Employment Offer Letter, dated December 13, 2021, between Turnstone Biologics Corp. and Venkat Ramanan, Ph.D

You will be employed on a full-time basis as the Chief Financial Officer, reporting to the CEO of Turnstone. You will be expected to devote your full time, attention and efforts to the business of the Company. Your start date will be February 15, 2022 or such other date as we mutually agree (“Start Date”).

Your base salary will be at the annual rate of $412,000.00 USD, less applicable taxes and withholdings, which shall be paid on a bi-monthly basis in accordance with our regular payroll schedule. You are also be eligible for an annual conditional performance bonus of 35%, less applicable taxes and withholdings, based upon a combination of individual and Company performance. You must be actively employed as of the pay-out date of any bonus in order to earn and be eligible to receive it.

You may participate in any and all benefit programs that the Company establishes and makes available to its employees from time to time, provided you are eligible under and subject to all provisions of the plan documents governing those programs. Please note that the Company reserves the right at any time to amend benefits, and/or to switch to a different benefit carrier or plan, and you will not have any right to compensation as a consequence. If you need details about current benefits before accepting this offer, please contact [***]

You will also be eligible for 20 days of vacation time per calendar year, which shall accrue on a pro-rata basis and be used in accordance with the Company’s regular policies. You are also entitled to all applicable public holidays in the United states.

You will be eligible for paid sick time in accordance with applicable laws.

Subject to the approval of the Board of Directors of the Company, the Company will grant to you 1,400,000 incentive stock options (the “Options”) for the purchase of common stock of the Company, at a price to be determined by the Board of Directors. The Options shall be subject to all terms, vesting schedules, limitations, restrictions and termination provisions set forth in the applicable Company stock option plan and in a separate option agreement that shall be executed by you and the Company to evidence the grant of the Options. A copy of the current Equity Plan will be provided to you on your Start Date but if you wish to review it before accepting this offer, a copy will be provided on request.

In the event that the Company opts to terminate your employment without Cause (as defined below), the Company will provide you with the following as your sole severance benefits (“Severance Benefits”). Any Severance Benefits for which you may be eligible shall be contingent upon your signing a separation agreement (including a release of claims against the Company) and your full and continued compliance with the enclosed Nondisclosure, Assignment of Inventions and Noncompetition Agreement

Severance Pay. Severance pay for nine (9) months at your then regular base rate, subject to standard payroll deductions and paid in accordance with the Company’s regular payroll practices.

Health Insurance. If you timely and properly elect continued group health insurance coverage pursuant to COBRA, the Company will, as an additional severance benefit, pay your COBRA premium payments sufficient to continue your group coverage at its then current level (including dependent coverage, if applicable) through nine (9) months post separation or the date that you become eligible for group health coverage.

Cause. “Cause” as used in this letter shall mean, as reasonably determined by the the Company (i) your material breach of any of the terms or representations contained in this letter or in any agreement between you and the Company or its affiliates, (ii) your conviction of, or guilty plea or no contest plea, to any criminal charge involving moral turpitude or that could reasonably be expected to have a material adverse effect on the business or affairs of the Company; (iii) your commission of any act of dishonesty, fraud, theft or embezzlement, or breach of fiduciary duty, against the Company or its affiliates; (iv) your material breach of Company policies; or (v) your willful breach of or habitual neglect of the duties of your position, or refusal to comply with any reasonable or proper direction given by or on behalf of superior officer of the Company or the Board of Directors consistent with your position.

As a condition of employment, you will be required to execute the enclosed Nondisclosure, Assignment of Inventions and Noncompetition Agreement This Agreement forms part of the terms of your employment, and many of its obligations survive and remain in effect if you leave Turnstone for any reason whatsoever. Because we understand the importance of protecting confidential information and proprietary property, we expect and direct you to honor any confidentiality and ownership of inventions/proprietary property obligations that you owe to your former employer(s) or other third parties.

As a condition of employment, you will be required to abide by all Company policies and procedures that shall be in effect from time to time, because we are an early stage Company, rules and policies are a work in progress. The Company reserves the right to revise, revoke, or introduce new rules and policies, as the Company may deem necessary from time to time, and you will also be required to abide by any changes in the rules and policies, once you are advised of the changes and they come into effect

You represent that you are not bound by any employment contract, restrictive covenant or other restriction preventing you from entering into employment with or carrying out your responsibilities for the Company, or which is in any way inconsistent with the terms of this letter.

You agree to provide to the Company, within three days of your hire date, documentation of your eligibility to work in the United States, as required by the Immigration Reform and Control Act.

This letter shall not be construed as an agreement, either express or implied, to employ you for any stated term, and shall in no way alter the Company’s policy of employment at will, under which both you and the Company remain free to end the employment relationship, for any reason, at any time, with or without cause or notice. Similarly, nothing in this letter shall be construed as an agreement, either express or implied, to pay you any compensation or grant you any benefit for the duration of or beyond the end of your employment with the Company. This letter supersedes any and all prior understandings, whether written or oral, relating to the terms of your employment.

/s/ Venkat Ramanan

December 13, 2021