Exhibit 10.12

TCR² THERAPEUTICS, INC.

CONSULTING AGREEMENT

This Consulting Agreement (the “Agreement”) is effective October 1^st, 2017 (the “Effective Date”) and entered into by TCR² Therapeutics, Inc., a Delaware corporation (the “Company”), and Globeways Holdings Limited, a British Virgin Islands corporation with a correspondence address at 8 Rue Saint Leger, 1205 Geneva, Switzerland (the “Consultant”).

WHEREAS, the Company and the Consultant desire to have the Consultant serve as an advisor to the Company.

NOW, THEREFORE, in consideration of the mutual covenants and promises contained herein and other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged by the parties hereto, the parties agree as follows:

1. Services. The Consultant agrees to serve as a Consultant to Company and provide such consulting, advisory and related services (o and for the Company as may be reasonably requested as a Strategic Advisor.

During the Consultation Period (as defined below), except as otherwise provided herein, the Consultant shall not engage in any activity that has a conflict of interest with the Company, including any commercially competitive employment, and shall not directly and knowingly assist any other person or organization that competes, or intends to compete, with the Company.

2. Term. This Agreement shall commence on the Effective Date and shall renew annually (such period, as it may be extended or sooner terminated in accordance with the provisions of Section 4, being referred to as the “Consultation Period”).

3. Compensation.

3.1 Consulting Fees. The Company shall pay to the Consultant a consulting fee of $25,000 per quarter ($100,000 per year), payable on the last day of each quarter. Payment for any partial month shall be prorated.

3.2 Expenses. The Company shall reimburse the Consultant for all reasonable and necessary documented out of pocket expenses incurred or paid by the Consultant in connection with, or related to, the performance of Consultant’s services under this Agreement. The Consultant shall submit to the Company itemized monthly statements, in a form satisfactory to the Company, of such expenses incurred in the previous month. The Company shall pay to the Consultant amounts shown on each such statement within thirty (30) days after receipt thereof. Notwithstanding the foregoing, the Consultant shall not incur total expenses in excess of $1,000 per month without the prior written approval of the Company. Consultant shall not incur expenses that are not consistent with the expense reimbursement guidelines of the Company.

3.3 Benefits. The Consultant shall not be entitled to any benefits, coverages or privileges, including, without limitation, health insurance, social security, unemployment, medical or pension payments, made available to employees of the Company.

4. Termination. This Agreement may be terminated prior to the Term Date in the following manner: (a) by either the Company or the Consultant upon not less than thirty (30) days prior written notice to the other party; (b) by the non-breaching party, upon twenty-four (24) hours prior written notice to the breaching party if one party has materially breached this Agreement; or (c) at any time upon the mutual written consent of the parties hereto. In the event of termination, the Consultant shall be entitled to payment for services performed and (subject to the limitation in Section 3.2) for expenses paid or incurred prior to the effective date of termination that have not been previously paid. Such payment shall constitute full settlement of any and all claims of the Consultant of every description against the Company. Notwithstanding the foregoing, the Company may terminate this Agreement effective immediately by giving written notice to the Consultant if the Consultant breaches or threatens to breach any provision of Sections 6 or 7.

5. Cooperation. The Consultant shall use Consultant’s best efforts in the performance of Consultant’s obligations under this Agreement. The Company shall provide such access to its information and property as may be reasonably required in order to permit the Consultant to perform Consultant’s obligations hereunder. The Consultant shall cooperate with the Company’s personnel, shall not interfere with the conduct of the Company’s business and shall observe all rules, regulations and security requirements of the Company concerning the safety of persons and property.

6. Proprietary Information and Inventions.

6.1 Proprietary Information.

(a) The Consultant acknowledges that Consultant’s relationship with the Company is one of high trust and confidence and that in the course of Consultant’s service to the Company, Consultant will have access to and contact with Proprietary Information. The Consultant will not disclose any Proprietary Information to any person or entity other than employees of the Company or use the same for any purposes (other than in the performance of the services) without written approval by an officer or executive of the Company, either during or after the Consultation Period, unless and until such Proprietary Information has become public knowledge without fault by the Consultant.

(b) For purposes of this Agreement, Proprietary Information shall mean, by way of illustration and not limitation, all information, whether or not in writing, whether or not patentable and whether or not copyrightable, of a private, secret or confidential nature, owned, possessed or used by the Company, concerning the Company’s business, business relationships or financial affairs, including, without limitation, any Invention, formula, vendor information, customer information, apparatus, equipment, trade secret, process, research, report, technical or research data, clinical data, know-how, computer program, software, software documentation, hardware design, technology, product, processes, methods, techniques, formulas, compounds, projects, developments, marketing or business plan, forecast, unpublished financial statement, budget, license, price, cost, customer, supplier or personnel information or employee list that is communicated to, learned of, developed or otherwise acquired by the Consultant in the course of Consultant’s service as a consultant to the Company.

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(c) The Consultant’s obligations under this Section 6.1 shall not apply to any information that (i) is or becomes known to the general public under circumstances involving no breach by the Consultant or others of the terms of this Section 6.1, (ii) is generally disclosed to third parties by the Company without restriction on such third parties, or (iii) is approved for release by written authorization of an officer of the Company.

(d) The Consultant agrees that the Proprietary Information contained within all files, documents, letters, memoranda, reports, records, data sketches, drawings, models, laboratory notebooks, program listings, computer equipment or devices, computer programs or other written, photographic, or other tangible material, whether created by the Consultant or others, which shall come into Consultant’s custody or possession, shall be and are the exclusive property of the Company to be used by the Consultant only in the performance of Consultant’s duties for the Company and shall not be copied or removed from the Company premises except in the pursuit of the business of the Company. All such materials or copies thereof and all tangible property of the Company in the custody or possession of the Consultant shall be delivered to the Company, upon the earlier of (i) a request by the Company or (ii) the termination of this Agreement. After such delivery, the Consultant shall not retain any such materials or copies thereof or any such tangible property.

(e) The Consultant agrees that Consultant’s obligation not to disclose or to use information and materials of the types set forth in paragraphs (b) and (d) above, and Consultant’s obligation to return materials and tangible property set forth in paragraph (d) above extends to such types of information, materials and tangible property of customers of the Company or suppliers to the Company or other third parties who may have disclosed or entrusted the same to the Company or to the Consultant.

(f) The Consultant acknowledges that the Company from time to time may have agreements with other persons or with the United States or foreign governments, or agencies thereof, that impose obligations or restrictions on the Company regarding inventions made during the course of work under such agreements or regarding the confidential nature of such work. The Consultant agrees to be bound by all such obligations and restrictions that are known to him and to take all action necessary to discharge the obligations of the Company under such agreements.

6.2 Inventions.

(a) All inventions, ideas, creations, discoveries, computer programs, works of authorship, data, developments, technology, designs, innovations and improvements (whether or not patentable and whether or not copyrightable) which are made, conceived, reduced to practice, created, written, designed or developed by the Consultant, solely or jointly with others or under Consultant’s direction and whether during normal business hours or otherwise, (i) during the Consultation Period if arising out of the performance of the Services for the Company or (ii) after the Consultation Period if resulting or directly derived from the Company’s Proprietary Information (collectively under clauses (i) and (ii), “Inventions”) and which are not owned by Institution pursuant to the Uniform Provisions, shall be the sole property of the Company. The Consultant hereby assigns to the Company all Inventions and any and all related patents, copyrights, trademarks, trade names, and other industrial and intellectual

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property rights and applications therefor, that are not owned by Institution pursuant to the Uniform Provisions, in the United States and elsewhere and appoints any officer of the Company as his duly authorized attorney to execute, file, prosecute and protect the same before any government agency, court or authority. However, this paragraph shall not apply to Inventions which do not relate to the research and development conducted or planned to be conducted by the Company at the time such Invention is created, made, conceived or reduced to practice and which are made and conceived by the Consultant not during normal working hours, not on the Company’s premises and not using the Company’s tools, devices, equipment or Proprietary Information.

Company acknowledges that Consultant has, to the extent required by Institution’s policy, assigned or is obligated to assign to Institution any and all intellectual property rights made, conceived, reduced to practice, created, written, designed or developed by the Consultant, solely or jointly with others or under Consultant’s direction, within the scope of his employment to Institution and any rights so assigned are not subject in any way to the terms of this Agreement and the Company shall have no rights by reason of the Agreement in any publication, invention, discovery, improvement, or other intellectual property whatsoever, whether or not publishable, patentable, or copyrightable, which is developed as a result of Consultant’s employment at Institution. Consultant agrees not to provide any services for the Company hereunder on the premises of, or using any funds received from, Institution, without the express prior written consent of the Company.

(b) Upon the request of the Company and at the Company’s expense, the Consultant shall execute such further assignments, documents and other instruments as may be necessary or desirable to fully and completely assign all Inventions to the Company and to assist the Company in applying for, obtaining and enforcing patents or copyrights or other rights in the United States and in any foreign country with respect to any Invention. The Consultant also hereby waives all claims to moral rights in any Inventions.

(c) The Consultant shall promptly disclose to the Company all Inventions and will maintain adequate and current written records (in the form of notes, sketches, drawings and as may be specified by the Company) to document the conception and/or first actual reduction to practice of any Invention. Such written records shall be available to and remain the sole property of the Company at all times.

7. Non-Solicitation. During the Consultation Period and for a period of six (6) months thereafter (the “Post-Termination Period”), the Consultant shall not, either alone or in association with others, (i) solicit, or permit any organization directly or indirectly controlled by the Consultant to solicit, any employee of the Company to leave the employ of the Company; (ii) solicit for employment, hire or engage as an independent contractor, or permit any organization directly or indirectly controlled by the Consultant to solicit for employment, hire or engage as an independent contractor, any person who is employed or engaged by the Company; and/or (iii) solicit, divert or take away, the business or patronage of any of the clients, customers or accounts or prospective clients, customers or accounts, of the Company that were contacted, solicited or served by the Consultant on behalf of the Company during the term of the Consultant’s engagement with the Company. During the Post-Termination Period Consultant shall be paid Consulting Fees at the rate and the manner provided for in Section 3.1.

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8. Other Agreements. The Consultant hereby represents that, except as the Consultant has disclosed in writing to the Company, the Consultant is not bound by the terms of any agreement with any third party to refrain from using or disclosing any trade secret or confidential or proprietary information in the course of Consultant’s consultancy with the Company, to refrain from competing, directly or indirectly, with the business of such third party or to refrain from soliciting employees, customers or suppliers of such third party. The Consultant further represents that Consultant’s performance of all the terms of this Agreement and the performance of the services as a consultant of the Company do not and will not breach any agreement with any third party to which the Consultant is a party (including, without limitation, any nondisclosure or non-competition agreement), and that the Consultant will not disclose to the Company or induce the Company to use any confidential or proprietary information or material belonging to any current or previous employer or others.

9. Non-Exclusivity. Except as set forth in the second paragraph of Section 1, the Consultant retains the right to contract with other companies or entities for Consultant’s consulting services without restriction. The Company retains a right to contract with other companies and/or individuals for consulting services without restriction.

10. Remedies. The Consultant acknowledges that any breach of the provisions of Sections 6 or 7 of this Agreement shall result in serious and irreparable injury to the Company for which the Company cannot be adequately compensated by monetary damages alone. The Consultant agrees, therefore, that, in addition to any other remedy the Consultant may have, the Company shall be entitled to enforce the specific performance of this Agreement by the Consultant and to seek both temporary and permanent injunctive relief (to the extent permitted by law) without the necessity of proving actual damages or posting a bond.

11. Indemnification. The Company hereby agrees to indemnify and hold Consultant harmless from all liabilities incurred by, or claims against, Consultant as a result of his performance of his obligations under this Agreement, other than liability incurred or claims against the Consultant caused by his gross negligence or willful misconduct. Consultant hereby agrees to indemnify and hold Company harmless from claims made by Institution against the Company and liabilities associated therewith, resulting from Consultant’s gross negligence or willful misconduct.

12. Notices. All notices required or permitted under this Agreement shall be in writing and shall be deemed effective upon personal delivery or upon deposit in the United States Post Office, by registered or certified mail, postage prepaid, addressed to the other party at the address shown above, or at such other address or addresses as either party shall designate to the other in accordance with this Section 13.

13. Pronouns. Whenever the context may require, any pronouns used in this Agreement shall include the corresponding masculine, feminine or neuter forms, and the singular forms of nouns and pronouns shall include the plural, and vice versa.

14. Entire Agreement. This Agreement constitutes the entire agreement between the parties and supersedes all prior agreements and understandings, whether written or oral, relating to the subject matter of this Agreement

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15. Amendment. This Agreement may be amended or modified only by a written instrument executed by both the Company and the Consultant.

16. Non-Assignability of Contract. This Agreement is personal to the Consultant and the Consultant shall not have the right to assign any of Consultant’s rights or delegate any of Consultant’s duties without the express written consent of the Company. Any non-consented-to assignment or delegation, whether express or implied or by operation of law, shall be void and shall constitute a breach and a default by the Consultant.

17. Governing Law. This Agreement shall be governed by and construed in accordance with the laws of the Commonwealth of Massachusetts without giving effect to any choice or conflict of law provision or rule that would cause the application of laws of any other jurisdiction.

18. Successors and Assigns. This Agreement shall be binding upon, and inure to the benefit of, both parties and their respective successors and assigns, including any corporation with which, or into which, the Company may be merged or which may succeed to its assets or business, provided, however, that the obligations of the Consultant are personal and shall not be assigned by him.

19. Interpretation. If any restriction set forth in Section 6 or Section 7 is found by any court of competent jurisdiction to be unenforceable because it extends for too long a period of time or over too great a range of activities or in too broad a geographic area, it shall be interpreted to extend only over the maximum period of time, range of activities or geographic area as to which it may be enforceable.

20. Survival. Sections 4 through 22 shall survive the expiration or termination of this Agreement.

21. Miscellaneous.

21.1 No delay or omission by the Company in exercising any right under this Agreement shall operate as a waiver of that or any other right. A waiver or consent given by the Company on any one occasion shall be effective only in that instance and shall not be construed as a bar or waiver of any right on any other occasion.

21.2 The captions of the sections of this Agreement are for convenience of reference only and in no way define, limit or affect the scope or substance of any section of this Agreement.

21.3 In the event that any provision of this Agreement shall be invalid, illegal or otherwise unenforceable, the validity, legality and enforceability of the remaining provisions shall in no way be affected or impaired thereby.

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IN WITNESS WHEREOF, the parties hereto have executed this Consulting Agreement effective as of the date and year first above written.