Alterity reports 52% slower functional decline with ATH434 50 mg in adjusted Phase 2 analysis of multiple system atrophy, while the primary imaging endpoint was not met.
Written By: Anamika Koshti, PharmD
Reviewed By: Pharmacally Editorial Team
Alterity Therapeutics presented new analyses from its ATH434-201 Phase 2 trial (NCT05109091) in multiple system atrophy (MSA) at the 2026 International Congress of Parkinson’s Disease and Movement Disorders in Seoul, South Korea. Announced October 5, 2026, the analysis examined clinical, biomarker and imaging outcomes after adjustment for baseline cerebrospinal fluid neurofilament light chain (CSF NfL).
After adjustment, Alterity reported that ATH434 50 mg twice daily was associated with approximately 52% slower functional decline than placebo at Week 52.
Why Baseline Severity Matters in MSA
MSA is a rare, rapidly progressive neurodegenerative disorder with no approved treatment shown to slow disease progression. Differences in baseline disease severity can influence clinical trial outcomes.
ATH434 is an investigational oral iron chaperone designed to redistribute reactive iron associated with neurodegenerative pathology. The ATH434-201 trial randomized 77 adults with MSA to ATH434 50 mg, 75 mg or placebo, administered twice daily for 12 months.
CSF NfL, a biomarker of neuroaxonal injury, was a prespecified covariate. Higher baseline NfL predicted greater functional decline, with each 1,000 pg/mL increase associated with approximately 0.9 additional points of worsening on the 11-item Unified MSA Rating Scale (UMSARS) Part I at Week 52 (p=0.033).
Adjusted Analysis Shows 52% Slowing
After adjustment for baseline CSF NfL, the ATH434 50 mg group showed a 4.64-point difference versus placebo in change from baseline on UMSARS Part I at Week 52 (p=0.032). Alterity characterized this as approximately 52% slower functional decline. The difference exceeded the 1.5-point minimal clinically important difference cited by the company by roughly threefold.
The 75 mg dose showed a 2.81-point difference, which was not statistically significant at Week 26 (p=0.072) or Week 52 (p=0.179).
The 52% estimate requires cautious interpretation. The analysis used a modified intent-to-treat population of 61 of 77 randomized participants who had been dosed, tested positive for cerebrospinal fluid alpha-synuclein by seed amplification assay and had at least one post-baseline iron MRI assessment.
It also used a mixed model for repeated measures added post hoc, whereas the prespecified clinical analysis used a Week 52 analysis of covariance. An earlier analysis of the clinical population reported approximately 46% slowing (p=0.037). Alterity attributed the difference to the populations and statistical models used. The company did not state whether p-values were adjusted for multiple comparisons.
Primary Brain Iron Endpoint Not Met
The analysis also assessed brain iron using quantitative susceptibility mapping MRI. The trial’s primary imaging endpoint, change in substantia nigra iron at Week 52, was not met.
Iron changes were numerically lower with ATH434 than placebo in the putamen and globus pallidus. However, the 50 mg group showed an increase relative to placebo in dentate nucleus iron signal of 0.016 ppm (p=0.021).
Alterity hypothesizes that this finding could reflect mobilization of iron through the brain’s glymphatic system. Because this explanation remains unconfirmed, the imaging findings are best considered hypothesis-generating.
Safety and Other Signals
Alterity reported adverse event rates similar to placebo and no serious adverse events attributed to ATH434, although event counts were not provided.
The company also reported trends toward improved clinician-rated severity, swallowing and orthostatic hypotension symptoms, along with higher outpatient activity measured by wearable sensors and trends toward preserved brain volume. These remain exploratory findings.
Phase 3 Development
Alterity said the NfL findings will inform its confirmatory Phase 3 program. Earlier FDA meeting updates described a pivotal study of approximately 200 patients evaluating ATH434 50 mg twice daily, with 11-item UMSARS Part I as the primary endpoint. Phase 3 trial activities are expected to begin by year-end 2026.
The FDA indicated that a single pivotal trial, together with confirmatory evidence, could potentially support approval. The Phase 3 program will therefore need to determine whether the functional benefit can be reproduced in a larger population without relying on the restricted, post hoc adjusted Phase 2 analysis.
The findings support further clinical development of ATH434, but the unmet primary imaging endpoint and limitations of the adjusted analysis underscore the need for confirmatory evidence.
Reference
Alterity Therapeutics Presents New Analyses of ATH434 Phase 2 Data in Multiple System Atrophy at the 2026 International Congress of Parkinson’s Disease and Movement Disorders, Alterity Therapeutics, 05 October 2026
Study of ATH434 in Participants with Multiple System Atrophy, ClinicalTrials.gov ID NCT05109091
About the Writer
Anamika Koshti (LinkedIn) is a PharmD professional and healthcare writer with interests in clinical research, pharmacovigilance, and evidence-based medicine. She has authored peer-reviewed publications on Alzheimer’s disease and PCOS, presented research at national conferences, and gained hands-on experience in medical content development and clinical data interpretation. She is committed to translating complex medical research into accurate, accessible content for healthcare professionals and patients.