection.

Payment

Unless we give you different information in the applicable prospectus supplement, the principal of, and any premium or make-whole amount, and interest on, any series of the debt securities will be payable at the corporate trust office of the trustee. We will provide you with the address of the trustee in the applicable prospectus supplement. We may also pay interest by mailing a check to the address of the person entitled to it as it appears in the applicable register for the debt securities or by wire transfer of funds to that person at an account maintained within the United States.

All monies that we pay to a paying agent or a trustee for the payment of the principal of, and any premium or make-whole amount, or interest on, any debt security will be repaid to us if unclaimed at the end of two years after the obligation underlying payment becomes due and payable. After funds have been returned to us, the holder of the debt security may look only to us for payment, without payment of interest for the period which we hold the funds.

Denomination, Interest, Registration and Transfer

Unless otherwise described in the applicable prospectus supplement, the debt securities of any series will be issuable in denominations of $1,000 and integral multiples of $1,000.

Subject to the limitations imposed upon debt securities that are evidenced by a computerized entry in the records of a depository company rather than by physical delivery of a note, a holder of debt securities of any series may:

•

exchange them for any authorized denomination of other debt securities of the same series and of a like aggregate principal amount and kind upon surrender of such debt securities at the corporate trust office of the applicable trustee or at the office of any transfer agent that we designate for such purpose; and

•

surrender them for registration of transfer or exchange at the corporate trust office of the applicable trustee or at the office of any transfer agent that we designate for such purpose.

Every debt security surrendered for registration of transfer or exchange must be duly endorsed or accompanied by a written instrument of transfer satisfactory to the applicable trustee or transfer agent. Payment of a service charge will not be required for any registration of transfer or exchange of any debt securities, but we or the trustee may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection therewith. If in addition to the applicable trustee, the applicable prospectus supplement refers to any transfer agent initially designated by us for any series of debt securities, we may at any time rescind the designation of any such transfer agent or approve a change in the location through which any such transfer agent acts, except that we will be required to maintain a transfer agent in each place of payment for such series. We may at any time designate additional transfer agents for any series of debt securities.

Neither we, nor any trustee, will be required to:

•

issue, register the transfer of or exchange debt securities of any series during a period beginning at the opening of business 15 days before the day that the notice of redemption of any debt securities selected for redemption is mailed and ending at the close of business on the day of such mailing;

•

register the transfer of or exchange any debt security, or portion thereof, so selected for redemption, in whole or in part, except the unredeemed portion of any debt security being redeemed in part; and

•

issue, register the transfer of or exchange any debt security that has been surrendered for repayment at the option of the holder, except the portion, if any, of such debt security not to be so repaid.

Merger, Consolidation or Sale of Assets

The indentures provide that we may, without the consent of the holders of any outstanding debt securities, (i) consolidate with, (ii) sell, lease or convey all or substantially all of our assets to, or (iii) merge with or into, any other entity provided that:

•

either we are the continuing entity, or the successor entity, if other than us, assumes the obligations (a) to pay the principal of, and any premium or make-whole amount, and interest on, all of the debt securities and (b) to duly perform and observe all of the covenants and conditions contained in each indenture;

•

after giving effect to the transaction, there is no event of default under the indentures and no event which, after notice or the lapse of time, or both, would become such an event of default, occurs and continues; and

•

an officers’ certificate and legal opinion covering such conditions are delivered to each applicable trustee.

Covenants

Existence. Except as described under “Merger, Consolidation or Sale of Assets,” the indentures require us to do or cause to be done all things necessary to preserve and keep in full force and effect our existence, rights and franchises. However, the indentures do not require us to preserve any right or franchise if we determine that any right or franchise is no longer desirable in the conduct of our business.

Payment of taxes and other claims. The indentures require us to pay, discharge or cause to be paid or discharged, before they become delinquent (i) all taxes, assessments and governmental charges levied or imposed on us, and (ii) all lawful claims for labor, materials and supplies which, if unpaid, might by law become a lien upon our property. However, we will not be required to pay, discharge or cause to be paid or discharged any such tax, assessment, charge or claim whose amount, applicability or validity is being contested in good faith by appropriate proceedings.

Provision of financial information. The indentures require us to (i) within 15 days of each of the respective dates by which we are required to file our annual reports, quarterly reports and other documents with the SEC, file with the trustee copies of the annual report, quarterly report and other documents that we file with the SEC under Section 13 or 15(d) of the Exchange Act, (ii) file with the trustee and the SEC any additional information, documents and reports regarding compliance by us with the conditions and covenants of the indentures, as required, (iii) within 30 days after the filing with the trustee, mail to all holders of debt securities, as their names and addresses appear in the applicable register for such debt securities, without cost to such holders, summaries of any documents and reports required to be filed by us pursuant to (i) and (ii) above, and (iv) supply, promptly upon written request and payment of the reasonable cost of duplication and delivery, copies of such documents to any prospective holder.

Additional covenants. The applicable prospectus supplement will set forth any of our additional covenants relating to any series of debt securities.

Events of Default, Notice and Waiver

Unless the applicable prospectus supplement states otherwise, when we refer to “events of default” as defined in the indentures with respect to any series of debt securities, we mean:

•

default in the payment of any installment of interest on any debt security of such series continuing for 30 days;

•

default in the payment of principal of, or any premium or make-whole amount on, any debt security of such series for five business days at its stated maturity;

•

default in making any sinking fund payment as required for any debt security of such series for five business days;

•

default in the performance or breach of any covenant or warranty in the debt securities or in the indenture by us continuing for 60 days after written notice as provided in the applicable indenture, but not of a covenant added to the indenture solely for the benefit of a series of debt securities issued thereunder other than such series;

•

a default under any bond, debenture, note, mortgage, indenture or instrument:

(i)

having an aggregate principal amount of at least $30,000,000; or

(ii)

under which there may be issued, secured or evidenced any existing or later created indebtedness for money borrowed by us, if we are directly responsible or liable as obligor or guarantor,

if the default results in the indebtedness becoming or being declared due and payable prior to the date it otherwise would have, without such indebtedness having been discharged, or such acceleration having been rescinded or annulled, within 30 days after notice to the issuing company specifying such default. Such notice shall be given to us by the trustee, or to us and the trustee by the holders of at least 10% in principal amount of the outstanding debt securities of that series. The written notice shall specify such default and require us to cause such indebtedness to be discharged or cause such acceleration to be rescinded or annulled and shall state that such notice is a “Notice of Default” under such indenture;

•

bankruptcy, insolvency or reorganization, or court appointment of a receiver, liquidator or trustee of us; and

•

any other event of default provided with respect to a particular series of debt securities.

If an event of default occurs and is continuing with respect to debt securities of any series outstanding, then the applicable trustee or the holders of 25% or more in principal amount of the debt securities of that series will have the right to declare the principal amount of all the debt securities of that series to be due and payable. If the debt securities of that series are original issue discount securities or indexed securities, then the applicable trustee or the holders of 25% or more in principal amount of the debt securities of that series will have the right to declare the portion of the principal amount as may be specified in the terms thereof to be due and payable. However, at any time after such a declaration of acceleration has been made, but before a judgment or decree for payment of the money due has been obtained by the applicable trustee, the holders of at least a majority in principal amount of outstanding debt securities of such series or of all debt securities then outstanding under the applicable indenture may rescind and annul such declaration and its consequences if:

•

we have deposited with the applicable trustee all required payments of the principal, any premium or make-whole amount, interest and, to the extent permitted by law, interest on overdue installment of interest, plus applicable fees, expenses, disbursements and advances of the applicable trustee; and

•

all events of default, other than the non-payment of accelerated principal, or a specified portion thereof, and any premium or make-whole amount, have been cured or waived.

The indentures also provide that the holders of at least a majority in principal amount of the outstanding debt securities of any series or of all debt securities then outstanding under the applicable indenture may, on behalf of all holders, waive any past default with respect to such series and its consequences, except a default:

•

in the payment of the principal, any premium or make-whole amount, or interest;

•

in respect of a covenant or provision contained in the applicable indenture that cannot be modified or amended without the consent of the holders of the outstanding debt security that is affected by the default; or

•

in respect of a covenant or provision for the benefit or protection of the trustee, without its express written consent.

The indentures require each trustee to give notice to the holders of debt securities within 90 days of a default unless such default has been cured or waived. However, the trustee may withhold notice if specified persons of such trustee consider such withholding to be in the interest of the holders of debt securities. The trustee may not withhold notice of a default in the payment of principal, any premium or interest on any debt security of such series or in the payment of any sinking fund installment in respect of any debt security of such series.

The indentures provide that holders of debt securities of any series may not institute any proceedings, judicial or otherwise, with respect to such indenture or for any remedy under the indenture, unless the trustee

fails to act for a period of 60 days after the trustee has received a written request to institute proceedings in respect of an event of default from the holders of 25% or more in principal amount of the outstanding debt securities of such series, as well as an offer of indemnity reasonably satisfactory to the trustee. However, this provision will not prevent any holder of debt securities from instituting suit for the enforcement of payment of the principal of, and any premium or make-whole amount, and interest on, such debt securities at the respective due dates thereof.

The indentures provide that, subject to provisions in each indenture relating to its duties in the case of a default, a trustee has no obligation to exercise any of its rights or powers at the request or direction of any holders of any series of debt securities then outstanding under the indenture, unless the holders have offered to the trustee reasonable security or indemnity. The holders of at least a majority in principal amount of the outstanding debt securities of any series or of all debt securities then outstanding under an indenture shall have the right to direct the time, method and place of conducting any proceeding for any remedy available to the applicable trustee, or of exercising any trust or power conferred upon such trustee. However, a trustee may refuse to follow any direction which:

•

is in conflict with any law or the applicable indenture;

•

may involve the trustee in personal liability; or

•

may be unduly prejudicial to the holders of debt securities of the series not joining the proceeding.

Within 120 days after the close of each fiscal year, we will be required to deliver to each trustee a certificate, signed by one of our several specified officers, stating whether or not that officer has knowledge of any default under the applicable indenture. If the officer has knowledge of any default, the notice must specify the nature and status of the default.

Modification of the Indentures

The indentures provide that modifications and amendments may be made only with the consent of the affected holders of a majority in principal amount of all outstanding debt securities issued under that indenture. However, no such modification or amendment may, without the consent of the holders of the debt securities affected by the modification or amendment:

•

change the stated maturity of the principal of, or any premium or make-whole amount on, or any installment of principal of or interest on, any such debt security;

•

reduce the principal amount of, the rate or amount of interest on, or any premium or make-whole amount payable on redemption of, any such debt security;

•

reduce the amount of principal of an original issue discount security that would be due and payable upon declaration of acceleration of the maturity thereof or would be provable in bankruptcy, or adversely affect any right of repayment of the holder of any such debt security;

•

change the place of payment or the coin or currency for payment of principal of, or any premium or make-whole amount, or interest on, any such debt security;

•

impair the right to institute suit for the enforcement of any payment on or with respect to any such debt security;

•

reduce the percentage in principal amount of any outstanding debt securities necessary to modify or amend the applicable indenture with respect to such debt securities, to waive compliance with particular provisions thereof or defaults and consequences thereunder or to reduce the quorum or voting requirements set forth in the applicable indenture; and

•

modify any of the foregoing provisions or any of the provisions relating to the waiver of particular past defaults or covenants, except to increase the required percentage to effect such action or to provide that some of the other provisions may not be modified or waived without the consent of the holder of such debt security.

The holders of a majority in aggregate principal amount of the outstanding debt securities of each series may, on behalf of all holders of debt securities of that series, waive, insofar as that series is concerned, our compliance with material restrictive covenants of the applicable indenture.

We and our respective trustee may make modifications and amendments of an indenture without the consent of any holder of debt securities for any of the following purposes:

•

to evidence the succession of another person to us as obligor under such indenture;

•

to add to our covenants for the benefit of the holders of all or any series of debt securities or to surrender any right or power conferred upon us in such indenture;

•

to add events of default for the benefit of the holders of all or any series of debt securities;

•

to add or change any provisions of an indenture (i) to change or eliminate restrictions on the payment of principal of, or premium or make-whole amount, or interest on, debt securities in bearer form, or (ii) to permit or facilitate the issuance of debt securities in uncertificated form, provided that such action shall not adversely affect the interests of the holders of the debt securities of any series in any material respect;

•

to change or eliminate any provisions of an indenture, provided that any such change or elimination shall become effective only when there are no debt securities outstanding of any series created prior thereto which are entitled to the benefit of such provision;

•

to secure the debt securities;

•

to establish the form or terms of debt securities of any series;

•

to provide for the acceptance of appointment by a successor trustee or facilitate the administration of the trusts under an indenture by more than one trustee;

•

to cure any ambiguity, defect or inconsistency in an indenture, provided that such action shall not adversely affect the interests of holders of debt securities of any series issued under such indenture; and

•

to supplement any of the provisions of an indenture to the extent necessary to permit or facilitate defeasance and discharge of any series of such debt securities, provided that such action shall not adversely affect the interests of the holders of the outstanding debt securities of any series.

Voting

The indentures provide that in determining whether the holders of the requisite principal amount of outstanding debt securities of a series have given any request, demand, authorization, direction, notice, consent or waiver under the indentures or whether a quorum is present at a meeting of holders of debt securities:

•

the principal amount of an original issue discount security that shall be deemed to be outstanding shall be the amount of the principal thereof that would be due and payable as of the date of such determination upon declaration of acceleration of the maturity thereof;

•

the principal amount of any debt security denominated in a foreign currency that shall be deemed outstanding shall be the United States dollar equivalent, determined on the issue date for such debt security, of the principal amount or, in the case of an original issue discount security, the United States dollar equivalent on the issue date of such debt security of the amount determined as provided in the preceding bullet point;

•

the principal amount of an indexed security that shall be deemed outstanding shall be the principal face amount of such indexed security at original issuance, unless otherwise provided for such indexed security under such indenture; and

•

debt securities owned by us or any other obligor upon the debt securities or by any affiliate of ours or of such other obligor shall be disregarded.

The indentures contain provisions for convening meetings of the holders of debt securities of a series. A meeting will be permitted to be called at any time by the applicable trustee, and also, upon request, by us or the holders of at least 25% in principal amount of the outstanding debt securities of such series, in any such case upon notice given as provided in such indenture. Except for any consent that must be given by the holder of each debt security affected by the modifications and amendments of an indenture described above, any resolution presented at a meeting or adjourned meeting duly reconvened at which a quorum is present may be adopted by the affirmative vote of the holders of a majority of the aggregate principal amount of the outstanding debt securities of that series represented at such meeting.

Notwithstanding the preceding paragraph, except as referred to above, any resolution relating to a request, demand, authorization, direction, notice, consent, waiver or other action that may be made, given or taken by the holders of a specified percentage, which is less than a majority of the aggregate principal amount of the outstanding debt securities of a series, may be adopted at a meeting or adjourned meeting duly reconvened at which a quorum is present by the affirmative vote of such specified percentage.

Any resolution passed or decision taken at any properly held meeting of holders of debt securities of any series will be binding on all holders of such series. The quorum at any meeting called to adopt a resolution, and at any reconvened meeting, will be persons holding or representing a majority in principal amount of the outstanding debt securities of a series. However, if any action is to be taken relating to a consent or waiver which may be given by the holders of at least a specified percentage in principal amount of the outstanding debt securities of a series, the persons holding such percentage will constitute a quorum.

Notwithstanding the foregoing provisions, the indentures provide that if any action is to be taken at a meeting with respect to any request, demand, authorization, direction, notice, consent, waiver or other action that such indenture expressly provides may be made, given or taken by the holders of a specified percentage in principal amount of all outstanding debt securities affected by such action, or of the holders of such series and one or more additional series:

•

there shall be no minimum quorum requirement for such meeting; and

•

the principal amount of the outstanding debt securities of such series that vote in favor of such request, demand, authorization, direction, notice, consent, waiver or other action shall be taken account in determining whether such request, demand, authorization, direction, notice, consent, waiver or other action has been made, given or taken under such indenture.

Subordination

Unless otherwise provided in the applicable prospectus supplement, subordinated debt securities will be subject to the following subordination provisions.

Upon any distribution to our creditors in a liquidation, dissolution or reorganization, the payment of the principal of and interest on any subordinated debt securities will be subordinated to the extent provided in the applicable indenture in right of payment to the prior payment in full of all senior debt. However, our obligation to make payments of the principal of and interest on such subordinated debt securities otherwise will not be affected. No payment of principal or interest will be permitted to be made on subordinated debt securities at any time if a default on senior debt exists that permits the holders of such senior debt to accelerate its maturity and the default is the subject of judicial proceedings or we receive notice of the default. After all senior debt is paid in full and until the subordinated debt securities are paid in full, holders of subordinated debt securities will be subrogated to the rights of holders of senior debt to the extent that distributions otherwise payable to holders of subordinated debt securities have been applied to the payment of senior debt. The subordinated indenture will not restrict the amount of senior debt or other indebtedness of ours. As a result of these subordination provisions, in the event of a distribution of assets upon insolvency, holders of subordinated debt securities may recover less, ratably, than our general creditors.

The term “senior debt” will be defined in the applicable indenture as the principal of and interest on, or substantially similar payments to be made by us in respect of, other outstanding indebtedness, whether outstanding at the date of execution of the applicable indenture or subsequently incurred, created or assumed. The prospectus supplement may include a description of additional terms implementing the subordination feature.

No restrictions will be included in any indenture relating to subordinated debt securities upon the creation of additional senior debt.

If this prospectus is being delivered in connection with the offering of a series of subordinated debt securities, the accompanying prospectus supplement or the information incorporated in this prospectus by reference will set forth the approximate amount of senior debt outstanding as of the end of our most recent fiscal quarter.

Discharge, Defeasance and Covenant Defeasance

Unless otherwise indicated in the applicable prospectus supplement, the indentures allow us to discharge our obligations to holders of any series of debt securities issued under any indenture when:

•

either (i) all securities of such series have already been delivered to the applicable trustee for cancellation; or (ii) all securities of such series have not already been delivered to the applicable trustee for cancellation but (a) have become due and payable, (b) will become due and payable within one year, or (c) if redeemable at our option, are to be redeemed within one year, and we have irrevocably deposited with the applicable trustee, in trust, funds in such currency or currencies, currency unit or units or composite currency or currencies in which such debt securities are payable, an amount sufficient to pay the entire indebtedness on such debt securities in respect of principal and any premium or make-whole amount, and interest to the date of such deposit if such debt securities have become due and payable or, if they have not, to the stated maturity or redemption date;

•

we have paid or caused to be paid all other sums payable; and

•

an officers’ certificate and an opinion of counsel stating the conditions to discharging the debt securities have been satisfied has been delivered to the trustee.

Unless otherwise indicated in the applicable prospectus supplement, the indentures provide that, upon our irrevocable deposit with the applicable trustee, in trust, of an amount, in such currency or currencies, currency unit or units or composite currency or currencies in which such debt securities are payable at stated maturity, or government obligations, or both, applicable to such debt securities, which through the scheduled payment of principal and interest in accordance with their terms will provide money in an amount sufficient to pay the principal of, and any premium or make-whole amount, and interest on, such debt securities, and any mandatory sinking fund or analogous payments thereon, on the scheduled due dates therefor, the issuing company may elect either:

•

to defease and be discharged from any and all obligations with respect to such debt securities; or

•

to be released from its obligations with respect to such debt securities under the applicable indenture or, if provided in the applicable prospectus supplement, its obligations with respect to any other covenant, and any omission to comply with such obligations shall not constitute an event of default with respect to such debt securities.

Notwithstanding the above, we may not elect to defease and be discharged from the obligation to pay any additional amounts upon the occurrence of particular events of tax, assessment or governmental charge with respect to payments on such debt securities and the obligations to register the transfer or exchange of such debt securities, to replace temporary or mutilated, destroyed, lost or stolen debt securities, to maintain an office or agency in respect of such debt securities, or to hold monies for payment in trust.

The indentures only permit us to establish the trust described in the paragraph above if, among other things, we have delivered to the applicable trustee an opinion of counsel to the effect that the holders of such debt securities will not recognize income, gain or loss for United States federal income tax purposes as a result of such defeasance or covenant defeasance and will be subject to United States federal income tax on the same amounts, in the same manner and at the same times as would have been the case if such defeasance or covenant defeasance had not occurred. Such opinion of counsel, in the case of defeasance, will be required to refer to and be based upon a ruling received from or published by the Internal Revenue Service or a change in applicable United States federal income tax law occurring after the date of the indenture. In the event of such defeasance, the holders of such debt securities would be able to look only to such trust fund for payment of principal, any premium or make-whole amount, and interest.

When we use the term “government obligations,” we mean securities that are:

•

direct obligations of the United States or the government that issued the foreign currency in which the debt securities of a particular series are payable, for the payment of which its full faith and credit is pledged; or

•

obligations of a person controlled or supervised by and acting as an agency or instrumentality of the United States or other government that issued the foreign currency in which the debt securities of such series are payable, the payment of which is unconditionally guaranteed as a full faith and credit obligation by the United States or such other government, which are not callable or redeemable at the option of the issuer thereof and shall also include a depository receipt issued by a bank or trust company as custodian with respect to any such government obligation or a specific payment of interest on or principal of any such government obligation held by such custodian for the account of the holder of a depository receipt. However, except as required by law, such custodian is not authorized to make any deduction from the amount payable to the holder of such depository receipt from any amount received by the custodian in respect of the government obligation or the specific payment of interest on or principal of the government obligation evidenced by such depository receipt.

Unless otherwise provided in the applicable prospectus supplement, if after we have deposited funds and/or government obligations to effect defeasance or covenant defeasance with respect to debt securities of any series, (i) the holder of a debt security of such series is entitled to, and does, elect under the terms of the applicable indenture or the terms of such debt security to receive payment in a currency, currency unit or composite currency other than that in which such deposit has been made in respect of such debt security, or (ii) a conversion event occurs in respect of the currency, currency unit or composite currency in which such deposit has been made, the indebtedness represented by such debt security will be deemed to have been, and will be, fully discharged and satisfied through the payment of the principal of, and premium or make-whole amount, and interest on, such debt security as they become due out of the proceeds yielded by converting the amount so deposited in respect of such debt security into the currency, currency unit or composite currency in which such debt security becomes payable as a result of such election or such cessation of usage based on the applicable market exchange rate.

When we use the term “conversion event,” we mean the cessation of use of:

•

a currency, currency unit or composite currency both by the government of the country that issued such currency and for the settlement of transactions by a central bank or other public institutions of or within the international banking community;

•

the European Currency Unit both within the European Monetary System and for the settlement of transactions by public institutions of or within the European Communities; or

•

any currency unit or composite currency other than the European Currency Unit for the purposes for which it was established.

Unless otherwise provided in the applicable prospectus supplement, all payments of principal of, and any premium or make-whole amount, and interest on, any debt security that is payable in a foreign currency that ceases to be used by its government of issuance shall be made in United States dollars.

In the event that (i) we effect covenant defeasance with respect to any debt securities and (ii) those debt securities are declared due and payable because of the occurrence of any event of default, the amount in the currency, currency unit or composite currency in which such debt securities are payable, and government obligations on deposit with the applicable trustee, will be sufficient to pay amounts due on such debt securities at the time of their stated maturity but may not be sufficient to pay amounts due on such debt securities at the time of the acceleration resulting from such event of default. However, the issuing company would remain liable to make payments of any amounts due at the time of acceleration.

The applicable prospectus supplement may further describe the provisions, if any, permitting such defeasance or covenant defeasance, including any modifications to the provisions described above, with respect to the debt securities of or within a particular series.

Conversion Rights

The terms and conditions, if any, upon which the debt securities are convertible into common stock or other securities of ours will be set forth in the applicable prospectus supplement. The terms will include whether the debt securities are convertible into shares of common stock or other securities of ours, the conversion price, or manner of calculation thereof, the conversion period, provisions as to whether conversion will be at the issuing company’s option or the option of the holders, the events requiring an adjustment of the conversion price and provisions affecting conversion in the event of the redemption of the debt securities and any restrictions on conversion.

Global Securities

The debt securities of a series may be issued in whole or in part in the form of one or more global securities that will be deposited with, or on behalf of, a depository identified in the applicable prospectus supplement relating to such series. Global securities, if any, issued in the United States are expected to be deposited with The Depository Trust Company, or DTC, as depository. We may issue global securities in either registered or bearer form and in either temporary or permanent form. We will describe the specific terms of the depository arrangement with respect to a series of debt securities in the applicable prospectus supplement relating to such series. We expect that unless the applicable prospectus supplement provides otherwise, the following provisions will apply to depository arrangements.

Once a global security is issued, the depository for such global security or its nominee will credit on its book-entry registration and transfer system the respective principal amounts of the individual debt securities represented by such global security to the accounts of participants that have accounts with such depository. Such accounts shall be designated by the underwriters, dealers or agents with respect to such debt securities or by us if we offer such debt securities directly. Ownership of beneficial interests in such global security will be limited to participants with the depository or persons that may hold interests through those participants.

We expect that, under procedures established by DTC, ownership of beneficial interests in any global security for which DTC is the depository will be shown on, and the transfer of that ownership will be effected only through, records maintained by DTC or its nominee, with respect to beneficial interests of participants with the depository, and records of participants, with respect to beneficial interests of persons who hold through participants with the depository. Neither we nor the trustee will have any responsibility or liability for any aspect of the records of DTC or for maintaining, supervising or reviewing any records of DTC or any of its participants relating to beneficial ownership interests in the debt securities. The laws of some states require that certain purchasers of securities take physical delivery of such securities in definitive form. Such limits and laws may impair the ability to own, pledge or transfer beneficial interest in a global security.

So long as the depository for a global security or its nominee is the registered owner of such global security, such depository or such nominee, as the case may be, will be considered the sole owner or holder of the debt securities represented by the global security for all purposes under the applicable indenture. Except as described below or in the applicable prospectus supplement, owners of beneficial interest in a global security will not be entitled to have any of the individual debt securities represented by such global security registered in their names, will not receive or be entitled to receive physical delivery of any such debt securities in definitive form and will not be considered the owners or holders thereof under the applicable indenture. Beneficial owners of debt securities evidenced by a global security will not be considered the owners or holders thereof under the applicable indenture for any purpose, including with respect to the giving of any direction, instructions or approvals to the trustee under the indenture. Accordingly, each person owning a beneficial interest in a global security with respect to which DTC is the depository must rely on the procedures of DTC and, if such person is not a participant with the depository, on the procedures of the participant through which such person owns its interests, to exercise any rights of a holder under the applicable indenture. We understand that, under existing industry practice, if DTC requests any action of holders or if an owner of a beneficial interest in a global security desires to give or take any action which a holder is entitled to give or take under the applicable indenture, DTC would authorize the participants holding the relevant beneficial interest to give or take such action, and such participants would authorize beneficial owners through such participants to give or take such actions or would otherwise act upon the instructions of beneficial owners holding through them.

Payments of principal of, and any premium or make-whole amount, and interest on, individual debt securities represented by a global security registered in the name of a depository or its nominee will be made to or at the direction of the depository or its nominee, as the case may be, as the registered owner of the global security under the applicable indenture. Under the terms of the applicable indenture, we and the trustee may treat the persons in whose name debt securities, including a global security, are registered as the owners thereof for the purpose of receiving such payments. Consequently, neither we nor the trustee have or will have any responsibility or liability for the payment of such amounts to beneficial owners of debt securities including principal, any premium or make-whole amount, or interest. We believe, however, that it is currently the policy of DTC to immediately credit the accounts of relevant participants with such payments, in amounts proportionate to their respective holdings of beneficial interests in the relevant global security as shown on the records of DTC or its nominee. We also expect that payments by participants to owners of beneficial interests in such global security held through such participants will be governed by standing instructions and customary practices, as is the case with securities held for the account of customers in bearer form or registered in street name, and will be the responsibility of such participants. Redemption notices with respect to any debt securities represented by a global security will be sent to the depository or its nominee. If less than all of the debt securities of any series are to be redeemed, we expect the depository to determine the amount of the interest of each participant in such debt securities to be redeemed to be determined by lot. Neither we, the trustee, any paying agent nor the security registrar for such debt securities will have any responsibility or liability for any aspect of the records relating to or payments made on account of beneficial ownership interests in the global security for such debt securities or for maintaining any records with respect thereto.

Neither we nor the trustee will be liable for any delay by the holders of a global security or the depository in identifying the beneficial owners of debt securities, and we and the trustee may conclusively rely on, and will be protected in relying on, instructions from the holder of a global security or the depository for all purposes. The rules applicable to DTC and its participants are on file with the SEC.

If a depository for any debt securities is at any time unwilling, unable or ineligible to continue as depository and we do not appoint a successor depository within 90 days, we will issue individual debt securities in exchange for the global security representing such debt securities. In addition, we may at any time and at our sole discretion, subject to any limitations described in the applicable prospectus supplement relating to such debt securities, determine not to have any of such debt securities represented by one or more global securities and in such event will issue individual debt securities in exchange for the global security or securities representing such debt securities. Individual debt securities so issued will be issued in denominations of $1,000 and integral multiples of $1,000.

The debt securities of a series may also be issued in whole or in part in the form of one or more bearer global securities that will be deposited with a depository, or with a nominee for such depository, identified in the applicable prospectus supplement. Any such bearer global securities may be issued in temporary or permanent form. The specific terms and procedures, including the specific terms of the depositary arrangement, with respect to any portion of a series of debt securities to be represented by one or more bearer global securities will be described in the applicable prospectus supplement.

No Recourse

There is no recourse under any obligation, covenant or agreement in the applicable indenture or with respect to any security against any of our or our successor’s past, present or future shareholders, employees, officers or directors.

DESCRIPTION OF WARRANTS

The following description, together with the additional information we may include in any applicable prospectus supplements, summarizes the material terms and provisions of the warrants that we may offer under this prospectus and the related warrant agreements and warrant certificates. While the terms summarized below will apply generally to any warrants that we may offer, we will describe the particular terms of any series of warrants in more detail in the applicable prospectus supplement. If we indicate in the prospectus supplement, the terms of any warrants offered under that prospectus supplement may differ from the terms described below. Specific warrant agreements will contain additional important terms and provisions and will be incorporated by reference as an exhibit to the registration statement, which includes this prospectus.

General

We may issue warrants for the purchase of common stock, preferred stock and/or debt securities in one or more series. We may issue warrants independently or together with common stock, preferred stock and/or debt securities, and the warrants may be attached to or separate from these securities.

We will evidence each series of warrants by warrant certificates that we will issue under a separate warrant agreement. We will enter into the warrant agreement with a warrant agent. We will indicate the name and address of the warrant agent in the applicable prospectus supplement relating to a particular series of warrants.

We will describe in the applicable prospectus supplement the terms of the series of warrants, including:

•

the offering price and aggregate number of warrants offered;

•

the currency for which the warrants may be purchased;

•

if applicable, the designation and terms of the securities with which the warrants are issued and the number of warrants issued with each such security or each principal amount of such security;

•

if applicable, the date on and after which the warrants and the related securities will be separately transferable;

•

in the case of warrants to purchase debt securities, the principal amount of debt securities purchasable upon exercise of one warrant and the price at, and currency in which, this principal amount of debt securities may be purchased upon such exercise;

•

in the case of warrants to purchase common stock or preferred stock, the number of shares of common stock or preferred stock, as the case may be, purchasable upon the exercise of one warrant and the price at which these shares may be purchased upon such exercise;

•

the effect of any merger, consolidation, sale or other disposition of our business on the warrant agreement and the warrants;

•

the terms of any rights to redeem or call the warrants;

•

any provisions for changes to or adjustments in the exercise price or number of securities issuable upon exercise of the warrants;

•

the periods during which, and places at which, the warrants are exercisable;

•

the manner of exercise;

•

the dates on which the right to exercise the warrants will commence and expire;

•

the manner in which the warrant agreement and warrants may be modified;

•

federal income tax consequences of holding or exercising the warrants;

•

the terms of the securities issuable upon exercise of the warrants; and

•

any other specific terms, preferences, rights or limitations of or restrictions on the warrants.

DESCRIPTION OF UNITS

We may issue units comprised of shares of common stock, shares of preferred stock, debt securities and warrants in any combination. We may issue units in such amounts and in as many distinct series as we wish. This section outlines certain provisions of the units that we may issue. If we issue units, they will be issued under one or more unit agreements to be entered into between us and a bank or other financial institution, as unit agent. The information described in this section may not be complete in all respects and is qualified entirely by reference to the unit agreement with respect to the units of any particular series. The specific terms of any series of units offered will be described in the applicable prospectus supplement. If so described in a particular supplement, the specific terms of any series of units may differ from the general description of terms presented below. We urge you to read any prospectus supplement related to any series of units we may offer, as well as the complete unit agreement and unit certificate that contain the terms of the units. If we issue units, forms of unit agreements and unit certificates relating to such units will be incorporated by reference as exhibits to the registration statement, which includes this prospectus.

Each unit that we may issue will be issued so that the holder of the unit is also the holder of each security included in the unit. Thus, the holder of a unit will have the rights and obligations of a holder of each included security. The unit agreement under which a unit is issued may provide that the securities included in the unit may not be held or transferred separately, at any time or at any time before a specified date. The applicable prospectus supplement may describe:

•

the designation and terms of the units and of the securities comprising the units, including whether and under what circumstances those securities may be held or transferred separately;

•

any provisions of the governing unit agreement;

•

the price or prices at which such units will be issued;

•

the applicable United States federal income tax considerations relating to the units;

•

any provisions for the issuance, payment, settlement, transfer or exchange of the units or of the securities comprising the units; and

•

any other terms of the units and of the securities comprising the units.

The provisions described in this section, as well as those described under “Description of Capital Stock,” “Description of Debt Securities” and “Description of Warrants” will apply to the securities included in each unit, to the extent relevant and as may be updated in any prospectus supplements.

Issuance in Series

We may issue units in such amounts and in as many distinct series as we wish. This section summarizes terms of the units that apply generally to all series. Most of the financial and other specific terms of your series will be described in the applicable prospectus supplement.

Unit Agreements

We will issue the units under one or more unit agreements to be entered into between us and a bank or other financial institution, as unit agent. We may add, replace or terminate unit agents from time to time. We will identify the unit agreement under which each series of units will be issued and the unit agent under that agreement in the applicable prospectus supplement.

The following provisions will generally apply to all unit agreements unless otherwise stated in the applicable prospectus supplement:

Modification without Consent

We and the applicable unit agent may amend any unit or unit agreement without the consent of any holder:

•

to cure any ambiguity, including modifying any provisions of the governing unit agreement that differ from those described below;

•

to correct or supplement any defective or inconsistent provision; or

•

to make any other change that we believe is necessary or desirable and will not adversely affect the interests of the affected holders in any material respect.

We do not need any approval to make changes that affect only units to be issued after the changes take effect. We may also make changes that do not adversely affect a particular unit in any material respect, even if they adversely affect other units in a material respect. In those cases, we do not need to obtain the approval of the holder of the unaffected unit; we need only obtain any required approvals from the holders of the affected units.

Modification with Consent

We may not amend any particular unit or a unit agreement with respect to any particular unit unless we obtain the consent of the holder of that unit, if the amendment would:

•

impair any right of the holder to exercise or enforce any right under a security included in the unit if the terms of that security require the consent of the holder to any changes that would impair the exercise or enforcement of that right; or

•

reduce the percentage of outstanding units or any series or class the consent of whose holders is required to amend that series or class, or the applicable unit agreement with respect to that series or class, as described below.

Any other change to a particular unit agreement and the units issued under that agreement would require the following approval:

•

If the change affects only the units of a particular series issued under that agreement, the change must be approved by the holders of a majority of the outstanding units of that series; or

•

If the change affects the units of more than one series issued under that agreement, it must be approved by the holders of a majority of all outstanding units of all series affected by the change, with the units of all the affected series voting together as one class for this purpose.

These provisions regarding changes with majority approval also apply to changes affecting any securities issued under a unit agreement, as the governing document.

In each case, the required approval must be given by written consent.

Unit Agreements Will Not Be Qualified under Trust Indenture Act

No unit agreement will be qualified as an indenture, and no unit agent will be required to qualify as a trustee, under the Trust Indenture Act. Therefore, holders of units issued under unit agreements will not have the protections of the Trust Indenture Act with respect to their units.

Mergers and Similar Transactions Permitted; No Restrictive Covenants or Events of Default

The unit agreements will not restrict our ability to merge or consolidate with, or sell our assets to, another corporation or other entity or to engage in any other transactions. If at any time we merge or consolidate with, or

sell our assets substantially as an entirety to, another corporation or other entity, the successor entity will succeed to and assume our obligations under the unit agreements. We will then be relieved of any further obligation under these agreements.

The unit agreements will not include any restrictions on our ability to put liens on our assets, nor will they restrict our ability to sell our assets. The unit agreements also will not provide for any events of default or remedies upon the occurrence of any events of default.

Governing Law

The unit agreements and the units will be governed by Delaware law.

Form, Exchange and Transfer

Unless the accompanying prospectus supplement states otherwise, we will issue each unit in global—i.e., book-entry—form only. Units in book-entry form will be represented by a global security registered in the name of a depositary, which will be the holder of all the units represented by the global security. Those who own beneficial interests in a unit will do so through participants in the depositary’s system, and the rights of these indirect owners will be governed solely by the applicable procedures of the depositary and its participants. We will describe book-entry securities, and other terms regarding the issuance and registration of the units in the applicable prospectus supplement.

Unless the accompanying prospectus supplement states otherwise, each unit and all securities comprising the unit will be issued in the same form.

If we issue any units in registered, non-global form, the following will apply to them.

The units will be issued in the denominations stated in the applicable prospectus supplement. Holders may exchange their units for units of smaller denominations or combined into fewer units of larger denominations, as long as the total amount is not changed.

•

Holders may exchange or transfer their units at the office of the unit agent. Holders may also replace lost, stolen, destroyed or mutilated units at that office. We may appoint another entity to perform these functions or perform them ourselves.

•

Holders will not be required to pay a service charge to transfer or exchange their units, but they may be required to pay for any tax or other governmental charge associated with the transfer or exchange. The transfer or exchange, and any replacement, will be made only if our transfer agent is satisfied with the holder’s proof of legal ownership. The transfer agent may also require an indemnity before replacing any units.

•

If we have the right to redeem, accelerate or settle any units before their maturity, and we exercise our right as to less than all those units or other securities, we may block the exchange or transfer of those units during the period beginning 15 days before the day we mail the notice of exercise and ending on the day of that mailing, in order to freeze the list of holders to prepare the mailing. We may also refuse to register transfers of or exchange any unit selected for early settlement, except that we will continue to permit transfers and exchanges of the unsettled portion of any unit being partially settled. We may also block the transfer or exchange of any unit in this manner if the unit includes securities that are or may be selected for early settlement.

Only the depositary will be entitled to transfer or exchange a unit in global form, since it will be the sole holder of the unit.

Payments and Notices

In making payments and giving notices with respect to our units, we will follow the procedures as described in the applicable prospectus supplement.

SELLING STOCKHOLDERS

This prospectus also relates to the possible resale from time to time by the stockholders named herein, who we refer to in this prospectus as the “selling stockholders,” of up to an aggregate maximum amount of 12,445,646 shares of our common stock in one or more offerings, subject to market conditions and prices, liquidity objectives and other investment considerations. Such shares of common stock were issued and outstanding prior to the original filing date of the registration statement of which this prospectus forms a part. The selling stockholders originally acquired the shares of our common stock included in this prospectus through (i) our initial public offering or otherwise on the open market, and (ii) several private placements of our common stock or convertible preferred stock prior to our initial public offering, with all such shares of convertible preferred stock converted into shares of our common stock in connection with our initial public offering. Additional information about the selling stockholders, where applicable, will be set forth in an applicable prospectus supplement, documents incorporated by reference in this prospectus or in a free writing prospectus we file with the SEC. We will not receive any proceeds from the resale of the common stock by the selling stockholders.

The following table sets forth the information about the selling stockholders, including the number of shares of our common stock beneficially owned by such selling stockholders immediately prior to the date of this prospectus, the number of shares offered hereby and registered by the registration statement of which this prospectus is a part, and the number of shares of our common stock to be beneficially owned by such selling stockholders after this offering. The number of shares to be owned after this offering assumes that all shares covered by this prospectus will be sold by the selling stockholders and that no additional shares of our common stock are subsequently bought or sold by the selling stockholders. Except as otherwise disclosed herein and in the footnotes below with respect to the selling stockholder, the selling stockholder does not and within the past three years has not had, any position, office or other material relationship with us.

The information set forth below is based upon information obtained from the selling stockholder. The percentages of shares owned after the offering are based on 28,055,344 shares of our common stock outstanding as of December 31, 2018, including the shares of common stock covered hereby.


	Shares Beneficially Owned Prior to the Date of this Prospectus						Shares Subject to Sale Pursuant to this Prospectus		Shares Beneficially Owned After Sale of All Shares Subject to Sale Pursuant to this Prospectus(1)
Name	Number of Shares			Percent			Shares Subject to Sale Pursuant to this Prospectus		Number of Shares		Percent
PureTech Health LLC		9,800,396	(2)		34.9	%		7,680,700		2,119,696		7.6	%
OrbiMed Private Investments VI, LP		4,830,387	(3)		17.2	%		4,297,054		533,333		1.9	%
Quan Venture Fund I, L.P.		667,892	(4)		2.4	%		467,892		200,000		0.7	%

(1)

We do not know when or in what amounts the selling stockholder may offer shares for sale. The selling stockholder might not sell any or all of the shares offered by this prospectus. Because the selling stockholder may offer all or some of the shares pursuant to this offering, and because there are currently no agreements, arrangements or understandings with respect to the resale of any of the shares, we cannot estimate the number of the shares that will be held by the selling stockholder after completion of the offering. However, for purposes of this table, we have assumed that, after completion of the offering, none of the shares covered by this prospectus will be held by the selling stockholder.

(2)

Voting and investment power over the shares held by PureTech Health LLC is exercised by its parent entity, PureTech Health plc. The board of directors of PureTech Health plc consists of Mr. Joi Ito, Dr. Raju Kucherlapati, Dr. John LaMattina, Dr. Robert Langer, Dame Marjorie Scarino, Dr. Ben Shapiro, Mr. Christopher Viehbacher, Ms. Daphne Zohar and Mr. Stephen Muniz. None of the members of the board of directors of PureTech Health plc or PureTech Health LLC has individual voting or investment power

with respect to such shares. The address for PureTech Health LLC and the individuals listed above is c/o PureTech Health LLC, 501 Boylston St., Suite 6102, Boston, MA 02116.

(3)

OrbiMed Capital GP VI LLC (“GP VI”) is the sole general partner of OrbiMed Private Investments VI, L.P. (“OPI VI”). OrbiMed Advisors LLC (“OrbiMed Advisors”) is the managing member of GP VI. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting and investment power with respect to the shares held by OPI VI and as a result may be deemed to have beneficial ownership of such shares. Jonathan Silverstein, a member of OrbiMed Advisors, is a member of the Company’s board of directors. Advisors exercises investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho and Jonathan T. Silverstein. Each of GP VI, OrbiMed Advisors, Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein disclaims beneficial ownership of the shares held by OPI VI, except to the extent of its or his pecuniary interest therein if any. The address of these entities is 601 Lexington Avenue, 54th floor, New York, New York 10022.

(4)	The address of Quan Venture Fund I, L.P. is Ugland House, PO Box 309, Grand Cayman, Cayman Islands KY1-1104.

Relationship with Selling Stockholders

PureTech Health LLC

PureTech Health is a greater than 5% stockholder and a founder of our company and in that capacity provided us with strategic medical, clinical and scientific advice pursuant to a business services, personnel and information management agreement until December 2017. Daphne Zohar, PureTech Health LLC’s founder and Chief Executive Officer, served on our board of directors until November 2018. David Steinberg is a member of our board of directors and previously served as co-founder and Chief Innovation Officer of PureTech Health, LLC until August 2018. PureTech Health LLC purchased shares of Series A preferred stock in our Series A financing in March 2017, August 2017 and October 2017. We were a subsidiary of PureTech Health LLC until the closing of our Series B financing in November 2017. PureTech Health LLC’s board designation rights terminated upon the consummation of our initial public offering. PureTech Health LLC is entitled to the registration rights described in this prospectus under “Description of Capital Stock.”

OrbiMed Private Investments VI, LP

OPI VI is a greater than 5% stockholder that participated in our Series B financing in November 2017, in which it obtained the right to appoint a representative to our board of directors. Although Jonathan Silverstein was OPI VI’s representative prior to our initial public offering, OPI VI’s board designation rights terminated upon the consummation of our initial public offering. OPI VI is also entitled to the registration rights described in this prospectus under “Description of Capital Stock.”

PLAN OF DISTRIBUTION

We and/or the selling stockholders, if applicable, may sell the securities offered through this prospectus and any accompanying prospectus supplement, if required, in any of the following ways: (1) to or through underwriters or dealers, (2) directly to purchasers, including our affiliates, (3) through agents, or (4) through a combination of any these methods. The securities may be distributed at a fixed price or prices, which may be changed, market prices prevailing at the time of sale, prices related to the prevailing market prices, or negotiated prices.

In addition, we may issue the securities as a dividend or distribution or in a subscription rights offering to our existing security holders.

We may directly solicit offers to purchase securities, or agents may be designated to solicit such offers. In the prospectus supplement relating to such offering, we will name any agent that could be viewed as an underwriter under the Securities Act and describe any commissions that we must pay to any such agent. Any such agent will be acting on a best efforts basis for the period of its appointment or, if indicated in the applicable prospectus supplement, on a firm commitment basis. This prospectus may be used in connection with any offering of our securities through any of these methods or other methods described in the applicable prospectus supplement.

Each prospectus supplement will describe the method of distribution of the securities and any applicable restrictions.

The prospectus supplement with respect to the securities of a particular series will describe the terms of the offering of the securities, including the following:

•

the name of the agent or any underwriters;

•

the public offering or purchase price;

•

any discounts and commissions to be allowed or paid to the agent or underwriters;

•

all other items constituting underwriting compensation;

•

any discounts and commissions to be allowed or paid to dealers; and

•

any exchanges on which the securities will be listed.

A selling stockholder that is an entity may elect to make a pro rata in-kind distribution of shares of our common stock to its members, partners or stockholders pursuant to the registration statement of which this prospectus forms a part by delivering a prospectus. To the extent that such members, partners or stockholders are not affiliates of such selling stockholder, such members, partners or stockholders would thereby receive freely tradeable shares of our common stock pursuant to the distribution through a registration statement.

If any underwriters or agents are used in the sale of the securities in respect of which this prospectus is delivered, we or the selling stockholders, as applicable, will enter into an underwriting agreement, sales agreement or other agreement with them at the time of sale to them, and we or the selling stockholders, as applicable, will set forth in the prospectus supplement relating to such offering the names of the underwriters or agents and the terms of the related agreement with them. To our knowledge, there are currently no plans, arrangements or understandings between the selling stockholders and any underwriter, dealer or agent regarding the sale of the shares covered by this prospectus by such selling stockholders. If any selling stockholder notifies us that a material arrangement has been entered into with an underwriter, dealer or other agent for the sale of shares through a block trade, special offering or secondary distribution, we may be required to file a prospectus supplement pursuant to applicable SEC rules promulgated under the Securities Act.

In connection with the offering of securities, we may grant to the underwriters an option to purchase additional securities with an additional underwriting commission, as may be set forth in the accompanying prospectus supplement. If we grant any such option, the terms of such option will be set forth in the prospectus supplement for such securities.

If a dealer is used in the sale of the securities in respect of which the prospectus is delivered, we or the selling stockholders will sell such securities to the dealer, as principal. The dealer, who may be deemed to be an “underwriter” as that term is defined in the Securities Act, may then resell such securities to the public at varying prices to be determined by such dealer at the time of resale.

If we offer securities in a subscription rights offering to our existing security holders, we may enter into a standby underwriting agreement with dealers, acting as standby underwriters. We may pay the standby underwriters a commitment fee for the securities they commit to purchase on a standby basis. If we do not enter into a standby underwriting arrangement, we may retain a dealer-manager to manage a subscription rights offering for us.

Agents, underwriters, dealers and other persons may be entitled under agreements which they may enter into with us to indemnification by us against certain civil liabilities, including liabilities under the Securities Act, and may be customers of, engage in transactions with or perform services for us in the ordinary course of business.

If so indicated in the applicable prospectus supplement, we will authorize underwriters or other persons acting as our agents to solicit offers by certain institutions to purchase securities from us pursuant to delayed delivery contracts providing for payment and delivery on the date stated in the prospectus supplement. Each contract will be for an amount not less than, and the aggregate amount of securities sold pursuant to such contracts shall not be less nor more than, the respective amounts stated in the prospectus supplement. Institutions with whom the contracts, when authorized, may be made include commercial and savings banks, insurance companies, pension funds, investment companies, educational and charitable institutions and other institutions, but shall in all cases be subject to our approval. Delayed delivery contracts will not be subject to any conditions except that:

•

the purchase by an institution of the securities covered under that contract shall not at the time of delivery be prohibited under the laws of the jurisdiction to which that institution is subject; and

•

if the securities are also being sold to underwriters acting as principals for their own account, the underwriters shall have purchased such securities not sold for delayed delivery. The underwriters and other persons acting as our agents will not have any responsibility in respect of the validity or performance of delayed delivery contracts.

Offered securities may also be offered and sold, if so indicated in the prospectus supplement, in connection with a remarketing upon their purchase, in accordance with a redemption or repayment pursuant to their terms, or otherwise, by one or more remarketing firms, acting as principals for their own accounts or as agents for us. Any remarketing firm will be identified and the terms of its agreement, if any, with us and its compensation will be described in the applicable prospectus supplement. Remarketing firms may be deemed to be underwriters in connection with their remarketing of offered securities.

Certain agents, underwriters and dealers, and their associates and affiliates, may be customers of, have borrowing relationships with, engage in other transactions with, or perform services, including investment banking services, for us or one or more of our respective affiliates in the ordinary course of business.

In order to facilitate the offering of the securities, any underwriters may engage in transactions that stabilize, maintain or otherwise affect the price of the securities or any other securities the prices of which may be used to determine payments on such securities. Specifically, any underwriters may overallot in connection with the offering, creating a short position for their own accounts. In addition, to cover overallotments or to stabilize the

price of the securities or of any such other securities, the underwriters may bid for, and purchase, the securities or any such other securities in the open market. Finally, in any offering of the securities through a syndicate of underwriters, the underwriting syndicate may reclaim selling concessions allowed to an underwriter or a dealer for distributing the securities in the offering if the syndicate repurchases previously distributed securities in transactions to cover syndicate short positions, in stabilization transactions or otherwise. Any of these activities may stabilize or maintain the market price of the securities above independent market levels. Any such underwriters are not required to engage in these activities and may end any of these activities at any time.

We or the selling stockholders may engage in at the market offerings into an existing trading market in accordance with Rule 415(a)(4) under the Securities Act. In addition, we or the selling stockholders may enter into derivative transactions with third parties, or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement so indicates, in connection with those derivatives, the third parties may sell securities covered by this prospectus and the applicable prospectus supplement, including in short sale transactions. If so, the third party may use securities pledged by us or borrowed from us or others to settle those sales or to close out any related open borrowings of stock, and may use securities received from us in settlement of those derivatives to close out any related open borrowings of stock. The third party in such sale transactions will be an underwriter and, if not identified in this prospectus, will be named in the applicable prospectus supplement (or a post-effective amendment). In addition, we may otherwise loan or pledge securities to a financial institution or other third party that in turn may sell the securities short using this prospectus and an applicable prospectus supplement. Such financial institution or other third party may transfer its economic short position to investors in our securities or in connection with a concurrent offering of other securities.

Under Rule 15c6-1 of the Exchange Act, trades in the secondary market generally are required to settle in two business days, unless the parties to any such trade expressly agree otherwise. The applicable prospectus supplement may provide that the original issue date for your securities may be more than two scheduled business days after the trade date for your securities. Accordingly, in such a case, if you wish to trade securities on any date prior to the second business day before the original issue date for your securities, you will be required, by virtue of the fact that your securities initially are expected to settle in more than two scheduled business days after the trade date for your securities, to make alternative settlement arrangements to prevent a failed settlement.

The securities may be new issues of securities and may have no established trading market. The securities may or may not be listed on a national securities exchange. We can make no assurance as to the liquidity of or the existence of trading markets for any of the securities.

The specific terms of any lock-up provisions in respect of any given offering will be described in the applicable prospectus supplement.

The underwriters, dealers and agents may engage in transactions with us, or perform services for us, in the ordinary course of business for which they receive compensation.

The anticipated date of delivery of offered securities will be set forth in the applicable prospectus supplement relating to each offer.

LEGAL MATTERS

Certain legal matters in connection with this offering will be passed upon for us by Goodwin Procter LLP, Boston, Massachusetts. Any underwriters will also be advised about the validity of the securities and other legal matters by their own counsel, which will be named in the prospectus supplement.

EXPERTS

The consolidated financial statements of resTORbio, Inc. and subsidiaries as of December 31, 2017 and 2016 and for the year ended December 31, 2017 and the period July 5, 2016 (inception) through December 31, 2016, have been incorporated by reference herein and in the registration statement in reliance upon the report of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

This prospectus is part of a registration statement that we have filed with the SEC. Certain information in the registration statement has been omitted from this prospectus in accordance with the rules of the SEC. We are subject to the information requirements of the Exchange Act and, in accordance therewith, file annual, quarterly and special reports, proxy statements and other information with the SEC. These documents may be accessed through the SEC’s electronic data gathering, analysis and retrieval system, or EDGAR, via electronic means, including the SEC’s home page on the Internet (www.sec.gov).

We have the authority to designate and issue more than one class or series of stock having various preferences, conversion and other rights, voting powers, restrictions, limitations as to dividends, qualifications, and terms and conditions of redemption. See “Description of Capital Stock.” We will furnish a full statement of the relative rights and preferences of each class or series of our stock which has been so designated and any restrictions on the ownership or transfer of our stock to any shareholder upon request and without charge. Written requests for such copies should be directed Investor Relations Department, resTORbio, Inc., 500 Boylston Street, 12^th Floor, Boston, MA 02116, and our website is located at www.restorbio.com. Information contained on our website is not incorporated by reference into this prospectus and, therefore, is not part of this prospectus or any accompanying prospectus supplement.

INCORPORATION BY REFERENCE

The SEC allows us to incorporate by reference the information and reports we file with it, which means that we can disclose important information to you by referring you to these documents. The information incorporated by reference is an important part of this prospectus, and information that we file later with the SEC will automatically update and supersede the information already incorporated by reference. We are incorporating by reference the documents listed below, which we have already filed with the SEC, and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act, including all filings made after the date of the filing of this registration statement and prior to the effectiveness of this registration statement, except as to any portion of any future report or document that is not deemed filed under such provisions, until we sell all of the securities:

•

our Annual Report on Form 10-K for the year ended December 31, 2017, filed with the SEC on March 29, 2018 and as amended on April 27, 2018;

•

our Quarterly Reports on Form 10-Q for the quarters ended March 31, 2018, June 30, 2018, and September 30, 2018, filed with the SEC on May 10, 2018, August 9, 2018 and November 13, 2018, respectively;

•

our Current Reports on Form 8-K filed with the SEC on January 30, 2018, March 19, 2018, March 29, 2018, May 9, 2018, May 10, 2018, July 25, 2018, July 30, 2018, August 9, 2018, August 15, 2018, September 18, 2018, October 16, 2018, November 6, 2018, November 13, 2018 and January 7, 2019 (in each case, except for information contained therein which is furnished rather than filed); and

•

the description of our common stock contained in our registration statement on Form 8-A filed with the SEC on January 22, 2018, including any amendments or reports filed for the purposes of updating this description.

Upon request, we will provide, without charge, to each person, including any beneficial owner, to whom a copy of this prospectus is delivered, a copy of the documents incorporated by reference into this prospectus but not delivered with the prospectus. You may request a copy of these filings, and any exhibits we have specifically incorporated by reference as an exhibit in this prospectus, at no cost by writing us at the following address: Investor Relations Department, resTORbio, Inc., 500 Boylston Street, 12^th Floor, Boston, MA 02116, telephone (857) 315-5521.

This prospectus is part of a registration statement we filed with the SEC. We have incorporated exhibits into this registration statement. You should read the exhibits carefully for provisions that may be important to you.

You should rely only on the information incorporated by reference or provided in this prospectus or any prospectus supplement. Neither we nor the selling stockholders have authorized anyone to provide you with different information. We are not making an offer of these securities in any state where the offer is not permitted. You should not assume that the information in this prospectus or in the documents incorporated by reference is accurate as of any date other than the date on the front of this prospectus or those documents.

LOGO

4,500,000 Shares

Common Stock

PROSPECTUS SUPPLEMENT

BofA Securities

Jefferies

SVB Leerink

Wedbush PacGrow

, 2020