Acadia Pharmaceuticals Inc. announced disappointing results from its Phase 3 COMPASS PWS trial, revealing that intranasal carbetocin (ACP-101) failed to demonstrate statistically significant improvement over placebo in treating hyperphagia associated with Prader-Willi syndrome (PWS). The trial did not meet its primary endpoint nor show separation from placebo on any secondary endpoints.
Trial Design and Results
COMPASS PWS was a 12-week, double-blind, randomized, placebo-controlled global Phase 3 trial that enrolled 175 children and adults aged 5 to 30 years with PWS. The study evaluated the efficacy and safety of intranasal carbetocin 3.2 mg administered three times daily compared to placebo.
The primary endpoint measured change from baseline to Week 12 on the Hyperphagia Questionnaire for Clinical Trials (HQ-CT), a caregiver-reported measure of food-seeking behaviors in individuals with PWS. Despite the therapeutic rationale, intranasal carbetocin failed to show meaningful clinical benefit over placebo.
Safety Profile Remains Consistent
The safety and tolerability profile of intranasal carbetocin remained consistent with previous clinical trials, demonstrating a low rate of adverse events. This finding suggests that while the treatment was well-tolerated, it lacked the therapeutic efficacy needed for PWS patients struggling with hyperphagia.
Company Response and Future Plans
"We are disappointed by these findings, especially for Prader-Willi syndrome patients, their families and the entire community," said Elizabeth H.Z. Thompson, Ph.D., Acadia's Head of Research and Development. Thompson acknowledged the dedication of patients, families, study site personnel, and physicians who participated in the clinical development program.
Given these results, Acadia announced it will not pursue further investigation of intranasal carbetocin. However, the company committed to sharing a summary of the data with the PWS community to ensure learning from the study outcomes.
Broader Pipeline and Growth Outlook
Despite this setback, CEO Catherine Owen Adams emphasized Acadia's strong position for future growth. "Acadia is well-positioned to deliver long-term, sustainable growth supported by two approved products projected to generate over $1 billion in net sales in 2025, and a robust pipeline that includes eight disclosed and multiple undisclosed programs," Adams stated.
The company anticipates seven Phase 2 or 3 study starts through 2026 and four data readouts by the end of 2027. Acadia's current portfolio includes FDA-approved treatments for Parkinson's disease psychosis and Rett syndrome, with ongoing clinical-stage development efforts focused on Alzheimer's disease psychosis, Lewy Body Dementia psychosis, and multiple other neuroscience and neuro-rare disease programs.
