SAN DIEGO — September 25, 2026
Acadia Pharmaceuticals Inc. announced topline Phase 2 results from the RADIANT clinical trial program evaluating remlifanserin for hallucinations and delusions associated with Alzheimer’s disease psychosis (ADP). At 60 mg once daily, remlifanserin showed a numerical improvement over placebo on the primary SAPS-H+D endpoint at Week 6, but the result narrowly missed conventional statistical significance (p=0.0603). The key secondary CGI-S-ADP endpoint showed a statistically significant nominal result (p=0.0077), supporting continued development of the 60 mg dose.
Remlifanserin Shows Efficacy Trends Across Key Endpoints
At Week 6, patients receiving 60 mg once-daily remlifanserin had a mean change from baseline of -12.6 on the SAPS-H+D subscales, compared with -10.4 for placebo, corresponding to a standardized effect size of 0.26. The primary endpoint result did not reach conventional statistical significance. On the key secondary CGI-S-ADP measure, the 60 mg group showed a -1.3 change from baseline versus -0.9 for placebo, with a standardized effect size of 0.37 and nominal p=0.0077. The company reported that the treatment-placebo separation increased over the six-week period, while the 30 mg dose showed minimal improvement compared with placebo.
Phase 2 Safety Profile Supports Continued Development
Across both remlifanserin dose groups, the company reported a favorable safety and tolerability profile, with rates of adverse events, serious adverse events and discontinuations due to adverse events similar to placebo. No QT prolongation signal versus placebo was observed, and the dataset showed no reported negative impact on motor symptoms or cognition. There were also no deaths in the remlifanserin treatment arms. The findings are preliminary topline results, with Acadia planning to provide more detailed safety and efficacy data at the Clinical Trials on Alzheimer’s Disease (CTAD) conference in November 2026.
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Acadia Advances 60 mg Dose Into Phase 3
Based on the Phase 2 findings, Acadia plans to continue enrolling two ongoing Phase 3 studies evaluating remlifanserin in ADP while amending the program to remove the 30 mg dose. RADIANT is a global, randomized, double-blind, placebo-controlled Phase 2/3 program evaluating once-daily remlifanserin. The company is also studying remlifanserin in a separate Phase 2 trial for Lewy body dementia psychosis. Remlifanserin is an investigational selective 5-HT2A receptor inverse agonist and is not FDA approved for Alzheimer’s disease psychosis.
Source :Acadia Pharmaceuticals press release
