Soleno Therapeutics stock jumps after rival’s Prader-Willi drug fails trial

Soleno Therapeutics (SLNO) stock surged 14% after competitor Acadia Pharmaceuticals (ACAD) announced its Phase 3 trial for a Prader-Willi syndrome treatment failed to meet its primary endpoint, leading to development discontinuation. This outcome significantly strengthens Soleno's market position as the current standard of care, removing a key competitive threat, with analysts noting no new competitive Phase 3 data is anticipated until Q3 2026.

Analysis

The failure of Acadia Pharmaceuticals' (ACAD) Phase 3 COMPASS PWS trial for its Prader-Willi syndrome (PWS) treatment, intranasal carbetocin, has materially altered the competitive landscape for this indication. Acadia's subsequent decision to discontinue the program's development triggered a 14% rise in the stock of its competitor, Soleno Therapeutics (SLNO). This event removes a significant near-term competitive threat, reinforcing Soleno's position as the provider of the standard of care and the only approved drug for PWS, as noted by Wells Fargo. The competitive runway for Soleno is now considerably clearer, with the next potential Phase 3 data from a competitor not anticipated until the third quarter of 2026 and intermediate Phase 2 data from Rhythm Pharmaceuticals expected by year-end 2025. While a Stifel analyst views this as a 'clearing event' for Acadia's stock, the primary strategic benefit accrues to Soleno, whose market dominance in PWS is now more firmly established.

Key Decisions for Investors

• The removal of a key competitor significantly de-risks Soleno's commercial outlook, and investors should re-evaluate SLNO's long-term revenue potential given its extended competitive moat until at least late 2025.
• For Acadia Pharmaceuticals, the trial failure is a clear pipeline setback, and investors should assess the company's valuation based on its remaining assets, excluding the now-discontinued PWS program.
• Market participants should monitor the PWS space for the next competitive catalysts, namely Phase 2 data from Rhythm Pharmaceuticals by year-end 2025 and Phase 3 data for ARD-101 in Q3 2026.