ACADIA posts Phase 3 carbetocin nasal spray results in Prader-Willi syndrome

ACADIA Pharmaceuticals Inc. posted results for a Phase 3 study of carbetocin nasal spray in hyperphagia in Prader-Willi syndrome. The study record, NCT06173531, lists results first posted on 2026-10-15. The study is marked completed, and primary completion is listed as 2025-08-19.

The study record

The official title describes a Phase 3, randomized, double-blind, placebo-controlled, parallel-group study. The record lists 175 participants. The record says 85 started on carbetocin and 90 started on placebo. Carbetocin nasal spray 3.2 mg was given three times daily, and a matching placebo nasal spray was given on the same schedule. Each dose was four sprays, two per nostril, over a 12-week double-blind treatment period.

The study began on 2023-11-27. Participants were aged 5 to 30 years, had a diagnosis of Prader-Willi syndrome with a documented disease-causing genetic mutation, and showed evidence of hyperphagia. The record says each participant lived with a caregiver. Caregivers acted as informants for the assessments. Caregivers were not enrolled participants, were not randomized, and received no study treatment.

The record says 82 participants on carbetocin and 86 on placebo completed the study. The record says 3 participants on carbetocin and 4 on placebo did not complete it. Efficacy outcomes were analyzed in the Full Analysis Set, which the record defines as all randomized participants with PWS who received at least one dose of study drug and had a Baseline HQ-CT assessment. The set held 83 participants on carbetocin and 88 on placebo.

The primary outcome

The primary outcome is the change from baseline at Week 12 in the Hyperphagia Questionnaire for Clinical Trials (HQ-CT) score. The record describes the HQ-CT as a caregiver-reported, 9-item assessment of observable hyperphagia-related behaviors. Each item is scored from 0 to 4, so the total score ranges from 0 to 36. The record says higher scores indicate greater severity of hyperphagia. Baseline decreases reflect improvement. The record says a reduction of 7.7 points has been identified as a clinically meaningful within-participant improvement.

The posted least squares mean change was -4.8 (standard error 0.78) in the carbetocin group and -5.1 (standard error 0.75) in the placebo group. The record lists a least squares mean difference of 0.3, with a 95 percent confidence interval of -1.8 to 2.4 and a p-value of 0.7889. The record names a mixed-effects model for repeated measures as the statistical method. The record says missing data were handled under a missing at random assumption.

The secondary outcomes

The record posts four secondary outcomes with comparisons between the groups.

Clinical Global Impression of Severity (CGI-S) for PWS, change from baseline at Week 12: -0.4 on carbetocin and -0.5 on placebo. The difference is 0.1, with a 95 percent confidence interval of -0.2 to 0.3 and a p-value of 0.6507.
Clinical Global Impression of Change (CGI-C) for PWS at Week 12: 3.6 in both groups. The difference is 0.0, with a 95 percent confidence interval of -0.3 to 0.4 and a p-value of 0.9272.
Treatment response at Week 12, defined as an improvement from baseline of at least 8 points in the HQ-CT total score: 25 participants on carbetocin and 32 on placebo. The odds ratio is 0.8, with a 95 percent confidence interval of 0.4 to 1.5 and a p-value of 0.4992.
CGI-S for hyperphagia in PWS, change from baseline at Week 12: -0.7 in both groups. The difference is -0.1, with a 95 percent confidence interval of -0.4 to 0.3 and a p-value of 0.6400.

The record describes the CGI-S as a clinician-rated assessment on a 7-point scale. The record describes the CGI-C as a clinician-rated assessment of change relative to Baseline, also on a 7-point scale.

Adverse events

The adverse event section covers participants with PWS only. The record lists no deaths and no serious adverse events in either group. Other adverse events at or above the posted frequency threshold of 5 affected 11 of 83 participants on carbetocin and 9 of 88 on placebo. The record lists diarrhea in 2 participants on carbetocin and 5 on placebo, pyrexia in 5 and 1, and headache in 6 and 3.

The publication and restrictions

The record lists a derived publication, a Clin Ther paper by Roof E and colleagues from the COMPASS PWS Investigators, dated 2026 Jul 22. The paper title is "Carbetocin Nasal Spray for the Treatment of Hyperphagia in Prader-Willi Syndrome: Results From the Randomized, Placebo-Controlled, Phase 3 Compass PWS Study." The record also lists a study protocol and a statistical analysis plan.

The record states a restrictive agreement. The principal investigator must submit proposed publications to the sponsor for review at least 60 days before submission. The record does not state what comes next for carbetocin nasal spray.