Exhibit 10.18

EXECUTIVE EMPLOYMENT AGREEMENT

This Employment Agreement (the “Agreement”), made and entered into this 19th day of September, 2019 (the “Effective Date”), by and between Checkmate Pharmaceuticals, Inc., a Delaware corporation (“Company”), and James E. Wooldridge, M.D. (“Executive”).

WHEREAS, Company wishes to employ Executive as its Chief Medical Officer (“CMO”)

WHEREAS, Executive represents that Executive possesses the necessary skills to perform the duties of this position and that Executive has no obligation to any other person or entity which would prevent, limit or interfere with Executive’s ability to do so; and

WHEREAS, Executive and Company desire to enter into a formal Employment Agreement to assure the harmonious performance of the affairs of Company.

NOW, THEREFORE, in consideration of the mutual promises, terms, provisions, and conditions contained herein, the parties agree as follows:

1.    Roles and Duties. Subject to the terms and conditions of this Agreement, Company shall employ Executive as its Chief Medical Officer reporting to the CEO. Executive accepts such employment upon the terms and conditions set forth herein, and agrees to perform to the best of Executive’s ability the duties normally associated with such position and as determined by Company in its sole discretion. During Executive’s employment, Executive shall devote all of Executive’s business time and energies to the business and affairs of Company, provided that nothing contained in this Section 1 shall prevent or limit Executive’s right to manage Executive’s personal investments on Executive’s own personal time, including the right to make passive investments in the securities of: (a) any entity which Executive does not control, directly or indirectly, and which does not compete with Company, or (b) any publicly held entity so long as Executive’s aggregate direct and indirect interest does not exceed two percent (2%) of the issued and outstanding securities of any class of securities of such publicly held entity. Executive may serve on one corporate Board of Directors (other than Checkmate’s Board of Directors) subject to prior approval by the CEO , for companies which are not developing a TLR9 agonist, and may be involved in civic and charitable activities so long as such activities do not interfere with Executive’s duties for Company.

2.    Term of Employment.

(a)    Term. Subject to the terms hereof, Executive’s employment hereunder shall commence on September 19, 2019 (the “Commencement Date”) and shall continue until terminated hereunder by either party (such term of employment referred to herein as the “Term”).

(b)    Termination. Notwithstanding anything else contained in this Agreement, Executive’s employment hereunder shall terminate upon the earliest to occur of the following:

(i)    Death. Immediately upon Executive’s death;

(ii)    Termination by Company.

(A)    If because of Executive’s Disability (as defined in Section 2(c)), upon written notice by Company to Executive that Executive’s employment is being terminated as a result of Executive’s Disability, which termination shall be effective on the date of such notice or such later date as specified in writing by Company;

(B)    If for Cause (as defined in Section 2(d)), upon written notice by Company to Executive that Executive’s employment is being terminated for Cause, which termination shall be effective on the date of such notice or such later date as specified in writing by Company; or

(C)    If by Company for reasons other than Disability or Cause, upon written notice by Company to Executive that Executive’s employment is being terminated, which termination shall be effective immediately after the date of such notice or such later date as specified in writing by Company.

(iii)    Termination by Executive.

(A)    If for Good Reason (as defined in Section 2(e)), upon written notice by Executive to Company that Executive is terminating Executive’s employment for Good Reason and that sets forth the factual basis supporting the alleged Good Reason, which termination shall be effective thirty (30) days after the date of such notice; provided that if Company has cured the circumstances giving rise to the Good Reason, then such termination shall not be effective; see Section 4 for Severance Payment provisions or

(B)    If without Good Reason, written notice by Executive to Company that Executive is terminating Executive’s employment, which termination shall be effective at least thirty (30) days after the date of such notice.

Notwithstanding anything in this Section 2(b), Company may at any point terminate Executive’s employment for Cause prior to the effective date of any other termination contemplated hereunder.

(c)    Definition of “Disability”. For purposes of this Agreement, “Disability” shall mean Executive’s incapacity or inability to perform Executive’s duties and responsibilities as contemplated herein for one hundred twenty (120) days or more within any one (1) year period (cumulative or consecutive), because Executive’s physical or mental health has become so impaired as to make it impossible or impractical for Executive to perform the duties and responsibilities contemplated hereunder. Determination of Executive’s physical or mental health shall be determined by Company after consultation with a medical expert appointed by mutual agreement between Company and Executive who has examined Executive. Executive hereby consents to such examination and consultation regarding Executive’s health and ability to perform as aforesaid.

(d)    Definition of “Cause”. As used herein, “Cause” shall include: (i) Executive’s willful engagement in illegal conduct or gross misconduct, which, in each case, is materially injurious to Company; (ii) Executive’s insubordination or substantial malfeasance or nonfeasance of duty, which, in each case, is materially injurious to Company; (iii) Executive’s embezzlement, misappropriation or fraud; (iv) Executive’s unauthorized disclosure of confidential

information; or (v) Executive’s breach of a material provision of any employment, non-disclosure, invention assignment, non-competition, or similar agreement between Executive and Company; provided that (A) Company provides Executive with written notice that Company intends to terminate Executive’s employment hereunder for one of the circumstances set forth in this Section 2(d) within thirty (30) days of such circumstance occurring, (B) if such circumstance is capable of being cured, Executive has failed to cure such circumstance within a period of thirty (30) days from the date of such written notice, and (C) Company terminates Executive’s employment within sixty five (65) days from the date that Cause first occurs. For purposes of clarification, the above-listed conditions shall apply separately to each occurrence of Cause, and failure to adhere to such conditions in the event of Cause shall not disqualify Company from asserting Cause for any subsequent occurrence of Cause.

(e)    Definition of “Good Reason”. As used herein, “Good Reason” shall mean: (i) relocation of Executive’s principal business location to a location more than fifty (50) miles from Executive’s then-current business location; (ii) a material diminution in Executive’s duties, authority or responsibilities; or (iii) a material reduction in Executive’s Base Salary; provided that (A) Executive provides Company with written notice that Executive intends to terminate Executive’s employment hereunder for one of the circumstances set forth in this Section 2(e) within thirty (30) days of such circumstance occurring, (B) if such circumstance is capable of being cured, Company has failed to cure such circumstance within a period of thirty (30) days from the date of such written notice, and (C) Executive terminates Executive’s employment within sixty five (65) days from the date that Good Reason first occurs. For purposes of clarification, the above-listed conditions shall apply separately to each occurrence of Good Reason and failure to adhere to such conditions in the event of Good Reason shall not disqualify Executive from asserting Good Reason for any subsequent occurrence of Good Reason. For purposes of this Agreement, “Good Reason” shall be interpreted in a manner, and limited to the extent necessary, so that it shall not cause adverse tax consequences for either party with respect to Section 409A (“Section 409A”) of the Internal Revenue Code of 1986, as amended (the “Code”), and any successor statute, regulation and guidance thereto.

3.    Compensation.

(a)    Base Salary. Company shall pay Executive a base salary (the “Base Salary”) at the annual rate of three hundred seventy-five thousand dollars ($375,000), as of the Commencement Date). The Base Salary shall be payable in substantially equal periodic installments in accordance with Company’s payroll practices as in effect from time to time. Company shall deduct from each such installment all amounts required to be deducted or withheld under applicable law or under any employee benefit plan in which Executive participates. The Company shall review the Base Salary on an annual basis and may increase, but not decrease, the Base Salary.

(b)    Annual Performance Bonus. Executive shall be eligible to receive an annual cash bonus (the “Annual Performance Bonus”), with the target amount of such Annual Performance Bonus equal to Thirty Percent (30%) of Executive’s Base Salary in the year to which the Annual Performance Bonus relates, provided that the actual amount of the Annual Performance Bonus may be greater or less than such target amount. The amount of the Annual Performance Bonus shall be determined by the Board or an appropriate committee thereof in its sole discretion,

and shall be paid to Executive no later than March 15^th of the calendar year immediately following the calendar year in which it was earned. Executive must be employed by Company on the last day of the fiscal year on which the Annual Performance Bonus is based in order to be eligible for such Annual Performance Bonus. Company shall deduct from the Annual Performance Bonus all amounts required to be deducted or withheld under applicable law or under any employee benefit plan in which Executive participates. For the current calendar year, Executive shall be eligible for a prorated Annual Performance Bonus subject to the terms and conditions described above.

(c)    Paid Time Off. Executive may take up to twenty (20) days of paid time off (“PTO”) per year, to be scheduled to minimize disruption to Company’s operations, pursuant to the terms and conditions of Company policy and practices as applied to Company senior executives.

(d)    Fringe Benefits. Executive shall be entitled to participate in all benefit/welfare plans and fringe benefits provided to Company senior executives. Executive understands that, except when prohibited by applicable law, Company’s benefit plans and fringe benefits may be amended by Company from time to time in its sole discretion.

(e)    Equity Incentive Awards. Executive will eligible to participate in the Company’s equity incentive program and, subject to approval by the Company’s Board of Directors, a stock option grant equal to 1% of the Company’s fully diluted stock vesting over four years, with the first twenty-five percent (25%) vesting on the twelve (12) month anniversary of your Commencement Date, and the remaining vesting in equal monthly installments over the following thirty-six (36) months. In the case of a Sale Event, as defined in the Company’s 2015 Stock Option and Grant Plan (“the Plan”), this option shall be treated as provided in Section 3(c) of the Plan and all of the shares shall vest immediately upon the Completion of a Sale Event.

(f)    Reimbursement of Expenses. Company shall reimburse Executive for all ordinary and reasonable out-of-pocket business expenses incurred by Executive in furtherance of Company’s business in accordance with Company’s policies with respect thereto as in effect from time to time. Executive must submit any request for reimbursement no later than ninety (90) days following the date that such business expense is incurred. All reimbursements provided under this Agreement shall be made or provided in accordance with the requirements of Section 409A including, where applicable, the requirement that (i) any reimbursement is for expenses incurred during Executive’s lifetime (or during a shorter period of time specified in this Agreement); (ii) the amount of expenses eligible for reimbursement during a calendar year may not affect the expenses eligible for reimbursement in any other calendar year; (iii) the reimbursement of an eligible expense shall be made no later than the last day of the calendar year following the year in which the expense is incurred; and (iv) the right to reimbursement or in kind benefits is not subject to liquidation or exchange for another benefit.

(g)    Indemnification. Executive shall be entitled to indemnification with respect to Executive’s services provided hereunder pursuant to Delaware law, the terms and conditions of Company’s certificate of incorporation and/or by-laws, Company’s directors and officers (“D&O”) liability insurance policy, and Company’s standard indemnification agreement for directors and officers as executed by Company and Executive.

(h)    Relocation Bonus. Company shall pay Executive a relocation payment of one hundred thousand dollars ($100,000) within one month after the Commencement Date. In the event of Termination by Executive within 12 months after the Commencement Date, a prorated portion of the Relocation Bonus shall be repaid to the company reflecting the remaining portion of the first 12 months of service.

(i)    Initial Public Offering. If the Company completes an initial public offering, Executive’s compensation (base salary, target bonus, and equity) shall be reviewed relative to the compensation for CMOs at comparable public companies as determined by the Company’s Board of Directors and adjusted as deemed appropriate by the Board of Directors.

4.    Payments Upon Termination.

(a)    Definition of Accrued Obligations. For purposes of this Agreement, “Accrued Obligations” means the portion of Executive’s Base Salary that has accrued prior to any termination of Executive’s employment with Company and has not yet been paid, and the amount of any expenses properly incurred by Executive on behalf of Company prior to any such termination and not yet reimbursed. Executive’s entitlement to any other compensation or benefit under any plan of Company shall be governed by and determined in accordance with the terms of such plans, except as otherwise specified in this Agreement.

(b)    Termination by Company for Cause, by Executive Without Good Reason, or as a Result of Executive’s Disability or Death. If Executive’s employment hereunder is terminated by Company for Cause, by Executive without Good Reason, or as a result of Executive’s Disability or death, then Company shall pay the Accrued Obligations to Executive promptly following the effective date of such termination.

(c)    Termination by Company Without Cause or by Executive For Good Reason. In the event that Executive’s employment is terminated by action of Company other than for Cause, or Executive terminates Executive’s employment for Good Reason, then, in addition to the Accrued Obligations, Executive shall receive the following, subject to the terms and conditions of Section 4(d):

(i)    Severance Payments. Payment in an amount equal to Executive’s then-current Base Salary for a nine (9) month period, less customary and required taxes and employment- related deductions, paid in one lump sum amount on the first payroll date following the date on which the separation agreement under Section 4(d) becomes effective and non-revocable; provided that such payment shall be made within seventy (70) days following the effective date of termination from employment, and further provided that if the 70th day falls in the calendar year following the year during which the termination or separation from service occurred, then the payments will commence in such subsequent calendar year, and further provided that if such payments commence in such subsequent year, the first such payment shall be a lump sum in an amount equal to the payments that would have come due since Employee’s separation from service. For the avoidance of doubt, the severance payments in this Section 4(c)(i) apply in the event of a change of control of the Company.

(ii)    Benefits Payments. Upon completion of appropriate forms and subject to applicable terms and conditions under the Consolidated Omnibus Budget Reconciliation Act of 1985, as amended (“COBRA”), Company shall continue to provide Executive medical insurance coverage at no cost to Executive to the same extent that such insurance continues to be provided to similarly situated executives at the time of Executive’s termination, until the earlier to occur of twelve (12) months following Executive’s termination date or the date Executive begins employment with another employer. Executive shall bear responsibility for applying for COBRA continuation coverage.

(d)    Execution of Separation Agreement. Company shall not be obligated to pay Executive severance payments or benefits described in this Section 4 unless Executive has executed (without revocation) a timely separation agreement in a form acceptable to Company, which shall include a release of claims and standard terms regarding non-disparagement, confidentiality, cooperation and the like, which shall be provided to Executive within ten (10) days following separation from service, and signed by Executive and returned to Company no later than sixty (60) days following Executive’s separation from service (the “Review Period”).

(e)    COBRA. If the payment of any COBRA or health insurance premiums by Company on behalf of Executive as described herein would otherwise violate any applicable nondiscrimination rules or cause the reimbursement of claims to be taxable under the Patient Protection and Affordable Care Act of 2010, together with the Health Care and Education Reconciliation Act of 2010 (collectively, the “Act”) or Section 105(h) of the Code, the COBRA premiums paid by Company shall be treated as taxable payments (subject to customary and required taxes and employment-related deductions) and be subject to imputed income tax treatment to the extent necessary to eliminate any discriminatory treatment or taxation under the Act or Section 105(h) of the Code. If Company determines in its sole discretion that it cannot provide the COBRA benefits described herein under Company’s health insurance plan without potentially violating applicable law (including, without limitation, Section 2716 of the Public Health Service Act), Company shall in lieu thereof provide to Executive a taxable lump-sum payment in an amount equal to the sum of the monthly (or then remaining) COBRA premiums that Executive would be required to pay to maintain Executive’s group health insurance coverage in effect on the separation date for the remaining portion of the period for which Executive shall receive the payments described in Sections 4(b) or 4(c) above.

5.    Prohibited Competition And Solicitation. In light of the competitive and proprietary aspects of the business of Company, and as a condition of employment hereunder, Executive agrees to execute and abide by Company’s Confidentiality, Assignment of Inventions and Non-Competition Agreement.

6.    Property and Records. Upon the termination of Executive’s employment hereunder, or if Company otherwise requests, Executive shall: (a) return to Company all tangible business information and copies thereof (regardless how such Confidential Information or copies are maintained), and (b) deliver to Company any property of Company which may be in Executive’s possession, including, but not limited to, cell phones, smart phones, laptops, products, materials, memoranda, notes, records, reports or other documents or photocopies of the same.

7.    Code Sections 409A and 280G.

(a)    In the event that the payments or benefits set forth in Section 4 of this Agreement constitute “non-qualified deferred compensation” subject to Section 409A, then the following conditions apply to such payments or benefits:

(i)    Any termination of Executive’s employment triggering payment of benefits under Section 4 must constitute a “separation from service” under Section 409A(a)(2)(A)(i) of the Code and Treas. Reg. §1.409A-l(h) before distribution of such benefits can commence. To the extent that the termination of Executive’s employment does not constitute a separation of service under Section 409A(a)(2)(A)(i) of the Code and Treas. Reg. § 1.409A-1 (h) (as the result of further services that are reasonably anticipated to be provided by Executive to Company at the time Executive’s employment terminates), any such payments under Section 4 that constitute deferred compensation under Section 409A shall be delayed until after the date of a subsequent event constituting a separation of service under Section 409A(a)(2)(A)(i) of the Code and Treas. Reg. §1.409A-l(h). For purposes of clarification, this Section 7(a) shall not cause any forfeiture of benefits on Executive’s part, but shall only act as a delay until such time as a “separation from service” occurs.

(ii)    Notwithstanding any other provision with respect to the timing of payments under Section 4 if, at the time of Executive’s termination, Executive is deemed to be a “specified employee” of Company (within the meaning of Section 409A(a)(2)(B)(i) of the Code), then limited only to the extent necessary to comply with the requirements of Section 409A, any payments to which Executive may become entitled under Section 4 which are subject to Section 409A (and not otherwise exempt from its application) shall be withheld until the first (1^st) business day of the seventh (7^th) month following the termination of Executive’s employment, at which time Executive shall be paid an aggregate amount equal to the accumulated, but unpaid, payments otherwise due to Executive under the terms of Section 4.

(b)    It is intended that each installment of the payments and benefits provided under Section 4 of this Agreement shall be treated as a separate “payment” for purposes of Section 409A. Neither Company nor Executive shall have the right to accelerate or defer the delivery of any such payments or benefits except to the extent specifically permitted or required by Section 409A.

(c)    Notwithstanding any other provision of this Agreement to the contrary, this Agreement shall be interpreted and at all times administered in a manner that avoids the inclusion of compensation in income under Section 409A, or the payment of increased taxes, excise taxes or other penalties under Section 409A. The parties intend this Agreement to be in compliance with Section 409A. Executive acknowledges and agrees that Company does not guarantee the tax treatment or tax consequences associated with any payment or benefit arising under this Agreement, including but not limited to consequences related to Section 409A.

(d)    If any payment or benefit Executive would receive under this Agreement, when combined with any other payment or benefit Executive receives pursuant to a change of control (for purposes of this section, a “Payment”) would: (i) constitute a “parachute payment” within the meaning of Section 280G the Code; and (ii) but for this sentence, be subject to the excise

tax imposed by Section 4999 of the Code (the “Excise Tax”), then such Payment shall be either: (A) the full amount of such Payment; or (B) such lesser amount as would result in no portion of the Payment being subject to the Excise Tax, whichever of the foregoing amounts, taking into account the applicable federal, state and local employments taxes, income taxes and the Excise Tax, results in Executive’s receipt, on an after-tax basis, of the greater amount of the Payment notwithstanding that all or some portion of the Payment may be subject to the Excise Tax. With respect to subsection (B), if there is more than one method of reducing the payment as would result in no portion of the Payment being subject to the Excise Tax, then Executive shall determine which method shall be followed, provided that if Executive fails to make such determination within thirty (30) days after Company has sent Executive written notice of the need for such reduction, Company may determine the amount of such reduction in its sole discretion.

8.    General.

(a)    Notices. Except as otherwise specifically provided herein, any notice required or permitted by this Agreement shall be in writing and shall be delivered as follows with notice deemed given as indicated: (i) by personal delivery when delivered personally; (ii) by overnight courier upon written verification of receipt; (iii) by telecopy or facsimile transmission upon acknowledgment of receipt of electronic transmission; or (iv) by certified or registered mail, return receipt requested, upon verification of receipt.

The last known address in Company’s records or such other address as Executive may specify in writing.

Checkmate Pharmaceuticals, Inc.

101 Main St., 14^th Floor

Cambridge, MA 02142

Attn: President and CEO

or to such other Company representative as Company may specify in ‘writing, with a copy to:

Goodwin Procter LLP

100 Northern Avenue

Boston, MA 02210

(b)    Modifications; Amendments; Waivers; Consents. The terms of this Agreement may be modified or amended only by written agreement executed by the parties hereto. The terms of this Agreement may be waived, or consent for the departure therefrom granted, only by written document executed by the party entitled to the benefits of such terms or provisions. No such waiver or consent shall be deemed to be or shall constitute a waiver or consent with respect to any other terms of this Agreement, whether or not similar. Each such waiver or consent shall be effective only in the specific instance and for the purpose for which it was given, and shall not constitute a continuing waiver or consent.

(c)    Assignment. Company may assign its rights and obligations hereunder to any person or entity that succeeds to all or substantially all of Company’s business or that aspect of Company’s business in which Executive is principally involved. Executive may not assign Executive’s rights and obligations under this Agreement without the prior written consent of Company.

(d)    Governing Law; Jurisdiction; Venue. This Agreement shall be governed by and construed in accordance with the substantive laws of the Commonwealth of Massachusetts, without giving effect to any choice or conflict of law provision or rule. Any legal action permitted by this Agreement to enforce an award or for a claimed breach shall be governed by the laws of the Commonwealth of Massachusetts and shall be commenced and maintained solely in any state or federal court located in the Commonwealth of Massachusetts, and both parties hereby submit to the jurisdiction and venue of any such court.

(e)    Headings and Captions. The headings and captions of the various subdivisions of this Agreement are for convenience of reference only and shall in no way modify or affect the meaning or construction of any of the terms or provisions hereof.

(f)    Entire Agreement. This Agreement, together with the other agreements specifically referenced herein, embodies the entire agreement and understanding between the parties hereto with respect to the subject matter hereof and supersedes all prior oral or written agreements and understandings relating to the subject matter hereof. No statement, representation, warranty, covenant or agreement of any kind not expressly set forth in this Agreement shall affect, or be used to interpret, change or restrict, the express terms and provisions of this Agreement.

This Agreement may be executed in two or more counterparts, and by different parties hereto on separate counterparts, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument. For all purposes a signature by fax shall be treated as an original.

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