8-K

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):November 28, 2025

Gain Therapeutics, Inc.
(Exact Name of the Registrant as Specified in Charter)

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Delaware	001-40237	85-1726310
(State or Other Jurisdiction <br><br> of Incorporation)	(Commission File<br><br> Number)	(IRS Employer <br><br> Identification No.)

4800 Montgomery Lane**, Suite 220**

Bethesda , Maryland 20814

(Address of principal executive offices) (Zip Code)

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(301

)

500-1556

(Registrant’s telephone number, including area code)

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

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¨	Written<br> communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
¨	Soliciting<br> material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
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¨	Pre-commencement<br> communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
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¨	Pre-commencement<br> communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))
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Securities registered pursuant to Section 12(b) of the Act:

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Title of each class	Trading symbol(s)	Name of exchange on which registered
Common Stock, $0.0001 par value	GANX	The<br> NASDAQ Stock<br> 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 (17 CFR §230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2 of this chapter).

Emerging growth company x

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. ¨

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Item 8.01. Other Events.

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On November 28, 2025, Gain Therapeutics, Inc. (the “Company”), filed a prospectus supplement (the “Prospectus Supplement”) with the U.S. Securities and Exchange Commission (the “SEC”) in connection with the Company’s “at the market offering” program for the offer and sale of up to $35,530,980.56 of the Company’s common stock, par value $0.0001 per share (the “Common Stock”), from time to time through Oppenheimer & Co. Inc. (“Oppenheimer”), as sales agent, pursuant to the Company’s existing Equity Distribution Agreement (the “Distribution Agreement”), dated September 6, 2024. As of the date hereof, the Company has sold an aggregate of $14,469,019.44 of Common Stock pursuant to the Distribution Agreement and the related prospectus supplement, dated September 6, 2024 to the Company’s Registration Statement on Form S-3 (File No. 333-265061).

The offer and sale of additional Common Stock by the Company under the Distribution Agreement will be made pursuant to the Prospectus Supplement, dated November 28, 2025, and the accompanying base prospectus, dated November 26, 2025, contained therein, which together form a part of the Company’s shelf registration statement on Form S-3 (File No. 333-287622), initially filed with the SEC on May 28, 2025 and which became effective on November 26, 2025 (the “Registration Statement”).

Lowenstein Sandler LLP, counsel to the Company, has issued a legal opinion relating to the validity of the $35,530,980.56 of Common Stock that may be offered and sold pursuant to the Distribution Agreement and related Prospectus Supplement. A copy of such legal opinion, including the consent included therein, is attached as Exhibit 5.1 to this Current Report on Form 8-K.

This Current Report on Form 8-K shall not constitute an offer to sell or the solicitation of an offer to buy the Common Shares discussed herein, nor shall there be any sale of such securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

The exhibits listed below are furnished as part of this Current Report on Form 8-K.

Exhibit No.	Description
5.1	Opinion of Lowenstein Sandler LLP.
23.1	Consent of Lowenstein Sandler LLP (contained in Exhibit 5.1).
104	Cover Page Interactive Data File (embedded within the Inline XBRL document).

SIGNATURE

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.

	GAIN THERAPEUTICS, INC.
Date: November 28, 2025	By:	/s/ Gene Mack
	Name:	Gene Mack
	Title:	Chief Executive Officer

Exhibit 5.1

November 28, 2025

Gain Therapeutics, Inc.

4800 Montgomery Lane, Suite 220

Bethesda, Maryland 20814

Re: Sale of Common Stock registered pursuant to Shelf Registration Statement on Form S-3

Ladies and Gentlemen:

We have acted as counsel to Gain Therapeutics, Inc., a Delaware corporation (the “Company”), in connection with the offer and sale by the Company of up to an aggregate of $35,530,980.56 of shares of its common stock, par value $0.0001 per share (the “Shares”), pursuant to an Equity Distribution Agreement (the “Distribution Agreement”), dated September 6, 2024, by and between the Company and Oppenheimer & Co., Inc., as sales agent. The Shares are being offered for sale pursuant to the Company’s registration statement on Form S-3 (File No. 333-287622) (the “Registration Statement”) filed with the U.S. Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “SecuritiesAct”) and the rules and regulations promulgated thereunder, the prospectus, dated November 26, 2025 (the “Prospectus”), and the prospectus supplement that has been filed pursuant to Rule 424(b)(5) under the Securities Act, dated November 28, 2025 (the “Prospectus Supplement”).

We understand the Shares are to be issued by the Company and sold by Oppenheimer & Co., Inc. pursuant to the Distribution Agreement, as described in the Prospectus Supplement, and the form of which was filed with the Commission as Exhibit 1.1 to the Company’s Current Report on Form 8-K, filed on September 6, 2024.

In connection with this opinion, we have (i) investigated such questions of law, (ii) examined originals or certified, conformed or reproduction copies of such agreements, instruments, documents and records of the Company, such certificates of public officials and such other documents and (iii) received such information from officers and representatives of the Company as we have deemed necessary or appropriate for the purposes of this opinion.

In all such examinations, we have assumed the legal capacity of all natural persons, the genuineness of all signatures, the authenticity of original and certified documents and the conformity to original or certified documents of all copies submitted to us as conformed or reproduction copies. As to various questions of fact relevant to the opinion expressed herein, we have relied upon, and assume the accuracy of, the representations and warranties set forth in the Distribution Agreement, and certificates and oral or written statements and other information of or from public officials and officers and representatives of the Company.

Based upon the foregoing and subject to the limitations, qualifications and assumptions set forth herein, we are of the opinion that the Shares have been duly authorized for issuance, and when issued and paid for in accordance with the terms and conditions of the Distribution Agreement, the Shares will be validly issued, fully paid and non-assessable.

The opinion expressed herein is limited to the applicable provisions of the General Corporation Law of the State of Delaware (the “DGCL”), as currently in effect, and reported judicial decisions interpreting such provisions of the DGCL.

The opinion expressed herein is limited to the matters stated herein and no opinion is implied or may be inferred beyond the matters expressly stated herein. We undertake no obligation to supplement this letter if any applicable laws change after the date hereof or if we become aware of any facts that might change the opinion expressed herein after that date or for any other reason.

We hereby consent to the filing of this opinion as Exhibit 5.1 to the Current Report on Form 8-K filed by the Company on the date hereof and which is incorporated by reference into the Prospectus and to the references to this firm under the caption “Legal Matters” in the Prospectus Supplement. In giving these consents, we do not admit that we are “experts” within the meaning of Section 11 of the Securities Act or within the category of persons whose consent is required by Section 7 of the Securities Act.

Very truly yours,
/s/ Lowenstein Sandler LLP
Lowenstein Sandler LLP