Exhibit 10.1

March 14, 2018

Barbara A. Wood, Esq.

360 Riverside Drive, Apt. 8C

New York, NY 10025

Dear Barbara:

On behalf of SELLAS Life Sciences Group, Inc. (the “Company”) this letter will confirm our offer of employment to join the Company, effective on March 14, 2018 (the “Effective Date”) on the following terms:

1.     Employment : You will be employed on a full-time basis as the Company’s Executive Vice President, General Counsel and Corporate Secretary. You will report to the Company’s Chief Executive Officer (the “CEO”) and have the duties and responsibilities that are consistent with your position and such other duties as may from time to time be assigned to you by the Company.

2.     Annual Base Salary : You will be paid $365,000.00 per annum, less applicable witholdings, payable in accordance with the Company’s payroll schedule (the “Base Salary”). In accordance with normal policy, your Base Salary shall be reviewed by the Compensation Committee of the Company’s Board of Directors (the “Board”) on an annual basis.

3.     Sign-On Bonus : Employee shall receive a one-time signing bonus in the amount of $16,845.00, less applicable withholdings, which shall be payable on March 31, 2018.

4.     Short-Term Incentive Compensation : On an annual basis and subject to approval of the Board, you shall be entitled to annual short-term incentive compensation at a target level of up to 40% of your Base Salary, less applicable withholdings. The actual amount of such annual incentive compensation shall be determined in accordance with the applicable plans based on achievement of individual and Company performance objectives established in advance by the Board or the Board’s Compensation Committee, taking into account input from the CEO, and such actual annual short term incentive compensation amount may be more or less than the target amount. No minimum incentive is guaranteed. Company currently anticipates that the next review of your incentive compensation will occur on or before March 15 ^th of the following year. The Annual Bonus, if any, is paid no later than March 15th of the following year and is earned upon payment.

SELLAS ^TM Life Sciences Group, Inc., 315 Madison Avenue, 4 ^th Floor, New York, New York 10017, USA

Nasdaq: SLS

www.sellaslifesciences.com

5.     Equity . As of the Effective Date, you will be granted an option to purchase 50,000  shares of the Company’s common stock (“Common Stock”) at an exercise price per share of Common Stock equal to the closing price of the Common Stock on Nasdaq on the date of grant (the “Option”). To be eligible, you must still be employed by the Company when the Board grants the Option. To the extent it so qualifies, the Option will be an incentive stock option as defined in Section 422 of the Internal Revenue Code of 1986, as amended (the “Code”) and any regulations promulgated thereunder. Subject to any accelerated vesting provisions subsequently agreed to by the Company and you, the Option will vest as to 25% of the shares subject to the Option one year after the date of grant, and as to 1/48th of the shares subject to the Option monthly thereafter, so that the Option will be fully vested and exercisable four (4) years from the date of grant, subject to your Continuous Service Status (as defined in the Plan) to the Company through the relevant vesting dates. The Option will be subject to the terms, definitions and provisions of the Company’s 2017 Stock Plan (the “Option Plan”) and the stock option agreement by and between you and the Company (the “Option Agreement”), both of which documents are incorporated herein by reference.

6.     Employee Benefits . You will be eligible to participate in the Company’s employee benefits programs at the same level as provided to other senior executive level employees of Company, including, without limitation, the Company’s group medical, dental, vision, disability, life insurance, and flexible-spending account plans. You will be eligible for fifteen (15) days paid time off (vacation). In addition, you shall be entitled to up to four (4) paid “Personal Days/Floating Holiday” benefits and five (5) paid Sick Days. The Company will establish an annual list of U.S Federal holidays observed each year as well. The Company may change compensation and benefits from time to time in its discretion.

Vacation days, sick days and floating holidays may be used during the calendar year in which they are earned and accrued, and all earned and accrued sick days and floating holidays that are not used within the calendar year in which they are earned and accrued will be forfeited without compensation, unless applicable federal, state or local law requires otherwise. Accrued but unused vacation days, sick days and floating holidays are forfeited upon termination from employment, except as prohibited by law. Except as set forth in this offer letter, all vacation days, sick days and floating holidays shall accrue and be used and compensated in accordance with the Company’s paid time off policy(ies) as in effect from time to time, unless applicable federal, state, or local law requires otherwise.

7.     Business Expenses . During the Employment Term, the Company will reimburse you for reasonable business travel, entertainment or other business expenses (including bar membership fees and professional association dues) incurred by you in the furtherance of or in connection with the performance of your duties hereunder, in accordance with the Company’s expense reimbursement policy as in effect from time to time.

SELLAS ^TM Life Sciences Group, Inc., 315 Madison Avenue, 4 ^th Floor, New York, New York 10017, USA

Nasdaq: SLS

www.sellaslifesciences.com

8.     Employment Agreement . Promptly following the Effective Date, you and the Company will negotiate in good faith a written employment agreement containing the preceding provisions and additional terms including but not limited to: (i) the benefits to which you are entitled upon a termination upon death or disability, (ii) the benefits to which you are entitled upon an involuntary termination for cause and resignation without good reason, (iii) the benefits to which you are entitled upon an involuntary termination without cause and resignation for good reason, (iv) the ramifications of change of control, (v) tax provisions, including without limitation, under Sections 409A and 280G of the Internal Revenue Code of 1986, or any successor provisions, and (vi) and other mutually-agreeable customary employment terms. Any such provisions shall be consistent with like terms provided to other senior executives.

9.     Proprietary Information and Inventions . You acknowledge and agree that you have signed, is bound by, and will continue to abide by the terms of the Employee Confidential Information and Invention Assignment Agreement, which was executed on March 1, 2018 (the “Confidential Information Agreement”), including the provisions governing the non-disclosure of confidential information and restrictive covenants contained therein.

10.     No Conflict. 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 offer letter.

11.     Prior Agreements . We also ask that, if you have not already done so, you disclose to the Company any and all agreements relating to your prior employment that may affect your eligibility to be employed by the Company or limit the manner in which you may be employed. It is the Company’s understanding that any such agreements will not prevent you from performing the duties of your position and you represent that such is the case. Moreover, you agree that, during the term of your employment with the Company, you will not engage in any other employment, occupation, consulting, or other business activity directly related to the business in which the Company is now involved or becomes involved during the term of your employment, nor will you engage in any other activities that conflict with your obligations to the Company. Similarly, you agree not to bring any third-party confidential information to the Company, including that of your former employer, and that you will not in any way utilize any such information in performing your duties for the Company.

12.     Immigration . For purposes of federal immigration law, you will be required to provide to the Company documentary evidence of your identity and eligibility for employment in the United States. Such documentation must be provided to us within three (3) business days of your date of hire, or our employment relationship with you may be terminated.

SELLAS ^TM Life Sciences Group, Inc., 315 Madison Avenue, 4 ^th Floor, New York, New York 10017, USA

Nasdaq: SLS

www.sellaslifesciences.com

13.     Arbitration . To ensure the timely and economical resolution of disputes that may arise in connection with your employment with the Company, you and the Company agree that any and all disputes, claims, or causes of action arising from or relating to the enforcement, breach, performance, negotiation, execution, or interpretation of this letter agreement, or your employment, or the termination of your employment, including but not limited to all statutory claims, will be resolved pursuant to the Federal Arbitration Act, 9 U.S.C. §1-16, and to the fullest extent permitted by law, by final, binding and confidential arbitration by a single arbitrator conducted in New York, New York by Judicial Arbitration and Mediation Services Inc. (“JAMS”) under the then applicable JAMS rules (at the following web address: http://www.jamsadr.com/rulesclauses). A hard copy of the rules will be provided to you upon request. By agreeing to this arbitration procedure, both you and the Company waive the right to resolve any such dispute through a trial by jury or judge or administrative proceeding. In addition, all claims, disputes, or causes of action under this provision, whether by you or the Company, must be brought in an individual capacity, and shall not be brought as a plaintiff (or claimant) or class member in any purported class or representative proceeding, nor joined or consolidated with the claims of any other person or entity. The Arbitrator may not consolidate the claims of more than one person or entity, and may not preside over any form of representative or class proceeding. To the extent that the preceding sentences regarding class claims or proceedings are found to violate applicable law or are otherwise found unenforceable, any claim(s) alleged or brought on behalf of a class shall proceed in a court of law rather than by arbitration. The Company acknowledges that you will have the right to be represented by legal counsel at any arbitration proceeding. Questions of whether a claim is subject to arbitration under this agreement) shall be decided by the arbitrator. Likewise, procedural questions which grow out of the dispute and bear on the final disposition are also matters for the arbitrator. The arbitrator shall: (a) have the authority to compel adequate discovery for the resolution of the dispute and to award such relief as would otherwise be permitted by law; (b) issue a written arbitration decision, to include the arbitrator’s essential findings and conclusions and a statement of the award; and (c) be authorized to award any or all remedies that you or the Company would be entitled to seek in a court of law. You and the Company shall equally share all JAMS’ arbitration fees. Each party is responsible for its own attorneys’ fees, except as expressly set forth in your CONFIDENTIAL INFORMATION AGREEMENT. Nothing in this letter agreement is intended to prevent either you or the Company from obtaining injunctive relief in court to prevent irreparable harm pending the conclusion of any such arbitration. Any awards or orders in such arbitrations may be entered and enforced as judgments in the federal and state courts of any competent jurisdiction.

SELLAS ^TM Life Sciences Group, Inc., 315 Madison Avenue, 4 ^th Floor, New York, New York 10017, USA

Nasdaq: SLS

www.sellaslifesciences.com

14.     At-Will Employment . This offer 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 the Company and you remain free to end the employment relationship for any reason, at any time, with or without cause or notice. Although your job duties, title, compensation and benefits, as well as the Company’s personnel policies and procedures, may change from time to time, the “at-will” nature of your employment may only be changed by a written agreement signed by you and the CEO that expressly states the intention to modify the at-will nature of your employment. 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 beyond the end of your employment with the Company. This letter supersedes all prior understandings, whether written or oral, relating to the terms of your employment.

We are extremely pleased to have an individual of your background and experience join the Company and look forward to a long and successful business relationship. Please acknowledge your acceptance of these terms at your earliest convenience. Please keep one copy of this letter for your files and return the original as soon as possible.

[Signature Page to Follow]

SELLAS ^TM Life Sciences Group, Inc., 315 Madison Avenue, 4 ^th Floor, New York, New York 10017, USA

Nasdaq: SLS

www.sellaslifesciences.com

SELLAS ^TM Life Sciences Group, Inc., 315 Madison Avenue, 4 ^th Floor, New York, New York 10017, USA

Nasdaq: SLS

www.sellaslifesciences.com

Exhibit 10.2

SELLAS L IFE S CIENCES G ROUP , I NC .

S TOCK O PTION G RANT N OTICE

(2017 E QUITY I NCENTIVE P LAN )

SELLAS Life Sciences Group, Inc. (the “ Company ”), pursuant to its 2017 Equity Incentive Plan (the “ Plan ”), hereby grants to Optionholder an option to purchase the number of shares of the Company’s Common Stock set forth below. This option is subject to all of the terms and conditions as set forth in this Stock Option Grant Notice, in the Option Agreement, the Plan 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 Option Agreement will have the same definitions as in the Plan or the Option Agreement. If there is any conflict between the terms in this Stock Option Grant Notice and the Plan, the terms of the Plan will control.

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Additional Terms/Acknowledgements: Optionholder acknowledges receipt of, and understands and agrees to, this Stock Option Grant Notice, the Option Agreement and the Plan. Optionholder acknowledges and agrees that this Stock Option Grant Notice and the Option Agreement may not be modified, amended or revised except as provided in the Plan. Optionholder further acknowledges that as of the Date of Grant, this Stock Option Grant Notice, the Option Agreement, and the Plan set forth the entire understanding between Optionholder and the Company regarding this option award and supersede all prior oral and written agreements, promises and/or representations on that subject with the exception of, if applicable, (i) equity awards previously granted and delivered to Optionholder, (ii) any compensation recovery policy that is adopted by the Company or is otherwise required by applicable law and (iii) any written employment or severance arrangement or other written agreement entered into between the Company and Participant that would provide for vesting acceleration of this option upon the terms and conditions set forth therein. By accepting this option, Optionholder consents to receive such documents by electronic delivery and to participate in the Plan through an on-line or electronic system established and maintained by the Company or another third party designated by the Company.

A TTACHMENTS : Option Agreement, 2017 Equity Incentive Plan and Notice of Exercise

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A TTACHMENT I

SELLAS LIFE SCIENCES GROUP, INC.

O PTION A GREEMENT

(2017 E QUITY I NCENTIVE P LAN )

(I NCENTIVE S TOCK O PTION OR N ONSTATUTORY S TOCK O PTION )

Pursuant to your Stock Option Grant Notice (“ Grant Notice ”) and this Option Agreement, SELLAS Life Sciences Group, Inc. (the “ Company ”) has granted you an option under its 2017 Equity Incentive Plan (the “ Plan ”) to purchase the number of shares of the Company’s Common Stock indicated in your Grant Notice at the exercise price indicated in your Grant Notice. The option is granted to you effective as of the date of grant set forth in the Grant Notice (the “ Date of Grant ”). If there is any conflict between the terms in this Option Agreement and the Plan, the terms of the Plan will control. Capitalized terms not explicitly defined in this Option Agreement or in the Grant Notice but defined in the Plan will have the same definitions as in the Plan.

The details of your option, in addition to those set forth in the Grant Notice and the Plan, are as follows:

1.      V ESTING . Subject to the provisions contained herein, your option will vest as provided in your Grant Notice. Vesting will cease upon the termination of your Continuous Service.

2.      N UMBER OF S HARES AND E XERCISE P RICE . The number of shares of Common Stock subject to your option and your exercise price per share in your Grant Notice will be adjusted for Capitalization Adjustments.

3.      E XERCISE R ESTRICTION FOR N ON -E XEMPT E MPLOYEES . If you are an Employee eligible for overtime compensation under the Fair Labor Standards Act of 1938, as amended (that is, a “ Non-Exempt Employee ”), and except as otherwise provided in the Plan, you may not exercise your option until you have completed at least six (6) months of Continuous Service measured from the Date of Grant, even if you have already been an employee for more than six (6) months. Consistent with the provisions of the Worker Economic Opportunity Act, you may exercise your option as to any vested portion prior to such six (6) month anniversary in the case of (i) your death or disability, (ii) a Corporate Transaction in which your option is not assumed, continued or substituted, (iii) a Change in Control or (iv) your termination of Continuous Service on your “retirement” (as defined in the Company’s benefit plans).

4.      M ETHOD OF P AYMENT . You must pay the full amount of the exercise price for the shares you wish to exercise. You may pay the exercise price in cash or by check, bank draft or money order payable to the Company or in any other manner permitted by your Grant Notice, which may include one or more of the following:

(a)     Provided that at the time of exercise the Common Stock is publicly traded, pursuant to a program developed under Regulation T as promulgated by the Federal Reserve Board that, prior to the issuance of Common Stock, results in either the receipt of cash (or check) by the Company or the receipt of irrevocable instructions to pay the aggregate exercise price to the Company from the sales proceeds. This manner of payment is also known as a “broker-assisted exercise”, “same day sale”, or “sell to cover”.

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(b)     Provided that at the time of exercise the Common Stock is publicly traded, by delivery to the Company (either by actual delivery or attestation) of already-owned shares of Common Stock that are owned free and clear of any liens, claims, encumbrances or security interests, and that are valued at Fair Market Value on the date of exercise. “Delivery” for these purposes, in the sole discretion of the Company at the time you exercise your option, will include delivery to the Company of your attestation of ownership of such shares of Common Stock in a form approved by the Company. You may not exercise your option by delivery to the Company of Common Stock if doing so would violate the provisions of any law, regulation or agreement restricting the redemption of the Company’s stock.

(c)     If this option is a Nonstatutory Stock Option, subject to the consent of the Company at the time of exercise, by a “net exercise” arrangement pursuant to which the Company will reduce the number of shares of Common Stock issued upon exercise of your option by the largest whole number of shares with a Fair Market Value that does not exceed the aggregate exercise price. You must pay any remaining balance of the aggregate exercise price not satisfied by the “net exercise” in cash or other permitted form of payment. Shares of Common Stock will no longer be outstanding under your option and will not be exercisable thereafter if those shares (i) are used to pay the exercise price pursuant to the “net exercise,” (ii) are delivered to you as a result of such exercise, and (iii) are withheld to satisfy your tax withholding obligations.

5.      W HOLE S HARES . You may exercise your option only for whole shares of Common Stock.

6.      S ECURITIES L AW C OMPLIANCE . In no event may you exercise your option unless the shares of Common Stock issuable upon exercise are then registered under the Securities Act or, if not registered, the Company has determined that your exercise and the issuance of the shares would be exempt from the registration requirements of the Securities Act. The exercise of your option also must comply with all other applicable laws and regulations governing your option, and you may not exercise your option if the Company determines that such exercise would not be in material compliance with such laws and regulations (including any restrictions on exercise required for compliance with Treas. Reg. 1.401(k)-1(d)(3), if applicable).

7.      T ERM . You may not exercise your option before the Date of Grant or after the expiration of the option’s term. The term of your option expires, subject to the provisions of Section 5(h) of the Plan, upon the earliest of the following:

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

(b)     three (3) months after the termination of your Continuous Service for any reason other than Cause, your Disability or your death (except as otherwise provided in Section 7(d) below); provided, however, that if during any part of such three (3) month period your option is not exercisable solely because of the condition set forth in the section above regarding “Securities Law Compliance,” your option will not expire until the earlier of the Expiration Date or until it has been exercisable for an aggregate period of three (3) months after the termination of your Continuous Service; provided further, if during any part of such three (3) month period, the sale of any Common Stock received upon exercise of your option would violate the Company’s insider trading policy, then your option will not expire until the earlier of the Expiration Date or until it has been exercisable for an aggregate period of three (3) months after the termination of your Continuous Service during which the sale of the Common Stock received upon exercise of your option would not be in violation of the Company’s insider trading policy. Notwithstanding the foregoing, if (i) you are a Non-Exempt Employee, (ii) your Continuous Service terminates within six (6) months after the Date of Grant, and (iii) you have vested in a portion of your option at the time of your termination of Continuous Service, your option will not expire until the earlier of (x) the later of (A) the date that is seven (7) months after the Date of Grant, and (B) the date that is three (3) months after the termination of your Continuous Service, and (y) the Expiration Date;

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(c)     twelve (12) months after the termination of your Continuous Service due to your Disability (except as otherwise provided in Section 7(d) below);

(d)     eighteen (18) months after your death if you die either during your Continuous Service or within three (3) months after your Continuous Service terminates for any reason other than Cause;

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

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

If your option is an Incentive Stock Option, note that 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 and ending on the day three (3) 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. The Company has provided for extended exercisability of your option under certain circumstances for your benefit but cannot guarantee that your option will necessarily be treated as an Incentive Stock Option if you continue to provide services to the Company or an Affiliate as a Consultant or Director after your employment terminates or if you otherwise exercise your option more than three (3) months after the date your employment with the Company or an Affiliate terminates.

8.    E XERCISE .

(a)     You may exercise the vested portion of your option (and the unvested portion of your option if your Grant Notice so permits) during its term by (i) delivering a Notice of Exercise (in a form designated by the Company) or completing such other documents and/or procedures designated by the Company for exercise and (ii) paying the exercise price and any applicable withholding taxes to the Company’s Secretary, stock plan administrator, or such other person as the Company may designate, together with such additional documents as the Company may then require.

(b)     By exercising your option you agree that, as a condition to any exercise of your option, the Company may require you to enter into an arrangement providing for the payment by you to the Company of any tax withholding obligation of the Company arising by reason of (i) the exercise of your option, (ii) the lapse of any substantial risk of forfeiture to which the shares of Common Stock are subject at the time of exercise, or (iii) the disposition of shares of Common Stock acquired upon such exercise.

(c)     If your option is an Incentive Stock Option, by exercising your option you agree that you will notify the Company in writing within fifteen (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 (2) years after the Date of Grant or within one (1) year after such shares of Common Stock are transferred upon exercise of your option.

9.      T RANSFERABILITY . Except as otherwise provided in this Section 9, your option is not transferable, except by will or by the laws of descent and distribution, and is exercisable during your life only by you.

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(a)      Certain Trusts. Upon receiving written permission from the Board or its duly authorized designee, you may transfer your option to a trust if you are considered to be the sole beneficial owner (determined under Section 671 of the Code and applicable state law) while the option is held in the trust. You and the trustee must enter into transfer and other agreements required by the Company.

(b)      Domestic Relations Orders. Upon receiving written permission from the Board or its duly authorized designee, and provided that you and the designated transferee enter into transfer and other agreements required by the Company, you may transfer your option pursuant to the terms of a domestic relations order, official marital settlement agreement or other divorce or separation instrument as permitted by Treasury Regulation 1.421-1(b)(2) that contains the information required by the Company to effectuate the transfer. You are encouraged to discuss the proposed terms of any division of this option with the Company prior to finalizing the domestic relations order or marital settlement agreement to help ensure the required information is contained within the domestic relations order or marital settlement agreement. If this option is an Incentive Stock Option, this option may be deemed to be a Nonstatutory Stock Option as a result of such transfer.

(c)      Beneficiary Designation. Upon receiving written permission from the Board or its duly authorized designee, you may, by delivering written notice to the Company, in a form approved by the Company and any broker designated by the Company to handle option exercises, designate a third party who, on your death, will thereafter be entitled to exercise this option and receive the Common Stock or other consideration resulting from such exercise. In the absence of such a designation, your executor or administrator of your estate will be entitled to exercise this option and receive, on behalf of your estate, the Common Stock or other consideration resulting from such exercise.

10.      O PTION NOT A S ERVICE C ONTRACT . 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.

11.    W ITHHOLDING O BLIGATIONS .

(a)     At the time you exercise your option, in whole or in part, and 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 “same day sale” pursuant to a program developed 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 of the Company or an Affiliate, if any, which arise in connection with the exercise of your option.

(b)     If this option is a Nonstatutory Stock Option, then upon your request and subject to approval by the Company, and compliance with any applicable legal conditions or restrictions, the Company may withhold from fully vested shares of Common Stock otherwise issuable to you upon the exercise of your option a number of whole shares of Common Stock having a Fair Market Value, determined by the Company as of the date of exercise, not in excess of the minimum amount of tax required to be withheld by law (or such lower amount as may be necessary to avoid classification of your option as a liability for financial accounting purposes). Notwithstanding the filing of such election, shares of Common Stock shall be withheld solely from fully vested shares of Common Stock determined as of the date of exercise of your option that are otherwise issuable to you upon such exercise. Any adverse consequences to you arising in connection with such share withholding procedure shall be your sole responsibility.

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(c)     You may not exercise your option unless the tax withholding obligations of the Company and/or any Affiliate are satisfied. Accordingly, you may not be able to exercise your option when desired even though your option is vested, and the Company will have no obligation to issue a certificate for such shares of Common Stock or release such shares of Common Stock from any escrow provided for herein, if applicable, unless such obligations are satisfied.

12.      T AX C ONSEQUENCES . You hereby agree that the Company does not have a duty to design or administer the Plan or its other compensation programs in a manner that minimizes your tax liabilities. You will not make any claim against the Company, or any of its Officers, Directors, Employees or Affiliates related to tax liabilities arising from your option or your other compensation. In particular, you acknowledge that this option is exempt from Section 409A of the Code only if the exercise price per share specified in the Grant Notice is at least equal to the “fair market value” per share of the Common Stock on the Date of Grant and there is no other impermissible deferral of compensation associated with the option.

13.      N OTICES . Any notices provided for in your option or the Plan will be given in writing (including electronically) and will be deemed effectively given upon receipt or, in the case of notices delivered by mail by the Company to you, five (5) days after deposit in the United States mail, postage prepaid, addressed to you at the last address you provided to the Company. The Company may, in its sole discretion, decide to deliver any documents related to participation in the Plan and this option by electronic means or to request your consent to participate in the Plan by electronic means. By accepting this option, you consent to receive such documents by electronic delivery and to participate in the Plan through an on-line or electronic system established and maintained by the Company or another third party designated by the Company.

14.      G OVERNING P LAN D OCUMENT . Your option is subject to all the provisions of the Plan, the provisions of which are hereby made a part of your option, and is further subject to all interpretations, amendments, rules and regulations, which may from time to time be promulgated and adopted pursuant to the Plan. If there is any conflict between the provisions of your option and those of the Plan, the provisions of the Plan will control. In addition, your option (and any compensation paid or shares issued under your option) is subject to recoupment in accordance with The Dodd–Frank Wall Street Reform and Consumer Protection Act and any implementing regulations thereunder, any clawback policy adopted by the Company and any compensation recovery policy otherwise required by applicable law.

15.      O THER D OCUMENTS . You hereby acknowledge receipt of and the right to receive a document providing the information required by Rule 428(b)(1) promulgated under the Securities Act, which includes the Plan prospectus. In addition, you acknowledge receipt of the Company’s policy permitting certain individuals to sell shares only during certain “window” periods and the Company’s insider trading policy, in effect from time to time.

16.      E FFECT ON O THER E MPLOYEE B ENEFIT P LANS . The value of this option will not be included as compensation, earnings, salaries, or other similar terms used when calculating your benefits under any employee benefit 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 of the Company’s or any Affiliate’s employee benefit plans.

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17.      V OTING R IGHTS . You will not have voting or any other rights as a stockholder of the Company with respect to the shares to be issued pursuant to this option until such shares are issued to you. Upon such issuance, you will obtain full voting and other rights as a stockholder of the Company. Nothing contained in this option, and no action taken pursuant to its provisions, will create or be construed to create a trust of any kind or a fiduciary relationship between you and the Company or any other person.

18.      S EVERABILITY . If all or 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 shall, 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.

19.      M ISCELLANEOUS .

(a)     The rights and obligations of the Company under your option will be transferable to any one or more persons or entities, and all covenants and agreements hereunder will inure to the benefit of, and be enforceable by the Company’s successors and assigns.

(b)     You agree upon request to execute any further documents or instruments necessary or desirable in the sole determination of the Company to carry out the purposes or intent of your option.

(c)     You acknowledge and agree that you have reviewed your option in its entirety, have had an opportunity to obtain the advice of counsel prior to executing and accepting your option, and fully understand all provisions of your option.

(d)     This Option Agreement will be subject to all applicable laws, rules, and regulations, and to such approvals by any governmental agencies or national securities exchanges as may be required.

(e)     All obligations of the Company under the Plan and this Option Agreement will be binding on any successor to the Company, whether the existence of such successor is the result of a direct or indirect purchase, merger, consolidation, or otherwise, of all or substantially all of the business and/or assets of the Company.

*            *              *

This Option Agreement will be deemed to be signed by you upon the signing by you of the Stock Option Grant Notice to which it is attached.

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A TTACHMENT II

2017 E QUITY I NCENTIVE P LAN

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A TTACHMENT III

N OTICE OF E XERCISE

This constitutes notice to SELLAS Life Sciences Group, Inc. (the “ Company ”) under my stock option that I elect to purchase the below number of shares of Common Stock of the Company (the “ Shares ”) for the price set forth below.

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By this exercise, I agree (i) to provide such additional documents as you may require pursuant to the terms of the SELLAS Life Sciences Group, Inc. 2017 Equity Incentive Plan, (ii) to provide for the payment by me to you (in the manner designated by you) of your withholding obligation, if any, relating to the exercise of this option, and (iii) if this exercise relates to an incentive stock option, to notify you in writing within fifteen (15) days after the date of any disposition of any of the Shares issued upon exercise of this option that occurs within two (2) years after the date of grant of this option or within one (1) year after such Shares are issued upon exercise of this option.

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