Prothena stock soars despite study miss

Investing.com — Shares of Prothena Corporation plc (NASDAQ:PRTA) surged 43% today, marking the most significant intraday rise since September 2022, even though the company announced that its Phase IIb PADOVA study, conducted by partner Roche, did not meet its primary endpoint in a trial for an experimental Parkinson’s disease drug. Despite the missed endpoint, the stock’s rise indicates investor optimism, potentially buoyed by the drug’s other positive trends and the anticipation of future development.

The Dublin-based biotechnology firm revealed that the study of prasinezumab in patients with early-stage Parkinson’s disease showed a numerical delay in motor progression and positive trends on multiple secondary and exploratory endpoints. The drug was well tolerated with no new safety signals observed. While the primary endpoint was not met, with a hazard ratio (HR) of 0.84 and a p-value of 0.0657, the results were more pronounced in a pre-specified analysis of patients treated with levodopa, showing a nominal p-value of 0.0431.

Prothena’s President and Chief Executive Officer, Gene Kinney, Ph.D., stated that the PADOVA study results represent a significant step forward in potentially delivering the first disease-modifying treatment for Parkinson’s disease. The company looks forward to discussing the study results with health authorities to determine the most appropriate path forward.

Analysts have provided mixed reactions to the news. BofA Securities analyst Tazeen Ahmad adjusted the price target on Prothena to $22.00 from $26.00 while maintaining a Neutral rating. Ahmad noted the uncertainty about the program’s future due to the lack of definitive evidence of clinical benefit after two failed phase 2 trials. Conversely, Oppenheimer analyst Jay Olson reduced the price target to $58.00 from $62.00 but maintained an Outperform rating, highlighting the upcoming AFFIRM-AL study as a more significant catalyst for the company.

In light of today’s developments, BofA Securities commented, “Today’s data release could serve as a clearing event for investors who now turn focus to PRTA’s AL amyloidosis data read out – which is the biggest driver to our NPV for PRTA shares.”

Investors appear to be responding to the potential of prasinezumab and the broader pipeline of Prothena, with particular anticipation for the phase 3 readout of birtamimab in AL amyloidosis expected in the first half of 2025, and data updates for PRX012 in Alzheimer’s disease expected in mid-2025. Full results from the PADOVA study are scheduled to be presented at an upcoming medical meeting.

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