Document:

EX-10.74

 Exhibit 10.74 

CONVERTIBLE PROMISSORY NOTE 

			
	$232,440.00	  	February 6, 2018
	New York, NY	  	

 For value received SELLAS Life Sciences Group, Inc., a Delaware corporation (the
“Company”), promises to pay to CVI INVESTMENTS, INC. or its assigns (“Holder”) the principal sum of $232,440.00 (the
“Principal”) together with accrued and unpaid interest thereon (the “Interest”), each due and payable on the date and in the manner set forth below.

 This convertible promissory note (the “Note”) was issued in reliance on the exemption
provided in Rule 3(a)(9) of the Securities Act of 1933, as amended, pursuant to the terms of that certain Exchange Agreement, dated as of February 6 2018 (the “Exchange Agreement”), by and
between the Company and the Holder in exchange for that certain Warrant (as defined in the Exchange Agreement) originally issued on February 13, 2017 and shall be subject to the following terms (capitalized terms not defined herein shall have the
meaning as set forth in the Exchange Agreement): 
 1. Repayment. All payments of Interest and Principal shall be in lawful
money of the United States of America. All payments shall be applied first to accrued Interest, and thereafter to Principal. The outstanding Principal amount of the Note shall be due and payable on August 6, 2018 (the “Maturity
Date”). 
 2. Interest. The Company promises to pay simple Interest on the outstanding Principal amount hereof
from the date hereof until payment in full, which Interest shall be payable at the rate of 5% per annum (the “Interest Rate”) or the maximum rate permissible by law, whichever is less. Interest shall be due and
payable by way of inclusion of the Interest in the Conversion Amount on any Conversion Date in accordance with Section 3 below or in cash on the Maturity Date and shall be calculated on the basis of a 365-day year for the actual number of days
elapsed. From and after the occurrence and during the continuance of any Event of Default (as defined below), the Interest Rate shall automatically be increased to eighteen percent (18.0%) per annum (the “Default
Rate”). In the event that such Event of Default is subsequently cured (and no other Event of Default then exists (including, without limitation, for the Company’s failure to pay such Interest at the Default Rate on the
Maturity Date)), the adjustment referred to in the preceding sentence shall cease to be effective as of the calendar day immediately following the date of such cure; provided that the Interest as calculated and unpaid at such increased rate during
the continuance of such Event of Default shall continue to apply to the extent relating to the days after the occurrence of such Event of Default through and including the date of such cure of such Event of Default. 

 3. Conversion. 

At the election of the Holder made at any time after April 30, 2018, this Note shall be convertible into validly issued, fully paid and non-assessable shares of Common Stock (as defined below), on the terms and conditions set forth in this Section 3. 

(a) Conversion Right. Subject to the provisions of Section 3(d), at any time or times on or after April 30, 2018, the
Holder shall be entitled to convert any portion of the outstanding and unpaid Conversion Amount (as defined below) into validly issued, fully paid and non-assessable shares of Common Stock in accordance with
Section 3(c), at the Conversion Rate (as defined below). The Company shall not issue any fraction of a share of Common Stock upon any conversion. If the issuance would result in the issuance of a fraction of a share of Common Stock, the Company
shall round such fraction of a share of Common Stock up to the nearest whole share. The Company shall pay any and all transfer, stamp, issuance and similar taxes, costs and expenses (including, without limitation, fees and expenses of the
Company’s transfer agent (the “Transfer Agent”)) that may be payable with respect to the issuance and delivery of Common Stock upon conversion of any Conversion Amount. 

(b) Conversion Rate. The number of shares of Common Stock issuable upon conversion of any Conversion Amount pursuant to
Section 3(a) shall be determined by dividing (x) such Conversion Amount by (y) the Conversion Price (the “Conversion Rate”). 

(i) “Conversion Amount” means the sum of(x) portion of the Principal to be
converted, redeemed or otherwise with respect to which this determination is being made and (y) all accrued and unpaid Interest with respect to such portion of the Principal amount. 

(ii) “Conversion Price” means, as of any Conversion Date or other date of
determination, $7.00, subject to adjustment as provided herein. 
 (c) Mechanics of Conversion. 

(i) Optional Conversion. To convert any Conversion Amount into shares of Common Stock on any date (a “Conversion
Date”), the Holder shall deliver (whether via facsimile, electronic mail or otherwise), for receipt on or prior to 11:59 p.m., New York time, on such date, a copy of an executed notice of conversion (the
“Conversion Notice”) to the Company. If required by Section 3(c)(iii), within two (2) Trading Days following a conversion of this Note as aforesaid, the Holder shall surrender this Note
to a nationally recognized overnight delivery service for delivery to the Company (or an indemnification undertaking with respect to this Note in the case of its loss, theft or destruction). On or before the first (1st) Trading Day following the
date of receipt of a Conversion Notice, the Company shall transmit by facsimile or electronic mail an acknowledgment of confirmation and representation as to whether such shares of Common Stock may then be resold pursuant to Rule 144 or an effective
and available registration statement, of receipt of such Conversion Notice to the Holder and the Transfer Agent which confirmation shall constitute an instruction to the Transfer Agent to process such Conversion Notice in accordance with the terms
herein. On or before the second (2nd) Trading Day following the date on which the Company has received a Conversion Notice (or such earlier date as required pursuant to the Exchange Act or other applicable law, rule or regulation for the settlement
of a trade initiated on the applicable Conversion Date of such shares of 

  
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Common Stock issuable pursuant to such Conversion Notice) (the “Share Delivery Deadline”), the Company shall (1) provided that the
Transfer Agent is participating in the DTC Fast Automated Securities Transfer Program, credit such aggregate number of shares of Common Stock to which the Holder shall be entitled pursuant to such conversion to the Holder’s or its
designee’s balance account with DTC through its Deposit/Withdrawal at Custodian system or (2) if the Transfer Agent is not participating in the DTC Fast Automated Securities Transfer Program, upon the request of the Holder, issue and
deliver (via reputable overnight courier) to the address as specified in the Conversion Notice, a certificate, registered in the name of the Holder or its designee, for the number of shares of Common Stock to which the Holder shall be entitled
pursuant to such conversion. If this Note is physically surrendered for conversion pursuant to Section 3(c)(iii) and the outstanding Principal of this Note is greater than the Principal portion of the Conversion Amount being converted, then the
Company shall as soon as practicable and in no event later than two (2) Business Days after receipt of this Note and at its own expense, issue and deliver to the Holder (or its designee) a new Note representing the outstanding Principal not
converted. 
 (ii) Company’s Failure to Timely Convert. If the Company shall fail, for any reason or for no reason, on or prior
to the applicable Share Delivery Deadline, if the Transfer Agent is not participating in the DTC Fast Automated Securities Transfer Program, to issue and deliver to the Holder (or its designee) a certificate for the number of shares of Common Stock
to which the Holder is entitled and register such shares of Common Stock on the Company’s share register or, if the Transfer Agent is participating in the DTC Fast Automated Securities Transfer Program, to credit the balance account of the
Holder or the Holder’s designee with DTC for such number of shares of Common Stock to which the Holder is entitled upon the Holder’s conversion of this Note (as the case may be) (a “Conversion
Failure”), and if on or after such Share Delivery Deadline the Holder purchases (in an open market transaction or otherwise) shares of Common Stock corresponding to all or any portion of the number of shares of
Common Stock issuable upon such conversion that the Holder is entitled to receive from the Company and has not received from the Company in connection with such Conversion Failure (a
“Buy-In”), then, in addition to all other remedies available to the Holder, the Company shall, within two (2) Business Days after receipt of the
Holder’s request and in the Holder’s discretion, either: (I) pay cash to the Holder in an amount equal to the Holder’s total purchase price (including brokerage commissions and other out-of-pocket expenses, if any) for the shares of Common Stock so purchased (including, without limitation, by any other Person in respect, or on behalf, of the Holder) (the “Buy-In
Price”), at which point the Company’s obligation to so issue and deliver such certificate (and to issue such shares of Common Stock) or credit the balance account of such Holder or such Holder’s designee, as applicable,
with DTC for the number of shares of Common Stock to which the Holder is entitled upon the Holder’s conversion hereunder (as the case may be) (and to issue such shares of Common Stock) shall terminate, or (II) promptly honor its obligation
to so issue and deliver to the Holder a certificate or certificates representing such shares of Common Stock or credit the balance account of such Holder or such Holder’s designee, as applicable, with DTC for the number of shares of Common
Stock to which the Holder is entitled upon the Holder’s conversion hereunder (as the case may be) and pay cash to the Holder in an amount equal to the excess (if any) of the Buy-In Price over the product
of (x) such number of shares of Common Stock multiplied by (y) the lowest Closing Sale Price of the Common Stock on any Trading Day during the period commencing on the date of the applicable Conversion Notice and ending on the date of such
issuance and payment under this clause (II) (the “Buy-InPayment Amount” ). Nothing shall limit 

  
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 the Holder’s right to pursue any other remedies available to it hereunder, at law or in equity, including,
without limitation, a decree of specific performance and/or injunctive relief with respect to the Company’s failure to timely deliver certificates representing shares of Common Stock (or to electronically deliver such shares of Common Stock)
upon the conversion of this Note as required pursuant to the terms hereof. 
 (iii) Registration; Book-Entry. The Holder and the
Company shall maintain records showing the Principal and Interest converted and/or Paid (as the case may be) and the dates of such conversions, and/or payments (as the case may be) or shall use such other method, reasonably satisfactory to the
Holder and the Company, so as not to require physical surrender of this Note upon conversion. Notwithstanding anything to the contrary set forth in this Section 3, following conversion of any portion of this Note in accordance with the terms
hereof, the Holder shall not be required to physically surrender this Note to the Company unless (A) the full Conversion Amount represented by this Note is being converted (in which event this Note shall be delivered to the Company following
conversion thereof as contemplated by Section 3(c)(i)) or (B) the Holder has provided the Company with prior written notice (which notice may be included in a Conversion Notice) requesting reissuance of this Note upon physical surrender of
this Note. 
 (d) Limitations on Conversions. The Company shall not effect the conversion of any portion of this Note, and the
Holder shall not have the right to convert any portion of this Note pursuant to the terms and conditions of this Note and any such conversion shall be null and void and treated as if never made, to the extent that after giving effect to such
conversion, the Holder together with the other Attribution Parties collectively would beneficially own in excess of 4.99% (the “Maximum Percentage”) of the shares of Common Stock outstanding
immediately after giving effect to such conversion. For purposes of the foregoing sentence, the aggregate number of shares of Common Stock beneficially owned by the Holder and the other Attribution Parties shall include the number of shares of
Common Stock held by the Holder and all other Attribution Parties plus the number of shares of Common Stock issuable upon conversion of this Note with respect to which the determination of such sentence is being made, but shall exclude shares of
Common Stock which would be issuable upon (A) conversion of the remaining, nonconverted portion of this Note beneficially owned by the Holder or any of the other Attribution Parties and (B) exercise or conversion of the unexercised or
nonconverted portion of any other securities of the Company (including, without limitation, any convertible notes or convertible preferred stock or warrants, including, without limitation, the Warrants) beneficially owned by the Holder or any other
Attribution Party subject to a limitation on conversion or exercise analogous to the limitation contained in this Section 3(d). For purposes of this Section 3(d), beneficial ownership shall be calculated in accordance with
Section 13(d) of the Exchange Act. For purposes of determining the number of outstanding shares of Common Stock the Holder may acquire upon the conversion of this Note without exceeding the Maximum Percentage, the Holder may rely on the number
of outstanding shares of Common Stock as reflected in (x) the Company’s most recent Annual Report on Form 10-K, Quarterly Report on Form 10-Q, Current Report
on Form 8-K or other public filing with the SEC, as the case may be, (y) a more recent public announcement by the Company or (z) any other written notice by the Company or the Transfer Agent, if any,
setting forth the number of shares of Common Stock outstanding (the “Reported Outstanding Share Number”). If the Company receives a Conversion Notice from the Holder at a time when the actual
number of outstanding shares of Common Stock is less than the Reported Outstanding Share 

  
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Number, the Company shall notify the Holder in writing of the number of shares of Common Stock then outstanding and, to the extent that such Conversion Notice would otherwise cause the
Holder’s beneficial ownership, as determined pursuant to this Section 3(d), to exceed the Maximum Percentage, the Holder must notify the Company of a reduced number of shares of Common Stock to be purchased pursuant to such Conversion
Notice. For any reason at any time, upon the written or oral request of the Holder, the Company shall within one (1) Business Day confirm orally and in writing or by electronic mail to the Holder the number of shares of Common Stock then
outstanding. In any case, the number of outstanding shares of Common Stock shall be determined after giving effect to the conversion or exercise of securities of the Company, including this Note, by the Holder and any other Attribution Party since
the date as of which the Reported Outstanding Share Number was reported. In the event that the issuance of shares of Common Stock to the Holder upon conversion of this Note results in the Holder and the other Attribution Parties being deemed to
beneficially own, in the aggregate, more than the Maximum Percentage of the number of outstanding shares of Common Stock (as determined under Section 13(d) of the Exchange Act), the number of shares so issued by which the Holder’s and the
other Attribution Parties’ aggregate beneficial ownership exceeds the Maximum Percentage (the “Excess Shares”) shall be deemed null and void and shall be cancelled ab initio, and the Holder shall not have the power to
vote or to transfer the Excess Shares. Upon delivery of a written notice to the Company, the Holder may from time to time increase (with such increase not effective until the sixty-first (6!51) day after delivery of such notice) or decrease the
Maximum Percentage to any other percentage not in excess of 4.99% as specified in such notice; provided that (i) any such increase in the Maximum Percentage will not be effective until the sixty-first (61s1) day after such notice is delivered
to the Company and (ii) any such increase or decrease will apply only to the Holder and the other Attribution Parties and not to any other holder of Notes that is not an Attribution Party of the Holder. For purposes of clarity, the shares of
Common Stock issuable pursuant to the terms of this Note in excess of the Maximum Percentage shall not be deemed to be beneficially owned by the Holder for any purpose including for purposes of Section 13(d) or Rule 16a-l(a)(l) of the Exchange Act. No prior inability to convert this Note pursuant to this paragraph shall have any effect on the applicability of the provisions of this paragraph with respect to any subsequent
determination of convertibility. The provisions of this paragraph shall be construed and implemented in a manner otherwise than in strict conformity with the terms of this Section 3(d) to the extent necessary to correct this paragraph (or any
portion of this paragraph) which may be defective or inconsistent with the intended beneficial ownership limitation contained in this Section 3(d) or to make changes or supplements necessary or desirable to properly give effect to such
limitation. The limitation contained in this paragraph may not be waived and shall apply to a successor holder of this Note. Further, notwithstanding anything in this Note to the contrary, under no circumstances shall the Company be obligated to
issue or the Holder entitled to receive, an aggregate number of shares of Common Stock that would exceed 19.9% of the total number of shares of Common Stock issued and outstanding as of the date of this Note (the “Maximum
Issuance”); provided, that to the extent the aggregate number of shares of Common Stock would exceed the Maximum Issuance, the Company shall issue and deliver to Holder a number of shares of Common Stock up to the
Maximum Issuance and the unconverted Principal of this Note shall remain outstanding. 

  
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 (e) Right of Alternate Conversion. 

(i) General. At any time at any time after the occurrence of an Event of Default (regardless of whether such Event of Default has been
cured), the Holder may, at the Holder’s option, convert (each, an “Alternate Conversion”, and the date of such Alternate Conversion, each, an “Alternate Conversion
Date”) all , or any part of, the Conversion Amount (such portion of the Conversion Amount subject to such Alternate Conversion, the “Alternate Conversion Amount”)
into shares of Common Stock at the Alternate Conversion Price. 
 (ii) Mechanics of Alternate Conversion. On any Alternate
Conversion Date, the Holder may voluntarily convert any Alternate Conversion Amount pursuant to Section 3(c) (with “Alternate Conversion Price” replacing “Conversion Price” for all purposes hereunder with respect to such
Alternate Conversion) by designating in the Conversion Notice delivered pursuant to this Section 3(e) of this Note that the Holder is electing to use the Alternate Conversion Price for such conversion. Notwithstanding anything to the contrary
in this Section 3(e), but subject to Section 3(d), until the Company delivers shares of Common Stock representing the applicable Alternate Conversion Amount to the Holder, such Alternate Conversion Amount may be converted by the Holder
into shares of Common Stock pursuant to Section 3(c) without regard to this Section 3(e). 
 (f) Voluntary Adjustment by
Company. The Company may at any time during the term of this Note, with the prior written consent of the Holder, reduce the then current Conversion Price of each of the Notes to any amount and for any period of time deemed appropriate by the
board of directors of the Company. 
 4. Maturity. Unless this Note has been previously converted or prepaid in accordance
with the terms of Section 3(a) above, the entire outstanding Conversion Amount shall become fully due and payable in cash on the Maturity Date; provided, that if the Conversion Amount is not paid in full in cash on the Maturity Date, subject to
Section 3(d) above, the Holder shall retain the right to convert all, or any part, at such Holder’s sole discretion, of the Conversion Amount into shares of Common Stock in accordance with Section 3 above. 

5. Expenses. In the event of any default hereunder, the Company shall pay all reasonable attorneys’ fees and court costs
incurred by Holder in enforcing and collecting this Note. 
 6. Prepayment. The Company may prepay this Note and accrued but
unpaid Interest prior to the Maturity Date at any time without the consent of the Holder; provided, that the Company may not prepay any Conversion Amount submitted for conversion pursuant to Section 3 above from and after the applicable
Conversion Date unless such corresponding Conversion Notice is withdrawn by the Holder. 
 7. Default. If there shall be any Event of
Default hereunder, at the option and upon the declaration of the Holder and upon written notice to the Company (which election and notice shall not be required in the case of an Event of Default under Section 7(v), 7(vi) or 7(vii)), this Note
shall accelerate and all Principal and unpaid accrued Interest shall become immediately due and payable. The occurrence of any one or more of the following shall constitute an “Event of Default’: 

(i) the suspension (or threatened suspension) from trading or the failure (or threatened failure) of the Common Stock to be trading or
listed (as applicable) on the Nasdaq Capital Market for a period of five (5) consecutive Trading Days; 

  
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 (ii) the Company’s (A) failure to cure a Conversion Failure by delivery of the
required number of shares of Common Stock within five (5) Trading Days after the applicable Conversion Date or exercise date (as the case may be) or (B) notice, written or oral, to any holder of the Notes, including, without limitation, by
way of public announcement or through any of its agents, at any time, of its intention not to comply, as required, with a request for conversion of any Notes into shares of Common Stock that is requested in accordance with the provisions of the
Notes, other than pursuant to Section 3(d); 
 (iii) the Company’s or any Subsidiary’s failure to pay to the Holder
any amount of Principal, Interest or other amounts when and as due under this Note (including, without limitation, the Company’s failure to pay any redemption payments or amounts hereunder) or any other Exchange Document or any other agreement,
document, certificate or other instrument delivered in connection with the transactions contemplated hereby and thereby, except, in the case of a failure to pay Interest when and as due, in which case only if such failure remains uncured for a
period of at least two (2) Trading Days; 
 (iv) [INTENTIONALLY OMITTED]; 

(v) bankruptcy, insolvency, reorganization or liquidation proceedings or other proceedings for the relief of debtors shall be
instituted by or against the Company or any Subsidiary and, if instituted against the Company or any Subsidiary by a third party, shall not be dismissed within thirty (30) days of their initiation; 

(vi) the commencement by the Company or any Subsidiary of a voluntary case or proceeding under any applicable federal, state or
foreign bankruptcy, insolvency, reorganization or other similar law or of any other case or proceeding to be adjudicated a bankrupt or insolvent, or the consent by it to the entry of a decree, order, judgment or other similar document in respect of
the Company or any Subsidiary in an involuntary case or proceeding under any applicable federal, state or foreign bankruptcy, insolvency, reorganization or other similar law or to the commencement of any bankruptcy or insolvency case or proceeding
against it, or the filing by it of a petition or answer or consent seeking reorganization or relief under any applicable federal, state or foreign law, or the consent by it to the filing of such petition or to the appointment of or taking possession
by a custodian, receiver, liquidator, assignee, trustee, sequestrator or other similar official of the Company or any Subsidiary or of any substantial part of its property, or the making by it of an assignment for the benefit of creditors, or the
execution of a composition of debts, or the occurrence of any other similar federal, state or foreign proceeding, or the admission by it in writing of its inability to pay its debts generally as they become due, the taking of corporate action by the
Company or any Subsidiary in furtherance of any such action or the taking of any action by any Person to commence a Uniform Commercial Code foreclosure sale or any other similar action under federal, state or foreign law; 

  
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 (vii) the entry by a court of (i) a decree, order, judgment or other similar
document in respect of the Company or any Subsidiary of a voluntary or involuntary case or proceeding under any applicable federal, state or foreign bankruptcy, insolvency, reorganization or other similar law or (ii) a decree, order, judgment
or other similar document adjudging the Company or any Subsidiary as bankrupt or insolvent, or approving as properly filed a petition seeking liquidation, reorganization, arrangement, adjustment or composition of or in respect of the Company or any
Subsidiary under any applicable federal, state or foreign law or (iii) a decree, order, judgment or other similar document appointing a custodian, receiver, liquidator, assignee, trustee, sequestrator or other similar official of the Company or
any Subsidiary or of any substantial part of its property, or ordering the winding up or liquidation of its affairs, and the continuance of any such decree, order, judgment or other similar document or any such other decree, order, judgment or other
similar document unstayed and in effect for a period of thirty (30) consecutive days; or 
 (viii) other than as specifically
set forth in another clause of this Section 7, the Company or any Subsidiary breaches any representation, warranty, covenant or other term or condition of any Exchange Document, except, in the case of a breach of a covenant or other term or
condition that is curable, only if such breach remains uncured for a period of three (3) consecutive Trading Days. 
 8.
Adjustment of Conversion Price upon Subdivision or Combination of Common Stock. If the Company at any time on or after the date hereof subdivides (by any stock split, stock dividend, stock combination, recapitalization or other similar
transaction) one or more classes of its outstanding shares of Common Stock into a greater number of shares, the Conversion Price in effect immediately prior to such subdivision will be proportionately reduced. If the Company at any time on or after
the date hereof combines (by any stock split, stock dividend, stock combination, recapitalization or other similar transaction) one or more classes of its outstanding shares of Common Stock into a smaller number of shares, the Conversion Price in
effect immediately prior to such combination will be proportionately increased. Any adjustment pursuant to this Section 8 shall become effective immediately after the effective date of such subdivision or combination. If any event requiring an
adjustment under this Section 8 occurs during the period that a Conversion Price is calculated hereunder, then the calculation of such Conversion Price shall be adjusted appropriately to reflect such event. 

9. Rights upon Fundamental Transaction. The Company shall not enter into or be party to a Fundamental Transaction unless
(i) the Successor Entity assumes in writing all of the obligations of the Company under this Note and the other Exchange Documents in accordance with the provisions of this Section 9 pursuant to written agreements in form and substance
satisfactory to the Holder and approved by the Holder prior to such Fundamental Transaction, including agreements to deliver to each holder of Notes in exchange for such Notes a security of the Successor Entity evidenced by a written instrument
substantially similar in form and substance to the Notes, including, without limitation, having a principal amount and interest rate equal to the principal amounts then outstanding and the interest rates of the Notes held by such holder, having
similar conversion rights as the Notes and having similar ranking and security to the Notes, and satisfactory to the Holder and (ii) the Successor Entity (including its Parent Entity) is a publicly traded corporation whose common stock is
quoted on or listed for trading on an Eligible Market. Upon the occurrence of any Fundamental Transaction, the Successor Entity shall succeed to, and be substituted for (so that from and after the date of such Fundamental Transaction, the provisions
of this Note and the other Exchange Documents referring to the “Company” shall refer instead to the Successor Entity), and may exercise every right and power of the Company and shall assume all of the obligations of the Company under this
Note and the 

  
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other Exchange Documents with the same effect as if such Successor Entity had been named as the Company herein. Upon consummation of a Fundamental Transaction, the Successor Entity shall deliver
to the Holder confirmation that there shall be issued upon conversion or redemption of this Note at any time after the consummation of such Fundamental Transaction, in lieu of the shares of Common Stock (or other securities, cash, assets or other
property (except such items still issuable under Sections 10(a) and 11, which shall continue to be receivable thereafter) issuable upon the conversion or redemption of the Notes prior to such Fundamental Transaction, such shares of the publicly
traded common stock (or their equivalent) of the Successor Entity (including its Parent Entity) which the Holder would have been entitled to receive upon the happening of such Fundamental Transaction had this Note been converted immediately prior to
such Fundamental Transaction (without regard to any limitations on the conversion of this Note), as adjusted in accordance with the provisions of this Note. Notwithstanding the foregoing, the Holder may elect, at its sole option, by delivery of
written notice to the Company to waive this Section 9 to permit the Fundamental Transaction without the assumption of this Note. The provisions of this Section 9 shall apply similarly and equally to successive Fundamental Transactions and
shall be applied without regard to any limitations on the conversion of this Note. 
 10. Rights Upon Issuance of Purchase Rights and
Other Corporate Events. 
 (a) Purchase Rights. If at any time the Company grants, issues or sells any Options,
Convertible Securities or rights to purchase stock, warrants, securities or other property pro rata to all or substantially all of the record holders of any class of Common Stock (the “Purchase Rights”),
then the Holder will be entitled to acquire, upon the terms applicable to such Purchase Rights, the aggregate Purchase Rights which the Holder could have acquired if the Holder had held the number of shares of Common Stock acquirable upon
complete conversion of this Note (without taking into account any limitations or restrictions on the convertibility of this Note and assuming for such purpose that the Note was converted at the Alternate Conversion Price as of the applicable record
date) immediately prior to the date on which a record is taken for the grant, issuance or sale of such Purchase Rights, or, if no such record is taken, the date as of which the record holders of shares of Common Stock are to be determined for the
grant, issue or sale of such Purchase Rights (provided, however, that to the extent that the Holder’s right to participate in any such Purchase Right would result in the Holder and the other Attribution Parties exceeding the
Maximum Percentage, then the Holder shall not be entitled to participate in such Purchase Right to the extent of the Maximum Percentage (and shall not be entitled to beneficial ownership of such shares of Common Stock as a result of such Purchase
Right (and beneficial ownership) to the extent of any such excess) and such Purchase Right to such extent shall be held in abeyance (and, if such Purchase Right has an expiration date, maturity date or other similar provision, such term shall be
extended by such number of days held in abeyance, if applicable) for the benefit of the Holder until such time or times, if ever, as its right thereto would not result in the Holder and the other Attribution Parties exceeding the Maximum Percentage,
at which time or times the Holder shall be granted such right (and any Purchase Right granted, issued or sold on such initial Purchase Right or on any subsequent Purchase Right held similarly in abeyance (and, if such Purchase Right has an
expiration date, maturity date or other similar provision, such term shall be extended by such number of days held in abeyance, if applicable)) to the same extent as if there had been no such limitation). 

  
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 (b) Other Corporate Events. In addition to and not in substitution for any other
rights hereunder, prior to the consummation of any Fundamental Transaction pursuant to which holders of shares of Common Stock are entitled to receive securities or other assets with respect to or in exchange for shares of Common Stock (a
“Corporate Event”), the Company shall make appropriate provision to ensure that the Holder will thereafter have the right to receive upon a
conversion of this Note, at the Holder’s option (i) in addition to the shares of Common Stock receivable upon such conversion, such securities or other assets to which the Holder would have been entitled with respect to such shares of Common
Stock had such shares of Common Stock been held by the Holder upon the consummation of such Corporate Event (without taking into account any limitations or restrictions on the convertibility of this Note) or (ii) in lieu of the shares of Common
Stock otherwise receivable upon such conversion, such securities or other assets received by the holders of shares of Common Stock in connection with the consummation of such Corporate Event in such amounts as the Holder would have been entitled to
receive had this Note initially been issued with conversion rights for the form of such consideration (as opposed to shares of Common Stock) at a conversion rate for such consideration commensurate with the Conversion Rate. Provision made pursuant
to the preceding sentence shall be in a form and substance satisfactory to the Holder. The provisions of this Section lO(b) shall apply similarly and equally to successive Corporate Events and shall be applied without regard to any limitations on
the conversion or redemption of this Note. 
 11. Remedies, Characterizations, Other Obligations, Breaches and Injunctive Relief.
The remedies provided in this Note shall be cumulative and in addition to all other remedies available under this Note and any of the other Exchange Documents at law or in equity (including a decree of specific performance and/or other
injunctive relief), and nothing herein shall limit the Holder’s right to pursue actual and consequential damages for any failure by the Company to comply with the terms of this Note. The Company covenants to the Holder that there shall be no
characterization concerning this instrument other than as expressly provided herein. Amounts set forth or provided for herein with respect to payments, conversion and the like (and the computation thereof) shall be the amounts to be received by the
Holder and shall not, except as expressly provided herein, be subject to any other obligation of the Company (or the performance thereof). The Company acknowledges that a breach by it of its obligations hereunder will cause irreparable harm to the
Holder and that the remedy at law for any such breach may be inadequate. The Company therefore agrees that, in the event of any such breach or threatened breach, the Holder shall be entitled, in addition to all other available remedies, to specific
performance and/or temporary, preliminary and permanent injunctive or other equitable relief from any court of competent jurisdiction in any such case without the necessity of proving actual damages and without posting a bond or other security. The
Company shall provide all information and documentation to the Holder that is requested by the Holder to enable the Holder to confirm the Company’s compliance with the terms and conditions of this Note. 

12. Severability. If any provision of this Note is prohibited by law or otherwise determined to be invalid or unenforceable by a
court of competent jurisdiction, the provision that would otherwise be prohibited, invalid or unenforceable shall be deemed amended to apply to the broadest extent that it would be valid and enforceable, and the invalidity or unenforceability of
such provision shall not affect the validity of the remaining provisions of this Note so long as this Note as so modified continues to express, without material change, the original intentions of the parties as to the subject matter hereof and the
prohibited nature, invalidity or unenforceability of the provision(s) in question does not substantially impair the respective expectations or reciprocal obligations of the parties or the practical realization of the benefits that would otherwise be
conferred upon the parties. The parties will endeavor in good faith negotiations to replace the prohibited, invalid or unenforceable provision(s) with a valid provision(s), the effect of which comes as close as possible to that of the prohibited,
invalid or unenforceable provision(s). 

  
 Note: Page 10 

 13. Maximum Payments. Nothing contained herein shall be deemed to establish or
require the payment of a rate of interest or other charges in excess of the maximum permitted by applicable law. In the event that the rate of interest required to be paid or other charges hereunder exceed the maximum permitted by such law, any
payments in excess of such maximum shall be credited against amounts owed by the Company to the Holder and thus refunded to the Company. 

14. Waiver. The Company hereby waives demand, notice, presentment, protest and notice of dishonor. 

15. Governing Law. This Note shall be construed and enforced in accordance with, and all questions concerning the construction,
validity, interpretation and performance of this Note shall be governed by, the internal laws of the State of New York, without giving effect to any choice of law or conflict of law provision or rule (whether of the State of New York or any other
jurisdictions) that would cause the application of the laws of any jurisdictions other than the State of New York. The Company hereby irrevocably submits to the exclusive jurisdiction of the state and federal courts sitting in The City of New York,
Borough of Manhattan, for the adjudication of any dispute hereunder or in connection herewith or with any transaction contemplated hereby or discussed herein, and hereby irrevocably waives, and agrees not to assert in any suit, action or proceeding,
any claim that it is not personally subject to the jurisdiction of any such court, that such suit, action or proceeding is brought in an inconvenient forum or that the venue of such suit, action or proceeding is improper. Nothing contained herein
shall be deemed to limit in any way any right to serve process in any manner permitted by law. Nothing contained herein shall be deemed to limit in any way any right to serve process in any manner permitted by law. Nothing contained herein shall be
deemed or operate to preclude the Holder from bringing suit or taking other legal action against the Company in any other jurisdiction to collect on the Company’s obligations to the Holder, to realize on any collateral or any other security for
such obligations, or to enforce a judgment or other court ruling in favor of the Holder. THE COMPANY HEREBY IRREVOCABLY WAIVES ANY RIGHT IT MAY HAVE TO, AND AGREES NOT TO REQUEST, A JURY TRIAL FOR THE ADJUDICATION OF ANY DISPUTE HEREUNDER OR IN
CONNECTION WITH OR ARISING OUT OF THIS NOTE OR ANY TRANSACTION CONTEMPLATED HEREBY. 
 16. Failure Or Indulgence Not Waiver.
No failure or delay on the part of the Holder in the exercise of any power, right or privilege hereunder shall operate as a waiver thereof, nor shall any single or partial exercise of any such power, right or privilege preclude other or further
exercise thereof or of any other right, power or privilege. No waiver shall be effective unless it is in writing and signed by an authorized representative of the waiving party. Notwithstanding the foregoing, nothing contained in this
Section 16 shall permit any waiver of any provision of Section 3(d). 

  
 Note: Page 11 

 17. Amending the Terms of this Note. The prior written consent of the Holder shall
be required for any change, waiver or amendment to this Note. 
 18. Notices; Currency; Payments. 

(a) Notices. Whenever notice is required to be given under this Note, unless otherwise provided herein, such notice shall be
given in accordance with the terms of the Exchange Agreement. The Company shall provide the Holder with prompt written notice of all actions taken pursuant to this Note, including in reasonable detail a description of such action and the reason
therefore. Without limiting the generality of the foregoing, the Company will give written notice to the Holder (i) immediately upon any adjustment of the Conversion Price, setting forth in reasonable detail, and certifying, the calculation of
such adjustment and (ii) at least fifteen (15) days prior to the date on which the Company closes its books or takes a record (A) with respect to any dividend or distribution upon the Common Stock, and (B) for determining rights
to vote with respect to any Fundamental Transaction, dissolution or liquidation, provided in each case that such information shall be made known to the public prior to or in conjunction with such notice being provided to the Holder. 

(b) Currency. All dollar amounts referred to in this Note are in United States Dollars (“U.S.
Dollars”), and all amounts owing under this Note shall be paid in U.S. Dollars. All amounts denominated in other currencies (if any) shall be converted into the U.S. Dollar equivalent amount in accordance with
the Exchange Rate on the date of calculation. “Exchange Rate” means, in relation to any amount of currency to be converted into U.S. Dollars pursuant to this Note, the U.S. Dollar exchange
rate as published in the Wall Street Journal on the relevant date of calculation (it being understood and agreed that where an amount is calculated with reference to, or over, a period of time, the date of calculation shall be the final date of such
period of time). 
 (c) Payments. Whenever any payment of cash is to be made by the Company to any Person pursuant to this
Note, unless otherwise expressly set forth herein, such payment shall be made in lawful money of the United States of America by a certified check drawn on the account of the Company and sent via overnight courier service to such Person at such
address as previously provided to the Company in writing, provided that the Holder may elect to receive a payment of cash via wire transfer of immediately available funds by providing the Company with prior written notice setting out such request
and the Holder’s wire transfer instructions. Whenever any amount expressed to be due by the terms of this Note is due on any day which is not a Business Day, the same shall instead be due on the next succeeding day which is a Business Day. 

19. Waiver of Notice. To the extent permitted by law, the Company hereby irrevocably waives demand, notice, presentment, protest
and all other demands and notices in connection with the delivery, acceptance, performance, default or enforcement of this Note and the Exchange Agreement. 

20. Assignment. This Note may be transferred only upon its surrender to the Company for registration of transfer, duly endorsed,
or accompanied by a duly executed written instrument of transfer in form satisfactory to the Company. Thereupon, this Note shall be reissued to, and registered in the name of, the transferee, or a new Note for like Principal amount and Interest
shall be issued to, and registered in the name of, the transferee. Interest and Principal shall be paid solely to the registered holder of this Note. Such payment shall constitute full discharge of the Company’s obligation to pay such Interest
and Principal. 

  
 Note: Page 12 

 21. CERTAIN DEFINITIONS. For purposes of this Note, the following terms shall have
the following meanings: 
 (a) “Adjustment Right” means any right granted with respect to any securities
issued in connection with, or with respect to, any issuance or sale (or deemed issuance or sale) of shares of Common Stock that could result in a decrease in the net consideration received by the Company in connection with, or with respect to, such
securities (including, without limitation, any cash settlement rights, cash adjustment or other similar rights). 
 (b)
“Alternate Conversion Price” means, with respect to any Alternate Conversion that price which shall be the lowest of (i) the applicable Conversion Price as in effect on the applicable Conversion Date of the applicable
Alternate Conversion, (ii) 70% of the lowest VWAP of the Common Stock as of the Trading Day during the ten (10) consecutive Trading Day period ending and including the applicable Alternate Conversion Date (such period, the
“Alternate Conversion Measuring Period”). All such determinations to be appropriately adjusted for any stock dividend, stock split, stock combination, reclassification or similar transaction that
proportionately decreases or increases the Common Stock during such Alternate Conversion Measuring Period. 
 (c)
“Attribution Parties” means, collectively, the following Persons and entities: (i) any investment vehicle, including, any funds, feeder funds or managed accounts, currently, or from time to time after the date hereof,
directly or indirectly managed or advised by the Holder’s investment manager or any of its Affiliates or principals, (ii) any direct or indirect Affiliates of the Holder or any of the foregoing, (iii) any Person acting or who could be
deemed to be acting as a Group together with the Holder or any of the foregoing and (iv) any other Persons whose beneficial ownership of the Company’s Common Stock would or could be aggregated with the Holder’s and the other
Attribution Parties for purposes of Section 13(d) of the Exchange Act. For clarity, the purpose of the foregoing is to subject collectively the Holder and all other Attribution Parties to the Maximum Percentage. 

(d) “Bloomberg” means Bloomberg, L.P. 

(e) “Business Day” means any day other than Saturday, Sunday or other day on which commercial banks in The City
of New York are authorized or required by law to remain closed. 
 (t) “Closing Bid Price” and
“Closing Sale Price” means, for any security as of any date, the last closing bid price and last closing trade price, respectively, for such security on the Principal Market, as reported by Bloomberg, or, if the Principal
Market begins to operate on an extended hours basis and does not designate the closing bid price or the closing trade price (as the case may be) then the last bid price or last trade price, respectively, of such security prior to 4:00:00 p.m., New
York time, as reported by Bloomberg, or, if the Principal Market is not the principal securities exchange or trading market for such security, the last closing bid price or last trade price, respectively, of such security on the principal securities
exchange or trading market where such security is listed or traded as reported by 

  
 Note: Page 13 

 
Bloomberg, or if the foregoing do not apply, the last closing bid price or last trade price, respectively, of such security in the over-the-counter market on the electronic bulletin board for
such security as reported by Bloomberg, or, if no closing bid price or last trade price, respectively, is reported for such security by Bloomberg, the average of the bid prices, or the ask prices, respectively, of any market makers for such security
as reported in the “pink sheets” by OTC Markets Group Inc. (formerly Pink Sheets LLC). If the Closing Bid Price or the Closing Sale Price cannot be calculated for a security on a particular date on any of the foregoing bases, the Closing
Bid Price or the Closing Sale Price (as the case may be) of such security on such date shall be the fair market value as mutually determined by the Company and the Holder. If the Company and the Holder are unable to agree upon the fair market value
of such security, then such dispute shall be resolved in accordance with the procedures in Section 22. All such determinations shall be appropriately adjusted for any stock splits, stock dividends, stock combinations, recapitalizations or other
similar transactions during such period. 
 (g) “Common Stock” means (i) the Company’s shares of
common stock, $0.0001 par value per share, and (ii) any capital stock into which such common stock shall have been changed or any share capital resulting from a reclassification of such common stock. 

(h) “Convertible Securities” means any stock or other security (other than Options) that is at any time and
under any circumstances, directly or indirectly, convertible into, exercisable or exchangeable for, or which otherwise entitles the holder thereof to acquire, any shares of Common Stock. 

(i) “Eligible Market” means The New York Stock Exchange, the NYSE American, the Nasdaq Global Select Market,
the Nasdaq Global Market or the Principal Market. 
 (j) “Fundamental Transaction” means (A) that the Company
shall, directly or indirectly, including through subsidiaries, Affiliates or otherwise, in one or more related transactions, (i) consolidate or merge with or into (whether or not the Company is the surviving corporation) another Subject Entity, or
(ii) sell, assign, transfer, convey or otherwise dispose of all or substantially all of the properties or assets of the Company or any of its “significant subsidiaries” (as defined in Rule 1-02 of Regulation S-X) to one or more Subject
Entities, or (iii) make, or allow one or more Subject Entities to make, or allow the Company to be subject to or have its Common Stock be subject to or party to one or more Subject Entities making, a purchase, tender or exchange offer that is
accepted by the holders of at least either (x) 50% of the outstanding shares of Common Stock, (y) 50% of the outstanding shares of Common Stock calculated as if any shares of Common Stock held by all Subject Entities making or party to, or
Affiliated with any Subject Entities making or party to, such purchase, tender or exchange offer were not outstanding; or (z) such number of shares of Common Stock such that all Subject Entities making or party to, or Affiliated with any Subject
Entity making or party to, such purchase, tender or exchange offer, become collectively the beneficial owners (as defined in Rule 13d-3 under the Exchange Act) of at least 50% of the outstanding shares of Common Stock, or (iv) consummate a stock or
share purchase agreement or other business combination (including, without limitation, a reorganization, recapitalization, spin-off or scheme of arrangement) with one or more Subject Entities whereby all such Subject Entities, individually or in the
aggregate, acquire, either (x) at least 50% of the outstanding shares of Common Stock, (y) at least 50% of the outstanding shares of Common Stock calculated as if any shares of Common Stock held by all the Subject Entities making or party to, or
Affiliated with any Subject Entity making or party to, such stock purchase agreement or other business 

  
 Note: Page 14 

 
combination were not outstanding; or (z) such number of shares of Common Stock such that the Subject Entities become collectively the beneficial owners (as defined in Rule 13d-3 under the
Exchange Act) of at least 50% of the outstanding shares of Common Stock, or (v) reorganize, recapitalize or reclassify its Common Stock, (B) that the Company shall, directly or indirectly, including through subsidiaries, Affiliates or
otherwise, in one or more related transactions, allow any Subject Entity individually or the Subject Entities in the aggregate to be or become the “ beneficial owner” (as defined in Rule 13d-3 under
the Exchange Act), directly or indirectly, whether through acquisition, purchase, assignment, conveyance, tender, tender offer, exchange, reduction in outstanding shares of Common Stock, merger, consolidation, business combination, reorganization,
recapitalization, spin-off, scheme of arrangement, reorganization, recapitalization or reclassification or otherwise in any manner whatsoever, of either (x) at least 50% of the aggregate ordinary voting
power represented by issued and outstanding Common Stock, (y) at least 50% of the aggregate ordinary voting power represented by issued and outstanding Common Stock not held by all such Subject Entities as of the date of this Note calculated as
if any shares of Common Stock held by all such Subject Entities were not outstanding, or (z) a percentage of the aggregate ordinary voting power represented by issued and outstanding shares of Common Stock or other equity securities of the
Company sufficient to allow such Subject Entities to effect a statutory short form merger or other transaction requiring other shareholders of the Company to surrender their shares of Common Stock without approval of the shareholders of the Company
or (C) directly or indirectly, including through subsidiaries, Affiliates or otherwise, in one or more related transactions, the issuance of or the entering into any other instrument or transaction structured in a manner to circumvent, or that
circumvents, the intent of this definition in which case this definition shall be construed and implemented in a manner otherwise than in strict conformity with the terms of this definition to the extent necessary to correct this definition or any
portion of this definition which may be defective or inconsistent with the intended treatment of such instrument or transaction. 

(k) “Group” means a “group” as that term is used in Section 13(d) of the Exchange Act and as
defined in Rule 13d-5 thereunder. 
 (I) “Options” means any rights,
warrants or options to subscribe for or purchase shares of Common Stock or Convertible Securities issued to Persons other than the Company. 

(m) “Parent Entity” of a Person means an entity that, directly or indirectly, controls the applicable Person
and whose common stock or equivalent equity security is quoted or listed on an Eligible Market, or, if there is more than one such Person or Parent Entity, the Person or Parent Entity with the largest public market capitalization as of the date of
consummation of the Fundamental Transaction. 
 (n) “Principal Market” means the Nasdaq Capital Market. 

(o) “Subject Entity” means any Person, Persons or Group or any Affiliate or associate of any such Person,
Persons or Group. 
 (p) “Successor Entity” means the Person (or, if so elected by the Holder, the Parent
Entity) formed by, resulting from or surviving any Fundamental Transaction or the Person (or, if so elected by the Holder, the Parent Entity) with which such Fundamental Transaction shall have been entered into. 

  
 Note: Page 15 

 (q) “Trading Day” means, as applicable, (x) with respect to
all price or trading volume determinations relating to the Common Stock, any day on which the Common Stock is traded on the Principal Market, or, if the Principal Market is not the principal trading market for the Common Stock, then on the principal
securities exchange or securities market on which the Common Stock is then traded, provided that “Trading Day” shall not include any day on which the Common Stock is scheduled to trade on such exchange or market for less than 4.5 hours or
any day that the Common Stock is suspended from trading during the final hour of trading on such exchange or market (or if such exchange or market does not designate in advance the closing time of trading on such exchange or market, then during the
hour ending at 4:00:00 p.m., New York time) unless such day is otherwise designated as a Trading Day in writing by the Holder or (y) with respect to all determinations other than price determinations relating to the Common Stock, any day on
which The New York Stock Exchange (or any successor thereto) is open for trading of securities. 
 (r) “VWA.P’
means, for any security as of any date, the dollar volume-weighted average price for such security on the Principal Market (or, if the Principal Market is not the principal trading market for such security, then on the principal securities
exchange or securities market on which such security is then traded) during the period beginning at 9:30:01 a.m., New York time, and ending at 4:00:00 p.m., New York time, as reported by Bloomberg through its “HP” function (set to weighted
average) or, if the foregoing does not apply, the dollar volume-weighted average price of such security in the over-the-counter market on the electronic bulletin board for such security during the period
beginning at 9:30:01 a.m., New York time, and ending at 4:00:00 p.m., New York time, as reported by Bloomberg, or, if no dollar volume-weighted average price is reported for such security by Bloomberg for such hours, the average of the highest
closing bid price and the lowest closing ask price of any of the market makers for such security as reported in the “pink sheets” by OTC Markets Group Inc. (formerly Pink Sheets LLC). If the VWAP cannot be calculated for such security on
such date on any of the foregoing bases, the VWAP of such security on such date shall be the fair market value as mutually determined by the Company and the Holder. If the Company and the Holder are unable to agree upon the fair market value of such
security, then such dispute shall be resolved in accordance with the procedures in Section 22. All such determinations shall be appropriately adjusted for any stock dividend, stock split, stock combination, recapitalization or other similar
transaction during such period. 
 22. Disclosure. Upon receipt or delivery by the Company of any notice in accordance with
the terms of this Note, unless the Company has in good faith determined that the matters relating to such notice do not constitute material, non-public information relating to the Company or any of its Subsidiaries, the Company shall within the
later of (a) the Cleansing Deadline and (b) one (1) Business Day after any such receipt or delivery, publicly disclose such material, non-public information on a Current Report on Form 8-K or otherwise. In the event that the Company believes that a notice contains material, non-public information relating to the Company or any of its Subsidiaries, the
Company so shall indicate to the Holder contemporaneously with delivery of such notice, and in the absence of any such indication, the Holder shall be allowed to presume that all matters relating to such notice do not constitute material, non-public information relating to the Company or any of its Subsidiaries. If the Company or any of its Subsidiaries provides material non-public information to the Holder
after the 

  
 Note: Page 16 

 
Cleansing Deadline that is not simultaneously filed in a Current Report on Form 8-K and the Holder has not agreed to receive such material non-public information, the Company hereby covenants and
agrees that the Holder shall not have any duty of confidentiality to the Company, any of its Subsidiaries or any of their respective officers, directors, employees, affiliates or agents with respect to, or a duty to any of the foregoing not to trade
on the basis of, such material non-public information. Nothing contained in this Section 22 shall limit any obligations of the Company, or any rights of the Holder, under the Exchange Agreement. 

[signature page follows] 

  
 Note: Page 17 

 [SIGNATURE PAGE TO CONVERTIBLE PROMISSORY NOTE OF SELLAS LIFE SCIENCES GROUP, INC.] 

SELLAS LIFE SCIENCES GROUP, INC. 

 

			
	 By:
	 	 /s/ Angelos Stergiou

	 Name:
	 	 Angelos Stergiou, M.D., ScD h.c.

	 Title:
	 	 Chief Executive OfficerEX-10.75

 Exhibit 10.75 

CONFIDENTIAL DRAFT 

SELLAS LIFE SCIENCES GROUP, INC. 

WARRANT EXCHANGE AGREEMENT 

This Warrant Exchange Agreement (this “Agreement”) is made as of February 7, 2018 (“Effective Date”), by and
between SELLAS Life Sciences Group, Inc., a Delaware corporation (the “Company”), and ANSON INVESTMENTS MASTER FUND LP (collectively, the “Holder”). 

RECITALS 
 WHEREAS, the
Holder currently holds 30,000 warrants (the “Warrants”) to purchase shares of the Company’s common stock, par value $0.0001 per share (“Common Stock”); and 

WHEREAS, subject to the terms and conditions set forth herein, the Company and the Holder desire to cancel and retire the Warrants in exchange
(the “Exchange”) for shares of Common Stock (the “Exchange Shares”), the number of which is the quotient of $70,200.00 divided by the closing price of the Exchange Shares on the NASDAQ Capital Market on the Closing
Date of the Exchange Shares in reliance on the exemption from registration provided by Section 3(a)(9) of the Securities Act of 1933, as amended (the “Securities Act”). 

In consideration of the mutual covenants contained in this Agreement, and for other good and valuable consideration, the receipt of which is
hereby acknowledged, the Company and the Holder hereby agree as follows: 
 AGREEMENT 

SECTION 1. EXCHANGE AND TERMINATION. 
 a)
In consideration of and in express reliance upon the representations, warranties, covenants, terms and conditions of this Agreement, the Holder agrees to deliver and surrender to the Company for cancellation the Warrants in exchange for the Exchange
Shares, and the Company agrees to issue and deliver the Exchange Shares to the Holder. 
 b) The closing under this Agreement (the
“Closing”) shall take place upon the satisfaction of each of the conditions set forth in Sections 4 and 5 hereof (the “Closing Date”). By February 8, 2018, (i) the Company shall cause the transfer agent for the
Common Stock to issue and deliver the Exchange Shares duly registered and freely tradable through the facilities of DTC by DWAC to the custodian and account provided to the Company in writing by the Holder and (ii) the Holder shall deliver and
surrender or cause to be delivered and surrendered to the Company for cancellation the Warrants. 
 c) If the Closing has not occurred by
February 6, 2018, this Agreement shall terminate. 

 SECTION 2. REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE COMPANY. 

The Company hereby represents and warrants as of the date hereof to, and covenants with, the Holder as follows: 

a) Organization and Standing. The Company has been duly incorporated and is validly existing as a corporation in good standing under the
laws of Delaware, has full corporate power and authority to own or lease its properties and conduct its business as presently conducted, and is duly qualified as a foreign corporation and in good standing in each jurisdiction in which the character
of the property owned or leased or the nature of the business transacted by it makes qualification necessary, except where the failure to be so qualified would not have a material adverse effect on the business, properties, financial condition or
results or operations of the Company (a “Material Adverse Effect”). 
 b) Authorization; Corporate Power. This
Agreement has been duly authorized, validly executed and delivered on behalf of the Company and is a valid and binding obligation of the Company enforceable against the Company in accordance with its terms (except as limited by (i) applicable
bankruptcy, insolvency, reorganization, moratorium or similar laws relating to or affecting the enforcement of creditors’ rights generally, and (ii) equitable principles generally, including any specific performance), and the Company has
the requisite corporate power and authority to execute and deliver this Agreement and the other agreements and documents contemplated hereby and to perform its obligations hereunder and thereunder. 

c) Issuance and Delivery of the Exchange Shares. The Exchange Shares have been duly authorized and, will be validly issued, fully paid
and nonassessable. Assuming the Warrants were purchased by Holder in the Company’s offering of Common Stock and warrants made pursuant to the Company’s prospectus filed with the Securities and Exchange Commission (the
“SEC”) pursuant to Rule 424(b)(5) on February 9, 2017 (the “Registered Offering”) and the Holder is not an “Affiliate” (as such term is defined in Rule 405 promulgated under the Securities Act
of 1933, as amended (the “Securities Act”)) of the Company, the Exchange Shares will be issued to the Holder without legend and will be freely tradable by the Holder. 

d) Governmental Consents. No consent, approval or authorization of or designation, declaration or filing with any governmental
authority on the part of the Company is required in connection with the valid execution and delivery of this Agreement or the offer, sale or issuance of the Exchange Shares or the consummation of any other transaction contemplated by this Agreement.

 e) No Default or Violation. The execution and delivery of the Agreement and the consummation of the transactions contemplated by
this Agreement by the Company will not (i) result in a breach of or a default under any of the terms or provisions of (A) the Company’s certificate of incorporation or by-laws, or (B) any
material provision of any indenture, mortgage, deed of trust or other material agreement or instrument to which the Company is a party or by which it or any of its material properties or assets is bound or (ii) result in a violation of any
provision of any law, statute, rule, regulation, or any existing applicable decree, judgment or order by any court, Federal or state regulatory body, administrative agency, or other governmental body having jurisdiction over the Company, or any of
its material properties or assets except in the case of clauses (i)(B) or (ii) for any such breaches, defaults or violations which would not have a Material Adverse Effect. 

  
 2 

 f) Disclosure of Agreement. The Company shall, on or before 8:30 a.m., New York City time,
on February 13, 2018 file with the SEC a Current Report on Form 8-K disclosing all material terms of the transaction contemplated hereby (such Current Report on Form
8-K, the “8-K Filing”). From and after the filing of the 8-K Filing, the Holder shall not be in possession of any
material, nonpublic information received from the Company or any of its subsidiaries or any of their respective officers, directors, employees, affiliates or agents, that is not disclosed in the 8-K Filing.
The Company shall not, and shall cause its officers, directors, employees, affiliates and agents, not to, provide the Holder with any material, nonpublic information regarding the Company from and after the filing of the 8-K Filing without the express written consent of the Holder. To the extent that the Company delivers any material, non-public information to the Holder without the
Holder’s express prior written consent, the Company hereby covenants and agrees that the Holder shall not have any duty of confidentiality to the Company, any of its subsidiaries or any of their respective officers, directors, employees,
affiliates or agents with respect to, or a duty to the Company, any of its subsidiaries or any of their respective officers, directors, employees, affiliates or agents not to trade on the basis of, such material,
non-public information. The Company shall not disclose the name of the Holder in any filing, announcement, release or otherwise, unless such disclosure is required by law or regulation. In addition, effective
upon the filing of the 8-K Filing, the Company acknowledges and agrees that any and all confidentiality or similar obligations under any agreement, whether written or oral, between the Company, any of its
subsidiaries or any of their respective officers, directors, affiliates, employees or agents, on the one hand, and the Holder or any of its affiliates, on the other hand, shall terminate and be of no further force or effect. The Company understands
and confirms that the Holder will rely on the foregoing representations in effecting transactions in securities of the Company. 
 SECTION 3.
REPRESENTATIONS, WARRANTIES AND COVENANTS OF THE HOLDER. 
 (i) The Holder represents and warrants to and covenants with the Company that: 

(a) Valid Existence; Good Standing. To the extent the Holder is a corporation, limited liability company or other type of entity, the
Holder is validly existing and in good standing under the laws of the jurisdiction of its organization. 
 (b) Authority;
Authorization. The Holder has full right, power, authority and capacity to enter into this Agreement and the other agreements and documents contemplated hereby and to perform its obligations hereunder and thereunder and has taken all necessary
action to authorize the execution, delivery and performance of this Agreement. Upon the execution and delivery of this Agreement by the Holder, this Agreement shall constitute a valid and binding obligation of the Holder, enforceable in accordance
with its terms (except (i) as limited by applicable bankruptcy, insolvency, reorganization, moratorium or similar laws relating to or affecting the enforcement of creditors’ rights generally, and (ii) as limited by equitable
principles generally, including any specific performance). 

  
 3 

 (c) Title. The Holder owns and holds the entire right, title and interest in and to, and
is the record and beneficial owner of, the Warrants and the Holder owns the Warrants free and clear of all Encumbrances (as defined below). The Holder has the full power and authority to vote, transfer and dispose of the Warrants free and clear of
any right or Encumbrances. There is no restriction affecting the ability of the Holder to transfer the legal and beneficial title and ownership of the Warrants to the Company and, at the Closing, the Company will acquire legal and valid title to the
Warrants, free and clear of all Encumbrances. Other than the transactions contemplated by this Agreement, there is no outstanding vote, plan, pending proposal, or other right of any person to acquire all or any of the Warrants.
“Encumbrances” shall mean any security or other property interest or right, claim, lien, pledge, option, charge, security interest, contingent or conditional sale, or other title claim or retention agreement, interest or other right or
claim of third parties, whether perfected or not perfected, voluntarily incurred or arising by operation of law, and including any agreement (other than this Agreement) to grant or submit to any of the foregoing in the future. 

(d) Purchase of Warrants in the Registered Offering. The Holder purchased the Warrants in the Registered Offering. 

(e) Securities Act Exemption. Neither the Holder nor anyone acting on behalf of the Holder has received any commission or remuneration
directly or indirectly in connection with or in order to solicit or facilitate the Exchange. The Holder understands that the Exchange contemplated hereby is intended to be exempt from registration by virtue of Section 3(a)(9) of the Securities
Act. The Holder understands that the Company is relying upon the truth and accuracy of the representations, warranties, agreements, acknowledgments and understandings of the Holder set forth herein for purposes of qualifying for the exemption under
Section 3(a)(9) of the Securities Act as well as qualifying for exemptions under applicable state securities laws. 
 (f) Non-Affiliate. The Holder is not an Affiliate of the Company and has not been an Affiliate during the three months prior to the date hereof. 

(g) Information. The Holder has, in connection with its decision to acquire the Exchange Shares, relied with respect to the Company and
its affairs solely upon the Company’s filings with the SEC and the representations and warranties of the Company contained herein. 

(h) Advisors. The Holder understands that nothing in this Agreement or any other materials presented to the Holder in connection with
the exchange of the Warrants and issuance and acquisition of the Exchange Shares constitutes legal, tax or investment advice. The Holder has consulted such legal, tax and investment advisors as it, in its sole discretion, has deemed necessary or
appropriate in connection with its acquisition of the Exchange Shares. With respect to such matters, the Holder relies solely on such advisors and not on any statements or representations of the Company or any of its agents, written or oral. The
Holder understands that it (and not the Company) shall be responsible for its own tax liability that may arise as a result of this investment or the transactions contemplated by this Agreement. 

  
 4 

 (i) Limitation on Resales. For thirty (30) trading days following the Closing Date,
the Holder shall not sell more than 2.0% of trading volume of Common Stock as reported by Bloomberg, LP for the applicable date of determination through open market sales through the NASDAQ Capital Market on any trading day in which the NASDAQ
Capital Market is open for trading. 
 SECTION 4. CONDITIONS TO COMPANY’S OBLIGATIONS AT THE CLOSING. 

The Company’s obligation to complete the issuance of the Exchange Shares and deliver the Exchange Shares to the Holder at the Closing
shall be subject to the following conditions to the extent not waived by the Company: 
 a) Execution and Delivery. The Holder shall
have executed and delivered this Agreement. 
 b) Covenants. The Holder shall have performed, satisfied and complied in all material
respects with all covenants, agreements and conditions required by this Agreement to be performed, satisfied or complied with by the Holder at or prior to the Closing Date. 

c) Surrender of Warrants. The Company shall have received in physical form or through book-entry transfer from the Holder all
certificates or book-entry notation representing the Warrants to be exchanged for the Exchange Shares. 
 d) Representations and
Warranties. The representations and warranties of the Holder shall be true and correct in all material respects as of the date when made and as of the Closing Date as though made at that time, except for representations and warranties that are
expressly made as of a particular date, which shall be true and correct in all material respects as of such date. 
 SECTION 5. CONDITIONS TO THE
HOLDER’S OBLIGATIONS AT THE CLOSING. 
 The Holder’s obligation to deliver the Warrants and accept delivery of the Exchange
Shares shall be subject to the following conditions to the extent not waived by the Holder: 
 (a) Execution and Delivery. The
Company shall have executed and delivered this Agreement. 
 (b) Covenants. The Company shall have performed, satisfied and
complied in all material respects with all covenants, agreements and conditions required by this Agreement to be performed, satisfied or complied with by the Company at or prior to the Closing Date. 

(d) Delivery of Exchange Shares. The Company shall have delivered the Exchange Shares in accordance with the instructions provided
pursuant to Section 1.b) hereof. 
 (e) Representations and Warranties. Each of the representations and warranties of the
Company shall be true and correct in all material respects as of the date when made and as of the Closing Date as though made at that time, except for representations and warranties that are expressly made as of a particular date, which shall be
true and correct in all material respects as of such date. 

  
 5 

 SECTION 6. NOTICES. 

All notices, requests, consents and other communications hereunder shall be in writing, shall be sent by confirmed electronic mail, or mailed
by first-class registered or certified airmail, or nationally recognized overnight express courier, postage prepaid, and shall be deemed given when so sent in the case of electronic mail transmission, or when so received in the case of mail or
courier, and addressed as follows: 
 (a) if to the Company, to: 

SELLAS Life Sciences Group, Inc. 

315 Madison, 4th Flr. 

New York, New York 10017 

Attention: Angelos Stergiou, M.D., ScD h.c. 

E-Mail: astergiou@sellaslife.com 

or to such other person at such other place as the Company shall designate to the Holder in writing; and 

(b) if to the Holder, at the address as set forth at the end of this Agreement, or at such other address as may have been furnished by the
Holder to the Company in writing. 
 SECTION 7. MISCELLANEOUS. 

a) Headings. The headings of the various sections of this Agreement have been inserted for convenience of reference only and shall not
be deemed to be part of this Agreement. 
 b) Severability. In case any provision contained in this Agreement should be invalid,
illegal or unenforceable in any respect, the validity, legality and enforceability of the remaining provisions contained herein shall not in any way be affected or impaired thereby. 

c) Governing Law. This Agreement shall be governed by and construed under the laws of the State of New York without regard to the
choice of law principles thereof. Each party hereby irrevocably submits to the exclusive jurisdiction of the state and federal courts sitting in the State of New York located in The City of New York, Borough of Manhattan for the adjudication of any
dispute hereunder or in connection herewith or with any transaction contemplated hereby or thereby, and hereby irrevocably waives any objection that such suit, action or proceeding is brought in an inconvenient forum or that the venue of such suit,
action or proceeding is improper. Nothing contained herein shall be deemed to limit in any way any right to serve process in any manner permitted by law. EACH PARTY HEREBY IRREVOCABLY WAIVES ANY RIGHT IT MAY HAVE, AND AGREES NOT TO REQUEST, A JURY
TRIAL FOR THE ADJUDICATION OF ANY DISPUTE HEREUNDER OR IN CONNECTION WITH OR ARISING OUT OF THIS AGREEMENT OR ANY TRANSACTION CONTEMPLATED HEREBY. 

  
 6 

 d) Counterparts. This Agreement may be executed in two or more counterparts, each of which
shall constitute an original, but all of which, when taken together, shall constitute but one instrument, and shall become effective when one or more counterparts have been signed by each party hereto and delivered to the other parties. In the event
that any signature is delivered by facsimile transmission or by an e-mail which contains an electronic file of an executed signature page, such signature page shall create a valid and binding obligation of the
party executing (or on whose behalf such signature is executed) with the same force and effect as if such facsimile or electronic file signature page (as the case may be) were an original thereof. 

e) Successors and Assigns. Except as otherwise expressly provided herein, the provisions hereof shall inure to the benefit of, and be
binding upon, the successors, permitted assigns, heirs, executors and administrators of the parties hereto. 
 f) Entire Agreement;
Amendments. This Agreement and other documents delivered pursuant hereto constitute the full and entire understanding and agreement between the parties with regard to the subjects hereof and thereof. This Agreement may be amended, modified,
superseded, cancelled, renewed or extended, and the terms and conditions hereof may be waived, only by a written instrument signed by all parties, or, in the case of a waiver, by the party waiving compliance. Except as expressly stated herein, no
delay on the part of any party in exercising any right, power or privilege hereunder shall operate as a waiver thereof, nor shall any waiver on the part of any party of any right, power or privilege hereunder preclude any other or future exercise of
any other right, power or privilege hereunder. 
 g) Survival. The representations, warranties, covenants and agreements made in this
Agreement shall survive the closing of the transactions contemplated hereby and the exchange and delivery of the Warrants and the Exchange Shares. 

[signature pages follow] 

  
 7 

 IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be executed by their
duly authorized representatives as of the day and year first above written. 
  

			
	SELLAS LIFE SCIENCES GROUP, INC.
		
	By: 	 	/s/ Angelos Stergiou
	Name:	 	Angelos Stergiou, M.D., ScD h.c.
	Title:	 	Chief Executive Officer

 COMPANY SIGNATURE PAGE TO 

WARRANT EXCHANGE AGREEMENT 

 HOLDER: 
  

			
	ANSON INVESTMENTS MASTER FUND LP
		
	By:	 	/s/ Amin Nathoo

 
			
	Name:	 	Amin Nathoo
	Title:	 	Advising Rep, Anson Advisors Inc.

 
			
	
	Address:

 
			
		
	E-Mail:  	 	 

 
			
	
	DWAC INSTRUCTIONS
	
	Broker Name and DTC Number:
	 
	 
	 
	
	Account Number at DTC Participant
	(if
applicable):                                       
                      
	 

 HOLDER SIGNATURE PAGE TO 

WARRANT EXCHANGE AGREEMENT

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