ACAD Stock Down 10% Following Phase III Hyperphagia Study Failure

Core Insights - Acadia Pharmaceuticals' shares fell by 9.9% following disappointing results from a late-stage study of ACP-101 for hyperphagia in Prader-Willi syndrome [1][3] Study Results - The phase III COMPASS PWS study evaluated a 3.2 mg thrice-daily dose of ACP-101 in 175 participants aged 5 to 30 years [2] - ACP-101 did not achieve a statistically significant benefit over placebo on the primary endpoint and failed to show separation from placebo on secondary endpoints [3] Financial Performance - Despite the setback, Acadia's shares have gained 15.8% year-to-date, outperforming the industry growth of 3.6% [3] - Nuplazid and Daybue sales rose significantly in the first half of 2025, contributing to revenue growth [5] Marketed Products - Nuplazid generated $328.2 million in sales in H1 2025, a 14% increase year-over-year, benefiting from volume growth [7] - Daybue recorded $180.7 million in sales in H1 2025, up 13% year-over-year, indicating strong growth in new patient starts and treatment persistence [8] Pipeline Development - Acadia is focused on developing its pipeline candidates to reduce reliance on Nuplazid for revenue [9] - A regulatory filing for trofinetide for Rett syndrome is under review in the EU, with approval expected in Q1 2026 [9] - ACP-204 is being developed for Alzheimer's disease psychosis, with enrollment completion anticipated in Q1 2026 and top-line data expected mid-2026 [10] Competitive Landscape - Soleno Therapeutics' Vykat XR has gained a stronger market position following Acadia's decision to discontinue ACP-101, as it is now the only FDA-approved treatment for hyperphagia in PWS [12][13]