Acadia Pharmaceuticals Receives FDA Fast Track Designation for Remlifanserin in Alzheimer's Disease Psychosis
Key Insights
The FDA has granted Fast Track designation to remlifanserin (search), Acadia's investigational 5-HT2A receptor (search) inverse agonist, for treating hallucinations and delusions associated with Alzheimer's disease psychosis (search).
Alzheimer's disease psychosis (search) currently has no FDA-approved therapies, highlighting a significant unmet medical need for the affected patient population.
Enrollment in the Phase 2 portion of the RADIANT development program has been completed, with topline results now expected between September and October 2026.
Acadia Pharmaceuticals Inc. announced today that the U.S. Food and Drug Administration (FDA) has granted Fast Track designation to remlifanserin (search), an investigational, highly selective 5-HT2A receptor (search) inverse agonist, for the treatment of hallucinations and delusions associated with Alzheimer's disease psychosis (search) (ADP). The designation underscores the significant unmet need in this patient population, as there are currently no FDA-approved therapies for ADP.
"FDA Fast Track designation for remlifanserin (search) underscores the significant unmet need for new treatment options for people living with Alzheimer's disease psychosis (search), a serious condition for which there are currently no FDA-approved therapies," said Catherine Owen Adams, Chief Executive Officer of Acadia. "This is an important milestone for the remlifanserin program, and we look forward to sharing upcoming topline data from the RADIANT Phase 2 trial as we continue to advance remlifanserin as a potential new treatment option for patients and families impacted by this devastating condition."
Fast Track Designation and Regulatory Implications
Fast Track designation is designed to facilitate the development and expedite the review of drugs intended to treat serious conditions and fill an unmet medical need, with the goal of getting important new drugs to patients earlier. The designation provides Acadia with opportunities for more frequent interactions with the FDA, the potential for priority review of a future new drug application, and the possibility of rolling review.
RADIANT Development Program Update
Acadia also provided an update on RADIANT, its development program evaluating remlifanserin (search) for the treatment of hallucinations and delusions associated with ADP. Enrollment in the Phase 2 portion of the program has been completed, and the company now expects to report topline results in September to October 2026. Consistent with RADIANT's operationally seamless design, screening and enrollment are already underway in the Phase 3 studies, potentially accelerating the overall development timeline.
Mechanism of Action and Differentiation
Remlifanserin (search) (ACP-204) is a potent and highly selective serotonin 5-HT2A receptor (search) inverse agonist. The compound is believed to reduce hallucinations and delusions through selective 5-HT2A receptor inverse agonism, potentially restoring excitatory/inhibitory (E/I) balance without direct dopamine (D2) blockade. This mechanism may allow remlifanserin to avoid the common safety and tolerability issues associated with atypical antipsychotics, which are frequently used off-label in this population despite lacking an FDA-approved indication for ADP.
Beyond Alzheimer's disease psychosis (search), remlifanserin (search) is also being investigated for Lewy body–associated psychosis (search), representing a broader development strategy targeting dementia-related psychotic symptoms.
Acadia's Neuroscience Portfolio
Acadia Pharmaceuticals is focused on developing therapies for underserved neurological and rare disease communities. The company's commercial portfolio includes the first and only FDA-approved treatments for Parkinson's disease psychosis and Rett syndrome. The remlifanserin (search) program represents a key component of Acadia's mid- to late-stage pipeline, which also includes programs in Lewy body dementia psychosis, alongside earlier-stage programs addressing other underserved patient needs.