As filed with the Securities and Exchange Commission on March 23, 2023

Registration No. 333-            

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT

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 of Principal Executive Offices)

TCR² Therapeutics Inc. 2018 Stock Option and Incentive Plan

TCR² Therapeutics Inc. 2018 Employee Stock Purchase Plan

(Full Title of the Plans)

Garry E. Menzel, Ph.D.

President and Chief Executive Officer

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)

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 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 Registration Statement on Form S-8 is filed for the purposes of registering (i) 1,568,135 shares of common stock, par value $0.0001 per share (“Common Stock”), of TCR² Therapeutics Inc. (the “Registrant”) that may be issued pursuant to equity awards granted pursuant to the TCR² Therapeutics Inc. 2018 Stock Option and Incentive Plan, as amended (the “2018 Plan”) and (ii) an additional 392,034 shares of Common Stock of the Registrant that may be issued pursuant to the TCR² Therapeutics Inc. 2018 Employee Stock Purchase Plan (the “2018 ESPP”). The number of shares of Common Stock reserved and available for issuance under the 2018 Plan is subject to an automatic annual increase on each January 1 by an amount equal to up to four percent of the number of shares of Common Stock issued and outstanding on the immediately preceding December 31 or such lesser number of shares of Common Stock as determined by the Administrator (as defined in the 2018 Plan). Accordingly, on January 1, 2023, the number of shares of Common Stock reserved and available for issuance under the 2018 Plan increased by 1,568,135 shares of Common stock. This Registration Statement registers these additional 1,568,135 shares of Common Stock. The additional shares are of the same class as other securities relating to the 2018 Plan for which the Registrant’s registration statements filed on Form S-8 (Registration No. 333-229691) on February 14, 2019, on Form S-8 (Registration No. 333-237481) on March 30, 2020, on Form S-8 (Registration No. 333-254354) on March 16, 2021, and on Form S-8 (Registration No. 333-263770) on March 22, 2022, are effective. The information contained in the Registrant’s registration statements on Form S-8 listed above is hereby incorporated by reference pursuant to General Instruction E, except for “Item 8. Exhibits”. The number of shares of Common Stock reserved and available for issuance under the 2018 ESPP is subject to an automatic annual increase on each January 1 by an amount equal to the least of one percent of the number of shares of Common Stock issued and outstanding on the immediately preceding December 31, 500,000 shares of Common Stock or such lesser number of shares of Common Stock as determined by the Administrator (as defined in the 2018 ESPP). Accordingly, on January 1, 2023, the number of shares of Common Stock reserved and available for issuance under the 2018 ESPP increased by 392,034 shares of Common Stock. This Registration Statement registers these additional 392,034 shares of Common Stock. The additional shares are of the same class as other securities relating to the 2018 ESPP for which the Registrant’s registration statements filed on Form S-8 (Registration No.  333-229691) on February 14, 2019 and on Form S-8 (Registration No. 333-237481) on March 30, 2020, are effective. The information contained in the Registrant’s registration statements on Form S-8 listed above is hereby incorporated by reference pursuant to General Instruction E, except for “Item 8. Exhibits”.

See the Exhibit Index on the following page for a list of exhibits filed as part of this Registration Statement, which Exhibit Index is incorporated herein by reference.

EXHIBIT INDEX

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 Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the city of Cambridge, Commonwealth of Massachusetts, on the 23^rd day of March 2023.

POWER OF ATTORNEY AND SIGNATURES

KNOW ALL BY THESE PRESENT, that each individual whose signature appears below hereby constitutes and appoints Garry Menzel and Eric Sullivan, and each of them, either of whom may act without the joinder of the other, as his or her true and lawful attorney-in-fact and agent with full power of substitution and resubstitution, for him or her and in his or her name, place and stead, in any and all capacities, to sign any and all amendments (including post-effective amendments) to this Registration Statement on Form S-8, and to file the same, with all exhibits thereto, and all documents in connection therewith, with the Securities and Exchange Commission granting unto said attorney-in-fact and agent full power and authority to do and perform each and every act and thing requisite and necessary to be done in and about the premises, as fully to all intents and purposes as he or she might or could do in person, hereby ratifying and confirming all that said attorney-in-fact and agent, or his substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following person in the capacities and on the date indicated.

Exhibit 5.1

March 23, 2023

TCR² Therapeutics Inc.

100 Binney Street, Suite 710

Cambridge, MA 02142

Re: Securities Being Registered under Registration Statement on Form S-8

We have acted as counsel to you in connection with your filing of a Registration Statement on Form S-8 (the “Registration Statement”) pursuant to the Securities Act of 1933, as amended (the “Securities Act”), on or about the date hereof relating to an aggregate of 1,960,169 shares (the “Shares”) of common stock, par value $0.0001 per share (“Common Stock”), of TCR² Therapeutics Inc., a Delaware corporation (the “Company”), that may be issued pursuant to the Company’s 2018 Stock Option and Incentive Plan and the Company’s 2018 Employee Stock Purchase Plan (collectively, the “Plans”).

We have reviewed such documents and made such examination of law as we have deemed appropriate to give the opinion set forth below. We have relied, without independent verification, on certificates of public officials and, as to matters of fact material to the opinion set forth below, on certificates of officers of the Company.

The opinion set forth below is limited to the Delaware General Corporation Law.

For purposes of the opinion set forth below, we have assumed that no event occurs that causes the number of authorized shares of Common Stock available for issuance by the Company to be less than the number of then unissued Shares.

Based on the foregoing, we are of the opinion that the Shares have been duly authorized and, upon delivery against payment therefor in accordance with the terms of the Plans, will be validly issued, fully paid and nonassessable.

We hereby consent to the inclusion of this opinion as Exhibit 5.1 to the Registration Statement. In giving our consent, we do not admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations thereunder.

Very truly yours,

/s/ Goodwin Procter LLP                

GOODWIN PROCTER LLP

Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the use of our report dated March 23, 2023, with respect to the consolidated financial statements of TCR² Therapeutics Inc., incorporated herein by reference.

/s/ KPMG LLP

Boston, Massachusetts

March 23, 2023

Exhibit 107

Calculation of Filing Fee Tables

Form S-8

(Form Type)

TCR² Therapeutics Inc.

(Exact Name of Registrant as Specified in its Charter)

Table 1: Newly Registered Securities