SELLAS Life Sciences Group, Inc. Shares Common Stock ($0.0001 par value per share) and Pre-Funded Warrants to Purchase Shares of Common Stock and Warrants to Purchase Shares of Common Stock Underwriting Agreement

Exhibit 1.1

SELLAS Life Sciences Group, Inc.

Shares

Common Stock

($0.0001 par value per share)

and

Pre-Funded Warrants to Purchase Shares of Common Stock and

Warrants to Purchase Shares of Common Stock

Underwriting Agreement

New York, New York

, 2018

Cantor ▇▇▇▇▇▇▇▇▇▇ & Co.

▇▇▇▇▇▇▇▇▇▇▇ & Co. Inc.

As Representatives of the several Underwriters,

c/o Cantor ▇▇▇▇▇▇▇▇▇▇ & Co.

▇▇▇ ▇▇▇▇ ▇▇▇▇▇▇

New York, NY 10022

c/o Oppenheimer & Co. Inc.

▇▇ ▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇▇ Floor

New York, NY 10004

Ladies and Gentlemen:

SELLAS Life Sciences Group, Inc., a corporation organized under the laws of Delaware (including any predecessor entities, the “Company”), proposes to sell to the several underwriters named in Schedule I hereto (the “Underwriters”), for whom you (the “Representatives”) are acting as representatives, (i) an aggregate of shares of common stock, $0.0001 par value per share (“Common Stock”) of the Company (said shares to be issued and sold by the Company being hereinafter called the “Shares”), (ii) pre-funded warrants to purchase up to an aggregate of shares of Common Stock (the “Pre-Funded Warrants”) at an exercise price of $0.01 per share and (iii) warrants of the Company to purchase an aggregate

of shares of Common Stock (the “Common Warrants”) at an exercise price equal to $ per share. The Shares, the Pre-Funded Warrants and the Common Warrants to be sold by the Company are collectively referred to as the “Securities.” The Shares and Pre-Funded Warrants are being sold to investors with the Common Warrants as a fixed combination, with each Share and each Pre-Funded Warrant, as the case may be, being accompanied by a Common Warrant to purchase one share of Common Stock. To the extent there are no additional Underwriters listed on Schedule I other than you, the term Representatives as used herein shall mean you, as Underwriters, and the terms Representatives and Underwriters shall mean either the singular or plural as the context requires. Certain terms used herein are defined in Section 20 hereof. Any reference herein to the Registration Statement, any Preliminary Prospectus or the Prospectus or any amendment or supplement to any of the foregoing shall be deemed to refer to and include the documents incorporated by reference therein pursuant to General Instruction VII of Form S-1. As used herein, “Warrant Shares” means the shares of Common Stock issuable upon exercise of the Common Warrants or the Pre-Funded Warrants. The terms of the Common Warrants are set forth in the Form of Warrant Agreement (the “Warrant Agreement”) attached hereto as Exhibit C and to be entered into between the Company and Computershare Trust Company, N.A., as Warrant Agent. The terms of the Pre-Funded Warrants are set forth in the form of Pre-Funded Warrant attached hereto as Exhibit D.

1. Representations and Warranties. The Company represents and warrants to, and agrees with, each Underwriter as set forth below in this Section 1.

(a) The Company has prepared and filed with the Commission a registration statement (file number 333-225140) on Form S-1, including a related preliminary prospectus, for registration under the Act of the offering and sale of the Securities. Such Registration Statement, including any amendments thereto filed prior to the Execution Time, has become effective. The Company may have filed one or more amendments thereto, including a related preliminary prospectus, each of which has previously been furnished to you. The Company will file with the Commission a final prospectus in accordance with Rule 424(b). As filed, such final prospectus shall contain all information required by the Act and the rules thereunder and, except to the extent the Representatives shall agree in writing to a modification, shall be in all substantive respects in the form furnished to you prior to the Execution Time or, to the extent not completed at the Execution Time, shall contain only such specific additional information and other changes (beyond that contained in the latest Preliminary Prospectus) as the Company has advised you, prior to the Execution Time, will be included or made therein.

(b) On the Effective Date, the Registration Statement did, and when the Prospectus is first filed in accordance with Rule 424(b) and on the Closing Date (as defined herein), the Prospectus (and any supplement thereto as of the date of such supplement) will, comply in all material respects with the applicable requirements of the Act and the rules thereunder; on the Effective Date and at the Execution Time, the Registration Statement did not and will not contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary in order to make the statements therein not misleading; and on the date of any filing pursuant to Rule 424(b) and on the Closing Date, the Prospectus (together with any supplement thereto) will not include any untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances

under which they were made, not misleading; provided, however, that the Company makes no representations or warranties as to the information contained in or omitted from the Registration Statement, or the Prospectus (or any supplement thereto) in reliance upon and in conformity with information furnished in writing to the Company by or on behalf of any Underwriter through the Representatives specifically for inclusion in the Registration Statement or the Prospectus (or any supplement thereto), it being understood and agreed that the only such information furnished by any Underwriter consists of the information described as such in Section 8 hereof. The Company has complied to the Commission’s satisfaction with all requests of the Commission for additional or supplemental information, if any. No stop order suspending the effectiveness of the Registration Statement has been issued and, to the knowledge of the Company, no proceeding for that purpose has been instituted or threatened by the Commission or by the state securities authority of any jurisdiction. No order preventing or suspending the use of the Prospectus has been issued and, to the knowledge of the Company, no proceeding for that purpose has been instituted by the Commission or by the state securities authority of any jurisdiction.

(c) The Disclosure Package, when taken together as a whole, does not contain any untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading. The preceding sentence does not apply to statements in or omissions from the Disclosure Package based upon and in conformity with written information furnished to the Company by any Underwriter through the Representatives specifically for use therein, it being understood and agreed that the only such information furnished by or on behalf of any Underwriter consists of the information described as such in Section 8 hereof.

(d) The Company has not prepared or used or referred to any Free Writing Prospectus, including any electronic roadshow, or otherwise engaged in any activities which an Ineligible Issuer would be prohibited from taking.

(e) All documents filed by the Company pursuant to Sections 12, 13, 14 or 15 of the Exchange Act and incorporated or deemed to be incorporated by reference into the Registration Statement, any Preliminary Prospectus, the Disclosure Package or the Prospectus, when they became effective or were filed with the Commission, as the case may be, complied in all material respects with the requirements of the Act or the Exchange Act, as applicable and were filed on a timely basis with the Commission, and none of such documents contained an untrue statement of a material fact or omitted to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading. There are no contracts or other documents required to be described in the Disclosure Package or the Prospectus or to be filed as an exhibit to the Registration Statement which have not been described or filed as required.

(f) Each of the Company and its subsidiaries (i) has been duly incorporated and is validly existing as a corporation in good standing under the laws of the jurisdiction in which it is chartered or organized with full corporate power and authority to own or lease, as the case may be, and to operate its properties and conduct its business as described in the Registration Statement, the Disclosure Package and the Prospectus, and (ii) is duly qualified to do business as a foreign corporation and is in good standing under the laws of each jurisdiction which requires

such qualification, except where the failure to be so qualified or be in good standing or have such power or authority would not, individually or in the aggregate, have a material adverse effect or would not reasonably be expected to have a material adverse effect on or affect the assets, business, operations, earnings, properties, condition (financial or otherwise), prospects, stockholders’ equity or results of operations of the Company and the Subsidiaries taken as a whole or prevent or materially interfere with the consummation of the transactions contemplated hereby (a “Material Adverse Effect”).

(g) All the outstanding shares of capital stock of each subsidiary have been duly and validly authorized and issued and are fully paid and non-assessable, and, except as otherwise set forth in the Registration Statement, the Disclosure Package and the Prospectus, all outstanding shares of capital stock of the subsidiaries are owned by the Company either directly or through wholly owned subsidiaries free and clear of any perfected security interest or any other security interests, claims, liens or encumbrances. Except as set forth in the Registration Statement, the Disclosure Package and the Prospectus, there are no outstanding options, warrants or other rights to purchase, agreements or other obligations to issue, or rights to convert any obligations into or exchange any securities or interests for capital stock or other ownership interests of any subsidiary of the Company.

(h) The Company’s authorized equity capitalization is as set forth in the Registration Statement, the Disclosure Package and the Prospectus; the capital stock of the Company conforms in all material respects to the description thereof contained in the Registration Statement, the Disclosure Package and the Prospectus; other than as disclosed in the Registration Statement, the Disclosure Package and the Prospectus, the outstanding shares of capital stock of the Company have been duly and validly authorized and issued and are fully paid and non-assessable; except as disclosed in the Registration Statement, the Disclosure Package and the Prospectus with respect to the exchange rights of the holders of the Company’s Series A Preferred Stock, the issuance of the Securities is not subject to any preemptive rights, rights of first refusal or other similar rights to subscribe for or purchase the capital stock or other securities of the Company; and except as set forth in the Registration Statement, the Disclosure Package and the Prospectus, no options, warrants or other rights to purchase, agreements or other obligations to issue, or rights to convert any obligations into or exchange any securities for, shares of capital stock of or ownership interests in the Company are outstanding; and, other than as disclosed in the Registration Statement, the Disclosure Package and the Prospectus, and except as would not, individually or in the aggregate, have Material Adverse Effect, all offers and sales by the Company of the Company’s shares of Common Stock prior to the date hereof were at all relevant times duly registered under the Act or were exempt from the registration requirements of the Act and were duly registered or the subject of an available exemption from the registration requirements of the applicable state securities or blue sky laws. No holder of the Securities will be subject to personal liability for obligations of the Company solely by reason of being such a holder.

(i) The Shares have been duly and validly authorized, and, when issued and delivered to and paid for by the Underwriters pursuant to the terms of this Underwriting Agreement (this “Agreement”), will be fully paid and non-assessable. The Warrant Agreement, the Pre-Funded Warrants and the Common Warrants have been duly authorized by the Company and,

when executed and delivered by the Company, will be valid and binding agreements of the Company, enforceable against the Company in accordance with their terms, except as the enforcement thereof may be limited by bankruptcy, insolvency, reorganization, moratorium or other similar laws relating to or affecting the rights and remedies of creditors or by general equitable principles. The Warrant Shares have been duly authorized and validly reserved for issuance upon exercise of the Pre-Funded Warrants and the Common Warrants. The Warrant Shares, when issued and delivered upon exercise of the Common Warrants or the Pre-Funded Warrants and in accordance therewith, will be validly issued, fully paid and nonassessable and the issuance of the Warrant Shares is not subject to any preemptive rights, rights of first refusal or other similar rights to subscribe for or purchase the capital stock or other securities of the Company. The Securities, when issued, will conform to the description thereof set forth in or incorporated into the Registration Statement, the Disclosure Package and the Prospectus. The Shares and the Warrant Shares are duly listed, and admitted and authorized for trading, subject to official notice of issuance and evidence of satisfactory distribution, on the Nasdaq Capital Market.

(j) The Company does not have any outstanding debt or preferred equity securities that are rated by any “nationally recognized statistical rating organization” (as defined for purposes of Rule 3(a)(62) under the Exchange Act).

(k) The statements in the Preliminary Prospectus and the Prospectus under the headings “Risk Factors,” “Business – Strategic Collaborations and License Agreements,” “Business – Intellectual Property,” “Business – Government Regulation,” “Business – Legal Proceedings,” “Certain Relationships and Related Party Transactions,” “Description of Capital Stock,” “Description of the Securities We Are Offering” and “Material U.S. Federal Income Tax Consequences to Holders of Common Stock and Warrants” and in the Proxy Statement filed on April 30, 2018 under the heading “Executive Compensation – Agreements with Our Named Executive Officers” insofar as such statements summarize legal matters, agreements, documents or proceedings discussed therein, are accurate and fair summaries in all material respects of such legal matters, agreements, documents or proceedings.

(l) This Agreement has been duly authorized, executed and delivered by the Company. The Company has the requisite power and authority to execute and deliver the Warrant Agreement, the Pre-Funded Warrants, the Common Warrants and the Warrant Shares and to perform its obligations thereunder. The Company has duly and validly taken all action required to be taken for the due and proper authorization, execution and delivery by it of the Warrant Agreement, the Pre-Funded Warrants, the Common Warrants and the Warrant Shares.

(m) The Company is not and, after giving effect to the offering and sale of the Securities and the application of the proceeds thereof as described in the Registration Statement, the Disclosure Package and the Prospectus, will not be an “investment company” as defined in the Investment Company Act of 1940, as amended.

(n) No consent, approval, authorization, filing with or order of any court or governmental agency or body is required in connection with the transactions contemplated herein, except such as have been obtained under the Act and such as may be required under the

blue sky laws of any jurisdiction in connection with the purchase and distribution of the Securities by the Underwriters in the manner contemplated herein and in the Registration Statement, the Disclosure Package and the Prospectus.

(o) Neither the issue and sale of the Securities nor the consummation of any other of the transactions herein contemplated nor the fulfillment of the terms of the Securities or hereof will conflict with, result in a breach or violation of, or imposition of any lien, charge or encumbrance upon any property or assets of the Company or any of its subsidiaries pursuant to, (i) the charter or by-laws of the Company or any of its subsidiaries, (ii) the terms of any indenture, contract, lease, mortgage, deed of trust, note agreement, loan agreement or other agreement, obligation, condition, covenant or instrument to which the Company or any of its subsidiaries is a party or bound or to which its or their property is subject, or (iii) any statute, law, rule, regulation, judgment, order or decree applicable to the Company or any of its subsidiaries of any court, regulatory body, administrative agency, governmental body, arbitrator or other authority having jurisdiction over the Company or any of its subsidiaries or any of its or their properties, except in the case of clauses (ii) and (iii) for such conflicts, breaches or violations and impositions of any lien, charge or encumbrance that would not reasonably be expected, individually or in the aggregate, to have a Material Adverse Effect.

(p) No holders of securities of the Company have rights to the registration of such securities under the Registration Statement except as disclosed in the Registration Statement, the Disclosure Package and the Prospectus and no person has any registration rights in connection with the filing of the Registration Statement and the consummation of the offering (including the offering of the Securities contemplated under this Agreement) except for any such rights as have been validly waived.

(q) The consolidated historical financial statements, including the notes thereto, and schedules of the Company and its consolidated subsidiaries (including, for the avoidance of doubt, SELLAS Life Sciences Group, Ltd.) included or incorporated by reference in the Registration Statement, the Preliminary Prospectus and the Prospectus present fairly the financial condition, results of operations and cash flows of the Company as of the dates and for the periods indicated, comply as to form with the applicable accounting requirements of the Act and the Exchange Act and have been prepared in conformity with U.S. generally accepted accounting principles (“GAAP”) applied on a consistent basis throughout the periods involved (except as otherwise noted therein). The selected financial data set forth under the caption “Selected Financial Information” in the Registration Statement, the Preliminary Prospectus and the Prospectus fairly present, on the basis stated in the Registration Statement, the Preliminary Prospectus and the Prospectus, the information included therein. All non-GAAP financial information, if any, included or incorporated by reference in the Registration Statement, the Disclosure Package and the Prospectus complies with the requirements of Regulation G and Item 10 of Regulation S-K under the Act; and, except as disclosed in the Registration Statement, the Disclosure Package and the Prospectus, there are no material off-balance sheet arrangements (as defined in Item 303(a)(4)(ii) of Regulation S-K under the Act) or any other relationships with unconsolidated entities or other persons, that may have a material current or, to the Company’s knowledge, material future effect on the Company’s consolidated financial condition, results of operations, liquidity, capital expenditures, capital resources or significant components of revenue

or expenses that are required to be disclosed therein that are not disclosed. No other financial statements or notes, historical or pro forma, are required to be included or incorporated by reference in the Registration Statement, the Disclosure Package or the Prospectus other than those that have been included or incorporated by reference therein in compliance with the requirements of the Act and the Exchange Act.

(r) No action, suit or proceeding by or before any court or governmental agency, authority or body or any arbitrator involving the Company or any of its subsidiaries or its or their property is pending or, to the knowledge of the Company, threatened that could reasonably be expected, individually or in the aggregate, to have a Material Adverse Effect, except as set forth in or contemplated in the Registration Statement, the Disclosure Package and the Prospectus.

(s) Each of the Company and each of its subsidiaries owns or leases all such properties as are necessary to the conduct of its operations as presently conducted.

(t) Neither the Company nor any subsidiary is in violation or default of (i) any provision of its charter or bylaws, (ii) the terms of any indenture, contract, lease, mortgage, deed of trust, note agreement, loan agreement or other agreement, obligation, condition, covenant or instrument to which it is a party or bound or to which its property is subject, or (iii) any applicable statute, law, rule, regulation, judgment, order or decree of any court, regulatory body, administrative agency, governmental body, arbitrator or other authority having jurisdiction over the Company or such subsidiary or any of its properties, as applicable, except in the case of clauses (ii) and (iii), such violations or defaults as would not reasonably be expected, individually or in the aggregate, to have a Material Adverse Effect.

(u) KPMG Audit Limited, who audited the financial statements of SELLAS Life Sciences Ltd (“Private SELLAS”) and its subsidiaries as of and for the year ended December 31, 2016 and delivered its report with respect to such prior consolidated financial statements included or incorporated by reference in the Registration Statement, Disclosure Package and the Prospectus, at the time of such prior audit, was an independent public accountant with respect to Private SELLAS within the meaning of the Act and the applicable published rules and regulations thereunder.

(v) ▇▇▇▇ ▇▇▇▇▇ LLP, who certified certain financial statements of the Company and its consolidated subsidiaries and delivered its report with respect to the audited consolidated financial statements and schedules included or incorporated by reference in the Registration Statement, Disclosure Package and the Prospectus, is independent public accountant with respect to the Company within the meaning of the Act and the applicable published rules and regulations thereunder.

(w) The Company and each of its subsidiaries have filed all tax returns that are required to be filed or has requested extensions thereof (except in any case in which the failure so to file would not have a Material Adverse Effect and except as set forth in or contemplated in the Registration Statement, the Disclosure Package and the Prospectus) and has paid all taxes required to be paid by it and any other assessment, fine or penalty levied against it, to the extent that any of the foregoing is due and payable, except for any such assessment, fine or penalty that

is currently being contested in good faith and for which adequate reserves have been provided in accordance with GAAP or as would not have a Material Adverse Effect, except as set forth in or contemplated in the Registration Statement, the Disclosure Package and the Prospectus.

(x) No labor problem or dispute with the employees of the Company or any of its subsidiaries exists or, to the knowledge of the Company, is threatened or imminent, and the Company is not aware of any existing or imminent labor disturbance by the employees of any of its or its subsidiaries’ principal suppliers, contractors or customers, which could, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect.

(y) The Company and its subsidiaries, taken as a whole, are insured by insurers of recognized financial responsibility against such losses and risks and in such amounts as are in the Company’s reasonable judgment prudent and customary in the businesses in which it is engaged; the Company and its subsidiaries are in compliance with the terms of such policies and instruments in all material respects; and there are no claims by the Company or any of its subsidiaries under any such policy or instrument as to which any insurance company is denying liability or defending under a reservation of rights clause; and neither the Company nor any such subsidiary has any reason to believe that it will not be able to renew its existing insurance coverage as and when such coverage expires or to obtain similar coverage from similar insurers as may be necessary to continue its business at a cost that would not have a Material Adverse Effect, except as set forth in or contemplated in the Registration Statement, the Disclosure Package and the Prospectus.

(z) No subsidiary of the Company is currently prohibited, directly or indirectly, from paying any dividends to the Company, from making any other distribution on such subsidiary’s capital stock, from repaying to the Company any loans or advances to such subsidiary from the Company or from transferring any of such subsidiary’s property or assets to the Company or any other subsidiary of the Company, except as described in or contemplated by the Registration Statement, the Disclosure Package and the Prospectus.

(aa) The Company and its subsidiaries, taken as a whole, possess all licenses, certificates, permits and other authorizations issued by all applicable authorities necessary to conduct their respective businesses, except where such failure would not reasonably be expected to have a Material Adverse Effect, and neither the Company nor any such subsidiary has received any written notice of proceedings relating to the revocation or modification of any such certificate, authorization or permit which, singly or in the aggregate, if the subject of an unfavorable decision, ruling or finding, that would reasonably be expected to have a Material Adverse Effect, except as set forth in or contemplated in the Registration Statement, the Disclosure Package and the Prospectus.

(bb) The Company and its subsidiaries, taken as a whole, maintain a system of internal accounting controls sufficient to provide reasonable assurance that (i) transactions are executed in accordance with management’s general or specific authorizations; (ii) transactions are recorded as necessary to permit preparation of financial statements in conformity with generally accepted accounting principles and to maintain asset accountability; (iii) access to assets is permitted only in accordance with management’s general or specific authorization; and (iv) the

recorded accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences. Except as set forth in or contemplated in the Registration Statement, the Disclosure Package and the Prospectus the Company’s internal controls over financial reporting are effective and the Company is not aware of any material weakness in its internal control over financial reporting.

(cc) The Company and its subsidiaries maintain “disclosure controls and procedures” (as such term is defined in Rule 13a-15(e) under the Exchange Act); such disclosure controls and procedures are effective.

(dd) The Company has not taken, directly or indirectly, any action designed to or that would constitute or that might reasonably be expected to cause or result in, under the Exchange Act or otherwise, stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the Securities or the Warrant Shares.

(ee) (i) The Company and its subsidiaries (x) are in compliance with any and all applicable federal, state, local and foreign laws, rules, regulations, requirements, decisions and orders relating to the protection of human health or safety, the environment, natural resources, hazardous or toxic substances or wastes, pollutants or contaminants (collectively, “Environmental Laws”), (y) have received and are in compliance with all permits, licenses, certificates or other authorizations or approvals required of them under applicable Environmental Laws to conduct their respective businesses, and (z) have not received notice of any actual or potential liability under or relating to any Environmental Laws, including for the investigation or remediation of any disposal or release of hazardous or toxic substances or wastes, pollutants or contaminants, and have no knowledge of any event or condition that would reasonably be expected to result in any such notice, and (ii) there are no costs or liabilities associated with Environmental Laws of or relating to the Company or its subsidiaries, except in the case of each of (i) and (ii) above, for any such failure to comply, or failure to receive required permits, licenses or approvals, or cost or liability, as would not, individually or in the aggregate, have a Material Adverse Effect.

(ff) To the knowledge of the Company, none of the following events has occurred or exists: (i) a failure to fulfill the obligations, if any, under the minimum funding standards of Section 302 of the United States Employee Retirement Income Security Act of 1974, as amended (“ERISA”), and the regulations and published interpretations thereunder with respect to a Plan, determined without regard to any waiver of such obligations or extension of any amortization period; (ii) an audit or investigation by the Internal Revenue Service, the U.S. Department of Labor, the Pension Benefit Guaranty Corporation or any other federal or state governmental agency or any foreign regulatory agency with respect to the employment or compensation of employees by any of the Company or any of its subsidiaries that could have a Material Adverse Effect; (iii) any breach of any contractual obligation, or any violation of law or applicable qualification standards, with respect to the employment or compensation of employees by the Company or any of its subsidiaries that could have a Material Adverse Effect. To the knowledge of the Company, none of the following events has occurred or, is reasonably likely to occur: (i) a material increase in the aggregate amount of contributions required to be made to all Plans in the current fiscal year of the Company and its subsidiaries compared to the amount of such

contributions made in the most recently completed fiscal year of the Company and its subsidiaries; (ii) a material increase in the “accumulated post-retirement benefit obligations” (within the meaning of Statement of Financial Accounting Standards 106) of the Company and its subsidiaries compared to the amount of such obligations in the most recently completed fiscal year of the Company and its subsidiaries; (iii) any event or condition giving rise to a liability under Title IV of ERISA that could have a Material Adverse Effect; or (iv) the filing of a claim by one or more employees or former employees of the Company or any of its subsidiaries related to their employment that could have a Material Adverse Effect. For purposes of this paragraph, the term “Plan” means a material employee benefit plan (within the meaning of Section 3(3) of ERISA) subject to Title IV of ERISA with respect to which the Company or any of its subsidiaries may have any liability.

(gg) There is and has been no failure on the part of the Company and any of the Company’s directors or officers, in their capacities as such, to comply with any provision of the ▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act of 2002 and the rules and regulations promulgated in connection therewith (the “▇▇▇▇▇▇▇▇-▇▇▇▇▇ Act”), including Section 402 relating to loans and Sections 302 and 906 relating to certifications.

(hh) Neither the Company nor any of its subsidiaries nor, to the knowledge of the Company, any director, officer, agent, employee or affiliate of the Company or any of its subsidiaries is aware of or has taken any action, directly or indirectly, that would result in a violation by such persons of the Foreign Corrupt Practices Act of 1977, as amended, and the rules and regulations thereunder (the “FCPA”), including, without limitation, making use of the mails or any means or instrumentality of interstate commerce corruptly in furtherance of an offer, payment, promise to pay or authorization of the payment of any money, or other property, gift, promise to give, or authorization of the giving of anything of value to any “foreign official” (as such term is defined in the FCPA) or any foreign political party or official thereof or any candidate for foreign political office, in contravention of the FCPA; and the Company, its subsidiaries and, to the knowledge of the Company, its affiliates have conducted their businesses in compliance with the FCPA and have instituted and maintain policies and procedures designed to ensure, and which are reasonably expected to continue to ensure, continued compliance therewith.

(ii) The operations of the Company and its subsidiaries are and have been conducted at all times in compliance with all applicable financial recordkeeping and reporting requirements and the money laundering statutes and the rules and regulations thereunder, including but not limited to the Bank Secrecy Act, as amended by the USA PATRIOT Act, and any related or similar rules, regulations or guidelines, issued, administered or enforced by any governmental agency (collectively, the “Money Laundering Laws”) and no action, suit or proceeding by or before any court or governmental agency, authority or body or any arbitrator involving the Company or any of its subsidiaries with respect to the Money Laundering Laws is pending or, to the best knowledge of the Company, threatened.

(jj) None of the Company, any of its subsidiaries or, to the knowledge of the Company, any director, officer, agent, employee or affiliate of the Company or any of its subsidiaries is currently the subject or the target of any applicable sanctions administered or

enforced by the U.S. Government (including, without limitation, the Office of Foreign Assets Control of the U.S. Department of the Treasury (“OFAC”)), the United Nations Security Council (“UNSC”), the European Union, Her Majesty’s Treasury (“HMT”), or other relevant sanctions authority (collectively, “Sanctions”), nor is the Company or any of its subsidiaries located, organized or resident in a country or territory that is the subject or target of Sanctions; and the Company will not directly or indirectly use the proceeds of the offering hereunder, or lend, contribute or otherwise make available such proceeds to any subsidiary, joint venture partner or other person or entity (i) to fund any activities of or business with any person, or in any country or territory, that, at the time of such funding, is the subject of Sanctions or (ii) in any other manner that will result in a violation by any person (including any person participating in the transaction, whether as underwriter, advisor, investor or otherwise) of Sanctions.

(kk) Neither the Company nor any of its subsidiaries nor, to the knowledge of the Company, any director, officer, agent, employee or affiliate of the Company or any of its subsidiaries, is a person that is, or is 50% or more owned or otherwise controlled by a person that is: (i) the subject of any Sanctions (a “Sanctioned Person”); or (ii) located, organized or resident in a country or territory that is, or whose government is, the subject of Sanctions that broadly prohibit dealings with that country or territory (currently, Cuba, Iran, North Korea, Sudan, and Syria) (collectively, “Sanctioned Countries” and each, a “Sanctioned Country”).

(ll) Except as has been disclosed to the Underwriters or is not material to the analysis under any Sanctions, neither the Company nor any of its subsidiaries has engaged in any dealings or transactions with or for the benefit of a Sanctioned Person, or with or in a Sanctioned Country, in the preceding 5 years, nor does the Company or any of its subsidiaries have any plans to increase its dealings or transactions with Sanctioned Persons, or with or in Sanctioned Countries.

(mm) The interactive data in the eXtensible Business Reporting Language (“XBRL”) included as an exhibit to the Registration Statement fairly presents the information called for in all material respects and has been prepared in accordance with the Commission’s rules and guidelines applicable thereto.

(nn) Except as set forth in the Registration Statement, the Disclosure Package and the Prospectus, the Company and its subsidiaries have good and marketable title to all personal property owned by them, free and clear of all encumbrances and defects; and all personal property held under lease by the Company or any subsidiary is held by it under valid, subsisting and enforceable leases, in each case, with such exceptions as are not material and do not interfere with the use made and proposed to be made of such property by the Company or the subsidiary.

(oo) No relationship, direct or indirect, exists between or among the Company on the one hand, and the directors, officers, or shareholders of the Company on the other hand, which is required to be described in the Registration Statement, the Disclosure Package or the Prospectus and which is not so described. To the knowledge of the Company, no officer, director or significant shareholder of the Company is a person associated with a broker-dealer or controls, is controlled by or is under common control with a broker-dealer.

(pp) Exhibit 21.1 to the Registration Statement sets forth the only significant subsidiaries of the Company as defined by Rule 1-02 of Regulation S-X.

(qq) The statistical and market-related data included in the Registration Statement, the Disclosure Package and the Prospectus are based on or derived from sources that the Company believes to be reliable and accurate.

(rr) Neither the issuance, sale and delivery of the Securities nor the application of the proceeds thereof by the Company as described in each of the Registration Statement, the Disclosure Package and the Prospectus will violate Regulation T, U or X of the Board of Governors of the Federal Reserve System.

(ss) Since the date of the most recent financial statements of the Company included or incorporated by reference in each of the Registration Statement, the Disclosure Package and the Prospectus (i) there has not been any change in the capital stock or long-term debt of the Company or any of its subsidiaries, or any dividend or distribution of any kind declared, set aside for payment, paid or made by the Company on any class of capital stock, or any material adverse change, or any development involving a prospective material adverse change, in or affecting the business, properties, prospects, earnings, rights, assets, management, financial position, or results of operations of the Company and its subsidiaries taken as a whole; (ii) neither the Company nor any of its subsidiaries has entered into any transaction or agreement that is material to the Company and its subsidiaries taken as a whole or incurred any liability or obligation, direct or contingent, that is material to the Company and its subsidiaries taken as a whole; and (iii) neither the Company nor any of its subsidiaries has sustained any material loss or interference with its business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor disturbance or dispute or any action, order or decree of any court or arbitrator or governmental or regulatory authority, except in each case as otherwise disclosed in each of the Registration Statement, the Disclosure Package and the Prospectus.

(tt) No forward-looking statement (within the meaning of Section 27A of the Act and Section 21E of the Exchange Act) included in any of the Registration Statement, the Disclosure Package and the Prospectus has been made or reaffirmed without a reasonable basis or has been disclosed other than in good faith.

(uu) Except as disclosed in the Registration Statement, the Preliminary Prospectus and the Prospectus, to the Company’s knowledge, the Company and its subsidiaries own, possess, license or have other rights to use, on reasonable terms, all patents, patent applications, trade and service marks, trade and service mark registrations, trade names, copyrights, licenses, inventions, trade secrets, technology, know-how and other intellectual property (collectively, the “Intellectual Property”) necessary for the conduct of the Company’s business as now conducted or as proposed in the Prospectus to be conducted and as described in the Registration Statement, the Preliminary Prospectus and the Prospectus, except to the extent that the failure to own, possess, license or otherwise hold adequate rights to use such Intellectual Property would not, individually or in the aggregate, have a Material Adverse Effect. Except as set forth in the Registration Statement, the Preliminary Prospectus and the Prospectus, to the knowledge of the Company (a) there are no rights of third parties to any such Intellectual Property; (b) there is no

material infringement by third parties of any such Intellectual Property; (c) there is no pending or threatened action, suit, proceeding or claim by others challenging the Company’s rights in or to any such Intellectual Property, and the Company is unaware of any facts which would form a reasonable basis for any such claim; (d) there is no pending or threatened action, suit, proceeding or claim by others challenging the validity or scope of any such Intellectual Property, and the Company is unaware of any facts which would form a reasonable basis for any such claim; (e) there is no pending or threatened action, suit, proceeding or claim by others that the Company infringes or otherwise violates any patent, trademark, copyright, trade secret or other proprietary rights of others, and the Company is unaware of any other fact which would form a reasonable basis for any such claim; (f) there is no U.S. patent that contains claims that dominate or may dominate any Intellectual Property described in the Disclosure Package and the Prospectus as being owned by or licensed to the Company or that interferes with the issued or pending claims of any such Intellectual Property that is necessary for the conduct of the Company’s business as now conducted or as proposed in the Prospectus to be conducted and as described in the Registration Statement, the Preliminary Prospectus and the Prospectus; and (g) there is no prior art of which the Company is aware that may render any U.S. patent held by the Company invalid.

(vv) Except as disclosed in the Registration Statement, the Disclosure Package and the Prospectus, the Company (i) does not have any material lending or other relationship with any bank or lending affiliate of the Representatives and (ii) does not intend to use any of the proceeds from the sale of the Securities hereunder to repay any outstanding debt owed to any affiliate of the Representatives.

(ww) Except as disclosed in the Registration Statement, the Disclosure Package and the Prospectus, the Company and its Subsidiaries have made all filings, applications and submissions required by, possesses and is operating in compliance with, all approvals, licenses, certificates, certifications, clearances, consents, grants, exemptions, marks, notifications, orders, permits and other authorizations issued by, the appropriate federal, state or foreign governmental authority (collectively, “Governmental Authority”), including the United States Food and Drug Administration (the “FDA”), the United States Drug Enforcement Administration or any other foreign, federal, state, provincial or local Government Authorities engaged in the regulation of clinical trials, pharmaceuticals, biologics or biohazardous substances or materials, necessary for the ownership or lease of their respective properties or to conduct its businesses as described in the Registration Statement, the Disclosure Package and the Prospectus (collectively, “Permits”), except for such Permits the failure of which to possess, obtain or make the same would not have a Material Adverse Effect; the Company and its Subsidiaries are in compliance with the terms and conditions of all such Permits, except where the failure to be in compliance would not have a Material Adverse Effect; all of the Permits are valid and in full force and effect, except where any invalidity, individually or in the aggregate, would not be reasonably expected to have a Material Adverse Effect; and neither the Company nor any of its Subsidiaries has received any written notice relating to the limitation, revocation, cancellation, suspension, modification or non-renewal of any such Permit which, singly or in the aggregate, if the subject of an unfavorable decision, ruling, finding or non-renewal, would have a Material Adverse Effect, or has any reason to believe that any such Permit will not be renewed in the ordinary course. To the

extent required by applicable Laws of the FDA, the Company or the applicable subsidiary has submitted to the FDA an Investigational New Drug Application or amendment or supplement thereto for each clinical trial it has conducted or sponsored or is conducting or sponsoring; all such submissions were in material compliance with applicable Laws when submitted and no material deficiencies have been asserted by the FDA with respect to any such submissions. Neither the Company nor any subsidiary has received, or has any reason to believe that it will receive, any notice of proceedings relating to the revocation or modification of, or non-compliance with, any such Permit which, singly or in the aggregate, if the subject of an unfavorable decision, ruling or finding, could result in a Material Adverse Effect.

(xx) Except as disclosed in the Registration Statement, the Disclosure Package and the Prospectus, neither the Company nor any of its Subsidiaries has failed to file with the applicable Governmental Authority (including the FDA, or any foreign, federal, state, provincial or local Governmental Authority performing functions similar to those performed by the FDA) any required filing, declaration, listing, registration, report or submission, except for such failures that, individually or in the aggregate, would not have a Material Adverse Effect; except as disclosed in the Registration Statement, the Disclosure Package and the Prospectus, all such filings, declarations, listings, registrations, reports or submissions were in compliance with applicable Laws when filed and no deficiencies have been asserted by any applicable regulatory authority with respect to any such filings, declarations, listings, registrations, reports or submissions, except for any deficiencies that, individually or in the aggregate, would not have a Material Adverse Effect. The Company has no knowledge of any studies, tests or trials not described in the Registration Statement, the Disclosure Package and the Prospectus the results of which reasonably call into question in any material respect the results of the studies, tests and trials described in the Registration Statement, the Disclosure Package and the Prospectus.

(yy) The preclinical studies, tests and preclinical or clinical trials conducted by or on behalf of the Company that are described in the Registration Statement, the Disclosure Package and the Prospectus (the “Company Studies and Trials”) were, and, if still pending, are being conducted in all material respects with the United States Federal Food, Drug, and Cosmetic Act (“FDCA”), all applicable rules and regulations of the FDA, all requirements of any applicable Governmental Authority engaged in the regulation of pre-clinical or clinical studies or tests, and in accordance with the experimental protocols, procedures and controls pursuant to, where applicable, accepted professional and scientific standards for products or product candidates comparable to those being developed by the Company; the descriptions of the Company Studies and Trials, and the results thereof, contained in the Registration Statement, the Disclosure Package and the Prospectus are accurate and complete in all material respects; the Company is not aware of any tests, studies or trials not described in the Registration Statement, the Disclosure Package and the Prospectus, the results of which reasonably call into question the results of the Company Studies and Trials described in the Registration Statement, the Disclosure Package and the Prospectus; and the Company has not received any notice or correspondence from the FDA or any foreign, state or local Governmental Authority exercising comparable authority or any institutional review board or comparable authority requiring or threatening the termination, suspension, clinical hold or material modification of any of the Company Studies and Trials. To the Company’s knowledge, none of the Company Studies and Trials involve or

has involved any investigator who has been disqualified or restricted as a clinical investigator or been the subject of disqualification proceedings by FDA, or has been found by the FDA (or any foreign, federal, state or local governmental or regulatory authority performing functions similar to those performed by the FDA) to have engaged in scientific misconduct.

(zz) Except as otherwise disclosed in the Registration Statement, the Disclosure Package and the Prospectus, each of the Company and its subsidiaries, to the extent applicable, (i) are in compliance with, all health care laws applicable to the Company, any of its subsidiaries or any of its or their products or activities, including, but not limited to, the federal Anti-Kickback Statute (42 U.S.C. Section 1320a-7b(b)), the Civil Monetary Penalties Law (42 U.S.C. Section 1320a-7a), the civil False Claims Act (31 U.S.C. Section 3729 et seq.), the Criminal False Statements Law (42 U.S.C. Section 1320a-7b(a)), the Health Insurance Portability and Accountability Act of 1996 (42 U.S.C. Section 1320d et seq.) as amended by the Health Information Technology for Economic and Clinical Health Act (42 U.S.C. Section 17921 et seq.), the exclusion law (42 U.S.C. Section 1320a-7), the FDCA (21 U.S.C. Section 301 et seq.), the Public Health Service Act (42 U.S.C. Section 201 et seq.), and the Physician Payments Sunshine Act (42 U.S.C. Section 1320a-7h), the regulations promulgated pursuant to such laws, and any other applicable state, federal or foreign law (collectively, “Health Care Laws”), except for such non-compliance as would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect; (ii) have not received any written notice from any court or arbitrator or Governmental Authority or third party asserting non-compliance with any Permits required by any such Health Care Laws, except for such non-compliance as would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect; (iii) have not received written notice of any claim, action, suit, proceeding, hearing, enforcement, investigation, arbitration or other action from any court or arbitrator or Governmental Authority or third party alleging that any product operation of the Company or any of its subsidiaries is in violation of any Health Care Laws or Permits nor, to the Company’s knowledge, is any such claim, action, suit, proceeding, hearing, enforcement, investigation, arbitration or other action threatened, except as would not, individually or in the aggregate, reasonably be expected to have a Material Adverse Effect; and (iv) are not a party to any corporate integrity agreements, monitoring agreements, consent decrees, settlement orders, or similar agreements with or imposed by any Governmental Authority. In addition, none of the Company or its subsidiaries or, to the knowledge of the Company or its subsidiaries, any of their respective directors, officers, employees or agents is debarred, suspended or excluded, or has been convicted of any crime or, to the knowledge of the Company or its subsidiaries, engaged in any conduct that could result in a debarment, suspension or exclusion from any federal or state government health care program or human clinical research, or to the knowledge of the Company or its subsidiaries, is subject to any inquiry, investigation, proceeding, or other similar action by a Governmental Authority that could reasonably be expected to result in any such debarment, suspension or exclusion.

(aaa) The Company has complied with, and is currently in compliance with, the cease and desist order issued by the SEC on April 10, 2017 and the Company’s related settlement with the SEC. The Company maintains policies and procedures and supervisory policies and procedures reasonably designed to cause the Company and its officers, directors and employees to be and remain in compliance with all material laws, regulations and rules applicable to it and its businesses as currently conducted.

Any certificate signed by any officer of the Company and delivered to the Representatives or counsel for the Underwriters in connection with the offering of the Securities shall be deemed a representation and warranty by the Company, as to matters covered thereby, to each Underwriter.

2. Purchase and Sale. Subject to the terms and conditions and in reliance upon the representations and warranties herein set forth, the Company agrees to sell to each Underwriter, and each Underwriter agrees, severally and not jointly, to purchase from the Company, (i) the Shares at a purchase price of $ per share, (ii) the Pre-Funded Warrants at a purchase price of $ per warrant and (iii) the Common Warrants at a purchase price of $ per warrant, the respective amounts of the Shares, the Pre-Funded Warrants and the Common Warrants set forth opposite such Underwriter’s name in Schedule I hereto.

3. Delivery and Payment. Delivery of and payment for the Securities shall be made at 10:00 AM, New York City time, on , 2018, or at such time on such later date not more than three Business Days after the foregoing date as the Representatives shall designate, which date and time may be postponed by agreement between the Representatives and the Company or as provided in Section 9 hereof (such date and time of delivery and payment for the Securities being herein called the “Closing Date”). Delivery of the Securities shall be made to the Representatives for the respective accounts of the several Underwriters against payment by the several Underwriters through the Representatives of the purchase price thereof to or upon the order of the Company by wire transfer payable in same-day funds to an account specified by the Company. Delivery of the Securities shall be made through the facilities of The Depository Trust Company unless the Representatives shall otherwise instruct.

4. Offering by Underwriters. It is understood that the several Underwriters propose to offer the Securities for sale to the public as set forth in the Prospectus.

5. Agreements. The Company agrees with the several Underwriters that:

(a) Prior to the termination of the offering of the Securities, the Company will not file any amendment of the Registration Statement or supplement to the Prospectus or any Rule 462(b) Registration Statement unless the Company has furnished you a copy for your review prior to filing and will not file any such proposed amendment or supplement to which you reasonably object. The Company will cause the Prospectus, properly completed, and any supplement thereto to be filed in a form approved by the Representatives with the Commission pursuant to the applicable paragraph of Rule 424(b) within the time period prescribed and will provide evidence satisfactory to the Representatives of such timely filing. The Company will promptly advise the Representatives (i) when the Prospectus, any supplement thereto, shall have been filed (if required) with the Commission pursuant to Rule 424(b) or when any Rule 462(b) Registration Statement shall have been filed with the Commission, (ii) when, prior to termination of the offering of the Securities, any amendment to the Registration Statement shall have been filed or become effective, (iii) of any request by the Commission or its staff for any amendment

of the Registration Statement, or any Rule 462(b) Registration Statement, or for any supplement to the Prospectus, (iv) of the issuance by the Commission of any stop order suspending the effectiveness of the Registration Statement or of any notice objecting to its use or the institution or threatening of any proceeding for that purpose and (v) of the receipt by the Company of any notification with respect to the suspension of the qualification of the Securities for sale in any jurisdiction or the institution or threatening of any proceeding for such purpose. The Company will use its reasonable best efforts to prevent the issuance of any such stop order or the occurrence of any such suspension or objection to the use of the Registration Statement and, upon such issuance, occurrence or notice of objection, to obtain as soon as possible the withdrawal of such stop order or relief from such occurrence or objection, including, if necessary, by filing an amendment to the Registration Statement or a new registration statement and using its reasonable best efforts to have such amendment or new registration statement declared effective as soon as practicable.

(b) If, at any time prior to the filing of the Prospectus pursuant to Rule 424(b), any event or development occurs as a result of which the Disclosure Package would include an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made at such time not misleading, the Company will (i) notify promptly the Representatives so that any use of the Disclosure Package may cease until it is amended or supplemented; (ii) amend or supplement the Disclosure Package to correct such statement or omission; and (iii) supply any amendment or supplement to you in such quantities as you may reasonably request.

(c) If, at any time when a prospectus relating to the Securities is required to be delivered under the Act (including in circumstances where such requirement may be satisfied pursuant to Rule 172), any event occurs as a result of which the Prospectus as then supplemented would include any untrue statement of a material fact or omit to state any material fact necessary to make the statements therein in the light of the circumstances under which they were made or the circumstances then prevailing not misleading, or if it shall be necessary to amend the Registration Statement or supplement the Prospectus to comply with the Act or the rules thereunder, the Company promptly will (i) notify the Representatives of any such event; (ii) prepare and file with the Commission, subject to the second sentence of paragraph (a) of this Section 5, an amendment or supplement which will correct such statement or omission or effect such compliance; and (iii) supply any supplemented Prospectus to you in such quantities as you may reasonably request.

(d) As soon as practicable, the Company will make generally available to its security holders and to the Representatives an earnings statement or statements of the Company and its subsidiaries which will satisfy the provisions of Section 11(a) of the Act and Rule 158.

(e) The Company will furnish to the Representatives and counsel for the Underwriters, without charge, signed copies of the Registration Statement (including exhibits thereto) and to each other Underwriter a copy of the Registration Statement (without exhibits thereto) and, so long as delivery of a prospectus by an Underwriter or dealer may be required by the Act (including in circumstances where such requirement may be satisfied pursuant to Rule 172), as many copies of each Preliminary Prospectus and the Prospectus and any supplement thereto as the Representatives may reasonably request. The Company will pay the expenses of printing or other production of all documents relating to the offering.

(f) The Company will arrange, if necessary, for the qualification of the Securities for sale under the laws of such jurisdictions as the Representatives may designate and will maintain such qualifications in effect so long as required for the distribution of the Securities; provided that in no event shall the Company be obligated to qualify to do business in any jurisdiction where it is not now so qualified or to take any action that would subject it to service of process in suits, other than those arising out of the offering or sale of the Securities, in any jurisdiction where it is not now so subject.

(g) The Company will not, without the prior written consent of the Representatives, offer, sell, contract to sell, pledge, or otherwise dispose of, (or enter into any transaction which is designed to, or might reasonably be expected to, result in the disposition (whether by actual disposition or effective economic disposition due to cash settlement or otherwise) by the Company or any affiliate of the Company or any person in privity with the Company or any affiliate of the Company) directly or indirectly, including the filing (or participation in the filing) of a registration statement with the Commission in respect of, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Exchange Act, any other shares of Common Stock or any securities convertible into, or exercisable, or exchangeable for, shares of Common Stock or shares of any class of capital stock of the Company or any securities convertible into, or exercisable, or exchangeable for, any of the foregoing; or publicly announce an intention to effect any such transaction, for a period of 90 days after the date of this Agreement (the “Restricted Period”), provided, however, that the Company may (i) issue and sell the Securities pursuant to this Agreement, (ii) issue and sell Common Stock pursuant to any employee stock option plan, stock ownership plan or dividend reinvestment plan of the Company in effect at the Execution Time, (iii) issue Common Stock or other securities convertible into, or exercisable or exchangeable for, shares of Common Stock upon conversion, exercise, redemption or as payment pursuant to the terms of the Pre-Funded Warrants, the Common Warrants, or other securities outstanding at the Execution Time; (iv) issue Common Stock in settlement of or pursuant to contractual obligations outstanding at the Execution Time; and (v) file a registration statement on Form S-8 related to employee benefit plans, or amend an effective registration statement on Form S-8 previously filed with the Commission).

(h) If the Representative, in their sole discretion, agree to release or waive the restrictions set forth in a lock-up letter described in Section 6(k) hereof for an officer or director of the Company and provide the Company with notice of the impending release or waiver at least three Business Days before the effective date of the release or waiver, the Company agrees to announce the impending release or waiver by a press release substantially in the form of Exhibit B hereto through a major news service at least two Business Days before the effective date of the release or waiver.

(i) The Company will not take, directly or indirectly, any action designed to or that would constitute or that might reasonably be expected to cause or result in, under the Exchange Act or otherwise, stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the Securities or the Warrant Shares.

(j) The Company agrees to pay the costs and expenses relating to the following matters: (i) the preparation, printing or reproduction and filing with the Commission of the Registration Statement (including financial statements and exhibits thereto), each Preliminary Prospectus and the Prospectus and each amendment or supplement to any of them; (ii) the printing (or reproduction) and delivery (including postage, air freight charges and charges for counting and packaging) of such copies of the Registration Statement, each Preliminary Prospectus and the Prospectus, and all amendments or supplements to any of them, as may, in each case, be reasonably requested for use in connection with the offering and sale of the Securities; (iii) the preparation, printing, authentication, issuance and delivery of certificates for the Shares and Warrant Shares, including any stamp or transfer taxes in connection with the original issuance and sale of the Securities; (iv) the printing (or reproduction) and delivery of this Agreement, the Warrant Agreement, any blue sky memorandum and all other agreements or documents printed (or reproduced) and delivered in connection with the offering of the Securities; (v) the registration of the Securities under the Exchange Act and the listing of the Shares and the Warrant Shares on Nasdaq Capital Market; (vi) any registration or qualification of the Securities for offer and sale under the securities or blue sky laws of the several states (including filing fees and the reasonable fees and expenses of counsel for the Underwriters relating to such registration and qualification); (vii) any filings required to be made with the Financial Industry Regulatory Authority, Inc. (“FINRA”) (including filing fees and the reasonable fees and expenses of counsel for the Underwriters relating to such filings, with such fee and expenses of counsel, together with fees and expenses of counsel incurred pursuant to subsection (vi), not to exceed $25,000); (viii) the transportation and other expenses incurred by or on behalf of the Company representatives (other than the Underwriters) in connection with presentations to prospective purchasers of the Securities; (ix) the fees and expenses of the Company’s accountants and the fees and expenses of counsel (including local and special counsel) for the Company; and (x) all other costs and expenses incident to the performance by the Company of its obligations hereunder. Except as provided in this Section 5(j) and in Sections 7 and 8 below, the Underwriters will pay all of their own costs and expenses, including fees and disbursements of their counsel, stock transfer taxes payable on resale of any of the Securities by them and the transportation and other expenses incurred by them in connection with any road show.

(k) The Company agrees that it has not made and will not make any offer relating to the Securities that would constitute an Issuer Free Writing Prospectus or that would otherwise constitute a “free writing prospectus” (as defined in Rule 405).

(l) The Company will use the net proceeds received by the Company from the sale of the Securities in the manner specified in the Preliminary Prospectus and Prospectus under the caption “Use of Proceeds.”

(m) The Company will, at all times while any Pre-Funded Warrants or Common Warrants are outstanding, use its best efforts to maintain a registration statement covering the issue and sale of the Warrant Shares upon exercise of the Pre-Funded Warrants and Common Warrants such that the Warrant Shares, when issued, will not be subject to resale restrictions under the Securities Act except to the extent that the Warrant Shares are owned by affiliates.

(n) The Company will, at all times while any Pre-Funded Warrants or Common Warrants are outstanding, reserve and keep available out of the aggregate of its authorized but unissued and otherwise unreserved Common Stock, for the purpose of enabling it to issue Warrant Shares upon exercise of such Pre-Funded Warrants and Common Warrants, the number of Warrant Shares that are issuable and deliverable upon the exercise of the then-outstanding Pre-Funded Warrants and Common Warrants.

6. Conditions to the Obligations of the Underwriters. The obligations of the Underwriters to purchase the Securities shall be subject to the accuracy of the representations and warranties on the part of the Company contained herein as of the Execution Time, the Closing Date pursuant to Section 3 hereof, to the accuracy of the statements of the Company made in any certificates pursuant to the provisions hereof, to the performance by the Company of its obligations hereunder and to the following additional conditions:

(a) The Prospectus, and any supplement thereto, have been filed in the manner and within the time period required by Rule 424(b); and no stop order suspending the effectiveness of the Registration Statement or any notice objecting to its use shall have been issued and no proceedings for that purpose shall have been instituted or threatened.

(b) The Company shall have requested and caused ▇▇▇▇▇▇ LLP, counsel for the Company, to have furnished to the Representatives its opinion, dated the Closing Date and addressed to the Representatives, in form and substance reasonably satisfactory to the Representatives.

(c) The Company shall have requested and caused each of ▇▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇ & ▇▇▇▇▇▇▇▇▇▇▇, IP counsel for the Company, and ▇▇▇▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇ & ▇▇▇▇▇▇▇▇▇▇▇ LLP, IP counsel for the Company, to have furnished to the Representatives its opinion, dated the Closing Date and addressed to the Representatives, in form and substance reasonably satisfactory to the Representatives.

(d) The Company shall have requested and caused ▇▇▇▇▇▇▇ ▇▇▇▇ & ▇▇▇▇▇▇▇ Limited, special Bermuda counsel for the Company to have furnished to the Representatives its opinion, dated the Closing Date and addressed to the Representatives, in form and substance reasonably satisfactory to the Representatives.

(e) The Representatives shall have received from ▇▇▇▇▇▇, ▇▇▇▇ & ▇▇▇▇▇▇▇▇ LLP, counsel for the Underwriters, such opinion or opinions, dated the Closing Date and addressed to the Representatives, with respect to the issuance and sale of the Securities, the Registration Statement, the Disclosure Package, the Prospectus (together with any supplement thereto) and other related matters as the Representatives may reasonably require, and the Company shall have furnished to such counsel such documents as they request for the purpose of enabling them to pass upon such matters.

(f) The Company shall have furnished to the Representatives a certificate of the Company, signed by the principal executive officer and the principal financial or accounting officer of the Company, in each case on behalf of the Company, dated the Closing Date, to the effect that the signers of such certificate have carefully examined the Registration Statement, the Disclosure Package, the Prospectus and any amendment or supplement thereto, and this Agreement and that:

(i) the representations and warranties of the Company in this Agreement are true and correct on and as of the Closing Date with the same effect as if made on the Closing Date and the Company has complied with all the agreements and satisfied all the conditions on its part to be performed or satisfied at or prior to the Closing Date;

(ii) the Registration Statement has become effective under the Act and no stop order suspending the effectiveness of the Registration Statement or any notice objecting to its use has been issued and no proceedings for that purpose have been instituted or, to the Company’s knowledge, threatened; and

(iii) since the date of the most recent financial statements included or incorporated by reference in the Disclosure Package and the Prospectus, there has been no Material Adverse Effect, whether or not arising from transactions in the ordinary course of business, except as set forth in or contemplated in the Disclosure Package and the Prospectus.

(g) The Company shall have requested and caused each of KPMG Audit Limited and ▇▇▇▇ ▇▇▇▇▇ LLP to have furnished to the Representatives, at the Execution Time and at the Closing Date, letters, dated respectively as of the Execution Time and as of the Closing Date, in form and substance satisfactory to the Representatives.

(h) Subsequent to the Execution Time, there shall not have been (i) any change or decrease specified in the letter or letters referred to in paragraph (f) of this Section 6 or (ii) any material change, or any development involving a prospective change, in or affecting the condition (financial or otherwise), earnings, business or properties of the Company and its subsidiaries taken as a whole, whether or not arising from transactions in the ordinary course of business, except as set forth in or contemplated in the Disclosure Package and the Prospectus the effect of which, in any case referred to in clause (i) or (ii) above, is, in the sole reasonable judgment of the Representatives, so material and adverse as to make it impractical or inadvisable to proceed with the offering or delivery of the Securities as contemplated by the Registration Statement, the Disclosure Package and the Prospectus.

(i) On the date hereof and on the Closing Date, the Company shall have furnished to the Representatives a certificate, signed by the Company’s Chief Financial Officer, with respect to certain financial information contained in the Registration Statement, the Preliminary Prospectus, Disclosure Package, and the Prospectus, in form and substance reasonably satisfactory to the Underwriter.

(j) Prior to the Closing Date, the Company shall have furnished to the Representatives such further information, certificates and documents as the Representatives may reasonably request.

(k) The Shares and the Warrant Shares shall have been listed and admitted and authorized for trading on the Nasdaq Capital Market, subject to official notice of issuance, and satisfactory evidence of such actions shall have been provided to the Representatives.

(l) The FINRA, upon review, if any, of the terms of the public offering of the Securities, shall not have objected to such offering, such terms or the Underwriters’ participation in same.

Prior to the Execution Time, the Company shall have furnished to the Representatives a letter substantially in the form of Exhibit A hereto (the “Lock-Up Agreement”) from each executive officer and director of the Company and each stockholder of the Company listed on Schedule II hereto addressed to the Representatives. The Company will use its reasonable best efforts to enforce the terms of each Lock-Up Agreement and will issue stop-transfer instructions to the transfer agent for the Common Stock with respect to any transaction or contemplated transaction that would constitute a breach of or default under the applicable Lock-Up Agreement. If any of the conditions specified in this Section 6 shall not have been fulfilled when and as provided in this Agreement, or if any of the opinions and certificates mentioned above or elsewhere in this Agreement shall not be reasonably satisfactory in form and substance to the Representatives and counsel for the Underwriters, this Agreement and all obligations of the Underwriters hereunder may be canceled at, or at any time prior to, the Closing Date by the Representatives. Notice of such cancellation shall be given to the Company in writing or by telephone or facsimile confirmed in writing.

The documents required to be delivered by this Section 6 shall be delivered at the office of ▇▇▇▇▇▇, ▇▇▇▇ & ▇▇▇▇▇▇▇▇ LLP, counsel for the Underwriters, at ▇▇▇ ▇▇▇▇ ▇▇▇▇▇▇, ▇▇^▇▇ ▇▇▇▇▇, ▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇ ▇▇▇▇▇, on the Closing Date.

7. Reimbursement of Underwriters’ Expenses. If the sale of the Securities provided for herein is not consummated because any condition to the obligations of the Underwriters set forth in Section 6 hereof is not satisfied, because of any termination pursuant to Section 10 hereof or because of any refusal, inability or failure on the part of the Company to perform any agreement herein or comply with any provision hereof other than by reason of a default by any of the Underwriters, the Company will reimburse the Underwriters severally through Cantor ▇▇▇▇▇▇▇▇▇▇ & Co. on demand for all expenses (including reasonable fees and disbursements of counsel) that shall have been incurred by them in connection with the proposed purchase and sale of the Securities.

8. Indemnification and Contribution. (a) The Company agrees to indemnify and hold harmless each Underwriter, the directors, officers, employees and agents of each Underwriter and each person who controls any Underwriter within the meaning of either the Act or the Exchange Act against any and all losses, claims, damages or liabilities, joint or several, to which they or any of them may become subject under the Act, the Exchange Act or other Federal or

state statutory law or regulation, at common law or otherwise, insofar as such losses, claims, damages or liabilities (or actions in respect thereof) arise out of or are based upon (x) any untrue statement or alleged untrue statement of a material fact contained in the Registration Statement or any amendment thereof or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, or (y) any untrue statement or alleged untrue statement of a material fact contained in any Preliminary Prospectus or the Prospectus, any roadshow or in any amendment thereof or supplement thereto or arise out of or are based upon the omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein, in the case of this clause (y), in the light of the circumstances under which they were made, not misleading, and in each case agrees to reimburse each such indemnified party, as incurred, for any legal or other expenses reasonably incurred by them in connection with investigating or defending any such loss, claim, damage, liability or action; provided, however, that the Company will not be liable in any such case to the extent that any such loss, claim, damage or liability arises out of or is based upon any such untrue statement or alleged untrue statement or omission or alleged omission made therein in reliance upon and in conformity with written information furnished to the Company by or on behalf of any Underwriter through the Representatives specifically for inclusion therein. This indemnity agreement will be in addition to any liability which the Company may otherwise have.

(b) Each Underwriter severally and not jointly agrees to indemnify and hold harmless the Company, each of its directors, each of its officers who signs the Registration Statement, and each person who controls the Company within the meaning of either the Act or the Exchange Act, to the same extent as the foregoing indemnity from the Company to each Underwriter, but only with respect to written information relating to such Underwriter furnished to the Company by or on behalf of such Underwriter through the Representatives specifically for inclusion in the documents referred to in the foregoing indemnity. This indemnity agreement will be in addition to any liability which any Underwriter may otherwise have. The Company acknowledges that the following statements set forth in the Preliminary Prospectus and the Prospectus under the heading “Underwriting”: (i) the third paragraph thereof related to selling concessions and dealer reallowances and (ii) the tenth, eleventh and twelfth paragraphs thereof related to stabilization, market making, discretionary authority, syndicate covering transactions and penalty bids, constitute the only information furnished in writing by or on behalf of the several Underwriters for inclusion in the Preliminary Prospectus or the Prospectus.

(c) Promptly after receipt by an indemnified party under this Section 8 of notice of the commencement of any action, such indemnified party will, if a claim in respect thereof is to be made against an indemnifying party under subsection (a) or (b) above, notify the indemnifying party of the commencement thereof; but the failure to notify the indemnifying party shall not relieve it from any liability that it may have under subsection (a) or (b) above except to the extent that it has been materially prejudiced (through the forfeiture of substantive rights or defenses) by such failure; and provided further that the failure to notify the indemnifying party shall not relieve it from any liability that it may have to an indemnified party otherwise than under subsection (a) or (b) above. In the case of parties indemnified pursuant to Sections 8(a) above, counsel to the indemnified parties shall be selected by the Representatives,

and, in the case of parties indemnified pursuant to Section 8(b) above, counsel to the indemnified parties shall be selected by the Company. An indemnifying party may participate at its own expense in the defense of any such action; provided, however, that counsel to the indemnifying party shall not (except with the consent of the indemnified party) also be counsel to the indemnified party. In no event shall the indemnifying parties be liable for fees and expenses of more than one counsel (in addition to any relevant local counsel) separate from their own counsel for all indemnified parties in connection with any one action or separate but similar or related actions in the same jurisdiction arising out of the same general allegations or circumstances. No indemnifying party shall, without the prior written consent of the indemnified party, effect any settlement of any pending or threatened action in respect of which any indemnified party is or could have been a party and indemnity could have been sought hereunder by such indemnified party unless such settlement (i) includes an unconditional release of such indemnified party from all liability on any claims that are the subject matter of such action and (ii) does not include a statement as to, or an admission of, fault, culpability or a failure to act by or on behalf of an indemnified party.

(d) If at any time an indemnified party shall have requested an indemnifying party to reimburse the indemnified party for fees and expenses of counsel, such indemnifying party agrees that it shall be liable for any settlement of the nature contemplated by Section 8(a) hereof effected without its written consent if (i) such settlement is entered into more than 60 days after receipt by such indemnifying party of the aforesaid request, (ii) such indemnifying party shall have received notice of the terms of such settlement at least 30 days prior to such settlement being entered into and (iii) such indemnifying party shall not have reimbursed such indemnified party in accordance with such request prior to the date of such settlement.

(e) In the event that the indemnity provided in paragraph (a), (b) or (c) of this Section 8 is unavailable to or insufficient to hold harmless an indemnified party for any reason, the Company and the Underwriters severally agree to contribute to the aggregate losses, claims, damages and liabilities (including legal or other expenses reasonably incurred in connection with investigating or defending the same) (collectively “Losses”) to which the Company and one or more of the Underwriters may be subject in such proportion as is appropriate to reflect the relative benefits received by the Company on the one hand and by the Underwriters on the other from the offering of the Securities; provided, however, that in no case shall any Underwriter (except as may be provided in any agreement among underwriters relating to the offering of the Securities) be responsible for any amount in excess of the underwriting discount or commission applicable to the Securities purchased by such Underwriter hereunder. If the allocation provided by the immediately preceding sentence is unavailable for any reason, the Company and the Underwriters severally shall contribute in such proportion as is appropriate to reflect not only such relative benefits but also the relative fault of the Company on the one hand and of the Underwriters on the other in connection with the statements or omissions which resulted in such Losses as well as any other relevant equitable considerations. Benefits received by the Company shall be deemed to be equal to the total net proceeds from the offering (before deducting expenses) received by it, and benefits received by the Underwriters shall be deemed to be equal to the total underwriting discounts and commissions, in each case as set forth on the cover page of the Prospectus. Relative fault shall be determined by reference to, among other things,

whether any untrue or any alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information provided by the Company on the one hand or by the Underwriters on the other, the intent of the parties and their relative knowledge, access to information and opportunity to correct or prevent such untrue statement or omission. The Company and the Underwriters agree that it would not be just and equitable if contribution were determined by pro rata allocation or any other method of allocation which does not take account of the equitable considerations referred to above. Notwithstanding the provisions of this paragraph (d), no person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. For purposes of this Section 8, each person who controls an Underwriter within the meaning of either the Act or the Exchange Act and each director, officer, employee and agent of an Underwriter shall have the same rights to contribution as such Underwriter, and each person who controls the Company within the meaning of either the Act or the Exchange Act, each officer of the Company who shall have signed the Registration Statement and each director of the Company shall have the same rights to contribution as the Company, subject in each case to the applicable terms and conditions of this paragraph (d).

9. Default by an Underwriter. If any one or more Underwriters shall fail to purchase and pay for any of the Securities agreed to be purchased by such Underwriter or Underwriters hereunder and such failure to purchase shall constitute a default in the performance of its or their obligations under this Agreement, the remaining Underwriters shall be obligated severally to take up and pay for (in the respective proportions which the amount of Shares and Common Warrants set forth opposite their names in Schedule I hereto bears to the aggregate amount of Shares and Common Warrants set forth opposite the names of all the remaining Underwriters) the Securities which the defaulting Underwriter or Underwriters agreed but failed to purchase; provided, however, that in the event that the aggregate amount of Securities which the defaulting Underwriter or Underwriters agreed but failed to purchase shall exceed 10% of the aggregate amount of Shares and Common Warrants set forth in Schedule I hereto, the remaining Underwriters shall have the right to purchase all, but shall not be under any obligation to purchase any, of the Securities, and if such nondefaulting Underwriters do not purchase all the Securities, this Agreement will terminate without liability to any nondefaulting Underwriter or the Company. In the event of a default by any Underwriter as set forth in this Section 9, the Closing Date shall be postponed for such period, not exceeding five Business Days, as the Representatives shall determine in order that the required changes in the Registration Statement and the Prospectus or in any other documents or arrangements may be effected. Nothing contained in this Agreement shall relieve any defaulting Underwriter of its liability, if any, to the Company and any nondefaulting Underwriter for damages occasioned by its default hereunder.

10. Termination. This Agreement shall be subject to termination in the absolute discretion of the Representatives, by notice given to the Company prior to delivery of and payment for the Securities, if at any time prior to such delivery and payment (i) trading in the Company’s Common Stock shall have been suspended by the Commission or the Nasdaq Capital Market or trading in securities generally on NASDAQ shall have been suspended or limited or minimum prices shall have been established on such exchange, (ii) a banking moratorium shall have been declared either by Federal or New York State authorities or (iii) there shall have occurred any

outbreak or escalation of hostilities, declaration by the United States of a national emergency or war, or other calamity or crisis the effect of which on financial markets is such as to make it, in the sole judgment of the Representatives, impractical or inadvisable to proceed with the offering or delivery of the Securities as contemplated by the Preliminary Prospectus or the Prospectus.

11. Representations and Indemnities to Survive. The respective agreements, representations, warranties, indemnities and other statements of the Company or its officers and of the Underwriters set forth in or made pursuant to this Agreement will remain in full force and effect, regardless of any investigation made by or on behalf of any Underwriter or the Company or any of the officers, directors, employees, agents or controlling persons referred to in Section 8 hereof, and will survive delivery of and payment for the Securities. The provisions of Sections 7 and 8 hereof shall survive the termination or cancellation of this Agreement.

Notices. All communications hereunder will be in writing and effective only on receipt, and, if sent to the Representatives, will be mailed, delivered or telefaxed to Cantor ▇▇▇▇▇▇▇▇▇▇ & Co., ▇▇▇ ▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇ ▇▇▇▇, ▇▇ ▇▇▇▇▇, Attention: Equity Capital Markets, Fax: (▇▇▇) ▇▇▇-▇▇▇▇ , and to ▇▇▇▇▇▇▇▇▇▇▇ & Co. Inc., ▇▇ ▇▇▇▇▇ ▇▇▇▇▇▇, ▇▇▇▇ ▇▇▇▇▇, ▇▇▇ ▇▇▇▇, ▇▇ ▇▇▇▇▇, , Attention: Equity Capital Markets, Fax: (▇▇▇) ▇▇▇-▇▇▇▇; or, if sent to the Company, will be mailed or delivered to SELLAS Life Sciences Group, Inc., ▇▇▇ ▇▇▇▇▇▇▇ ▇▇▇▇▇▇, ▇^▇▇ ▇▇▇▇▇, ▇▇▇ ▇▇▇▇, ▇▇▇ ▇▇▇▇ ▇▇▇▇▇, and confirmed to it at (▇▇▇) ▇▇▇-▇▇▇▇, attention of the Legal Department.

12. Successors. This Agreement will inure to the benefit of and be binding upon the parties hereto and their respective successors and the officers, directors, employees, agents and controlling persons referred to in Section 8 hereof, and no other person will have any right or obligation hereunder.

13. No Fiduciary Duty. The Company hereby acknowledges that (a) the purchase and sale of the Securities pursuant to this Agreement is an arm’s-length commercial transaction between the Company, on the one hand, and the Underwriters and any affiliate through which it may be acting, on the other, (b) the Underwriters are acting as principal and not as an agent or fiduciary of the Company and (c) the Company’s engagement of the Underwriters in connection with the offering and the process leading up to the offering is as independent contractors and not in any other capacity. Furthermore, the Company agrees that it is solely responsible for making its own judgments in connection with the offering (irrespective of whether any of the Underwriters has advised or is currently advising the Company on related or other matters). The Company agrees that it will not claim that the Underwriters have rendered advisory services of any nature or respect, or owe an agency, fiduciary or similar duty to the Company, in connection with such transaction or the process leading thereto.

14. Integration. This Agreement supersedes all prior agreements and understandings (whether written or oral) between the Company and the Underwriters, or any of them, with respect to the subject matter hereof.

15. Applicable Law. This Agreement and any claim, controversy or dispute arising under or related to this Agreement or the transactions contemplated hereby (including without limitation, any claims sounding in equity, statutory law, contract law or tort law arising out of the subject matter hereof) shall be governed by and construed in accordance with the laws of the State of New York, without giving effect to its conflicts of laws doctrine.

16. Waiver of Jury Trial. The Company hereby irrevocably waives, to the fullest extent permitted by applicable law, any and all right to trial by jury in any legal proceeding arising out of or relating to this Agreement or the transactions contemplated hereby.

17. Counterparts. This Agreement may be signed in one or more counterparts, each of which shall constitute an original and all of which together shall constitute one and the same agreement.

18. Headings. The section headings used herein are for convenience only and shall not affect the construction hereof.

19. Definitions. The terms that follow, when used in this Agreement, shall have the meanings indicated.

“Act” shall mean the Securities Act of 1933, as amended, and the rules and regulations of the Commission promulgated thereunder.

“Business Day” shall mean any day other than a Saturday, a Sunday or a legal holiday or a day on which banking institutions or trust companies are authorized or obligated by law to close in New York City.

“Commission” shall mean the Securities and Exchange Commission.

“Disclosure Package” shall mean (i) the Preliminary Prospectus used most recently prior to the execution of this Agreement and that is generally distributed to investors and used to offer the Securities, including any document that is incorporated by reference therein and (ii) the number of Shares and Common Warrants and the price per Share to the public and the exercise price per Warrant.

“Effective Date” shall mean each date and time that the Registration Statement, any post-effective amendment or amendments thereto and any Rule 462(b) Registration Statement became or becomes effective.

“Exchange Act” shall mean the Securities Exchange Act of 1934, as amended, and the rules and regulations of the Commission promulgated thereunder.

“Execution Time” shall mean the date and time that this Agreement is executed and delivered by the parties hereto.

“Free Writing Prospectus” shall mean a free writing prospectus, as defined in Rule 405.

“Preliminary Prospectus” shall mean any preliminary prospectus referred to in paragraph 1(a) above and any preliminary prospectus included in the Registration Statement at the Effective Date that omits Rule 430A Information.

“Prospectus” shall mean the prospectus relating to the Securities that is first filed pursuant to Rule 424(b) after the Execution Time.

“Registration Statement” shall mean the registration statement referred to in paragraph 1(a) above, including exhibits and financial statements and any prospectus supplement relating to the Securities that is filed with the Commission pursuant to Rule 424(b) and deemed part of such registration statement pursuant to Rule 430A, as amended at the Execution Time and, in the event any post-effective amendment thereto or any Rule 462(b) Registration Statement becomes effective prior to the Closing Date, shall also mean such registration statement as so amended or such Rule 462(b) Registration Statement, as the case may be.

“Rule 158”, “Rule 163”, “Rule 164”, “Rule 172”, “Rule 405”, “Rule 415”, “Rule 424”, “Rule 430A” and “Rule 433” refer to such rules under the Act.

“Rule 430A Information” shall mean information with respect to the Securities and the offering thereof permitted to be omitted from the Registration Statement when it becomes effective pursuant to Rule 430A.

“Rule 462(b) Registration Statement” shall mean a registration statement and any amendments thereto filed pursuant to Rule 462(b) relating to the offering covered by the registration statement referred to in Section 1(a) hereof.

“subsidiary” shall mean each direct and indirect subsidiary of the Company.

[Remainder of page intentionally blank. Signature page follows]

If the foregoing is in accordance with your understanding of our agreement, please sign and return to us the enclosed duplicate hereof, whereupon this letter and your acceptance shall represent a binding agreement among the Company and the several Underwriters.


Very truly yours, SELLAS Life Sciences Group, Inc.

By:
Name:
Title:


The foregoing Agreement is hereby confirmed and accepted as of the date first above written.

Cantor ▇▇▇▇▇▇▇▇▇▇ & Co.
▇▇▇▇▇▇▇▇▇▇▇ & Co. Inc.

By:		▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇▇▇ & Co.

By:
Name:
Title:

By:		▇▇▇▇▇▇▇▇▇▇▇ & Co. Inc.

By:
Name:
Title:

For themselves and the other several Underwriters named in Schedule I to the foregoing Agreement.

Schedule I

Underwriters

Number of
Shares
to be Purchased

Number of Pre-
funded Warrants
to be Purchased

Number of
Common
Warrants
to be Purchased

Cantor ▇▇▇▇▇▇▇▇▇▇ & Co.

▇▇▇▇▇▇▇▇▇▇▇ & Co. Inc.

Maxim Group LLC

Total

Schedule II

Schedule of Directors, Officers and Stockholders Subject to Lock-Up:

Executive Officers

▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇, M.D., Sc.D. h.c.

▇▇▇▇ ▇▇▇▇

▇▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇, M.D., Ph.D., FACP

▇▇▇▇▇▇▇ ▇. ▇▇▇▇

Non-Employee Directors

▇▇▇▇ ▇▇▇▇▇▇

▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇▇

▇▇▇▇▇ ▇▇▇▇▇

▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇▇▇▇, M.D., Ph.D.

▇▇▇▇▇▇ ▇. ▇▇▇ ▇▇▇▇▇▇▇▇

▇▇▇▇ ▇▇▇▇▇▇

Significant Stockholders

Equilibria Capital Management Limited and affiliates (EQC Private Markets SAC Fund Ltd—EQC Biotech Sely I Fund; EQC Private Markets SAC Fund II Ltd—EQC Biotech Sely S Fund, EQC Private Markets SAC Fund Ltd—EQC Biotech Sely II Fund, EQC Private Markets II SAC Fund Ltd—EQC Biotech Sely III Fund, Varibobi Financial Holdings Limited, and ▇▇▇▇▇▇ ▇▇▇▇▇)

EXHIBIT A – Form of Lock-Up Agreement

, 2018

Cantor ▇▇▇▇▇▇▇▇▇▇ & Co.

▇▇▇▇▇▇▇▇▇▇▇ & Co. Inc.

As Representatives of the several Underwriters,

c/o Cantor ▇▇▇▇▇▇▇▇▇▇ & Co.

▇▇▇ ▇▇▇▇ ▇▇▇▇▇▇

New York, NY 10022

Ladies and Gentlemen:

This letter is being delivered to you in connection with the proposed Underwriting Agreement (the “Underwriting Agreement”), between SELLAS Life Sciences Group, Inc., a Delaware corporation (the “Company”), and you as representatives of a group of Underwriters named therein, relating to an underwritten public offering of common stock, $0.0001 par value per share (the “Common Stock”), of the Company (the “Offering”).

In order to induce you and the other Underwriters to enter into the Underwriting Agreement, the undersigned will not, without the prior written consent of Cantor ▇▇▇▇▇▇▇▇▇▇ & Co. and ▇▇▇▇▇▇▇▇▇▇▇ & Co. Inc. (the “Representatives”), offer, sell, contract to sell, pledge or otherwise dispose of (or enter into any transaction which is designed to, or might reasonably be expected to, result in the disposition (whether by actual disposition or effective economic disposition due to cash settlement or otherwise) by the undersigned), directly or indirectly, in respect of, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the rules and regulations of the SEC promulgated thereunder with respect to, any shares of capital stock of the Company or any securities convertible into, or exercisable or exchangeable for such capital stock, or publicly announce an intention to effect any such transaction, including the filing (or participation in the filing) of a registration statement with the Securities and Exchange Commission (the “SEC”) other than any Registration Statement on Form S-8 or Form S-4, for a period from the date hereof until 90 days after the date of the Underwriting Agreement (the “Lock Up Period”), other than:

(a) transfers of shares of Common Stock, or securities convertible into or exercisable or exchangeable for Common Stock, as (i) bona fide gifts, (ii) to any trust for the direct or indirect benefit of the undersigned or the immediate family of the undersigned, (iii) if the undersigned is a corporation, partnership, limited liability company, trust or other business entity (1) to another corporation, partnership, limited liability company, trust or other business entity that is a direct or indirect affiliate (as defined in Rule 405 promulgated under the Securities Act of 1933, as amended) of the undersigned or (2) as distributions of shares of Common Stock or any security convertible into or exercisable for Common Stock to limited partners, limited liability company members or stockholders of the undersigned or holders of similar equity interests in the undersigned; or (iv) by will or intestacy to the undersigned’s legal representative, heir or legatee;

(b) the exercise of any stock option issued pursuant to the Company’s existing equity compensation plans or arrangements or any warrants issued by the Company effected by the delivery of shares of Common Stock held by the undersigned;

(c) any sale or transfer of shares of Common Stock (including in open market transactions through a broker) to satisfy the undersigned’s tax withholding obligations in connection with the vesting of equity awards pursuant to the Company’s equity compensation plans or arrangements, which equity awards vest during the Lock-Up Period;

(d) pursuant to a sale or an offer to purchase the outstanding Common Stock, whether pursuant to a merger, tender offer or otherwise, to a third party or group of third parties resulting in a Change of Control (as defined below) and approved by the Company’s board of directors, provided that, in the event that such a Change of Control is not completed, the undersigned’s shares shall remain subject to the restrictions contained in this letter and title to the undersigned’s shares shall remain with the undersigned; or

(e) the establishment of a trading plan pursuant to Rule 10b5-1 under the Exchange Act for the transfer of Common Stock, provided that such plan does not provide for the transfer and sale of Common Stock during the Lock-Up Period and provided further that no public announcement of the establishment or existence of such plan, and no filing with the SEC or any other regulatory authority in respect thereof or for transactions thereunder or contemplated thereby, by the undersigned, the Company or any other person prior to the expiration of the Lock-Up Period.

In the case of any transfer or distribution pursuant to clause (a) above, each donee or distributee or transferee shall execute and deliver to the Representatives a lock-up letter for the balance of the Lock-up Period pursuant to which each recipient of a gift of shares agrees in writing to be bound by the same restrictions in place for the undersigned pursuant to this letter for the duration that such restrictions remain in effect at the time of transfer and no filing by any party (donor, donee, distributor, distributee, transferor or transferee) under the Exchange Act, or other public announcement reporting a reduction in the beneficial ownership shall be required or shall be made voluntarily in connection with such transfer or distribution. For the avoidance of doubt, any shares of Common Stock received by the undersigned upon the exercise of a stock option as described in foregoing clause (b) shall be subject to the restrictions under this letter. In the case of any sale or transfer pursuant to clause (c) above, any public filing, report or announcement of any such sale or transfer shall disclose that the sale or transfer was for the purpose of covering the withholding taxes payable.

If the undersigned is an officer or director of the Company, the undersigned further agrees that the foregoing restrictions shall be equally applicable to any issuer-directed shares of Common Stock the undersigned may purchase in the Offering.

If the undersigned is an officer or director of the Company, (i) the Representatives agree that, at least three business days before the effective date of any release or waiver of the foregoing restrictions in connection with a transfer of shares of Common Stock, the Representatives will notify the Company of the impending release or waiver, and (ii) the Company has agreed in the Underwriting Agreement to announce the impending release or waiver by press release through a major news service at least two business days before the effective date of the release or waiver. Any release or waiver granted by the Representatives hereunder to any such officer or director shall only be effective two business days after the publication date of such press release. The provisions of this paragraph will not apply if (a) the release or waiver is effected solely to permit a transfer not for consideration and (b) the transferee has agreed in writing to be bound by the same terms described in this letter to the extent and for the duration that such terms remain in effect at the time of the transfer.

For the purposes of the this letter agreement, “Change of Control” shall mean the transfer (whether by tender offer, merger, consolidation or other similar transaction), in one transaction or a series of related transactions, to a person or group of affiliated persons (other than an Underwriter pursuant to the Offering), of the Company’s voting securities if, after such transfer, such person or group of affiliated persons would hold more than 50% of the outstanding voting securities of the Company (or the surviving entity).

This letter agreement shall automatically terminate, and the undersigned shall be released from its obligations hereunder, upon the earliest to occur, if any, of (i) the Company advising the Representatives in writing, prior to the execution of the Underwriting Agreement, that it has determined not to proceed with the Offering, (ii) the executed Underwriting Agreement being terminated prior to the closing of the Offering (other than the provisions thereof that survive termination), and (iii) September 9, 2018.


Yours very truly,


Name:
Title:

EXHIBIT B – Form of Press Release

SELLAS Life Sciences Group, Inc.

, 2018

SELLAS Life Sciences Group, Inc. (the “Company”) announced today that ▇▇▇▇▇▇ ▇▇▇▇▇▇▇▇▇▇ & Co. and ▇▇▇▇▇▇▇▇▇▇▇ & Co. Inc., the lead book-running managers in the Company’s recent public sale of [ ] shares of common stock, are [waiving] [releasing] a lock-up restriction with respect to [ ] shares of the Company’s common stock held by [certain officers or directors] [an officer or director] of the Company. The [waiver] [release] will take effect on [ ], [ ] 2018, and the shares may be sold on or after such date.

This press release is not an offer for sale of the securities in the United States or in any other jurisdiction where such offer is prohibited, and such securities may not be offered or sold in the United States absent registration or an exemption from registration under the United States Securities Act of 1933, as amended.

ADDENDUM – Form of Waiver of Lock-Up

[Letterhead of Cantor]

Corporation

Public Offering of Common Stock

, 2018

[Name and Address of

Officer or Director

Requesting Waiver]

Dear Mr./Ms. [Name]:

This letter is being delivered to you in connection with the offering by SELLAS Life Sciences Group, Inc. (the “Company”) of [ ] shares of common stock, $0.0001 par value per share (the “Common Stock”), of the Company and the lock-up letter dated [ ], 2018 (the “Lock-up Letter”), executed by you in connection with such offering, and your request for a [waiver] [release] dated [ ], 2018, with respect to [ ] shares of Common Stock (the “Shares”).

Each of Cantor ▇▇▇▇▇▇▇▇▇▇ & Co. and ▇▇▇▇▇▇▇▇▇▇▇ & Co. Inc. ▇▇▇▇▇▇ agrees to [waive] [release] the transfer restrictions set forth in the Lock-up Letter, but only with respect to the Shares, effective [ ], 2018; provided, however, that such [waiver] [release] is conditioned on the Company announcing the impending [waiver] [release] by press release through a major news service at least two business days before effectiveness of such [waiver] [release]. This letter will serve as notice to the Company of the impending [waiver] [release].

Except as expressly [waived] [released] hereby, the Lock-up Letter shall remain in full force and effect.

Yours very truly,

[Signature of Cantor Representative]

[Name and title of Cantor Representative]

[Signature of ▇▇▇▇▇▇▇▇▇▇▇ Representative]

[Name and title of ▇▇▇▇▇▇▇▇▇▇▇ Representative]

cc: Company

EXHIBIT C – Form of Warrant Agreement

EXHIBIT D – Form of Pre-Funded Warrant

SELLAS Life Sciences Group, Inc. Shares Common Stock ($0.0001 par value per share) and Pre-Funded Warrants to Purchase Shares of Common Stock and Warrants to Purchase Shares of Common Stock Underwriting Agreement

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