ACP-204 · program

Remlifanserin for Lewy body dementia psychosis

Phase 2RecruitingACADIA Pharmaceuticals Inc. (ACAD)

Indications for ACP-204: Alzheimer's disease psychosis · Phase 3 Lewy body dementia psychosis · Phase 2

Remlifanserin (ACP-204) for psychosis associated with Lewy body dementia (LBDP — a term that as used by the sponsor and the registry encompasses dementia with Lewy bodies and Parkinson's disease dementia), the second indication for ACADIA's selective 5-HT2A inverse agonist. ACADIA guided at its inaugural R&D Day (2025-06-25) to a Phase 2 LBDP start in Q3 2025; the study, NCT07029581 (ACP-204-012), 'A Double-Blind, Placebo-Controlled, Phase 2, Efficacy and Safety Study of ACP-204 in Adults With Lewy Body Dementia Psychosis', started 2025-08-06 and is recruiting: approximately 180 adults aged 55–85, ACP-204 30 mg or 60 mg vs placebo over 6 weeks, primary endpoint change from baseline in SAPS-LBDP total score at Week 6. A 52-week open-label extension, NCT07095465 (ACP-204-013, 126 subjects, enrolling by invitation), started 2025-11-14; it is registered on ClinicalTrials.gov as Phase 3 but is a long-term safety extension, not a confirmatory efficacy study, so the program is recorded as Phase 2 — consistent with ACADIA's own pipeline page. No FDA designations have been announced for LBDP (the 2026-07-20 Fast Track applies to Alzheimer's disease psychosis only), and no company topline date has been guided.

Data current as of

Development timeline

Phase 2Aug 2025 – Feb 2028
  1. UpcomingClinicalTrials.gov estimated primary completion of the Phase 2 Lewy body dementia psychosis efficacy study (NCT07029581, ACP-204-012): February 2028 (estimated study completion March 2028).
  2. 52-week open-label extension NCT07095465 (ACP-204-013) started, enrolling by invitation (126 subjects; primary outcome proportion of subjects with TEAEs; estimated primary completion February 2029). Registered on ClinicalTrials.gov as Phase 3, but as a safety extension it is not treated as a Phase 3 advance for this program.
  3. ACADIA publicly confirmed the program in its Q3 2025 financial results and operating overview, citing initiation of a Phase 2 study of ACP-204 for Lewy Body Dementia Psychosis as a pipeline advance for the quarter.↗
  4. Phase 2 LBDP efficacy/safety study NCT07029581 (ACP-204-012) start date per ClinicalTrials.gov: 180 participants, ACP-204 30 mg / 60 mg / placebo, 6-week double-blind parallel-group design, primary endpoint change from baseline in SAPS-LBDP total score at Week 6. Estimated primary completion February 2028, study completion March 2028. Delivers on the Q3 2025 initiation target set at the 2025-06-25 R&D Day.

Readouts

  • February 2028AnticipatedRegistry resultsNCT07029581

    ClinicalTrials.gov estimated primary completion of the Phase 2 Lewy body dementia psychosis efficacy study (NCT07029581, ACP-204-012): February 2028 (estimated study completion March 2028).

Clinical trials in Lewy body dementia psychosis

NCT07095465ACP-204-013Phase 3Recruitingn=126

52-Week, Phase 3, Open-Label Extension Study of ACP-204 in Adults With Lewy Body Dementia Psychosis (LBDP)

Started Nov 2025· Primary completion Feb 2029· 📍 15 sites across 3 countries (United States, Bulgaria, Czechia)

NCT07029581ACP-204-012Phase 2Recruitingn=180

A Double-Blind, Placebo-Controlled, Phase 2, Efficacy and Safety Study of ACP-204 in Adults With Lewy Body Dementia Psychosis (LBDP)

Started Aug 2025· Primary completion Feb 2028· 📍 56 sites across 6 countries (United States, France, Bulgaria, Czechia)

Formulations

FormulationRouteRegimenPharmacokinetics
Remlifanserin oral capsule (30 mg / 60 mg once daily)
30 mg or 60 mg PO once daily in the Phase 2/3 RADIANT master protocol (ACP-204-006) and the ACP-204-008 open-label extension (60 mg QD initial dose, then flexible 30 or 60 mg QD); 30 mg and 60 mg QD in the Phase 2 Lewy body dementia psychosis study NCT07029581. Phase 1: single ascending oral doses 10-180 mg; multiple ascending doses up to 60 mg (healthy elderly) and 120 mg (healthy adults) for 10 days; the food-effect study used a 60 mg oral capsule.
OralOnce dailyt½ 19.8 h · Tmax 5.98 h

Mechanism of action (compound-wide)

Potent, highly selective inverse agonist and functional antagonist at the serotonin 5-HT2A receptor (HTR2A), a Gq-coupled class-A GPCR. Nonclinical characterization reports subnanomolar affinity in 5-HT2A radioligand binding and subnanomolar inverse-agonist and antagonist potency in cell-based functional assays, with 13-fold lower affinity for 5-HT2C in binding and 30- to 100-fold lower potency at 5-HT2C in functional assays, and >1000-fold selectivity against more than 70 other targets. No appreciable agonist activity was seen at 5-HT1A/1B/1D/1E/1F, 5-HT2B, 5-HT7, alpha-1A/alpha-2A/2B/2C adrenergic, D1, D2, H1, or M1-M5 muscarinic receptors. Compared with pimavanserin it has 9-fold lower hERG inhibitory potency and lower potency at Cav1.2 and Nav1.5. It was orally active in three rodent models of schizophrenia and engaged central 5-HT2A receptors in non-human primates. The clinical hypothesis is that selective 5-HT2A inverse agonism reduces hallucinations and delusions by restoring excitatory/inhibitory balance without direct dopamine D2 blockade.

TargetActionAffinity
5-HT2AprimaryHTR2AInverse agonist—ⓘ
5-HT2CHTR2CInverse agonist—ⓘ

← Full ACP-204 compound page (identity, identifiers, all indications)

Sources

  1. Acadia Pharmaceuticals Reports Third Quarter 2025 Financial Results and Operating Overview (2025-11-05) — initiation of a Phase 2 study of ACP-204 for Lewy Body Dementia Psychosis — ACADIA Pharmaceuticals Inc.
  2. Burstein ES, et al. Nonclinical characterization of ACP-204, a novel selective serotonin 5-HT2A receptor inverse agonist. J Pharmacol Exp Ther. 2026;393(6):104932 — Journal of Pharmacology and Experimental Therapeutics (ASPET) / PubMed
  3. Darwish M, et al. Effect of Food Consumption on the Pharmacokinetics of ACP-204, a Novel 5-HT2A Receptor Selective Antagonist/Inverse Agonist. Alzheimer's & Dementia. 2025 — Alzheimer's & Dementia (Wiley) via PubMed Central
  4. NCT07029581 (ACP-204-012) — A Double-Blind, Placebo-Controlled, Phase 2, Efficacy and Safety Study of ACP-204 in Adults With Lewy Body Dementia Psychosis (LBDP) — ClinicalTrials.gov (U.S. National Library of Medicine)
  5. NCT07095465 (ACP-204-013) — 52-Week, Phase 3, Open-Label Extension Study of ACP-204 in Adults With Lewy Body Dementia Psychosis (LBDP) — ClinicalTrials.gov (U.S. National Library of Medicine)