Gain Therapeutics Presents Positive Phase 1b Open-Label Extension Data For Rexaceract Demonstrating Further Evidence of Disease-Modifying Activity Through 12 Months Administration

MDS-UPDRS motor scores demonstrated stability to baseline recorded at study entry with no disease progression among the 12 evaluable participants who completed 12 months of daily oral administration of rexaceract by August 31, 2026

Participants with both high and low baseline levels of GluSph experienced stabilization of MDS-UPDRS motor scores by 12 months

Results support disease-modifying potential of rexaceract along with a favorable tolerability profile; no significant safety signals observed in the Phase 1b

BETHESDA, Md., Oct. 01, 2026 (GLOBE NEWSWIRE) -- Gain Therapeutics, Inc. (Nasdaq: GANX) (“Gain”, or the “Company”), a clinical-stage biotechnology company leading the discovery and development of the next generation of allosteric small molecule therapies, today announced the presentation of a poster at the International Congress of Parkinson’s Disease and Movement Disorders, being held October 4-8, 2026, in Seoul, Korea. The poster outlines long-term open-label extension (OLE) data from the Phase 1b clinical study of rexaceract showing stabilization of MDS-UPDRS scores over 360 days (12 months) of dosing, supporting the disease-modifying potential in Parkinson’s disease (PD).

A PDF of the poster presented at the MDS Congress is available on the Science and Technology section of the Company’s website at https://gaintherapeutics.com/science-and-technology/posters/.

The poster, titled, “Long-Term Open-Label Data on the GCase Modulator GT-02287 (Rexaceract) in People with Parkinson’s Disease,” will be presented on-site by the Company’s Chief Scientific Officer Joanne Taylor, Ph.D. The data, which includes safety, tolerability, and clinical scores from the Phase 1b nine-month study extension support continued development of rexaceract for PD.

Figure 1. Average MDS-UPDRS scores from baseline (Day 0) to 12 months (Day 360) in all participants who completed dosing regimen by August 31, 2026, and had evaluable MDS-UPDRS scores at each time point

As of August 31, 2026, 12 of the 13 evaluable patients have completed the full 12-month administration of rexaceract in the OLE with one additional participant scheduled to complete dosing in November 2026.

In the 12 evaluable participants, MDS-UPDRS motor scores were stable over the 12-month study period with rexaceract, demonstrating no clinically meaningful progression of motor symptoms on the MDS-UPDRS Parts II and III. A clinically meaningful change in PD disease progression is generally accepted to be an increase in MDS-UPDRS Part II and III together of approximately 6 points over a year, which also is the mean annual rate of disease progression among individuals with early PD. Part II of the MDS-UPDRS is patient-reported motor aspects of experiences of daily living and assesses the impact of Parkinson’s disease on activities such as eating, dressing, walking, and other everyday functions. Part III is a clinician-assessed motor examination, evaluating features such as tremor, rigidity, bradykinesia, speech, and gait.

The Company expects to submit a new Phase 2 study protocol to the U.S. Food and Drug Administration (FDA) in the coming weeks, informed by insights provided by the Phase 1b study results and recent discussion with potential partners, and initiate the Phase 2 clinical trial of rexaceract in people with Parkinson’s disease in 1Q27.

Gene Mack, President and CEO of Gain Therapeutics, stated, “Seeing MDS-UPDRS scores remain stable after a full year of dosing is an important clinical milestone for rexaceract. This data gives us greater confidence in the durability of the clinical profile we are seeing and strengthens our conviction as we advance rexaceract into the next stage of development. We have learned enough new information from the Phase 1b that we want to address in our Phase 2 planning to move the start of the study to 1Q27 and take the prudent step of submitting a new protocol to the FDA.”

Mr. Mack continued, “We believe rexaceract has the potential to shift the treatment paradigm beyond symptom management by addressing the underlying biology of Parkinson’s disease, and we expect rexaceract to be the backbone of the next generation of treatment for Parkinson’s disease.”

Figure 2. Average MDS-UPDRS scores from baseline (Day 0) to Day 360 (12 months) in participants with evaluable MDS-UPDRS scores from baseline to 12 months, and grouped according to high and low CSF GluSph levels at baseline

Additionally, participants with both high and low baseline levels of the glucocerebrosidase substrate glucosylsphingosine (GluSph) in cerebrospinal fluid (CSF) show stabilization of MDS-UPDRS motor scores after 12 months and no clinically meaningful progression of motor symptoms on the MDS-UPDRS Parts II and III. Though participants with high baseline levels of CSF GluSph experienced a large decrease back towards levels observed in healthy individuals after 90 days of treatment along with a quicker observed response to rexaceract, both groups’ MDS-UPDRS scores remained stable to baseline through 12 months of dosing.

Elevated GluSph is a hallmark of GCase dysfunction and has been shown to increase the aggregation of alpha synuclein and to impair mitochondrial function and other intracellular processes in neurons. A reduction in GluSph in CSF after treatment with rexaceract suggests increased GCase activity in the brain, which is expected to impact the progression of Parkinson’s disease

Joanne Taylor, Chief Scientific Officer of Gain Therapeutics commented on the results, saying, “The stabilization of MDS-UPDRS scores over one year of treatment with rexaceract regardless of biomarker stratification is particularly encouraging. The consistency in durability across both low and high GluSph groups provides encouraging support for the continued investigation of the relationship between GluSph biology, glucocerebrosidase target engagement, and clinical outcomes in Parkinson’s disease.”

Figure 3. Most frequently reported (in > 2 participants) Treatment-Emergent Adverse Events (TEAEs) by System Organ Class and Study Part

Preliminary long-term data suggest that rexaceract is safe and generally well tolerated over 12 months of dosing. No new safety signals were observed and overall, a lower incidence of TEAEs occurred in Part 2 of the study (9-month open-label extension) compared with Part 1 (initial 3-month administration).

About Rexaceract
Gain Therapeutics’ lead drug candidate rexaceract, formerly known as GT-02287, is in clinical development for the treatment of Parkinson’s disease (PD) with or without a GBA1 mutation. The orally administered, brain-penetrant small molecule is a beta-glucocerebrosidase (GCase) positive allosteric modulator, antiparkinsonian, that restores the function of the lysosomal enzyme GCase which becomes misfolded and impaired due to mutations in the GBA1 gene, the most common genetic abnormality associated with PD, or other age-related stress factors, by stabilizing and chaperoning it to the lysosomes and mitochondria. In preclinical models of PD, rexaceract restored GCase enzymatic function, reduced endoplasmic reticulum stress, lysosomal and mitochondrial pathology, aggregated α-synuclein, neuroinflammation and neuronal death, as well as plasma neurofilament light chain (NfL) levels, a biomarker of neurodegeneration. In rodent models of both GBA1-PD and idiopathic PD, rexaceract was shown to rescue deficits in motor function and gait and prevent the development of deficits in complex behaviors such as nesting. Washout experiments in both GBA1-PD and idiopathic PD models, in which behavioral and neurochemical rescue effects seen with rexaceract were maintained even once it had been removed, suggest that rexaceract may have the potential to slow or stop the progression of the disease.

Results from a Phase 1 study of rexaceract in healthy volunteers demonstrated favorable safety and tolerability, plasma and CNS exposures in the projected therapeutic range, and target engagement with an increase in GCase activity among those receiving rexaceract at clinically relevant doses.

Rexaceract is currently being evaluated in a Phase 1b clinical trial for the treatment of PD 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 rexaceract after three months of dosing in people with PD. The Phase 1b study extension allowed participants to continue to be treated with rexaceract for up to a total of 12 months.

Gain’s lead program in PD has been awarded funding support early in its development from The Michael J. Fox Foundation for Parkinson’s Research (MJFF) and The Silverstein Foundation for Parkinson’s with GBA, as well as from the Eurostars-2 joint program with co-funding from the European Union Horizon 2020 research and Innosuisse – Swiss Innovation Agency.

About Gain Therapeutics, Inc.
Gain Therapeutics, Inc. is a clinical-stage biotechnology company leading the discovery and development of next generation allosteric therapies. Gain’s lead drug candidate, rexaceract is currently being evaluated for the treatment of PD with or without a GBA1 mutation in a Phase 1b clinical trial. Rexaceract has further potential in Gaucher’s disease, dementia with Lewy bodies, and Alzheimer’s disease. Gain has multiple undisclosed preclinical assets targeting lysosomal storage disorders, metabolic diseases, and solid tumors.

Gain’s unique approach enables the discovery of novel, allosteric small molecule modulators that can restore or disrupt protein function. Deploying its highly advanced Magellan™ platform, Gain is accelerating drug discovery and unlocking novel disease-modifying treatments for untreatable or difficult-to-treat disorders including neurodegenerative diseases, rare genetic disorders and oncology.

Forward-Looking Statements
This release 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; expectations regarding the timing of patient enrollment and the completion and timing of results from a Phase 1b clinical study for rexaceract, including any extension studies; the timing of any submissions to the FDA or other regulatory bodies and agencies; the timing of the commencement of the Phase 2 clinical study for rexaceract; the Company’s ability to enroll patients in its planned Phase 2 clinical study for rexaceract; the Company’s ability to replicate positive results from earlier preclinical studies or clinical trials in current or future clinical trials; the Company’s business development activities, strategic collaborations, licensing opportunities and financing activities; the advancement, prioritization and timing of the Company’s pipeline programs, including GT-04686; 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, 2025, and other filings made with the SEC. 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 release. We have 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.

Investors:
Gain Therapeutics, Inc. 
Apaar Jammu 
Director, Investor Relations and Public Relations
ajammu@gaintherapeutics.com

LifeSci Advisors LLC
Chuck Padala
Managing Director
chuck@lifesciadvisors.com

Media:
Russo Partners LLC
Nic Johnson and Elio Ambrosio
nic.johnson@russopartnersllc.com
elio.ambrosio@russopartnersllc.com
(760) 846-9256

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