PRTA stock dropped 53.5% YTD due to pipeline setbacks, but restructuring efforts may boost prospects.

Shares of Prothena Corporation (PRTA) have plummeted 53.5% year to date, significantly underperforming the industry’s decline of 0.6%. The recent pipeline setbacks have impacted PRTA’s growth prospects, leading to a 63% reduction in its workforce to lower operating costs and revised annual guidance for 2025.

In May 2025, PRTA announced the discontinuation of birtamimab development after it failed to meet primary endpoints in a late-stage clinical study for AL amyloidosis. Despite being generally safe and well-tolerated, birtamimab did not show efficacy in the AFFIRM-AL study, resulting in its discontinuation.

Partner Roche’s decision to advance prasinezumab into phase III development for early-stage Parkinson’s disease is a positive development for PRTA. Roche will handle the development and commercialization of prasinezumab, with Prothena potentially earning up to $620 million in milestone payments and royalties.

Prothena is focusing on its other pipeline programs, including PRX012 for Alzheimer’s disease and Coramitug (formerly PRX004) for ATTR amyloidosis with cardiomyopathy in collaboration with partner Novo Nordisk. The company is also advancing programs for various neurological indications with Bristol Myers, including BMS-986446 for Alzheimer’s disease treatment.

PRTA expects to receive up to $105 million in clinical milestones from partnered programs in 2026. The company’s ongoing efforts in advancing its pipeline programs and collaborations with key partners are crucial for its future growth and development in the biopharmaceutical industry.

Read more at Nasdaq: PRTA Dives 53.5% YTD: Will the Restructuring Effort Boost Prospects?