Forms of Option Agreement, Stock Option Grant Notice and Notice of Exercise under the 2021 Equity Incentive Plan

Exhibit 10.5

2021 Equity Incentive Plan

Form of Global Stock Option Grant Package

ELIEM THERAPEUTICS, INC.

STOCK OPTION GRANT NOTICE

(2021 EQUITY INCENTIVE PLAN)

Eliem Therapeutics, Inc. (the “Company”), pursuant to the Company’s 2021 Equity Incentive Plan (the “Plan”), has granted to you (“Optionholder”) an option to purchase the number of shares of the Common Stock set forth below (the “Option”). Your Option is subject to all of the terms and conditions as set forth herein and in the Plan, and the Stock Option Agreement (which includes, if you are resident, subject to tax, or work outside the U.S., the general non-US terms and any special terms and conditions for your country, each set out in the attached appendix (the “Appendix”)) and the Notice of Exercise, all of which are attached hereto and incorporated herein in their entirety. Capitalized terms not explicitly defined herein but defined in the Plan or the Stock Option Agreement shall have the meanings set forth in the Plan or the Stock Option Agreement, as applicable.

Optionholder Acknowledgements: By your signature below or by electronic acceptance or authentication in a form authorized by the Company, you understand and agree that:

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ATTACHMENTS: Stock Option Agreement (including the Appendix), 2021 Equity Incentive Plan, Notice of Exercise

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ATTACHMENT I

ELIEM THERAPEUTICS, INC.

STOCK OPTION AGREEMENT

(2021 EQUITY INCENTIVE PLAN)

As reflected by your Stock Option Grant Notice (“Grant Notice”), Eliem Therapeutics, Inc. (the “Company”) has granted you an option under the Company’s 2021 Equity Incentive Plan (the “Plan”) to purchase a number of shares of Common Stock at the exercise price indicated in your Grant Notice (the “Option”). Capitalized terms not explicitly defined in this Agreement but defined in the Grant Notice or the Plan shall have the meanings set forth in the Grant Notice or Plan, as applicable. The terms of your Option as specified in the Grant Notice and this Stock Option Agreement (which includes, if you are resident, subject to tax, or work outside the U.S., the general non-US terms and any special terms and conditions for your country, each set out in the attached appendix (the “Appendix”)) constitute your Option Agreement.

The general terms and conditions applicable to your Option are as follows:

1. GOVERNING PLAN DOCUMENT. Your Option is subject to all the provisions of the Plan, including but not limited to the provisions in:

(a) Section 6 regarding the impact of a Capitalization Adjustment, dissolution, liquidation, or Corporate Transaction on your Option;

(b) Section 9(e) regarding the Company’s retained rights to terminate your Continuous Service notwithstanding the grant of the Option; and

(c) Section 8 regarding the tax consequences of your Option.

Your Option is further subject to all interpretations, amendments, rules and regulations, which may from time to time be promulgated and adopted pursuant to the Plan. In the event of any conflict between the Option Agreement and the provisions of the Plan, the provisions of the Plan shall control.

2. EXERCISE.

(a) You may generally exercise the vested portion of your Option for whole shares of Common Stock at any time during its term by delivery of payment of the exercise price and applicable withholding taxes and other required documentation to the Plan Administrator in accordance with the exercise procedures established by the Plan Administrator, which may include an electronic submission. Please review Sections 4(i), 4(j) and 7(b)(v) of the Plan, which may restrict or prohibit your ability to exercise your Option during certain periods.

(b) To the extent permitted by Applicable Law, you may pay your Option exercise price as follows:

(i) cash, check, bank draft or money order;

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(ii) subject to Company and/or Committee consent at the time of exercise, pursuant to a “cashless exercise” program as further described in Section 4(c)(ii) of the Plan if at the time of exercise the Common Stock is publicly traded;

(iii) subject to Company and/or Committee consent at the time of exercise, by delivery of previously owned shares of Common Stock as further described in Section 4(c)(iii) of the Plan; or

(iv) subject to Company and/or Committee consent at the time of exercise, if the Option is a Nonstatutory Stock Option, by a “net exercise” arrangement as further described in Section 4(c)(iv) of the Plan.

3. TERM. You may not exercise your Option before the commencement of its term or after its term expires. The term of your Option commences on the Date of Grant and expires upon the earliest of the following:

(a) immediately upon the termination of your Continuous Service for Cause;

(b) three months after the termination of your Continuous Service for any reason other than Cause, Disability or death;

(c) 12 months after the termination of your Continuous Service due to your Disability;

(d) 18 months after your death if you die during your Continuous Service;

(e) immediately upon a Corporate Transaction if the Board has determined that the Option will terminate in connection with a Corporate Transaction,

(f) the Expiration Date indicated in your Grant Notice; or

(g) the day before the 10th anniversary of the Date of Grant.

Notwithstanding the foregoing, if you die during the period provided in Section 3(b) or 3(c) above, the term of your Option shall not expire until the earlier of (i) 18 months after your death, (ii) upon any termination of the Option in connection with a Corporate Transaction, (iii) the Expiration Date indicated in your Grant Notice, or (iv) the day before the tenth anniversary of the Date of Grant. Additionally, the Post-Termination Exercise Period of your Option may be extended as provided in Section 4(i) of the Plan.

To obtain the federal income tax advantages associated with an Incentive Stock Option, the Code requires that at all times beginning on the date of grant of your Option and ending on the day three months before the date of your Option’s exercise, you must be an employee of the Company or an Affiliate, except in the event of your death or Disability. If the Company provides for the extended exercisability of your Option under certain circumstances for your benefit, your Option will not necessarily be treated as an Incentive Stock Option if you exercise your Option more than three months after the date your employment terminates.

4. WITHHOLDING OBLIGATIONS. As further provided in Section 8 of the Plan: (a) you may not exercise your Option unless the applicable tax withholding obligations are satisfied, and (b) at the time you exercise your Option, in whole or in part, or at any time thereafter as requested by the Company, you hereby authorize withholding from payroll and any other amounts payable to you, and otherwise agree to make adequate provision for (including by means of a “cashless exercise” pursuant to a program developed

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under Regulation T as promulgated by the Federal Reserve Board to the extent permitted by the Company), any sums required to satisfy the federal, state, local and foreign tax withholding obligations, if any, which arise in connection with the exercise of your Option in accordance with the withholding procedures established by the Company. Accordingly, you may not be able to exercise your Option even though the Option is vested, and the Company shall have no obligation to issue shares of Common Stock subject to your Option, unless and until such obligations are satisfied. In the event that the amount of the Company’s withholding obligation in connection with your Option was greater than the amount actually withheld by the Company, you agree to indemnify and hold the Company harmless from any failure by the Company to withhold the proper amount.

5. INCENTIVE STOCK OPTION DISPOSITION REQUIREMENT. If your Option is an Incentive Stock Option, you must notify the Company in writing within 15 days after the date of any disposition of any of the shares of the Common Stock issued upon exercise of your Option that occurs within two years after the date of your Option grant or within one year after such shares of Common Stock are transferred upon exercise of your Option.

6. LEAVE OF ABSENCE.

(a) During any Company-approved leave of absence (“LOA”), the vesting of your Option shall be suspended after the leave of absence exceeds a period of ninety (90) days (or such longer period as required by law). Vesting of your Option shall resume upon the termination of your LOA and return to service to the Company and/or its Affiliates. The vesting schedule of your Option shall be extended by the length of the suspension.

(b) You will be deemed to remain in Continuous Service during any LOA only through your Expected Return Date (as defined below), unless your Continuous Service is otherwise terminated for any reason prior to the Expected Return Date; provided, however, that if you notify the Company or the applicable Affiliate prior to the Expected Return Date (and prior to any earlier termination of Continuous Service) that you do not intend to resume employment or other eligible service with the Company or an Affiliate on or prior to the Expected Return Date (such notification, a “Notification”, and the date of such Notification, the “Notification Date”), then you will be deemed to remain in Continuous Service during the LOA only through the Notification Date. If you fail to report to work on the Expected Return Date, or if you provide a Notification prior to the Expected Return Date, then, on the Expected Return Date or the earlier Notification Date, as applicable, (i) your Continuous Service will be deemed terminated and (ii) vesting of your Option will cease immediately, in each case except to the extent required by applicable law. The first scheduled workday immediately following the Company-approved expiration date of the LOA or, if earlier, the date on which you actually return to employment or other eligible service with the Company or the applicable Affiliate is the “Expected Return Date”.

(c) The Board, Committee or the heads of the Company’s legal and human resources departments may make exceptions to the foregoing with respect to LOAs to comply with applicable laws, in cases where the application of the foregoing would not be in the interests of the Company or any Affiliate, or otherwise to the extent it deems necessary or advisable in its discretion.

(d) Nothing in this Agreement will confer upon you any right to remain in Continuous Service (or any other service) for any duration or to interfere with or otherwise restrict in any way the rights of the Company or any Affiliate to terminate your Continuous Service (or any other service) at any time for any reason, with or without cause, except as otherwise expressly set forth your employment or other service agreement with the Company or Affiliate, as applicable, or as required by applicable law.

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7. TRANSFERABILITY. Except as otherwise provided in the Plan, your Option is not transferable, except by will or by the applicable laws of descent and distribution, and is exercisable during your life only by you.

8. CORPORATE TRANSACTION. Your Option is subject to the terms of any agreement governing a Corporate Transaction involving the Company, including, without limitation, a provision for the appointment of a stockholder representative that is authorized to act on your behalf with respect to any escrow, indemnities and any contingent consideration.

9. NO LIABILITY FOR TAXES. As a condition to accepting the Option, you hereby (a) agree to not make any claim against the Company, or any of its Officers, Directors, Employees or Affiliates related to tax liabilities arising from the Option or other Company compensation and (b) acknowledge that you were advised to consult with your own personal tax, financial and other legal advisors regarding the tax consequences of the Option and have either done so or knowingly and voluntarily declined to do so. Additionally, you acknowledge that the Option is exempt from Section 409A only if the exercise price is at least equal to the “fair market value” of the Common Stock on the date of grant as determined by the Internal Revenue Service and there is no other impermissible deferral of compensation associated with the Option. Additionally, as a condition to accepting the Option, you agree not make any claim against the Company, or any of its Officers, Directors, Employees or Affiliates in the event that the Internal Revenue Service asserts that such exercise is less than the “fair market value” of the Common Stock on the date of grant as subsequently determined by the Internal Revenue Service.

10. SEVERABILITY. If any part of this Option Agreement or the Plan is declared by any court or governmental authority to be unlawful or invalid, such unlawfulness or invalidity will not invalidate any portion of this Option Agreement or the Plan not declared to be unlawful or invalid. Any Section of this Option Agreement (or part of such a Section) so declared to be unlawful or invalid will, if possible, be construed in a manner which will give effect to the terms of such Section or part of a Section to the fullest extent possible while remaining lawful and valid

11. EXECUTION OF DOCUMENTS. You hereby acknowledge and agree that the manner selected by the Company by which you indicate your consent to your Grant Notice is also deemed to be your execution of your Grant Notice and of this Agreement. You further agree that such manner of indicating consent may be relied upon as your signature for establishing your execution of any documents to be executed in the future in connection with your Option.

12. OTHER DOCUMENTS. You hereby acknowledge receipt of or the right to receive a document providing the information required by Rule 428(b)(1) promulgated under the Securities Act, which includes the Prospectus. In addition, you acknowledge receipt of the Company’s Trading Policy.

13. CHOICE OF LAW. The interpretation, performance and enforcement of this Option Agreement shall be governed by the laws of the State of Delaware without regard to that state’s conflicts of laws rules.

14. EFFECT ON OTHER EMPLOYEE BENEFIT PLANS. The value of your Option shall not be included as compensation, earnings, salaries, or other similar terms used when calculating benefits under any employee benefit plan (other than the Plan) sponsored by the Company or any Affiliate except as such plan otherwise expressly provides. The Company expressly reserves its rights to amend, modify, or terminate any or all of the employee benefit plans of the Company or any Affiliate.

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15. AMENDMENT. This Agreement may not be modified, amended or terminated except by an instrument in writing, signed by you and by a duly authorized representative of the Company. Notwithstanding the foregoing, this Agreement may be amended solely by the Board by a writing which specifically states that it is amending this Agreement, so long as a copy of such amendment is delivered to you, and provided that, except as otherwise expressly provided in the Plan, no such amendment materially adversely affecting your rights hereunder may be made without your written consent. Without limiting the foregoing, the Board reserves the right to change, by written notice to you, the provisions of this Agreement in any way it may deem necessary or advisable to carry out the purpose of your Option as a result of any change in applicable laws or regulations or any future law, regulation, ruling, or judicial decision, provided that any such change shall be applicable only to rights relating to that portion of your Option which is then subject to restrictions as provided herein.

16. APPENDIX. Notwithstanding any provisions in this Option Agreement, if you are resident, subject to tax, or work outside the U.S., your Option shall be subject to the general non-US terms and the special terms and conditions for your country set forth in the Appendix attached hereto. Moreover, if you relocate outside the U.S. and/or to one of the countries included therein, the terms and conditions for such country will apply to you to the extent the Company determines that the application of such terms and conditions is necessary or advisable for legal or administrative reasons. The Appendix constitutes part of this Option Agreement.

17. QUESTIONS. If you have questions regarding these or any other terms and conditions applicable to your Option, including a summary of the applicable federal income tax consequences please see the Prospectus.

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APPENDIX

This Appendix includes general terms and conditions that govern the Option granted to you under the Plan if you are resident, subject to tax, or work outside the U.S. and specific terms and conditions that apply if you are resident, subject to tax or work in any country listed herein.

The information contained herein is general in nature and may not apply to your particular situation, and you are advised to seek appropriate professional advice as to how the relevant laws in your country may apply to your situation. If you are a citizen or resident of a country other than the one in which you are currently working and/or residing, transfer employment and/or residency to another country after the date of grant, are a consultant, change employment status to a consultant position, or are considered a resident of another country for local law purposes, the Company shall, in its discretion, determine the extent to which the special terms and conditions contained herein shall be applicable to you. References to your employer shall include any entity that engages your services.

GENERAL NON-U.S. TERMS

1. TAX. All references in the Option Agreement to tax shall, to the extent applicable, include social security.

2. TRANSFERABILITY. Notwithstanding any other provision of this Option Agreement or the Plan, your Option is not transferable, except to your personal representative on your death, and is exercisable during your life only by you or by your personal representative after your death.

3. OPTION NOT A SERVICE CONTRACT. Your Option is not an employment or service contract, and nothing in your Option will be deemed to create in any way whatsoever any obligation on your part to continue in the employ of the Company or an Affiliate, or of the Company or an Affiliate to continue your employment. In addition, nothing in your Option will obligate the Company or an Affiliate, their respective stockholders, boards of directors, officers or employees to continue any relationship that you might have as a Director or Consultant for the Company or an Affiliate. By accepting your Option, you acknowledge, understand and agree that:

(a) the Plan is established voluntarily by the Company, it is discretionary in nature, and may be amended, suspended or terminated by the Company at any time, to the extent permitted under the Plan;

(b) the grant of your Option is voluntary and occasional and does not create any contractual or other right to receive future grants of options (whether on the same or different terms), or benefits in lieu of options, even if options have been granted in the past;

(c) your Options and any shares of Common Stock acquired under the Plan on exercise of your Options, and the income and value of same, are not part of normal or expected compensation for any purpose, including, without limitation, calculating any severance, resignation, termination, redundancy, dismissal, end-of-service payments, bonuses, holiday pay, long-service awards, pension or retirement or welfare benefits or similar payments;

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(d) the future value of the shares of Common Stock underlying the Option is unknown, indeterminable, and cannot be predicted with certainty;

(e) neither the Company nor any Affiliate shall be liable for any foreign exchange rate fluctuation between your local currency and the United States Dollar that may affect the value of your Options or of any amounts due to you pursuant to the exercise of your Option or the subsequent sale of any shares of Common Stock received;

(f) for the purposes of your Option, your Continuous Service will be considered terminated as of the date you are no longer actively providing services to the Company or one of its Affiliates (regardless of the reason for such termination and whether or not later found to be invalid or in breach of employment laws in the jurisdiction where you are employed or the terms of your employment agreement, if any), and unless otherwise expressly provided in this Agreement or determined by the Company, your right to vest in or exercise the Option under the Plan, if any, and the Board shall have the exclusive discretion to determine when you are no longer actively providing services for purposes of the Option (including whether you may still be considered to be providing services while on a leave of absence); and

(g) no claim or entitlement to compensation or damages shall arise from forfeiture of this Option resulting from the termination of your Continuous Service (for any reason whatsoever, whether or not later found to be invalid or in breach of employment laws in the jurisdiction where you are employed or the terms of your employment or service agreement, if any), and in consideration of the grant of this Option to which you are otherwise not entitled, you irrevocably agree never to institute any claim against the Company or any Affiliate, waive your ability, if any, to bring any such claim, and release the Company and any Affiliate from any such claim; if, notwithstanding the foregoing, any such claim is allowed by a court of competent jurisdiction, then, by participating in the Plan, you shall be deemed irrevocably to have agreed not to pursue such claim and agree to execute any and all documents necessary to request dismissal or withdrawal of such claim.

4. NO ADVICE REGARDING GRANT. The Company is not providing any tax, legal or financial advice, nor is the Company making any recommendations regarding your participation in the Plan, or your acquisition or sale of the underlying shares of Common Stock. You should consult with your own personal tax, legal and financial advisors regarding your participation in the Plan before taking any action.

5. DATA PRIVACY.

(a) You explicitly and unambiguously acknowledge and consent to the collection, use and transfer, in electronic or other form, of your personal data as described in this document by and among, as applicable, your employer, the Company and its Affiliates for the exclusive purpose of implementing, administering and managing your participation in the Plan. You understand that the Company, its Affiliates and your employer hold certain personal information about you, including, but not limited to, name, home address and telephone number, date of birth, social security number (or other identification number), salary, nationality, job title, any shares of stock or directorships held in the Company, details of all options or any other entitlement to shares of Common Stock awarded, canceled, purchased, exercised, vested, unvested or outstanding in your favor for the purpose of implementing, managing and administering the Plan (“Data”). You understand that the Data may be transferred to any third parties assisting in the implementation, administration and management of the Plan, that these recipients may be located in your country or elsewhere, in particular in the US, and that the recipient country may have different data privacy laws providing less protections of your personal data than your country. You may request a list with the names and addresses of any potential recipients of the Data by contacting the stock plan administrator at the Company (the “Stock Plan Administrator”). You acknowledge that the recipients may receive, possess,

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process, use, retain and transfer the Data, in electronic or other form, for the purposes of implementing, administering and managing your participation in the Plan, including any requisite transfer of such Data, as may be required to a broker or other third party with whom you may elect to deposit any shares of Common Stock acquired upon the exercise of your Option. You understand that Data will be held only as long as is necessary to implement, administer and manage your participation in the Plan. You may, at any time, view the Data, request additional information about the storage and processing of the Data, require any necessary amendments to the Data or refuse or withdraw the consents herein, in any case without cost, by contacting the Stock Plan Administrator in writing.

(b) For the purposes of operating the Plan in the European Union, Switzerland and the United Kingdom, the Company will collect and process information relating to you in accordance with the privacy notice from time to time in force.

6. LANGUAGE. You acknowledge that you are sufficiently proficient in the English language, or have consulted with an advisor who is sufficiently proficient in English, so as to allow you to understand the terms and conditions of this Option Agreement. If you have received this Option Agreement, or any other document related to your Option and/or the Plan translated into a language other than English and if the meaning of the translated version is different than the English version, the English version will control.

7. FOREIGN ASSET/ACCOUNT, EXCHANGE CONTROL AND TAX REPORTING. You may be subject to foreign asset/account, exchange control and/or tax reporting requirements as a result of the acquisition, holding and/or transfer of shares of Common Stock or cash (including dividends and the proceeds arising from the sale of shares of Common Stock) derived from your participation in the Plan in, to and/or from a brokerage/bank account or legal entity located outside your country. The applicable laws in your country may require that you report such accounts, assets and balances therein, the value thereof and/or the transactions related thereto to the applicable authorities in such country. You may also be required to repatriate sale proceeds or other funds received as a result of your participation in the Plan to your country through a designated bank or broker within a certain time after receipt. You acknowledge that it is your responsibility to be compliant with such regulations and you are encouraged to consult with your personal legal advisor for any details.

COUNTRY SPECIFIC TERMS

[To be included]

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ATTACHMENT II

ELIEM THERAPEUTICS, INC.

2021 EQUITY INCENTIVE PLAN

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ATTACHMENT III

ELIEM THERAPEUTICS, INC.

NOTICE OF EXERCISE

(2021 EQUITY INCENTIVE PLAN)

This constitutes notice to Eliem Therapeutics, Inc. (the “Company”) that I elect to purchase the below number of shares of Common Stock of the Company (the “Shares”) by exercising my Option for the price set forth below. Capitalized terms not explicitly defined in this Notice of Exercise but defined in the Stock Option Grant Notice, Stock Option Agreement or 2021 Equity Incentive Plan (the “Plan”) shall have the meanings set forth in the Stock Option Grant Notice, Stock Option Agreement or Plan, as applicable. Use of certain payment methods is subject to Company and/or Committee consent and certain additional requirements set forth in the Stock Option Agreement and the Plan.

By this exercise, I agree (i) to provide such additional documents as you may require pursuant to the terms of the Plan, the Stock Option Grant Notice and the Stock Option Agreement (including the Appendix thereto), (ii) to satisfy the tax and/or social security withholding obligations, if any, relating to

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the exercise of this Option as set forth in the Stock Option Agreement, and (iii) if this exercise relates to an incentive stock option, to notify you in writing within 15 days after the date of any disposition of any of the Shares issued upon exercise of this Option that occurs within two years after the Date of Grant or within one year after such Shares are issued upon exercise of this Option.

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