Remlifanserin (ACP-204) - (RADIANT)

September 24, 2026: Acadia Pharmaceuticals (NASDAQ: ACAD) reported Phase 3-enabling topline results from the Phase 2 portion of the ongoing RADIANT program of remlifanserin in hallucinations and delusions associated with Alzheimer’s disease psychosis (ADP). The 60 mg once-daily dose narrowly missed the primary endpoint, SAPS-H+D change at week 6, with -12.6 versus -10.4 for placebo (effect size 0.26; p=0.0603), but showed nominal significance on the key secondary endpoint CGI-S-ADP, with -1.3 versus -0.9 for placebo (effect size 0.37; p=0.0077). The treatment difference increased through the 6-week period. The 30 mg dose showed minimal improvement versus placebo.

Across both doses, safety and tolerability were favorable, with adverse event, serious adverse event, and discontinuation rates similar to placebo; no QT prolongation signal, no deaths in remlifanserin arms, and no negative impact suggested on motor symptoms or cognition.

Based on these data, Acadia will continue enrolling two ongoing Phase 3 ADP studies and amend the program to remove the 30 mg arm. Detailed Phase 2 results will be presented at CTAD, November 16-19, 2026, in Boston. Remlifanserin is also being studied in a separate Phase 2 trial in Lewy body dementia psychosis.