Alterity Therapeutics (NASDAQ:ATHE) outlined its development plans for ATH434 in multiple system atrophy (MSA) during a virtual key opinion leader event featuring company leadership and two academic neurologists. Chief Executive Officer David Stamler said the company believes ATH434 demonstrated “exceptional efficacy” in a Phase II study, with up to 48% slowing of disease progression versus placebo on a functional endpoint used in MSA trials, and he emphasized what he described as a favorable safety profile with no serious adverse events attributed to the drug.
MSA: a rare, rapidly progressive disease with no disease-modifying therapy
Roy Freeman, Professor of Neurology at Harvard Medical School, described MSA as a rare, orphan, progressive neurodegenerative disorder involving parkinsonism, cerebellar dysfunction, and dysautonomia. He said survival after symptom onset is typically “between 6 and 10 years,” and stressed that there is currently no therapy that “changes the natural history of the disease.”
Freeman also reviewed commonly used trial outcomes, highlighting the Unified Multiple System Atrophy Rating Scale (UMSARS). He said UMSARS-I, a patient-reported component focused on how patients feel and function, is “most critical and most commonly used” in disease-modifying studies because it aligns with FDA preferences for functional outcomes.
Alterity’s mechanism: targeting iron and alpha-synuclein biology
Stamler said ATH434 is an orally administered small molecule designed as an “iron chaperone” that binds and redistributes excess iron in the central nervous system. He argued excess “reactive” iron can promote alpha-synuclein aggregation and oxidative injury, contributing to cellular dysfunction and death. By reducing labile iron, Stamler said the company aims to reduce alpha-synuclein aggregation and oxidative damage, with the goal of slowing functional decline.
Stamler added that ATH434 has orphan drug designation in the U.S. and Europe and has received FDA Fast Track designation. He also said the drug crosses the blood-brain barrier and can enter cells, where key pathology is believed to occur.
Phase II (201 study): clinical signal and biomarker work
Daniel Claassen, Professor of Neurology at Vanderbilt University, reviewed additional analyses from the randomized, double-blind, placebo-controlled Phase II “201 study,” which tested 50 mg twice daily and 75 mg twice daily versus placebo over 52 weeks. Claassen said patients were required to have a clinical diagnosis of MSA, motor symptoms for four years or less, and no severe impairment. The study also required elevated brain iron on MRI and elevated plasma neurofilament light chain (NFL), which Claassen said increased the positive predictive value that enrolled participants truly had MSA.
Claassen described the modified UMSARS-I (excluding a sexual function item) as the main clinical endpoint and said participants were generally balanced across treatment arms, with baseline modified UMSARS-I reflecting mild-to-moderate symptoms.
Discussing previously disclosed topline results, Claassen said both doses showed separation from placebo, with a treatment effect “approach[ing] 50%” in the 50 mg group and roughly “a third” in the 75 mg group, corresponding to differences of 3.8 and 2.4 UMSARS points, respectively. He noted that published discussions in the field often cite about 1.5 points as meaningful.
Claassen then presented an analysis that adjusted for CSF NFL, which he said was pre-specified in the statistical analysis plan. With CSF NFL as a covariate, Claassen said the estimated treatment effect remained about 46% for 50 mg and the 75 mg group improved to about a one-third effect with a 2.7-point difference versus placebo.
He also reviewed an item-level analysis suggesting a broad effect across UMSARS-I domains—including speech and swallowing, dexterity-related tasks, and walking—rather than being driven by one or two items.
Imaging results: iron mapping and “decoupling” from clinical decline
A major focus of Claassen’s presentation was quantitative susceptibility mapping (QSM), an MRI-based method to quantify brain iron. He said the study was among the first global, multicenter MSA trials to deploy QSM, and described key MSA-related iron regions including the putamen and globus pallidus (lentiform nucleus), substantia nigra, and dentate nucleus.
Claassen said longitudinal QSM data suggested the substantia nigra and dentate nucleus were relatively flat over time, while the lentiform nucleus showed more informative increases over the one-year period. In model-based comparisons adjusting for age, sex, baseline CSF NFL, and baseline iron, Claassen described a pattern favoring therapy—particularly in the 50 mg group—suggesting reduced iron accumulation versus placebo in key regions, including the globus pallidus.
Claassen highlighted correlations between increased iron and worsening UMSARS in placebo-treated patients, especially in the lentiform nucleus. In treated patients, he said those correlations disappeared, describing this as a “decoupling” that supported mechanistic validity for ATH434’s intended effect on disease biology.
He also discussed an exploratory “atrophy index” approach to brain volume changes, noting the study was not powered for atrophy outcomes but that treated patients showed a pattern favoring reduced atrophy change versus placebo over time.
Phase III planning: dose selection, enrollment strategy, and FDA interactions
Stamler said Alterity plans to advance ATH434 into a single Phase III trial of approximately 200 patients, randomized 1:1 to 50 mg twice daily or placebo for 12 months. While Phase II showed signals at both dose levels, Stamler said exposure-response work suggested efficacy plateaued at the 50 mg dose, with no incremental benefit at higher exposure. He said pharmacokinetic modeling indicated about 50% higher exposure at 75 mg than 50 mg, but plotting efficacy versus exposure showed a “flat slope,” leading the company to select 50 mg twice daily as the Phase III dose.
For patient selection in Phase III, Stamler said participants will need to be ambulatory without assistance and will be screened using biomarkers to improve diagnostic precision. He said Alterity plans to use an MRI biomarker of brain atrophy “instead of brain iron,” describing atrophy as easier to operationalize and “equally or more reliable” for identifying MSA patients. The company also intends to require elevated plasma NFL to help exclude Parkinson’s disease patients, and will stratify randomization by NFL levels.
Stamler said the proposed primary endpoint is modified UMSARS-I, and he characterized this as consistent with prior FDA feedback. Secondary endpoints are expected to include orthostatic hypotension symptoms and wearable movement sensor metrics, among others. He added that covariates including CSF NFL will be incorporated into efficacy analyses.
On regulatory progress, Stamler said the company recently reached alignment with the FDA in two Type C meetings related to clinical pharmacology, bioanalytical and non-clinical elements, and that it also reached agreement on chemistry and manufacturing plans. He said Alterity expects an end-of-Phase II meeting with the FDA midyear to discuss the Phase III protocol, with site startup activities targeted by year-end and first patient dosing planned within six months of receiving written FDA feedback.
Clinician Q&A: endpoint relevance and trial approach
In the Q&A, Freeman said UMSARS “does a very good job” capturing the patient experience in a complex multisystem disease and measures variability and decline well, particularly when paired with diagnostic biomarkers to create a more homogeneous trial population. Claassen added that UMSARS captures items patients frequently cite as burdensome, including speech, swallowing, gait impairment, and dexterity.
Asked what differentiates Alterity’s approach, Claassen pointed to a “polymarker approach” to confirm diagnosis and track progression, and said the Phase II signal was supported across multiple measures, including wearable sensors, clinical impression of severity, and orthostatic hypotension symptom scores. Freeman said the Phase II data showing effects “across the board,” combined with study design and an upstream mechanism of action, supported moving forward.
Stamler said the company views Phase II changes as clinically meaningful, noting both dose groups exceeded an independently cited 1.5-point minimal clinically important difference on UMSARS. He said the FDA has encouraged use of UMSARS-I in prior interactions because it reflects how patients feel and function.
About Alterity Therapeutics (NASDAQ:ATHE)
Alterity Therapeutics is a clinical-stage biotechnology company focused on the development of novel treatments for neurological and neurodegenerative disorders. The company’s research portfolio centers on small molecules designed to target underlying disease mechanisms, with an emphasis on improving synaptic function and mitigating neuroinflammation.
Among its lead assets is trofinetide (NNZ-2566), a peptide analog derived from insulin-like growth factor 1, which is being investigated for the treatment of Rett syndrome and Fragile X syndrome in ongoing clinical trials.
