Acadia topline data supports 60 mg remlifanserin for Alzheimer's psychosis

Acadia Pharmaceuticals Inc. (Nasdaq: ACAD) released Phase 3 enabling topline results from the Phase 2 portion of the RADIANT clinical trial program. The data for remlifanserin in Alzheimer's disease psychosis (ADP) show efficacy trends that support continuing Phase 3 development of the 60 mg once-daily dose, while the 30 mg dose showed minimal improvement compared to placebo.

For the primary endpoint, measured as the change in hallucinations and delusions symptoms at week 6, the 60 mg dose demonstrated a change of -12.6 versus -10.4 for placebo. This result yielded a standardized effect size of 0.26 with a p-value of 0.0603, narrowly missing statistical significance. The key secondary endpoint, Clinical Global Impression Severity for ADP (CGI-S-ADP), showed a change from baseline of -1.3 for the 60 mg dose versus -0.9 for placebo at week 6. This secondary endpoint achieved nominal statistical significance with a p-value of 0.0077 and a standardized effect size of 0.37. All analyses were conducted in the pre-specified modified full analysis set population.

Across both doses, remlifanserin maintained a favorable safety and tolerability profile, with adverse event rates similar to placebo and no signal of QT prolongation. The dataset suggests no negative impact on motor symptoms or cognition, and there were no deaths in the remlifanserin treatment arms. Based on these findings, Acadia plans to continue enrolling in its two ongoing Phase 3 studies for ADP while implementing amendments to remove the 30 mg dosage arm.

Catherine Owen Adams, Chief Executive Officer of Acadia Pharmaceuticals, stated that the Phase 2 data support continuation of the Phase 3 ADP program and provide valuable information regarding efficacy, safety, and tolerability. Jeffrey Cummings, M.D., Sc.D., Director of the Chambers-Grundy Center for Neuroscience at the University of Nevada, Las Vegas, noted that the findings provide encouraging evidence that 60 mg once-daily remlifanserin may reduce hallucinations and delusions in patients with Alzheimer's disease.

Acadia will present detailed safety and efficacy results from the RADIANT Phase 2 study at the Clinical Trials on Alzheimer's Disease (CTAD) conference in Boston from November 16-19, 2026. The company is also investigating remlifanserin in an additional Phase 2 study for Lewy body dementia psychosis.