Ultragenyx, Mereo Shares Dive As Brittle Bone Disease Drug Misses Early Win

Core Viewpoint - Ultragenyx Pharmaceutical Inc. and Mereo BioPharma Group plc stocks are experiencing significant declines following the update on the Phase 3 Orbit study for UX143 (setrusumab) in patients with osteogenesis imperfecta (OI) [1][2]. Group 1: Study Progress and Analysis - The Phase 3 portion of the Orbit study is progressing towards a final analysis expected by the end of the year, in line with the original plan [2]. - The second interim analysis did not meet the minimal p-value threshold of p<0.01, which would have allowed the study to conclude early [3]. - The Data Monitoring Committee confirmed that UX143 has an acceptable safety profile, recommending the continuation of the study [3][4]. Group 2: Future Expectations - The final analyses for the Orbit and Cosmic studies will occur after patients have been on therapy for at least 18 months, with thresholds set at p<0.04 for Orbit and p<0.05 for Cosmic [5]. - Analysts express optimism regarding the final analysis, anticipating a positive outcome due to longer follow-up duration and a lower statistical significance threshold [6]. Group 3: Market Reaction - Following the update, RARE stock has dropped by 26.2% to $30.60, while MREO stock has decreased by 34.7% to $1.919 [7].