As filed with the U.S. Securities and Exchange Commission on January 28, 2021.

Registration No. 333- 249275

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

POST-EFFECTIVE AMENDMENT NO. 1

TO

FORM S-8

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Adicet Bio, Inc.

(Exact name of registrant as specified in its charter)

500 Boylston Street, 13th Floor

Boston, MA 02116

(857) 315-5528

(Address of Principal Executive Offices)

Adicet Bio, Inc. 2018 Stock Option and Incentive Plan

Adicet Bio, Inc. 2014 Share Option Plan

Adicet Bio, Inc. 2015 Stock Incentive Plan

Adicet Bio, Inc. Inducement Non-Qualified Stock Option Agreement

(Full Title of the Plans)

Chen Schor

President and Chief Executive Officer

Adicet Bio, Inc.

500 Boylston Street, 13th Floor

Boston, MA 02116

(857) 315-5528

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies to:

Danielle Lauzon, Esq.

Mitchell S. Bloom, Esq.

Goodwin Procter LLP

100 Northern Avenue

Boston, Massachusetts 02210

(617) 570-1000

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.   ☐

EXPLANATORY NOTE

This Post-Effective Amendment No. 1 to the Registration Statement on Form S-8 (Registration No. 333-249275) previously filed with the SEC on October 2, 2020 (the “Registration Statement”) is being filed solely for the purpose of filing Exhibit 23.2 thereto, which was inadvertently omitted when the Registration Statement was filed. All other portions of the Registration Statement, as previously filed, remain unchanged.

PART I

Item 8. Exhibits.

EXHIBIT INDEX

2

3

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Amendment No. 1 to the Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the city of Boston, Commonwealth of Massachusetts, on January 28, 2021.

Pursuant to the requirements of the Securities Act of 1933, as amended, this Amendment No. 1 to Registration Statement on Form S-8, has been signed by the following persons in the capacities and on the dates indicated.

EXHIBIT 23.2

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration Statement on Form S-8 of Adicet Bio, Inc. of our report dated June 23, 2020 relating to the financial statements of Adicet Therapeutics, Inc. (formerly known as Adicet Bio, Inc.), which appears in Adicet Bio, Inc.’s Current Report on Form 8-K dated September 15, 2020.

/s/ PricewaterhouseCoopers LLP

San Jose, California

January 28, 2021