Acadia's ACP-204 psychosis trial still recruiting as guided readout window opens
The registered completion date for Acadia's Alzheimer's psychosis study runs to 2028, well past the sponsor's own mid-2026 readout guidance, raising a timing gap the company has not reconciled.
Executive Summary
- Acadia has guided to a second-half 2026 topline readout for its lead Alzheimer's psychosis program, repeating that timeline across three consecutive disclosures rather than pushing it back.
- The trial's own registry record lists a primary completion date well beyond the guided readout window, a discrepancy the company has not addressed in its public statements.
- A positive result would address hallucinations and delusions in Alzheimer's disease psychosis, a population that currently lacks a dedicated approved treatment, and would be the more advanced of Acadia's two 5-HT2A programs in this disease.
- No other program in clinical testing shares this drug's mechanism in this indication, so the readout carries no same-mechanism precedent to benchmark against.
The guidance
Acadia first told investors in June 2025 that it expected topline results from the Phase 2 ACP-204 study in Alzheimer's disease psychosis in mid-2026. The company repeated that guidance in January 2026 and again in May 2026, the latter narrowing the window to August through October 2026 for what it now calls remlifanserin, the renamed asset formerly known as ACP-204. All three disclosures point to the same underlying study, registered as NCT06159673. Acadia+1Acadia Pharmaceuticals Hosts Inaugural R&D Day Showcasing Pipeline and Long-Term Value DriversJun 25, 2025ACP-204 in Adults With Alzheimer's Disease PsychosisNCT06159673
Probability of SuccessBased on the AppliedXL Probability of Success model. For more information about the methodology, read the research here.
The registry gap
NCT06159673 lists a primary completion date of January 1, 2028, and a study completion date of February 1, 2028. That is more than a year past the window in which Acadia says it will report topline results. The trial remains in Recruiting status, targeting 1,074 patients across the United States, Brazil, France, Italy, South Korea, and eight other countries. A single eligibility-criteria amendment has been logged since the study's November 2023 start, and the enrollment target has not changed. NCT06159673ACP-204 in Adults With Alzheimer's Disease PsychosisNCT06159673
What the trial tests
The study is a randomized, placebo-controlled design with two experimental arms and one placebo arm, testing oral remlifanserin against placebo. Its primary endpoint is the change from baseline on the Scale for the Assessment of Positive Symptoms-Hallucinations and Delusions subscales (SAPS-H+D), a hallucinations-and-delusions severity measure, across three substudies. The secondary endpoint is the Clinical Global Impression-Improvement score in the Alzheimer's disease psychosis context. Enrolled patients must have an MMSE score of 6 to 24, indicating mild to moderate dementia, along with biomarker or imaging evidence of amyloid pathology. NCT06159673ACP-204 in Adults With Alzheimer's Disease PsychosisNCT06159673
The competitive field
No other program in clinical testing shares remlifanserin's target and mechanism in Alzheimer's disease psychosis. The nearest active peer is MapLight Therapeutics' ML-007C-MA, which is being tested in two Phase 2 studies in the same indication but works through a different mechanism. Acadia itself runs the only other Alzheimer's disease psychosis trial in this competitive field, an open-label extension study (NCT06194799) tracking treatment-emergent adverse events rather than a placebo-controlled efficacy result. With no validated disease-modifying mechanism established for Alzheimer's disease psychosis in this competitive field, a SAPS-H+D result that separates from placebo and holds up on the secondary CGI-I-ADP measure would be the signal that distinguishes this readout.
This analysis was produced using AI-assisted reporting systems, AppliedXL data, and official public records. These systems undergo editorial review, quality checks, and regular audits by human experts. Errors may still occur, as with any automated system. Always consult the linked primary sources. Read our AI Editorial Policy.