Acadia Pulls Plug on Prader-Willi Drug After Phase 3 Trial Failure

Acadia Pharmaceuticals is discontinuing development of its drug carbetocin (ACP-101) for Prader-Willi syndrome after a Phase 3 clinical trial failed to show efficacy compared to placebo for reducing hyperphagia (insatiable hunger) in patients with the condition1 2 5 6.

The 12-week COMPASS PWS trial enrolled 175 participants with Prader-Willi syndrome aged 5–30 years and tested intranasal carbetocin three times daily against placebo1 2.

ACP-101 showed no statistically significant improvement in hyperphagia or any secondary endpoints versus placebo, leading to termination of the program1 2 4.

Acadia acquired the drug as part of its purchase of Levo Therapeutics in 2022; Levo had also failed to win regulatory approval for its use prior to acquisition1 7.

Following the news, Acadia’s stock declined by 11%, while that of Soleno Therapeutics, which markets Vykat XR—the first approved drug for hyperphagia in Prader-Willi syndrome—rose 13%1.

The result leaves Soleno’s Vykat XR as the only currently approved therapy for hyperphagia in Prader-Willi syndrome, with the market exit of Acadia’s candidate1 3.

Despite this setback, Acadia maintains a positive outlook regarding other drugs in its pipeline, including potential treatments for Alzheimer’s disease psychosis1.