UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

Date of report (Date of earliest event reported): June 1624, 2026

SELLAS Life Sciences Group, Inc.

(Exact name of registrant as specified in its charter)

Delaware	001-33958	20-8099512
(State or other jurisdiction of incorporation or organization)	(Commission File Number)	(I.R.S. Employer Identification No.)

	7 Times Square, Suite 2503 New York, NY 10036
	(Address of Principal Executive Offices) (Zip Code)

Registrant’s telephone number, including area code: (646) 200-5278

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligations of the registrant under any of the following provisions:

Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading symbol(s)	Name of each exchange on which registered
Common Stock, $0.0001 par value per share	SLS	The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ¨

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ¨

Item 5.0702. ~~Submission~~Departure of ~~Matters~~Directors toor aCertain ~~Vote~~Officers; Election of ~~Security~~Directors; ~~Holders~~Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

~~Annual~~(e) ~~Meeting~~Compensatory Arrangements of ~~Stockholders~~Certain Officers

On June 1624, 2026, SELLAS Life Sciences Group, Inc. (the “Company”) ~~held~~entered ~~its~~into ~~Annual~~(i) ~~Meeting~~an amendment (the “Stergiou Amendment”) to that certain employment agreement effective as of ~~Stockholders~~July 1, 2019 (the “~~Annual~~Stergiou ~~Meeting~~Employment Agreement”), by and between the Company and Dr. ~~There~~Angelos ~~were~~Stergiou, ~~115~~the Company’s President and Chief Executive Officer,~~511,771~~ ~~shares~~(ii) an amended and restated severance and change of ~~common~~control letter agreement with ~~stock~~John Burns, orthe ~~approximately~~Company’s ~~62.59%~~Senior Vice President and Chief Financial Officer (the “Burns Agreement”), and (iii) an amended and restated severance and change of ~~all~~control ~~outstanding~~letter ~~shares~~agreement with Dr. Dragan Cicic, ~~present~~the inCompany’s ~~person~~Senior orVice ~~represented~~President byand ~~proxy~~Chief Development Officer (the “Cicic Agreement” and collectively with the Stergiou Amendment and the Burns Agreement, the “Agreements”). The AtAgreements were approved by the ~~Annual~~Board ~~Meeting~~of Directors (the “Board”) of the Company, upon recommendation of the ~~stockholders~~Compensation ~~voted~~Committee onof the Board, following ~~five~~a ~~proposals~~review with the Company’s independent compensation consulting firm of certain market and ~~cast~~competitive practices ~~their~~relating ~~votes~~to asexecutive ~~described~~severance ~~below~~agreements.

~~Proposal~~Amendment 1to Stergiou Employment Agreement

The ~~Company’s~~Stergiou ~~stockholders~~Amendment ~~re-elected~~amends ~~each of~~ the ~~following~~Stergiou ~~nominees~~Employment Agreement asto aprovide ~~Class~~that Icertain ~~director~~payments made to ~~the~~Dr. ~~Board~~Stergiou ofas ~~the~~part ~~Company~~of tohis ~~hold~~change ~~office~~in ~~until~~control ~~the~~severance ~~2029~~benefits ~~Annual~~will ~~Meeting~~be ofpaid ~~Stockholders~~in a ~~and~~lump ~~until~~sum ~~their~~payment. ~~respective~~The ~~successors~~terms ~~have~~of ~~been~~the ~~duly~~Stergiou ~~elected~~Employment ~~and~~Agreement ~~qualified~~remain unchanged in all other respects.

NAME	FOR	WITHHELD	BROKER NON-VOTES
Robert Van Nostrand	66,490,143	4,544,035	44,477,593
Jane Wasman	65,928,448	5,105,730	44,477,593

Amended and Restated Severance and Change of Control Letter Agreements with John Burns and Dragan Cicic

~~Proposal~~The 2Burns Agreement and the Cicic Agreement each amend and restate in their entirety the prior change of control severance agreements and non-change of control severance benefits applicable to Mr. Burns and Dr. Cicic, respectively.

~~The~~Under ~~Company’s~~the ~~stockholders~~Burns ~~ratified~~Agreement and the ~~appointment~~Cicic Agreement, ofif ~~Baker~~Mr. ~~Tilly~~Burns USor Dr. Cicic, ~~LLP~~as applicable, is terminated by the Company without Cause or resigns for Good Reason, and such termination does not occur within the Change of Control Period (as defined below), the ~~successor~~executive will be entitled to ~~Moss~~receive ~~Adams~~the ~~LLP~~following severance payments and benefits: (i) ascontinuing severance pay equal to his then-current base salary for a period of nine months, payable in accordance with the Company’s ~~independent~~normal ~~registered~~payroll ~~public~~practices; ~~accounting~~(ii) ~~firm~~a pro rata portion of his target bonus for the ~~fiscal~~ year ~~ending~~of ~~December~~termination, 31payable in installments over the nine-month severance period; and (iii) reimbursement of COBRA premiums for continued participation in the Company’s medical and dental benefit plans for up to nine months following termination (or until the executive becomes eligible for coverage under another employer’s group health plan, ~~2026~~if earlier).

FOR		AGAINST		ABSTAIN		BROKER NON-VOTES
112,103,701		2,126,460		1,281,610		-

Under the Burns Agreement and the Cicic Agreement, if Mr. Burns or Dr. Cicic, as applicable, is terminated by the Company (or its successor) without Cause or resigns for Good Reason within one month prior to, or one year following, a Change of Control (such period, the “Change of Control Period”), the executive will be entitled to receive the following severance payments and benefits: (i) a lump sum payment equal to 15 months of his then-current base salary; (ii) a lump sum payment equal to his target bonus for the year of termination; (iii) reimbursement of COBRA premiums for continued participation in the Company’s medical and dental benefit plans for up to 18 months following termination (or until the executive becomes eligible for coverage under another employer’s group health plan, if earlier); and (iv) immediate vesting in full of all then-unvested equity awards held by the executive as of the date of termination.

~~Proposal~~Receipt 3of the severance payments and benefits is conditioned upon the effectiveness of a separation and general release agreement in a form to be provided by the Company.

The ~~Company’s~~foregoing ~~stockholders~~descriptions ~~approved~~of anthe ~~amendment~~Agreements do tonot ~~the~~purport ~~Company’s~~to ~~2023~~be ~~Amended~~complete and ~~Restated~~are ~~Equity~~qualified ~~Incentive~~by ~~Plan~~reference (to the ~~“2023~~full ~~Equity~~text ~~Plan”)~~of tothe ~~increase~~Stergiou Amendment, the ~~number~~Burns ofAgreement and the Cicic ~~shares~~Agreement, copies of ~~common~~which ~~stock~~are ~~available~~attached ~~for~~hereto ~~sale~~as ~~under~~Exhibits ~~the~~10.1, ~~2023~~10.2 ~~Equity~~and ~~Plan~~10.3, respectively, and incorporated herein by ~~20,000,000~~reference.

FOR		AGAINST		ABSTAIN		BROKER NON-VOTES
42,906,271		27,310,386		817,521		44,477,593

Item 9.01.

Financial Statements and Exhibits.

~~Proposal 4~~(d) Exhibits

The Company’s stockholders approved the non-binding, advisory resolution on the executive compensation of the Company’s named executive officers.

Exhibit Number		Description
10.1		Amendment to Employment Agreement by and between the Company and Dr. Angelos Stergiou, dated as of June 24, 2026.
10.2		Amended and Restated Severance and Change of Control Letter Agreement by and between the Company and John Burns, dated as of June 24, 2026.
10.3		Amended and Restated Severance and Change of Control Letter Agreement by and between the Company and Dr. Dragan Cicic, dated as of June 24, 2026.
104		Cover Page Interactive Data File (embedded within the Inline XBRL document)

FOR		AGAINST		ABSTAIN		BROKER NON-VOTES
52,930,792		15,906,732		2,196,654		44,477,593

SIGNATURES

~~Proposal~~Pursuant 5to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

The Company’s stockholders approved an adjournment of the Annual Meeting, if necessary, to solicit additional proxies in favor of proposals 1, 2, 3 and 4.

	SELLAS Life Sciences Group, Inc.


Date: June 25, 2026	By:	/s/ John T. Burns
		Name:	John T. Burns
		Title:	Senior Vice President, Chief Financial Officer

FOR		AGAINST		ABSTAIN		BROKER NON-VOTES
90,571,992		22,200,030		2,739,749		-

No other matters were submitted to or voted on by the Company’s stockholders at the Annual Meeting.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	SELLAS Life Sciences Group, Inc.
Date: June 18, 2026	By:	/s/ John T. Burns
		Name:	John T. Burns
		Title:	Senior Vice President, Chief Financial Officer

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