SEC Form S-8 POS filed by TCR2 Therapeutics Inc.

As filed with the Securities and Exchange Commission on June 1, 2023.

Registration No. 333-229691

Registration No. 333-237481

Registration No. 333-254354

Registration No. 333-263770

Registration No. 333-270766

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

POST-EFFECTIVE AMENDMENT NO. 1 TO

Form S-8 Registration No. 333-229691

Form S-8 Registration No. 333-237481

Form S-8 Registration No. 333-254354

Form S-8 Registration No. 333-263770

Form S-8 Registration No. 333-270766

UNDER THE SECURITIES ACT OF 1933

TCR² THERAPEUTICS INC.

(Exact name of registrant as specified in its charter)

100 Binney Street, Suite 710

Cambridge, Massachusetts 02142

(617) 949-5200

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

TCR² Therapeutics Inc. 2015 Stock Option and Grant Plan

TCR² Therapeutics Inc. 2018 Stock Option and Incentive Plan

TCR² Therapeutics Inc. 2018 Employee Stock Purchase Plan

TCR² Therapeutics Inc. 2022 Inducement Plan

(Full title of the plans)

William Bertrand

TCR² Therapeutics Inc.

100 Binney Street, Suite 710

Cambridge, Massachusetts 02142

(617) 949-5200

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

With copies to:

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a 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 Securities Exchange Act of 1934, as amended (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. ¨

DEREGISTRATION OF SECURITIES

This Post-Effective Amendment No. 1 (this “Post-Effective Amendment”) relates to the following Registration Statements on Form S-8 (each, a “Registration Statement,” and collectively, the “Registration Statements”), filed with the Securities and Exchange Commission (the “SEC”) by TCR² Therapeutics Inc., a Delaware corporation (the “Registrant”):

On June 1, 2023, pursuant to the terms of an Agreement and Plan of Merger dated as of March 5, 2023 (the “Merger Agreement”, as amended by that certain Amendment No. 1 to Agreement and Plan of Merger, dated as of April 5, 2023) by and among the Registrant, Adaptimmune Therapeutics plc, a public limited company incorporated under the laws of England and Wales (“Adaptimmune”) and CM Merger Sub, Inc., a Delaware corporation and an indirect wholly-owned subsidiary of Adaptimmune (“Merger Sub”), Merger Sub merged with and into the Registrant, with the Registrant surviving the merger as a wholly-owned direct subsidiary of CM Intermediate Sub II, Inc., a Delaware corporation and subsidiary of Adaptimmune (the “Merger”).

As a result of the Merger, the Registrant has terminated any and all offerings of its securities pursuant to the Registration Statements. In accordance with an undertaking made by the Registrant in the Registration Statements to remove from registration, by means of a post-effective amendment, any of the securities registered under the Registration Statements that remain unissued at the termination of the offerings, the Registrant hereby removes from registration all securities registered but unsold under such Registration Statements, if any, as of the date hereof.

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 Post-Effective Amendment to the Registration Statements described above to be signed on its behalf by the undersigned, thereunto duly authorized, in the city of Cambridge, Commonwealth of Massachusetts on June 1, 2023.

No other person is required to sign this Post-Effective Amendment in reliance upon Rule 478 under the Securities Act of 1933.