ACADIA Pharmaceuticals Announces Phase 2 Topline Results for Remlifanserin

What Happened
On September 24, 2026, Acadia Pharmaceuticals (ACAD) announced Phase 3‑enabling topline results from the Phase 2 portion of its RADIANT program evaluating remlifanserin for hallucinations and delusions in Alzheimer’s disease psychosis (ADP). The company reported efficacy and safety findings and said it will continue enrolling its two ongoing Phase 3 studies while implementing protocol amendments, including removing the 30 mg dose arm.

Key Details

• Primary endpoint (SAPS‑H+D, week 6): 60 mg remlifanserin change from baseline = −12.6 vs placebo = −10.4; standardized effect size 0.26 (p = 0.0603).
• Key secondary endpoint (CGI‑S‑ADP, week 6): 60 mg change = −1.3 vs placebo = −0.9; standardized effect size 0.37 (p = 0.0077, nominal).
• 30 mg dose showed minimal improvement versus placebo; company plans to remove the 30 mg arm from Phase 3.
• Safety: across doses, adverse event, serious adverse event, and discontinuation rates were similar to placebo; no QT prolongation signal, no deaths in remlifanserin arms, and no observed negative impact on motor symptoms or cognition.
• Next steps: detailed RADIANT Phase 2 results to be presented at CTAD (Nov 16–19, 2026). Remlifanserin is also in a separate Phase 2 study for Lewy body dementia psychosis.

Why It Matters
These topline data guide Acadia’s next development steps for remlifanserin in ADP: the 60 mg dose showed trends toward benefit (statistically nominal on the CGI‑S secondary endpoint) while the 30 mg dose did not, prompting removal of the lower dose from Phase 3. For investors, the update affects clinical risk and timelines—Acadia will continue Phase 3 enrollment with amendments and will present full data at CTAD. The filing also contains customary forward‑looking statements and risk disclosures about clinical development, funding, and regulatory outcomes.