Form 8-K

8-K — Gain Therapeutics, Inc.

Accession: 0001104659-26-066062

Filed: 2026-05-26

Period: 2026-05-26

CIK: 0001819411

SIC: 2834 (PHARMACEUTICAL PREPARATIONS)

Item: Other Events

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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):

May 26, 2026

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 May 26, 2026, Gain Therapeutics, Inc. (the

“Company”) disclosed interim clinical and biomarker data from Part 2 (the nine-month extension) of its Phase 1b open-label

clinical study of GT-02287 in patients with Parkinson’s disease with or without a GBA1 mutation. The data was released via an oral

presentation at the 3rd International GBA1 Meeting 2026, held May 22–23, 2026, in Phoenix, AZ.

The data presented, which includes safety, tolerability,

biomarkers, and clinical scores from the Phase 1b nine-month study extension support continued development of GT-02287 for PD. As previously

reported, 16 of 19 participants who completed dosing in Part 1 of the Phase 1b chose to continue in the ongoing nine-month extension (Part

2), further supporting the tolerability of GT-02287. A Data Monitoring Committee meeting on March 5, 2026, concluded that the study should

continue without any changes.

To date, all 16 participants remain on study and

have completed five months of dosing (Day 150).

As previously reported, in all participants with elevated baseline

levels of glucosylsphingosine (GluSph) in cerebrospinal fluid (CSF), GluSph decreased by an average of 81% after 90 days of treatment

with GT-02287. Elevated GluSph, a result of glucocerebrosidase (GCase) dysfunction, has been shown to increase the aggregation of alpha

synuclein and to impair mitochondrial and lysosomal function in neurons. Furthermore, in individuals with high levels of CSF GluSph at

baseline, levels of DOPA decarboxylase (DDC) decreased following 90 days of treatment with GT-02287. DDC is responsible for converting

levodopa into dopamine in the brain and is elevated in the CSF of people with Parkinson’s – likely due to dopaminergic neuron

dysfunction

Figure 1: Change in MDS-UPDRS scores from Baseline

at Day 150 in all patients for whom CSF GluSph and MDS-UPDRS scores were available, patients with low baseline GluSph, and patients with

high baseline GluSph.

Participants with elevated baseline levels of

GluSph in CSF continued to benefit more than those with low baseline levels of GluSph in CSF after 150 days of dosing with GT-02287, with

a difference of 4.8 points in the sum of MDS-UPDRS Part II and Part III scores between the two groups at Day 150. MDS-UPDRS scores remained

stable and durable across overall study population after 150 days of treatment with GT-02287.

Additionally, participants in the Phase 1b study

provided unsolicited descriptions of perceived benefit after 90 days of dosing with GT-02287. Perceived benefits most commonly described

included four instances of improved sense of smell and taste, four instances of improved balance or gait, and three instances of improved

sleep. The planned Phase 2 clinical trial is anticipated to include endpoints to further assess treatment effects beyond benefits perceived

and informally reported, including administration of the University of Pennsylvania Smell Identification Test (UPSIT) at baseline and

at the end of the study, as well as the use of Opal wearable sensors for in-clinic gait assessments to be conducted at multiple timepoints

throughout the study.

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: May 26, 2026

By:

/s/ Gene Mack

Gene Mack

Chief Executive Officer

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