[8-K] Gain Therapeutics, Inc. Reports Material Event

Rhea-AI Filing Summary

Gain Therapeutics reported new exploratory data from its Phase 1b study of GT-02287 in people with Parkinson’s disease. All participants who started with elevated levels of glucosylsphingosine (GluSph) in cerebrospinal fluid showed large decreases back toward levels seen in healthy individuals after 90 days of treatment, meeting a prespecified exploratory endpoint.

The Phase 1b trial enrolled 21 participants, with 19 completing the 90-day dosing period and 15 (79%) choosing to enter a nine‑month extension expected to conclude in September 2026. GT-02287 has been generally well-tolerated over 90 days at plasma exposures within the projected therapeutic range, and the data monitoring committee recommended the study continue with no changes.

Earlier Phase 1 data in healthy volunteers showed favorable safety, central nervous system exposure in the projected therapeutic range, and increased glucocerebrosidase (GCase) activity at clinically relevant doses. Gain Therapeutics stated it has sufficient capital to fund operations through completion of the Phase 1b extension and through year-end 2026.

Insights

Biotech clinical-stage analyst

Early Phase 1b biomarker signal and cash runway through 2026 support ongoing GT-02287 development.

Gain Therapeutics highlights that in its Phase 1b Parkinson’s study, all individuals with elevated glucosylsphingosine (GluSph) levels in cerebrospinal fluid had large decreases toward healthy levels after 90 days of GT-02287. This endpoint was prespecified as an exploratory measure, which helps link the drug’s biological activity to a disease-relevant biomarker rather than being a post‑hoc observation.

The company reports that GT-02287 remains generally well-tolerated over 90 days at plasma exposures within the projected therapeutic range, and the independent data monitoring committee recommended the study continue without modification. Combined with earlier Phase 1 data in healthy volunteers showing favorable safety, central nervous system exposure in the projected therapeutic range, and increased glucocerebrosidase (GCase) activity, these findings collectively suggest a consistent pharmacology profile across populations.

The Phase 1b trial enrolled 21 participants, 19 completed the initial 90‑day dosing, and 15 (79%) have entered a nine‑month extension expected to conclude by September 2026, which may provide longer-term safety and biomarker information. The company also states it has capital to fund operations through completion of the Phase 1b extension and through year‑end 2026, indicating that current plans for this program are financially supported under existing resources.

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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): December 18, 2025

Gain Therapeutics, Inc.

(Exact name of registrant as specified in its charter)

Delaware		001-40237		85-1726410
(State or Other Jurisdiction of Incorporation)		(Commission File Number)		(I.R.S. Employer Identification No.)

4800 Montgomery Lane, Suite 220

Bethesda, Maryland 20814

(Address of principal executive offices, including zip code)

(301) 500-1556

(Registrant’s telephone number, including area code)

N/A

(Former name or former address, if changed since last report)

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:

¨ 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		Name of Each Exchange on which Registered
Common Stock, par value $0.0001 per share		GANX		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 (17 CFR§230.405) or Rule 12b-2 of the Securities Exchange Act of 1934 (17 CFR §240.12b-2).

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. ¨

Item 8.01. Other Events.

On December 18, 2025, Gain Therapeutics, Inc. (the “Company”) issued a press release announcing results in exploratory endpoint from its Phase 1b clinical study of GT-02287 in people with Parkinson’s Disease (“PD”). All individuals with elevated levels of glucosylsphingosine (“GluSph”) in the cerebrospinal fluid (“CSF”) displayed large decreases back towards levels observed in healthy individuals after 90 days of treatment with GT-02287. The change observed in GluSph in CSF was a prespecified exploratory endpoint of this Phase 1b study. Part 1 (90 days of dosing) of the ongoing Phase 1b study has concluded. The Phase 1b study enrolled 21 participants, 19 completed the 90-day dosing period, and 15 (79%) chose to continue in the nine-month extension (Part 2) portion of the study that is anticipated to conclude in September 2026.

Consistent with the initial Phase 1b data presented at the International Congress of Parkinson’s Disease and Movement Disorders in October 2025, GT-02287 continues to be generally well-tolerated over 90 days of dosing at plasma exposures within the projected therapeutic range. The data monitoring committee has recommended that the Phase 1b study continue with no changes.

Results from a Phase 1 study of GT-02287 in healthy volunteers demonstrated favorable safety and tolerability, plasma and central nervous system exposures in the projected therapeutic range, and target engagement with an increase in glucocerebrosidase (“GCase”) activity among those receiving GT-02287 at clinically relevant doses.

GT-02287 is currently being evaluated in a Phase 1b clinical trial for the treatment of Parkinson’s disease with or without a GBA1 mutation. The primary endpoint of the trial, which enrolled participants across seven sites in Australia, is to evaluate the safety and tolerability of GT-02287 after three months of dosing in people with PD. The Phase 1b study extension allows participants to continue to be treated with GT-02287 for up to a total of 12 months.

The Company also announced that it has a capital position to fund operations through the end of the Phase 1b extension and year-end 2026.

Forward-Looking Statements

This Current Report on Form 8-K contains “forward-looking statements” made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. These statements are typically preceded by words such as “believes,” “expects,” “anticipates,” “intends,” “will,” “may,” “should,” or similar expressions. These forward-looking statements reflect management’s current knowledge, assumptions, judgment and expectations regarding future performance or events. Although management believes that the expectations reflected in such statements are reasonable, they give no assurance that such expectations will prove to be correct or that those goals will be achieved, and you should be aware that actual results could differ materially from those contained in the forward-looking statements. Forward-looking statements are subject to a number of risks and uncertainties, including, but not limited to, statements regarding: the development of the Company’s current or future product candidates including GT-02287; expectations regarding the completion and timing of results from a Phase 1b clinical study for GT-02287, including any extension studies; expectations regarding the timing of patient enrollment for a Phase 1b clinical study for GT-02287, including any extension studies; the timing of any submissions to the FDA or other regulatory bodies and agencies; whether results from preclinical studies and initial data from early clinical trials will be predictive of the final results of the clinical trials or future trials; and the potential therapeutic and clinical benefits of the Company’s product candidates. For a further description of the risks and uncertainties that could cause actual results to differ from those expressed in these forward-looking statements, as well as risks relating to the Company’s business in general, please refer to the Company’s Form 10-K for the year ended December 31, 2024. All forward-looking statements are expressly qualified in their entirety by this cautionary notice. You are cautioned not to place undue reliance on any forward-looking statements, which speak only as of the date of this Current Report on Form 8-K. The Company has no obligation, and expressly disclaim any obligation, to update, revise or correct any of the forward-looking statements, whether because of new information, future events or otherwise.

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.
Dated: December 18, 2025	By:	/s/ Gene Mack
		Gene Mack
		Chief Executive Officer

FAQ

What did Gain Therapeutics (GANX) report about its Phase 1b GT-02287 study in Parkinson’s disease?

Gain Therapeutics reported that in its Phase 1b study of GT-02287 in people with Parkinson’s disease, all individuals who had elevated glucosylsphingosine (GluSph) levels in cerebrospinal fluid showed large decreases back toward levels observed in healthy individuals after 90 days of treatment. This change in GluSph was a prespecified exploratory endpoint.

How many participants are in Gain Therapeutics’ Phase 1b GT-02287 trial and how many continued into the extension?

The Phase 1b GT-02287 study enrolled 21 participants, of whom 19 completed the initial 90‑day dosing period. 15 participants, representing 79% of those who completed Part 1, chose to continue into the nine‑month extension portion of the study.

What safety and tolerability results did Gain Therapeutics report for GT-02287?

Gain Therapeutics stated that GT-02287 continues to be generally well-tolerated over 90 days of dosing at plasma exposures within the projected therapeutic range in the Phase 1b Parkinson’s study. An independent data monitoring committee recommended that the Phase 1b study continue with no changes.

What earlier Phase 1 data support the GT-02287 program at Gain Therapeutics?

In an earlier Phase 1 study in healthy volunteers, GT-02287 showed favorable safety and tolerability, plasma and central nervous system exposures within the projected therapeutic range, and target engagement, evidenced by an increase in glucocerebrosidase (GCase) activity among those receiving GT-02287 at clinically relevant doses.

How long will Gain Therapeutics’ Phase 1b GT-02287 extension run and when is it expected to conclude?

The Phase 1b trial includes a nine‑month extension that allows participants to be treated with GT-02287 for up to a total of 12 months. The extension portion of the study is anticipated to conclude in September 2026.

What did Gain Therapeutics disclose about its capital position and funding runway?

Gain Therapeutics announced that it has a capital position to fund operations through the end of the Phase 1b GT-02287 extension and through year-end 2026, supporting its current development plans for this program.