Consulting Agreement by and between Richard A. Young and the Registrant, dated November 7, 2016

Services. The Consultant agrees to perform such consulting, advisory and related services to and for the Company as may be reasonably requested from time to time by the Company, including without limitation, consulting, advisory and related services to the Company with respect to matters related to the Field. The Consultant agrees to devote at most 12 days per year to the performance of such services. Without limiting the additional terms and conditions of Section 7 below, during the Consultation Period (as defined below), the Consultant shall not knowingly engage in any activity that has a conflict of interest with the Company, including without limitation any competitive employment, business, or other activity, and he shall not knowingly assist any other person or organization that competes or intends to compete with the Company. The Company acknowledges that Consultant has consulting obligations to those companies set forth on Annex 1 and does not view these as constituting a conflict of interest with the Company. The Company also acknowledges that the Consultant is a Member of the Whitehead Institute for Biomedical Research (“WIBR”) and faculty member in the Department of Biology of the Massachusetts Institute of Technology (“MIT”) and that no activity carried out by the Consultant in his capacity as a Member of WIBR will be considered a conflict of interest to Company. The Whitehead Institute Uniform Consulting Agreement Provisions (“Standard Provisions”) are attached hereto as Exhibit A and are incorporated herein by reference. The Parties agree that the Standard Provisions are an integral part of this Agreement and this Agreement shall have no force or effect unless the Standard Provisions are signed by both Parties. The Parties agree that in the event of any conflict between this Agreement and the Standard Provisions, the Standard Provisions shall govern and prevail.

Term. The initial term of this Agreement (the “Initial Term”) shall commence on the Effective Date and shall continue until the first anniversary of the Effective Date, unless sooner terminated in accordance with the provisions of Section 4. At the expiration of the Initial Term,

this Agreement will automatically renew for successive one-year periods and terminating on the fourth anniversary of the Effective Date, unless sooner terminated in accordance with the provisions of Section 4 (the term of effectiveness of this Agreement being referred to herein as the “Consultation Period”).

Compensation.

Consulting Fees. The Company has granted to the Founder shares of common stock of the Company, the continued vesting of which is subject to the Consultant’s provision of services to the Company pursuant to this Agreement.

Fees. From the Effective Date until the Qualified Financing Date (as defined below), the Company shall pay to the Consultant consulting fees at a rate of $25,000 per year, payable in arrears in equal quarterly installments. From and after the First Qualified Financing Date until the Second Qualified Financing Date, the Company shall pay to the Consultant consulting fees at a rate of $75,000 per year, payable in arrears in equal quarterly installments. Payment for any partial quarter shall be prorated. For purposes of this Agreement, “First Qualified Financing Date” shall mean the first date on which the Company receives aggregate gross proceeds of at least $10,000,000 from the sale to third parties of shares of its stock. From and after the Second Qualified Financing Date, the Company shall pay to the Consultant consulting fees at a rate of $120,000 per year, payable in arrears in equal quarterly installments. Payment for any partial quarter shall be prorated. For purposes of this Agreement, “Second Qualified Financing Date” shall mean the first date on which the Company receives aggregate gross proceeds of at least $20,000,000 from the sale to third parties of shares of its stock.

Reimbursement of 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 his services under this Agreement with the prior written approval of the Company. 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.

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

Termination. This Agreement may be terminated at any time during the Consultation Period 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, provided that the Company may in its discretion elect to terminate this Agreement immediately (i) if the Consultant delivers such written notice of termination or (ii) if the Company delivers such notice of termination and pays the Consultant within 15 days after such termination a lump-sum amount equal to the portion of the consulting fees payable hereunder that the Consultant would have earned during the thirty (30) day notice period; (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 and, except as

set forth in the last sentence of this Section 4, the breaching Party fails to cure such breach within thirty (30) days of such written notice; or (c) at any time upon the mutual written consent of the Parties hereto. In the event of such termination, the Consultant shall be entitled to payment for services performed and expenses paid or incurred prior to the effective date of termination, subject to the limitation on reimbursement of expenses set forth in Section 3.3. Such payments 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 the Consultation Period, effective immediately upon receipt of written notice, if the Consultant breaches or threatens to breach any provision of Section 6 or Section 7. The provisions of Sections 5, 6, 7, 8, 10 through 18 shall survive any termination of this Agreement.

Cooperation. The Consultant shall use his best efforts in the performance of his 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 his 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.

Inventions and Proprietary Information.

Inventions.

All inventions, discoveries, computer programs, data, 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 and whether during normal business hours or otherwise, (i) during the Consultation Period that result from the performance of Consultant’s services and if related to the business of the Company or (ii) during or after the Consultation Period if resulting or directly derived from Proprietary Information (as defined below), (“Inventions”) 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 property rights and applications therefor, 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. 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.

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.

Proprietary Information.

The Consultant acknowledges that his relationship with the Company is one of high trust and confidence and that in the course of his service to the Company he will have access to and contact with Proprietary Information. The Consultant agrees that he will not, during the Consultation Period or at any time thereafter, disclose to others, or use for his benefit or the benefit of others, any Proprietary Information or Invention.

For purposes of this Agreement, Proprietary Information shall mean, by way of illustration and not limitation, all information (whether or not patentable and whether or not copyrightable) owned, possessed or used by the Company, including, without limitation, any Invention, formula, vendor information, customer information, apparatus, equipment, process, research, report, technical data, know-how, computer program, software, software documentation, hardware design, technology, marketing or business plan, forecast, unpublished financial statement, budget, license, price, cost and employee list that is communicated to, learned of, developed or otherwise acquired by the Consultant in the course of his service as a consultant to the Company.

The Consultant’s obligations under this Section 6.2 shall not apply to any information (none of which shall be deemed Proprietary Information) that (i) is or becomes known to the general public under circumstances involving no breach by the Consultant of the terms of this Section 6.2, (ii) is generally disclosed to third parties by the Company without restriction on such third parties, (iii) is approved for release by written authorization of the Board of Directors of the Company, (iv) is independently developed by or for Consultant without use of Proprietary Information, or (v) Consultant is obligated to produce pursuant to an order of a court of competent jurisdiction or a valid administrative or Congressional subpoena, provided that the Consultant promptly notify Company and cooperate reasonably with Company’s efforts to contest or limit the scope of such order. The Consultant’s obligations hereunder shall survive for a period of five (5) years from the expiration or earlier termination of this Agreement.

Upon termination of this Agreement or at any other time upon request by the Company, the Consultant shall promptly deliver to the Company all records, files, memoranda, notes, designs, data, reports, price lists, customer lists, drawings, plans, computer programs, software, software documentation, sketches, laboratory and research notebooks and other documents (and all copies or reproductions of such materials) relating to the business of the Company.

The Consultant represents that his retention as a consultant with the Company and his performance under this Agreement does not, and shall not, breach any agreement that obligates him to keep in confidence any trade secrets or confidential or proprietary information of his or of any other party or to refrain from competing, directly or indirectly, with the business of any other party or otherwise conflict with any of his agreements or obligations to any other party. The Consultant shall not disclose to the Company any trade secrets or confidential or proprietary information of any other party.

The Consultant acknowledges that the Company from time to time may have agreements with other persons or with the United States Government, 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.

Defend Trade Secrets Act Notice of Immunity Rights. Consultant acknowledges that the Company has provided him with the following notice of immunity rights in compliance with the requirements of the Defend Trade Secrets Act: (a) Consultant shall not be held criminally or civilly liable under any Federal or State trade secret law for the disclosure of Proprietary Information that is made in confidence to a Federal, State, or local government official or to an attorney solely for the purpose of reporting or investigating a suspected violation of law, (b) Consultant shall not be held criminally or civilly liable under any Federal or State trade secret law for the disclosure of Proprietary Information that is made in a complaint or other document filed in a lawsuit or other proceeding, if such filing is made under seal and (c) Consultant files a lawsuit for retaliation by the Company for reporting a suspected violation of law, Consultant may disclose the Proprietary Information to his attorney and use the Proprietary Information in the court proceeding, if Consultant files any document containing the Proprietary Information under seal, and does not disclose the Proprietary Information, except pursuant to court order.

Non-Competition and Non-Solicitation.

Restrictions. During the term of this Agreement and for a period of one year after termination of this Agreement, the Consultant will not directly or indirectly:

Engage or assist others in engaging in any business or enterprise competing with the Company in the Field (whether as owner, partner, officer, director, employee, consultant, investor, lender or otherwise, except as the holder of not more than 1% of the outstanding stock of a publicly-held company), including but not limited to any business or enterprise that develops, manufactures, markets, licenses, sells or provides any product or service that competes with any product or service developed, manufactured, marketed, licensed, sold or provided, or planned to be developed, manufactured, marketed, licensed, sold or provided, by the Company in the Field while the Consultant was employed by the Company;

Either alone or in association with others, divert or take away, or attempt to divert or take away, the business or patronage of any of the clients, customers, or business partners of the Company which were contacted, solicited, or served by the Company during the 12-month period prior to the termination or cessation of the Consultant’s services with the Company; or

Either alone or in association with others (i) solicit, induce or attempt to induce, any employee or independent contractor of the Company to terminate his or her employment or other engagement with the Company, or (ii) hire, or recruit or attempt to hire, or

engage or attempt to engage as an independent contractor, any person who was employed or otherwise engaged by the Company at any time during the term of the Consultant’s services with the Company; provided, that this clause (ii) shall not apply to the recruitment or hiring or other engagement of any individual whose employment or other engagement with the Company has been terminated for a period of six months or longer.

Extension. If the Consultant violates the provisions of Section 7.1, the Consultant shall continue to be bound by the restrictions set forth in such paragraph until a period of one (1) year has expired without any violation of such provisions.

Company’s Business. For purposes of this Agreement, the “Company’s business” shall mean the any lawful act or activity relating to the Field.

Remedies. The Consultant acknowledges that any breach of the provisions of Section 6 or Section 7 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 it 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.

Other Agreements. The Consultant hereby represents that, except as the Consultant has disclosed in writing to the Company (which writing shall redact, however, any elements that Consultant is not lawfully permitted to disclose), the Consultant is not bound by the terms of any agreement with any third party (excluding for this purpose any academic and research institutions or not-for-profit organizations) to refrain from using or disclosing any trade secret or confidential or proprietary information in the course of the Consultant’s relationship 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 agrees to furnish the Company with a copy of any such agreement upon request.

Independent Contractor Status. The Consultant shall perform all services under this Agreement as an “independent contractor” and not as an employee or agent of the Company. The Consultant is not authorized to assume or create any obligation or responsibility, express or implied, on behalf of, or in the name of, the Company or to bind the Company in any manner.

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 11.

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.

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.

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

Governing Law. This Agreement shall be construed, interpreted and enforced in accordance with the laws of the Commonwealth of Massachusetts without regard to conflict of law principles that would result in the application of any law other than the Commonwealth of Massachusetts.

Interpretation. If any restriction set forth in Section 1 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.

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.

Miscellaneous.

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.

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. 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.

The Whitehead Institute for Biomedical Research (“WHITEHEAD”) is a non-profit biomedical research institute having a business address of Nine Cambridge Center, Cambridge, Massachusetts 02142. These Uniform Consulting Agreement Provisions (the “Uniform Provisions”) are attached to an agreement (the “Agreement”) under which a Member of WHITEHEAD (the “Consultant”) has agreed to provide consulting services to the company named in the Agreement (the “Company”). The Consultant and the Company agree that the Agreement shall have no force or effect unless these Uniform Provisions are signed by both parties and attached to the Agreement. By signing the Uniform Provisions, the Consultant and the Company agree to abide by them, and also agree that if anything in the Agreement is inconsistent with the Uniform Provisions, the Uniform Provisions shall govern.

The Agreement shall disclose all compensation of whatever kind that is to be provided to the Consultant in connection with the consulting services. The Agreement shall disclose the time commitment for the consulting services, which may not exceed one day per week for all outside activities of the Member of WHITEHEAD.

The Consultant’s services for the Company shall consist only of the exchange of ideas and provision of advice; the Consultant shall not direct or conduct research for or on behalf of the Company.

The Company acknowledges that the Consultant is a Member of WHITEHEAD and is subject to WHITEHEAD’s policies, including policies concerning consulting, conflicts of interest, and intellectual property. In accordance with WHITEHEAD policy, the Consultant may disclose to the Company any information that the Consultant would normally freely disclose to other members of the scientific community at large, whether by publication, by presentation at seminars, or in informal scientific discussions. However, the Consultant shall not disclose to the Company information that (i) is proprietary to WHITEHEAD and (ii) is not generally available to the public, except through formal technology transfer procedures.

Subject to the terms of paragraph 6, below, the Consultant may assign to the Company any right, title and interest the Consultant may have in any invention, discovery, improvement, or other intellectual property which the Consultant

(whether alone or with others) develops (i) during the course of performing consulting services for the Company under the Agreement and (ii) outside the course of the Consultant’s activities as a Member of WHITEHEAD.

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 a program of research financed, in whole or in part, by funds provided by or under the control of WHITEHEAD. The Company also acknowledges and agrees that it will enjoy no priority or advantage as a result of the consultancy created by the Agreement in gaining access, whether by license or otherwise, to any proprietary information or intellectual property that arises from any research undertaken by the Consultant in his or her capacity as a Member of WHITEHEAD.

The Company agrees, at its sole expense, to defend WHITEHEAD against, and to indemnify and hold WHITEHEAD harmless from, any claim, liability, judgment, cost, expense, damage, deficiency, loss, or obligation, of any kind or nature (including without limitation reasonable attorneys’ fees and other costs and expenses of defense) relating to a claim or suit by a third party against WHITEHEAD, either arising from the Agreement, the Consultant’s performance of services for the Company under the Agreement, or any Company products or services which result from the Consultant’s performance of services under the Agreement.

Nothing in the Agreement shall affect the Consultant’s right to use, disseminate, or publish any information that (i) is or becomes available to the public through no breach of the Agreement by the Consultant; (ii) is obtained by the Consultant from a third party who had the legal right to disclose the information to the Consultant; (iii) is already in the possession of the Consultant on the date the Agreement becomes effective; or (iv) is required to be disclosed by law, government regulation, or court order, provided that the Consultant takes reasonable steps to provide the Company with sufficient prior notice to allow the Company to consent to the disclosure or seek a protective order. In addition, the Company’s confidential information does not include information generated by the Consultant (whether alone or with others) unless the Consultant generated the information (i) during the course of performing consulting services for the Company under the Agreement and (ii) outside the course of the Consultant’s activities as a Member of WHITEHEAD.

The Company acknowledges and agrees that nothing in the Agreement shall affect the Consultant’s obligations to WHITEHEAD, the Consultant’s research on behalf

of WHITEHEAD, or research collaborations in which the Consultant is a participant, and that the Agreement shall have no effect upon transfers (by way of license or otherwise) to third parties of materials or intellectual property developed in whole or in part by the Consultant as a Member of WHITEHEAD.

Paragraphs 7, 8, 9, 10, 12, 13, and 14 of these Uniform Provisions shall survive termination of the Agreement.

The Company may use the Consultant’s name, and in doing so may cite the Consultant’s relationship with WHITEHEAD, so long as any such usage (i) is limited to reporting factual events or occurrences only, and (ii) is made in a manner that could not reasonably constitute an endorsement of the Company or of any Company program, product or service. However, the Company shall not use the Consultant’s name or WHITEHEAD’s name in any press release, or quote the Consultant in any company materials, or otherwise use the Consultant’s name or WHITEHEAD’s name in a manner not specifically permitted by the preceding sentence, unless in each case the Company obtains in advance WHITEHEAD’s written consent, and, in the case of the use of the Consultant’s name, the Consultant’s consent as well.

The Consultant and the Company acknowledge that (i) the Consultant is entering into the Agreement and these Uniform Provisions in the Consultant’s individual capacity and not as a Member of WHITEHEAD, (ii) WHITEHEAD is not a party to the Agreement or the Uniform Provisions and has no liability or obligation under them, and (iii) WHITEHEAD is an intended third-party beneficiary of the Agreement and certain provisions of the Agreement and the Uniform Provisions are for WHITEHEAD’s benefit and are enforceable by WHITEHEAD in its own name.

The Uniform Provisions shall be in effect for the full term of the Agreement. The Company and the Consultant agree that any amendment of the Agreement (including, without limitation, any extension of the Agreement’s term or any change in the consideration to be provided to the Consultant under the Agreement) or any other departure from the terms or conditions of the Agreement must be signed by the Consultant and an authorized representative of the Company, and also is subject to WHITEHEAD’s prior written approval.

If any of these Uniform Provisions is adjudicated to be invalid, unenforceable, contrary to, or prohibited under applicable laws or regulations of any jurisdiction, the Agreement shall terminate as of the date such adjudication is effective.