Alterity Eyes Phase 3 for MSA Drug After Data Shows 48% Slowing of Decline

Three conferences, one clear message: ATH434 is Phase 3 ready

Alterity Therapeutics (ASX: ATH, NASDAQ: ATHE) announced on 19 May 2026 that presentations related to its ATH434 development programme in Multiple System Atrophy (MSA) were delivered at three international medical conferences, each reinforcing the case for advancing into Phase 3 clinical development. The End-of-Phase 2 FDA meeting remains on track for mid-2026 to confirm the Phase 3 pathway. MSA currently has no approved disease-modifying therapy and affects up to 50,000 individuals in the United States.

David Stamler, M.D., CEO of Alterity Therapeutics

“Our Phase 2 trial showed statistically significant slowing of disease progression, and the use of advanced MRI methods gives us a powerful way to identify the right patients and measure how the drug is working.”

What the data actually showed across the three presentations

The three conference presentations collectively brought together clinical, biomarker, and imaging evidence in support of ATH434’s potential as a disease-modifying therapy. Each forum addressed a distinct dimension of the evidence base.

1. ISMRM 2026 — MRI imaging detects MSA before symptoms strike

Dr. Paula Trujillo, PhD, Research Assistant Professor at Vanderbilt University Medical Center, delivered an oral presentation at the International Society for Magnetic Resonance in Medicine (ISMRM) 2026 Annual Meeting and Exhibition. Her findings, recently published in NeuroImage, demonstrated that quantitative susceptibility mapping (QSM) can detect progressive iron accumulation in MSA even before clinical diagnosis.

The evaluation drew on longitudinal data from Alterity’s Biomarkers of Progression in Multiple System Atrophy (bioMUSE) Natural History Study, combined with cross-sectional MSA, Parkinson’s Disease, and healthy control data. Key QSM capabilities highlighted include:

• Detects iron dysregulation early, before clinical diagnosis
• Tracks brain iron changes over 12 months
• Provides individual-level, interpretable maps for patient monitoring
• Standardisable across scanners, making it viable for multicentre Phase 3 trials

2. MDSANZ — Phase 2 trial re-analysis using CSF NfL strengthens the treatment signal

Dr. Daniel Claassen, M.D., M.S., Professor of Neurology at Vanderbilt University Medical Center and Chief Medical Advisor for Alterity, delivered a poster at the Movement Disorder Society of Australia and New Zealand (MDSANZ) Scientific Meeting. The presentation evaluated cerebrospinal fluid neurofilament light chain (CSF NfL), an established prognostic biomarker of clinical decline in MSA that was prespecified as a disease-severity covariate in the trial. Four key outcomes were reported:

1. ATH434 at 50 mg BID slowed functional decline by approximately 48% (minus 4.0 UMSARS-I points, p=0.035); combined active arms significantly slowed Unified Multiple System Atrophy Rating Scale (UMSARS) Part I progression versus placebo (p=0.047).
2. Higher baseline CSF NfL predicted greater UMSARS-I worsening (β=0.90, p=0.033); adjusting for CSF NfL strengthened detection of treatment effects, supporting its use for stratification in future trials.
3. QSM showed a trend of reduced iron accumulation in the putamen and globus pallidus, consistent with the iron-chaperone mechanism of action; the dentate signal increase is consistent with glymphatic iron redistribution rather than disease progression.
4. Convergent clinical, biomarker, and imaging signals support ATH434 as a promising potential disease-modifying therapy.

3. MSA Symposium UCL London — new swallowing data adds a compelling patient-centred endpoint

CEO David Stamler, M.D., delivered an oral presentation at the University College London MSA Symposium 2026. The presentation introduced new analyses of swallowing outcomes, assessed using the validated 15-item Swallowing Disturbance Questionnaire (SDQ), which measures a symptom with significant impact on patient quality of life.

Over 52 weeks of treatment, placebo patients worsened by a mean adjusted score increase of 8.5 points on the SDQ, compared to increases of 1.2 points (50 mg) and 5.0 points (75 mg), with the 50 mg dose achieving statistical significance (p=0.003). The biomarker data also demonstrated that ATH434 “decouples iron accumulation from clinical progression,” supporting its role as an iron chaperone.

Understanding ATH434 and why iron matters in MSA

Multiple System Atrophy is a rare, rapidly progressive neurodegenerative disease characterised by the failure of the autonomic nervous system and impaired movement. It is caused by the progressive loss of nerve cells in the brain and spinal cord, with a pathological hallmark being the accumulation of the protein α-synuclein within glial cells (the brain’s support cells) and neuron loss across multiple brain regions. MSA affects up to 50,000 individuals in the United States, and currently no drugs exist that can slow disease progression.

Iron dysregulation is a key driver of α-synuclein pathology in the brain regions affected by MSA. ATH434 is an oral iron chaperone, meaning it is designed to restore normal iron balance in the brain, thereby reducing iron accumulation and inhibiting the abnormal protein aggregation linked to neurodegeneration. In preclinical models, ATH434 has been shown to reduce α-synuclein pathology and preserve neuronal function.

The drug has received Fast Track Designation from the U.S. Food and Drug Administration (FDA), which is a regulatory status that accelerates the review process for therapies addressing serious conditions with unmet medical needs. ATH434 also holds Orphan Drug Designation from both the FDA and the European Commission for the treatment of MSA, a designation that provides financial incentives and extended market exclusivity for treatments targeting rare diseases.

What comes next — Phase 3 pathway and the FDA meeting

The End-of-Phase 2 FDA meeting remains on track for mid-2026 to confirm the Phase 3 trial design and the regulatory pathway forward. The evidence presented across the three conferences directly informs that design, particularly around patient selection using QSM imaging and CSF NfL stratification to identify those most likely to benefit from treatment.

Alterity has indicated it is “moving beyond traditional trial paradigms,” with precision patient identification central to the Phase 3 strategy. From a safety perspective, ATH434 was well tolerated in Phase 2, with similar adverse event rates to placebo and no serious adverse events attributed to the drug.

For investors, the convergence of statistically significant efficacy data, validated imaging biomarkers, and an imminent regulatory milestone positions Alterity at a material inflection point heading into the second half of 2026. Key upcoming catalysts include:

• End-of-Phase 2 FDA meeting: mid-2026
• Phase 3 trial design confirmation
• Continued bioMUSE natural history data informing the trial enrichment strategy

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