Exhibit 99.1

Gain Therapeutics Presents Additional Preclinical Data and Design of Phase 1b Clinical Study of GT-02287 at AD/PD 2025 and Provides Enrollment Update

GT-02287 oral presentation demonstrates new evidence of disease-modifying capacity in GBA1 and idiopathic Parkinson’s disease models

Enrollment update provided for Phase 1b study

Phase 1b study ongoing to assess safety, tolerability, pharmacokinetics, and pharmacodynamics of GT-02287 in people with Parkinson’s disease; biomarker analysis to be conducted in Q2 2025

BETHESDA, Md., April 10, 2025 -- 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 that an oral presentation as well as a poster were presented at the AD/PD™ 2025 International Conference on Alzheimer’s and Parkinson’s Diseases and related neurological disorders held April 1-5, 2025, in Vienna, Austria. The oral presentation outlined new evidence further supporting the disease-modifying activity of GT-02287 in preclinical models of both GBA1 and idiopathic Parkinson’s disease (PD). Additionally, the poster presented detailed the design of the ongoing Phase 1b clinical study of GT-02287 in people with Parkinson’s disease.

An early biomarker analysis from the currently enrolled participants in the Phase 1b study will be conducted mid-year and will include samples from participants both with and without the GBA1 mutations for purposes of informing Phase 2 planning during the second half of 2025. Complete analysis of the Phase 1b endpoints, available after all patients have completed 90 days of treatment, is anticipated sometime during the fourth quarter of 2025.

“We continue to add to the robust preclinical dossier of GT-02287 and we believe the recent biomarker data, and the behavioral data we have presented previously, further support the potential of GT-02287 to be a disease-modifying therapy for people with Parkinson’s disease,” commented Joanne Taylor, Ph.D., Senior Vice President of Research of Gain.

“We are encouraged by the robust enrollment and interest in our Phase 1b study in people with Parkinson’s disease. We believe the study is on track to complete enrollment by the end of the second quarter of 2025. We look forward to seeing how the effects on relevant pathway abnormalities that we have observed preclinically and in healthy volunteers translate to people with Parkinson’s disease,” said Jonas Hannestad, M.D., Ph.D., Chief Medical Officer of Gain.

Oral Presentation Information

Title: “Clinical Stage Glucocerebrosidase Modulator, GT-02287, Shows Disease Modifying Potential in Preclinical Models Of Both GBA1 and Idiopathic Parkinson’s Disease”

Summary:  In animal models of both GBA1 and idiopathic Parkinson’s disease, GT-02287 is able to rescue motor deficits and prevent the development of deficits in complex behaviors such as nesting. These effects persist even following withdrawal of the compound, suggesting a disease-modifying potential of GT-02287. The new preclinical data that were presented additionally support a disease-modifying potential of GT-02287. Several biomarkers of disease progression, including aggregated α-synuclein, IRE-1 (a marker of ER stress), LAMP-1 (a marker of lysosomal integrity), Miro1 (a marker of damaged mitochondrial destined for mitophagy), phospho-Tau (a marker of neurodegeneration), and Iba-1 (a marker of neuroinflammation) were statistically reduced upon treatment with GT-02287 and remained reduced for several days following drug washout demonstrating a long-lasting effect.

Poster Presentation Information

Title: “Design of a Phase 1b Study to Evaluate the GCase-targeting Molecule GT-02287 in GBA1-PD and Sporadic PD”

Summary: The study will assess safety and tolerability of GT-02287 during three months of dosing in people with PD, using adverse events, laboratory tests, electrocardiograms, and vital signs as the key safety endpoints. Additionally, the study will characterize the single-dose and steady-state plasma pharmacokinetics (PK) profile of GT-02287. Exploratory endpoints include various biomarkers in the cerebrospinal fluid (CSF), dried blood spots, plasma, and whole blood. Biomarkers include GCase activity and protein levels, sphingolipid substrate levels, α-synuclein, lysosomal and mitochondrial markers, and inflammatory markers. Results from this Phase 1b study will guide the design of a subsequent randomized, placebo-controlled, double-blind dose-finding Phase 2 study to evaluate the efficacy of GT-02287 as measured by a clinically meaningful endpoint in PD over a longer treatment period. Phase 2 planning is expected to commence in the second half of 2025.

A PDF of the poster presented at AD/PD 2025 is available on the Science and Technology section of the Company’s website at https://gaintherapeutics.com/science-and-technology/posters.

Slides from the oral presentation at AD/PD 2025 will be available on the Company’s website at https://gaintherapeutics.com.

About the AD/PD™ Conference

The AD/PD conference explores the latest research, clinical trials and treatments for Alzheimer’s and Parkinson’s and other related neurological disorders. The conference has grown to be the leading event in the field of neurodegenerative disorders with over 4,700 participants from over 70 countries and over 2250 abstracts in 2024. For more information, visit https://adpd.kenes.com. 

About GT-02287

Gain Therapeutics’ lead drug candidate, 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 an allosteric enzyme modulator that restores the function of the lysosomal enzyme glucocerebrosidase (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. In preclinical models of PD, GT-02287 restored GCase enzymatic function, reduced ER 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, GT-02287 was shown to rescue deficits in motor function and gait and prevent the development of deficits in complex behaviors such as nesting.

Compelling preclinical data in models of both GBA1-PD and idiopathic PD, demonstrating a disease-modifying effect after administration of GT-02287, suggest that GT-02287 may have the potential to slow or stop the progression of Parkinson’s disease.

Results from a Phase 1 study of GT-02287 in healthy volunteers demonstrated favorable safety and tolerability, plasma and CNS exposures in the projected therapeutic range, and target engagement with a >50% 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 is currently enrolling participants across 7 sites in Australia, is to evaluate the safety and tolerability of GT-02287 after 3 months of dosing in people with Parkinson’s disease.

Gain’s lead program in Parkinson’s disease 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, GT-02287 is currently being evaluated for the treatment of Parkinson’s disease with or without a GBA1 mutation in a Phase 1b clinical trial. GT-02287 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 including GT-02287; expectations regarding the timing of results from a Phase 1b clinical study for GT-02287; expectations regarding the timing of patient enrollment for a Phase 1b clinical study for GT-02287; the timing of any submissions to the FDA or other regulatory bodies and agencies; 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 release. We have no obligation, and expressly disclaim any obligation, to update, revise or correct any of the forward-looking statements, whether as a result of new information, future events or otherwise. 

Investors:

Gain Therapeutics, Inc. 

Apaar Jammu 

Manager, 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

Exhibit 99.2

Corporate Presentation September 2024 GAIN THERAPEUTICS Corporate Presentation April 2025 NASDAQ: GANX

Certain statements set forth in this presentation are forward - looking andreflect the Company’s plans, beliefs, expectations and current views with respect to, among other things, future events and financial performance (collectively referred to herein as “forward - looking statements”). Forward - looking statements can be identified by the fact that they do not relate strictly to historical or current facts and are often characterized by the use of words such as “believe,” “can,” “could,” “potential,” “plan,” “predict,” “goals,” “seek,” “should,” “may,” “may have,” “would,” “estimate,” “continue,” “anticipate,” “intend,” “expect” or by discussions of strategy, plans or intentions. Such forward - looking statements involve known and unknown risks, uncertainties, assumptions and other important factors that could cause our actual results, performance or achievements or industry results to differ materially from historical results or any future results, performance or achievements expressed, suggested or implied by such forward - looking statements. These include, but are not limited to, statements about the Company’s ability to develop, obtain regulatory approval for and commercialize its product candidates ; the timing of future IND submissions, initiation of preclinical studies and clinical trials, and timing of expected clinical results for our product candidates ; the Company’s success in early preclinical studies, which may not be indicative of results obtained in later studies or clinical trials ; the outbreak of the novel strain of coronavirus disease, COVID - 19 , which could adversely impact our business, including our preclinical studies and any future clinical trials ; the potential benefits of our product candidates ; the Company’s ability to obtain regulatory approval to commercialize our existing or any future product candidates ; the Company’s ability to identify patients with the diseases treated by our product candidates, and to enroll patients in clinical trials ; the success of our efforts to expand our pipeline of product candidates and develop marketable products through the use of our Magellan platform ; the Company’s expectations regarding collaborations and other agreements with third parties and their potential benefits ; the Company’s ability to obtain, maintain and protect our intellectual property ; the Company’s reliance upon intellectual property licensed from third parties, including the license to use the Company’s Magellan platform ; the Company’s ability to identify, recruit and retain key personnel ; the Company’s financial performance ; developments or projections relating to the Company’s competitors or industry ; the impact of laws and regulations ; the Company’s expectations regarding the time during which it will be an emerging growth company under the JOBS Act ; and other factors andassumptions described in the Company’s public filings . These statements are based on the Company’s historical performance and on its current plans, estimates and projections in light of information currently available to the Company, and therefore, you should not place undue reliance on them. The inclusion of forward - looking information should not be regarded as a representation by the Company or any other person that the future plans, estimates or expectations contemplated by us will be achieved. Forward - looking statements made in this presentation speak only as of the date of this presentation, and the Company undertakes no obligation to update them in light of new information or future events, except asrequired by law. You should carefully consider the above factors, as well as the factors discussed elsewhere in this presentation and our public filings, before deciding to invest in our common stock . The factors identified above should not be construed as an exhaustive list of factors that could affect the Company’s future results, and should be read in conjunction with the other cautionary statements that are included in this presentation and our public filings . New risks and uncertainties arise from time to time, and it is impossible for the Company to predict those events or how they may affect the Company . If any of these trends, risks or uncertainties actually occurs or continues, the Company’s business, revenue and financial results could be harmed, the trading prices of its securities could decline andyou could lose all or part of your investment . All forward - looking statements attributable to the Company or persons acting on its behalf are expressly qualified in their entirety by this cautionary statement . Trademarks, Service Marks, and Trade Names This presentation includes our trademarks, and trade names, which are protected under applicable intellectual property laws . This presentation also may contain trademarks, service marks, trade names, and copyrights of other companies, which are the property of their respective owners . Solely for convenience, the trademarks, service marks, trade names, and copyrights referred to in this presentation are listed without the TM, SM, ©, and ® symbols, but we will assert, to the fullest extent under applicable law, our rights or the rights of the applicable licensors, if any, to these trademarks, service marks, trade names, andcopyrights . Industry Information Market data and industry information used throughout this presentation are based on management’s knowledge of the industry and the good faith estimates of management . We also relied, to the extent available, upon management’s review of independent industry surveys and publications and other publicly available information prepared by a number of third party sources . All of the market data and industry information used in this presentation involves a number of assumptions and limitations, and you are cautioned not to give undue weight to such estimates . Although we believe that these sources are reliable, we cannot guarantee the accuracy or completeness of this information, and we have not independently verified this information . While we believe the estimated market position, market opportunity and market size information included in this presentation are generally reliable, such information, which is derived in part from management’s estimates and beliefs, is inherently uncertain and imprecise . No representations or warranties are made by the Company or any of its affiliates as to the accuracy of any such statements or projections . Projections, assumptions and estimates of our future performance and the future performance of the industry in which we operate are necessarily subject to a high degree of uncertainty and risk due to a variety of factors, including those desc ribed above . These and other factors could cause results to differ materially from those expressed in our estimates and beliefs and in the estimates prepared by independent parties . 2 © 2 0 2 5 - G A I N T H E R A P E U T I C S Forward - Looking Statements

GANX Corporate Highlights Lead Product GT - 02287 Advancing into Parkinson’s Disease Patients Multiple assets in discovery and preclinical development Strong intellectual property estate Anticipated Upcoming Milestones • Allosteric modulator of glucocerebrosidase enzyme ( GCase ) • Disease modifying potential : slowing/stopping progression of motor and cognitive decline in GBA1 and idiopathic PD • Safe and well tolerated in Phase 1 SAD/MAD study and demonstrated target engagement • Biomarker analysis from Phase 1b trial in GBA1 and idiopathic PD patients expected mid - 2025 3 © 2 0 2 5 - G A I N T H E R A P E U T I C S • Assets identified and developed through application of our Proprietary Magellan AI platform • Initial disease targets include neurodegenerative diseases, lysosomal storage disorders including Gaucher disease as well as metabolic disease and solid tumors • GT - 02287 composition of matter patent application with term through 2038 not including Hatch Waxman extension • Patent applications for 5 NCE families under review • GT - 02287 Phase 1b biomarker analysis • GT - 02287 Phase 2 planning (US/EU) 1H25 2H25

Experienced Leadership: Extensive Biotech And Pharma Experience Gene Mack, MBA Chief Executive Officer Jonas Hannestad , MD, PhD Chief Medical Officer Joanne Taylor, PhD SVP Research © 2 0 2 5 - G A I N T H E R A P E U T I C S Gianluca Fuggetta Senior Vice President, Finance Terenzio Ignoni , PharmD SVP Technical Operations

Experienced Board of Directors: Extensive Biotech And Pharma Experience (>$30b Transactions) Khalid Islam, PhD Founder and Chairman Claude Nicaise, MD Independent Member Eric I. Richman Member Hans Peter Hasler Independent Member Dov Goldstein, MD Independent Member Gwen Melincoff Independent Member Jeffrey Riley Independent Member The picture can't be displayed. © 2 0 2 5 - G A I N T H E R A P E U T I C S

Gain Therapeutics Pipeline PHASE 1 PRECLINICAL RESEARCH DISCOVERY TARGET INDICATION ASSET GCase Parkinson’s Disease GT - 02287 GCase Gaucher’s Disease GCase Dementia with Lewy Bodies GCase Alzheimer’s Disease GALC GLB1 Lysosomal Storage Disorders Multiple Undisclosed AAT Metabolic Diseases Undisclosed DDR2 Oncology: Solid Tumors Multiple Undisclosed 6 © 2 0 2 5 - G A I N T H E R A P E U T I C S

Lead Clinical Program GT - 02287 GBA1 Parkinson’s Disease 7

© 2 0 2 5 - G A I N T H E R A P E U T I C S Parkinson’s disease is the second most common neurodegenerative disease 1 Current therapies only treat symptoms and do not prevent disease progression Parkinson’s Disease GBA1 - Parkinson’s Disease 1.“Parkinson’s Disease:Challenges , Progress, and Promise.” National Institute of Neurologi cal Disorders and Stroke, U.S. Department of Health and Human Services, 30 Sept. 2015 Parkinson’s Disease – Market Opportunity 8 Parkinson’s Disease (PD) 1M+ US Patients Up to15% of PD US Market Potential: $4B Genetically defined subpopulation of Parkinson's disease Largest genetic risk factor for development of Parkinson’s disease GBA1 mutations cause misfolding of an important enzyme called GCase GBA1 - PD patients experience earlier disease onset and more severe disease with faster decline in motor and cognition functions US Market Potential: $3B 2. Smith L a nd Schapir a AHV. G BA Varian ts and Parkinson Disease: Mecha nisms and Tr eatme nts. Cells. 20 22 Apr 8;11(8):126 1. doi: 1 0.3 390/ce lls11 081261

Dysfunctional GCase triggers disease cascade affecting multiple organelle functions and leads to neurodegeneration Healthy Dopaminergic Neuron Diseased Dopaminergic Neuron Nucleus Endoplasmic Reticulum Lysosome Mitochondria GBA1 Gene Normal GCase GCase maintains cell health: • Depletes toxic lysosomal substrates • Stabilizes mitochondrial respiratory complex I Mutated GBA1 Gene Defective GCase GCase protein misfolding • Increased ER stress and ER - associated protein degradation • Lysosomal and mitochondrial dysfunction • Accumulation of toxic lysosomal lipid substrates resulting from reduced GCase activity Alpha synuclein aggregation Increased Risk of PD: Core motor dysfunction, cognitive dysfunction 9 © 2 0 2 5 - G A I N T H E R A P E U T I C S

Allosteric modulator GT - 02287 restores GCase function, which improves disease cascade and neuronal survival Normal GCase Dopaminergic Neuron with Restored GCase Function Mutated GBA1 Gene • Corrects protein misfolding • Restores enzymatic activity Defective GCase Reduced ER Stress 0.0 0.5 1.0 BiP protein level (relative to untreated) GCase Activity Restoration 0 20 40 60 80 100 % of PFB+ positive fibroblasts 0 2 4 6 8 GlcCer in fibroblasts (ng/mg protein) Alpha - Synuclein Depletion Alpha - synuclein in TH+ neurons (% of control) Restored Lysosomal Function Restored Mitochondrial Function Lamp2 area in TH+ neurons (% of control) Ratio ROS/TH in TH+ neurons (% of control) 250 225 200 175 150 125 100 75 50 25 0 Neuronal Survival 10 © 2 0 2 5 - G A I N T H E R A P E U T I C S TH+ neuronal survival (% of control) Improved Cellular Health Toxic Substrate Depletion

Single - and Multiple - ascending Dose First - in - human Phase 1 Study 13.5 mg/kg/day 15 mg/kg SAD/MAD endpoints : • Treatment - emergent adverse events • Clinical labs, vital signs, ECGs, C - SSRS • Plasma pharmacokinetics 10 mg/kg fed 10 mg/kg/day 7.7 mg/kg/day 4 MAD cohorts Daily dosing for 14 days 4.8 mg/kg/day 10 mg/kg fasted 7.7 mg/kg 4.8 mg/kg 2.4 mg/kg 5 SAD cohorts Food effect at 10 mg/kg MAD Cohort 4 : • CSF drug levels • GCase activity in dry blood spots 11 © 2 0 2 5 - G A I N T H E R A P E U T I C S Participants : • Healthy men and women ages 18 - 65 • 8 subjects per cohort • 2 placebo; 6 active

GT - 02287 was Generally Well - Tolerated , No Serious Adverse Events Observed 12 © 2 0 2 5 - G A I N T H E R A P E U T I C S • No Serious Adverse Events • No Severe Adverse Events (CTCAE Grade 3) • No discontinuations due to AE • 56.7% (n=17) of active and 40% (n=4) of placebo participants in the SAD had 1 or more TEAE • 64% (n=16) of active and 50% (n=4) of placebo participants in the MAD had 1 or more TEAE

re 0 0 0 0 Serious 0 0 0 0 Leading to discontinuation

Adverse Event Profile 13 © 2 0 2 5 - G A I N T H E R A P E U T I C S Most common TEAEs in MAD: • Nausea 32% • Abdominal pain 8% • Diarrhea 8% • Headache 8% Nausea: • >90% of events were mild • >90% of events were <3h in duration • Incidence increased with dose level • Incidence decreased with continued dosing

Therapeutic Range: Phase 1 PK Data in Healthy Volunteers 0 2000 4000 6000 8000 10000 12000 4 5.5 7 8.5 10 Dose: mg/Kg 11.5 13 14.5 16 AUC: ng.h/mL Human AUC from MAD Study : Day 1 and Day 14 Onset of Therapeutic Effect (Animal Models) R² = 0.9663 R² = 0.9975 Linear Regression Day 14 Linear Regression Day 1 14 © 2 0 2 5 - G A I N T H E R A P E U T I C S

GT - 02287 Demonstrates CNS Exposure Comparable to that Observed in Rodents 15 • CSF levels in Humans comparable to those observed at efficacious dose levels in rodents • CSF levels are low in all species due to low aqueous solubility and high protein binding • Observed total brain levels in rodents are 2 - 8 times higher than total plasma levels Dose (mg/kg) Timepoint Mean plasma Cmax (ng/mL) mean Day 14 Total brain level (ng/mL) Mean CSF level (ng/mL) Species 13.5 PO Day 13 850 Nd 3.1 (1.7 - 4.9) Human (MAD4) 10 IV 15 min 2414 6592 4 Mouse 30 PO 1 hour 680 2441 3 Rat © 2 0 2 5 - G A I N T H E R A P E U T I C S

GT - 02287 Demonstrates Gcase Target Engagement In Healthy Volunteers Untreated 4 h 12h post - dose post - dose Pre - dose 4 h 12h post - dose post - dose 4 6 8 10 12 GCase activity (μmol/l/h) ns ns GCase Activity (DBS) ٓٓٓ ٓٓ ٓ Day 1 Day 14 One - way, paired, repeated measures ANOVA. *p < 0.05; **p < 0.01; ***p < 0.001 • GCase activity in dry blood spots was measured in MAD Cohort 4 • In GT - 02287 subjects, 5 out of 6 had increased GCase activity • In placebo subjects, no increase was observed (+4% change from baseline) 53% increase in GCase activity observed by Day 14 (p<0.001) 16 © 2 0 2 5 - G A I N T H E R A P E U T I C S

Phase 1 Blinded, Placebo Controlled SAD/MAD Trial Safety GT - 02287 is safe and generally well tolerated in SAD (40 HV) and MAD (32 HV, daily dosing 14 days) No SAEs, Grade 3 AEs, or clinically - significant changes in ECGs, BP/HR Plasma Exposure Plasma exposures in the projected therapeutic range Adequate safety margins based on toxicology studies CNS Exposure GT - 02287 is detectable in CSF and in line with rodent levels at effective doses Target Engagement GT - 02287 modulates GCase activity in blood 17 © 2 0 2 5 - G A I N T H E R A P E U T I C S

Upcoming Anticipated Milestones and Potential Value Inflection Points Potential clinical POC based on biomarkers of GBA1 - Parkinson’s disease ( first analysis from Phase 1b clinical trial) 1H 2025 18 © 2 0 2 5 - G A I N T H E R A P E U T I C S 2 H 2025 Start of Phase 2 planning

Design of Phase 1b Trial in Parkinson’s Disease Patients 19 © 2 0 2 5 - G A I N T H E R A P E U T I C S An Open - label Study to Assess the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of GT - 02287 in Participants with Parkinson’s Disease With or Without a Pathogenic GBA1 Mutation • Open - Label, single - arm, multicenter study • Approximately 15 - 20 patients with or without a GBA1 mutation will be enrolled • 90 - day treatment duration • 7 sites in Australia with potential to expand to other geographies Treatment Period Follow - up Period 13.5 mg/kg once a day 11 mg/kg once a day Dose decrease at any time during treatment if needed End of Study Day 1 Day 14 Day 30 Day 60 Day 90 Day 105 Blood collection Blood collection Blood collection Blood collection Lumbar Puncture Blood collection Biomarkers Site visit

Phase 1b Study Objectives 20 © 2 0 2 5 - G A I N T H E R A P E U T I C S Study Objectives Endpoints • To evaluate the safety and tolerability of GT - 02287 Primary • To characterize the single - dose and steady state plasma PK profile of GT - 02287 Secondary Concentration of GT - 02287 in CSF at 4 hours post - dose after at least 12 weeks of daily administration of GT - 02287 • To assess levels of GT - 02287 in CSF after at least 12 weeks of daily administration in participants with PD Exploratory • Gcase activity • Sphingolipid levels • Lysosomal and mitochondrial markers • Inflammatory markers • Pharmacodynamic response to GT - 02287 via biomarkers analysis of plasma, whole blood, blood cells, and CSF samples Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS - UPDRS, OFF state) and other standard functional scales including MoCA, ADL, etc. • To explore the effect of GT - 02287 on scores from selected clinical scales and questionnaires over a 90 - day treatment

© 2 0 2 5 - G A I N T H E R A P E U T I C S GT - 02287 Prevents GBA1 Disease Cascade in Mouse CBE Model of GBA1 - PD and Improves Motor Function in the GBA1 - PD Mouse Model +GT - 02287 (30mg/kg) +GT - 02287 (60mg/kg) +GT - 02287 (90mg/kg) +GT - 02287 (120mg/kg) GBA1 - PD Model: CBE causes partial knockdown of GCase activity 21 NfL Wire Hang Beam Walk 0.000 0.005 0.010 0.015 0.020 0.025 Fluorescence intensity (normalised IBA - 1/GAPDH) ٓٓٓٓ ٓٓٓٓ ٓٓٓٓ ٓٓٓٓ ٓٓٓ 0 50000 100000 150000 200000 250000 Fluorescent intensity ٓٓٓٓ ns ٓٓٓ ٓٓٓٓ ٓٓٓٓ 0 10 20 30 40 Dopamine levels (pg/mg) ٓٓٓٓ ns ٓٓٓ ٓٓٓٓ ٓٓٓٓ 0 2000 4000 6000 pg/ml ٓٓٓٓ ٓٓ ٓٓ ٓٓٓٓ ٓٓٓٓ ٓٓٓٓ 0 100 200 300 Latency to fall (s) ٓٓٓٓ ns ٓٓ ٓٓ ns p=0.057 0 5 10 15 Number of Foot slips ٓٓٓٓ ٓٓ ٓٓ ٓٓٓٓ ٓٓٓٓ • CBE is an irreversible GCase inhibitor • Administration of CBE models the effects of dysfunctional GCase seen in GBA1 - Parkinson’s disease Aggregated α - syn (SN) Tyrosine Hydroxylase (SN) Striatal Dopamine Iba - 1 (SN) NeuN (Cortex) 0 50000 100000 150000 200000 250000 Fluorescence Intensity ٓٓٓٓ ns ns ٓٓٓٓ ٓٓ 0 50000 100000 150000 200000 Fluorescence Intensity ٓٓٓٓ ٓٓٓٓ ٓٓٓٓ ٓٓٓٓ ٓٓٓٓ GluCer (Cortex) CBE Contro l

GT - 02287 displays a rescue and disease - modifying effect in animal models of GBA1 and iPD α - Syn PFFs α - Syn PFFs Washout No drug Low Level CBE Washout GT - 02287 No drug GBA1 - PD Model (CBE+PFFs) Idiopathic PD Model (PFFs only) Mouse Wire Hang Rescue & Washout Data is shown as Mean ± S.E.M.(n=14 till day 20, then n=7) GT - 02287 22 © 2 0 2 5 - G A I N T H E R A P E U T I C S

Fast - onset rescue effect of GT - 02287 driven by enhanced GCase activity, reduced ER stress and increased lysosomal and mitochondrial integrity GCase Activity C o n t r o l s C B E + P F F s C B E + P F F s + 6 0 m g / k g ( o r a l q . d . ) C B E + P F F s + 9 0 m g / k g ( o r a l q . d . ) 0 2 4 6 8 GCase activity n m o l / m g / h r ✱✱✱✱ ns ✱ LAMP - 1 Lysosomal Integrity Miro1 Mitochondrial Integrity C o n t r o l s C B E + P F F s C B E + P F F s + 6 0 m g / k g ( o r a l q . d . ) C B E + P F F s + 9 0 m g / k g ( o r a l q . d . ) 0 20000 40000 60000 80000 Lamp-1 F l u o r e s c e n c e i n t e n s i t y ( a . u . ) ✱✱✱✱ ✱✱✱ ✱✱✱✱ C o n t r o l s C B E + P F F s C B E + P F F s + 6 0 m g / k g ( o r a l q . d . ) C B E + P F F s + 9 0 m g / k g ( o r a l q . d . ) 0 50000 100000 150000 Miro-1 F l u o r e s c e n c e i n t e n s i t y ( a . u . ) ✱✱✱✱ ns ns IRE - 1 ER stress 2h post - treatment * Significant difference as compared to α - synuclein PFF+CBE. One - way ANOVA followed by Dunnett's Multiple Comparison Test. * P < 0.05, ** P < 0.01 , /*** P < 0.001 & **** P < 0.0001. 23 © 2 0 2 5 - G A I N T H E R A P E U T I C S

Brain biomarker changes maintained following GT - 02287 washout 24 IRE - 1 (ER stress) LAMP - 1 (lysosomal integrity) Aggregated α - syn $$$$ **** **** **** **** $$$$ **** **** $$$$ **** **** $$$ * GCase activity Washout d20 - d29 d29 $$$$ 0 20000 40000 60000 I R E - 1 ( f l u o r e s c e n c e i n t e n s i t y ) 0 20000 40000 60000 L A M P - 1 ( f l u o r e s c e n c e i n t e n s i t y ) No washout » Above biomarkers are being measured in blood and CSF in Phase 1b MIRO - 1 (mitochondrial health) Data is shown as Mean ± S.E.M. $ Significant difference as compared to sham control group * Significant difference as compared to α - synuclein PFF+CBE. One - way ANOVA followed by Dunnett's Multiple Comparison Test. $/* P < 0.05, $$/** P < 0.01 , $$$/*** P < 0.001 & $$$$/**** P < 0.0001. » Taken together, data support GT - 02287’s disease modifying effect CBE/PFF GBA1 - PD model © 2 0 2 5 - G A I N T H E R A P E U T I C S

Translational plasma - based biomarkers of GT - 02287 rescue effect Plasma GlcSph Plasma NfL Plasma GlcCer V e h i c l e C o n t r o l s C B E + P F F C B E + P F F + G T - 0 2 2 8 7 ( 3 0 m g / k g ) p o s t - 8 d a y s C B E + P F F + G T - 0 2 2 8 7 ( 6 0 m g / k g ) p o s t - 8 d a y s C B E + P F F + G T - 0 2 2 8 7 ( 9 0 m g / k g ) p o s t - 8 d a y s 0 200 400 600 800 1000 plasma NFL p g / m l Vehicle Controls CBE+PFF+GT-02287 (30 mg/kg) post-8days CBE+PFF+GT-02287 (60 mg/kg) post-8days ns ✱✱ ✱ ✱✱ p=0.09 CBE + PFF CBE+PFF+GT-02287 (90 mg/kg) post-8days Control CBE/PFFs + GT - 02287 30mg/kg + GT - 02287 60mg/kg + GT - 02287 90mg/kg Data shown as Mean “ S . E . M . (n= 10 ) . Significant difference as compared to PFFs or PFFs + CBE . One - way ANOVA followed by Dunnett’s Multiple Comparison test . ns (non significant) . * < P 0 . 05 , ** < P 0 . 01 , **** < 0 . 0001 . 25 © 2 0 2 5 - G A I N T H E R A P E U T I C S

GT - 02287 Improves Nest Building Performance in Therapeutic Model of GBA1 - PD 26 Improvements in Nest - building Performance Nest building is a non - invasive test to study activities of daily living and cognitive performance in rodent models CBE/PFFs Control 30mg/kg 60mg/kg 90mg/kg V e h i c l e C o n t r o l s C B E + P F F C B E + P F F + G T - 0 2 2 8 7 ( 3 0 m g / k g ) p o s t - 8 d a y s C B E + P F F + G T - 0 2 2 8 7 ( 6 0 m g / k g ) p o s t - 8 d a y s C B E + P F F + G T - 0 2 2 8 7 ( 9 0 m g / k g ) p o s t - 8 d a y s 0 2 4 6 N e s t i n g s c o r e ✱✱✱ ns ✱✱ ✱✱✱ Nest Building Score Improvements in Relevant Biomarkers Aggregated α - syn (SN) P lasma NfL 0 5 î 10 4 1 î 10 5 1.5 î 10 5 ٓٓٓٓ ٓٓ ٓٓ Fluorescence intensity ( a.u ) ٓٓٓٓ 0 200 400 600 800 1000 pg/ml ٓٓ ٓ p =0.09 ns ٓٓ 0 5 î 10 4 1 î 10 5 1.5 î 10 5 2 î 10 5 ٓٓٓٓ ns ٓ Fluorescence intensity ( a.u ) ٓٓٓ Fluorescence intensity ( a.u ) Biomarkers being assessed in ongoing Phase 1b study Tyrosine Hydroxylase (SN) GFAP (SN) Iba - 1 (SN) Vehicle Controls CBE + PFF CBE+PFF+GT - 02287 (30 mg/kg) post - 8 days CBE+PFF+GT - 02287 (60 mg/kg) post - 8 days CBE+PFF+GT - 02287 (90 mg/kg) post - 8 days © 2 0 2 5 - G A I N T H E R A P E U T I C S Data is shown as Mean ± S.E.M.(n= 7). $ Significant difference as compared to sham control group. One - way ANOVA followed by Dunnett's Multiple Comparison Test. $ P < 0.05, $$ P < 0.01 , $$$ P < 0.001 & $$$$ P < 0.0001.

Nesting score unaffected by drug washout: evidence of disease modifying effect on complex behaviors $$ $$$$ $$$$ $$$$ $$$$ Data is shown as Mean ± S.E.M.(n= 7). $ Significant difference as compared to sham control group One - way ANOVA followed by Dunnett's Multiple Comparison Test. $ P < 0.05, $$ P < 0.01 , $$$ P < 0.001 & $$$$ P < 0.0001. 18 20 22 24 26 28 30 2 3 4 5 Day N e s t i n g S c o r e Control CBE+PFFs GT-02287 90mg/Kg GT-02287 90mg/Kg + washout CBE+PFFs (GBA1 - PD) WASHOUT Mouse Nesting Building Washout $$$ $$$ $$$ $ 18 20 22 24 26 28 30 2 3 4 5 Day N e s t i n g S c o r e Control PFFs GT-02287 90mg/Kg GT-02287 90mg/Kg + washout PFFs only ( iPD ) WASHOUT © 2 0 2 5 - G A I N T H E R A P E U T I C S 27

GT - 02287 has Best - in - Class Profile for GBA1 - Parkinson's Disease VQ - 101 BIA 28 - 6156 GT - 02287 Effect on Disease Cascade ? Increases Lysosomal GCase Activity GCase Mechanism of Action ? ? Reduces ER Stress Reduces Toxic Lipid Substrates ? Reduces Aggregated α - Synuclein Improves Lysosomal Function ? ? Improves Mitochondrial Function ? ? Reduces Neuroinflammation ? ? Provides Neuroprotection Disease - Modifying Effect ? ? Increases Dopamine Levels ? ? Restores Motor Function ? ? Improves Cognitive Function Effect in Preclinical Studies No Data Shown No Clinical Effect Shown © 2 0 2 5 - G A I N T H E R A P E U T I C S 28

© 2 0 2 5 - G A I N T H E R A P E U T I C S 0 20 40 60 80 100 S t r i a t a l D o p a m i n e ( p g / m g ) $$$$ $$$$ **** ** * ** $$$$ $$$$ **** **** **** **** $$$$ $$$$ **** **** **** **** CBE+PFFS CBE+PFFS PFFS CBE+PFFS PFFS PFFS d29 Data shown as Mean ± S.E.M.(n=7). $ Significant difference as compared to sham control group. * Significant difference as compared to α - synuclein PFF+CBE or α - synuclein PFF alone. One - way ANOVA followed by Dunnett's Multiple Comparison Test. $/* P < 0.05, $$/** P < 0.01 , $$$/*** P < 0.001 & $$$$/**** P < 0.0001. Iba - 1 (SN) CBE+PFFS PFFS $$$$ $$$$ **** **** **** **** Phospho Tau (SN) Tyrosine Hydroxylase (SN) Striatal dopamine GT - 02287 Washout d20 - d29 Brain biomarker changes maintained following GT - 02287 washout 2/2 » Data support GT - 02287’s disease modifying effect CBE/PFF (GBA1 - PD) and PFF only ( iPD ) models washout

Large Market Potential for GT - 02287 for Various Neurodegenerative Diseases 29 © 2 0 2 5 - G A I N T H E R A P E U T I C S Number of Patients (US) Rationale Indication 150,000 Patients have dysfunctional GCase due to heterozygous GBA1 mutation GBA1 - Parkinson’s Disease 1,000,000 Increase in GCase activity and target activation in healthy volunteers suggests potential activity in iPD Idiopathic Parkinson’s Disease (IPD) 6,000 DysfunctionalGCase due to homozygous GBA1 mutation Gaucher Disease 1,000,000 GT - 02287 reduces aggregated alpha - synuclein,a componentof Lewy bodies Dementia with Lewy Bodies 5,800,000 GT - 02287 has shown positive effects in preclinical models of Alzheimer’s disease Alzheimer's Disease

© 2 0 2 5 - G A I N T H E R A P E U T I C S Tom Shrader, Ph.D., CFA Jay Olson, CFA Oppenheimer & Co Ram Selvaraju, Ph.D. HC Wainwright Keay Nakae , CFA Chardan Jason McCarthy, Ph.D. Maxim Boobalan Pachaiyappan , Ph.D. ROTH Louise Chen, MBA Scotiabank Company Background 30 CAPITAL STRUCTURE FINANCIAL AND STOCK DATA IPO (NASDAQ: GANX) − March 2021 − Led by BTIG and Oppenheimer & Co. − 2 6.5 million shares outstanding − No debt* CASH POSITION − $ 10.4 million a s of December 31 , 2024 GRANT SUPPORT − Michael J. Fox Foundation for Parkinson’s Research − The Silverstein Foundation for Parkinson’s with GBA − Innosuisse (Swiss Innovation Agency) *Except a 9 - year interest - free Swiss government loan ~$0.5 million outstandingat September 30, 2023 COR POR ATE BA CKGR OU ND Established in 2017 2 7 employees in three locations: HQ in Bethesda, Maryland, Lugano, Switzerland, Barcelona, Spain Founder and Executive Chairman: Dr. Khalid Islam ANALYST COVERAGE BTIG

Company Contacts Gene Mack President & CEO gmack@gaintherapeutics.com Apaar Jammu Manager, Investor Relations and Public Relations ajammu@gaintherapeutics.com

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