Acadia Pharmaceuticals reported Phase 2 topline results for remlifanserin in Alzheimer’s disease psychosis on September 24, 2026, via an 8-K filing with the SEC. The data come from the Phase 2 portion of the RADIANT clinical trial program, which enrolled approximately 318 patients with hallucinations and delusions associated with Alzheimer’s disease psychosis before enrollment closed in July 2026. Whether those results support the program’s advance into the already-enrolling Phase 3 studies is what the trial community is now watching.
Remlifanserin, also known as ACP-204, targets a specific mechanism in ADP rather than the general antipsychotic pathway, and Acadia has been building regulatory groundwork to match: the FDA granted Fast Track designation for remlifanserin in ADP on the same day Phase 2 enrollment closed, July 20, 2026. That designation matters in practical terms because it opens a rolling review channel, meaning Acadia can submit completed sections of a future NDA before the full package is assembled. Fast Track does not guarantee speed, but it removes one queue from the timeline if the Phase 3 data cooperate.
ADP is a condition with limited approved options and a patient population that is particularly difficult to treat safely, given the known risks antipsychotics carry in elderly patients with dementia. The 318-patient Phase 2 dataset is large enough to generate reasonably stable efficacy and safety signals, but Phase 2 in psychiatry and neurology has a long history of promising results that fail to replicate at scale. The Phase 3 studies are already underway, which means Acadia had effectively committed to that next step before the topline readout, a design and financing decision that compresses the development calendar but locks in the risk.
The full press release was attached to the 8-K filing; Acadia has not yet published the detailed dataset or a conference presentation. The specific efficacy outcomes from the 318-patient Phase 2 cohort, particularly the magnitude of symptom reduction on the primary endpoint, will determine whether the Phase 3 program design holds or needs adjustment before that larger enrollment completes.
Source link: https://www.sec.gov/Archives/edgar/data/1070494/000119312526401157/d168737d8k.htm
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
