Exhibit 10.1

FORM OF

INVESTOR AGREEMENT

This Investor Agreement (this “ Agreement ”) is entered into as of July [__], 2019, by and among SELLAS Life Sciences Group, Inc., a Delaware corporation (the “ Company ”), and [_______] (the “ Investor ”).

Recitals

WHEREAS , on June 18, 2019, the Company consummated an underwritten public offering (the “ Offering ”) of (i) 26,367,200 shares of common stock, par value $0.0001 per share (the “ Common Stock ”), (ii) 73,632,800 pre-funded warrants exercisable for shares of Common Stock, and (iii) accompanying Common Stock warrants to purchase up to an aggregate of 100,000,000 shares of Common Stock (the “ Warrants ”, and collectively with the Common Stock and the pre-funded warrants exercisable for shares of Common Stock, the “ Securities ”);

WHEREAS , the Investor purchased Securities in the Offering, pursuant to which the Company issued to the Investor a Warrant to purchase [______] shares of Common Stock;

[ WHEREAS , in connection with its purchase of Securities in the Offering, the Company and the Investor entered into that certain Leak-Out Agreement dated June 14, 2019 (the “ Leak-Out Agreement ”), pursuant to which the Investor agreed to certain limitations with respect to its ability to sell, dispose or otherwise transfer, directly or indirectly (including, without limitation, any sales, short sales, swaps or any derivative transactions that would be equivalent to any sales or short positions), shares of Common Stock (as well as the shares of Common Stock issuable upon exercise of the Warrants and the pre-funded warrants exercisable for shares of Common Stock) on or before August 2, 2019;] ¹

WHEREAS , on or before October 1, 2019, the Company intends to hold a special meeting of its stockholders (the “ Meeting ”) at which the Company’s stockholders of record as of a date to be determined in the future (the “ Record Date ”) shall be asked to adopt and/or approve, among other things, an amendment to the Company’s Amended and Restated Certificate of Incorporation to effect a reverse stock split of the Common Stock, at a ratio to be determined in the future by the Company’s board of directors (the “ Split Proposal ”); and

WHEREAS, as of the date hereof, the Investor beneficially owns or has sole or shared voting power with respect to certain shares of Common Stock, and is willing to agree to vote all of the shares of Common Stock that it owns as of the Record Date in favor of the Split Proposal.

NOW, THEREFORE, in consideration of the premises and other good and valuable consideration, receipt of which is hereby acknowledged, the Company and the Investor hereby agree as follows:

“ if, between July 10, 2019 and September 18, 2020 ”

“ if, between July 10, 2019 and September 18, 2020 ”

(a)       The Investor represents, warrants and agrees that (i) the Investor has all necessary power and authority to enter into this Agreement, (ii) this Agreement is the legal, valid and binding agreement of the Investor, and (iii) this Agreement is enforceable against the Investor in accordance with its terms.

(b)       The Company represents, warrants and agrees that (i) the Company has all necessary power and authority to enter into this Agreement, (ii) this Agreement is the legal, valid and binding agreement of the Company, and (iii) this Agreement is enforceable against the Company in accordance with its terms.

(c)       The Company represents to the Investor that the Investor has not been provided with any material, non-public information from the Company, any of its subsidiaries, or any of their respective officers, directors, employees, affiliates or agents.

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

[Signature Page to Investor Agreement]

Exhibit 10.2

AMENDMENT TO

WARRANT AGREEMENT

This Amendment to Warrant Agreement, dated as of July 8, 2019 (this “ Amendment ”), by and among SELLAS Life Sciences Group, Inc. (the “ Company ”), and Computershare Inc. and its wholly-owned subsidiary, Computershare Trust Company, N.A., as Warrant Agent (collectively, the “ Warrant Agent ”), amends that certain Warrant Agreement, dated as of June 18, 2019 (the “ Warrant Agreement ”), by and among the Company and the Warrant Agent.

For good and valuable consideration, the receipt of which is hereby acknowledged, the parties agree as follows:

1.        Amendment to Warrant Agreement .

“ (i) in whole or in part for a whole number of Warrant Shares, if, between July 10, 2019 and September 18, 2020, the Weighted Average Price of the Common Stock on the Trading Day immediately prior to the Exercise Date fails to exceed the initial Exercise Price (subject to adjustment for any stock splits, stock dividends, stock combinations, recapitalizations and similar events) in which event, in lieu of the formula below, the aggregate number of Warrant Shares issuable in such cashless exercise pursuant to any given Exercise Notice electing to effect a Cashless Exercise shall equal the product of (x) the aggregate number of Warrant Shares for which the Warrants are exercised as if such exercise were by means of a cash exercise rather than a Cashless Exercise and (y) one (1) ” .

2.        Miscellaneous .

2.01        Effect. Except as amended hereby, the Warrant Agreement shall remain in full force and effect. In the event that there is any conflict or inconsistency between the terms of this Amendment and the terms of the Warrant Agreement, the terms of this Amendment shall govern. All references in the Warrant Agreement to “this Warrant Agreement” shall be deemed to refer to the Warrant Agreement, as amended hereby.

2.02        No Waiver . This Amendment is effective only in the specific instance and for the specific purpose for which it is executed and shall not be considered a waiver or agreement to amend as to any provision of the Warrant Agreement in the future.

2.03        Defined Terms . All capitalized terms used but not specifically defined herein shall have the same meanings given such terms in the Warrant Agreement unless the context clearly indicates or dictates a contrary meaning.

2.04        Governing Law . This Amendment shall be deemed to be a contract made under the laws of the State of New York (without giving effect to any rule or principle that would result in application of the law of any other jurisdiction) and for all purposes shall be governed by and construed in accordance with the laws of such State applicable to contracts to be made and performed entirely within such State.

2.05        Counterparts . This Amendment may be executed in any number of counterparts, all of which taken together shall constitute one and the same instrument, and each of the parties hereto may execute this Amendment by signing any of such counterparts.

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