Core Insights - The Phase 3 Orbit study for UX143 (setrusumab) in pediatric and young adult patients with osteogenesis imperfecta (OI) is on track for final analysis by the end of the year [1][3] - The Data Monitoring Committee has confirmed an acceptable safety profile for UX143, allowing the study to proceed [2] - Ultragenyx and Mereo BioPharma are collaborating on the development of setrusumab, targeting OI sub-types I, III, and IV [5][12] Study Details - The Phase 3 Orbit study has enrolled 159 patients across 45 sites in 11 countries, with a primary efficacy endpoint focused on annualized clinical fracture rate [7] - The Cosmic study, which is also in Phase 3, has enrolled 69 patients aged 2 to <7 years, comparing setrusumab to intravenous bisphosphonates [8] - Both studies will conduct final analyses after patients have been on therapy for at least 18 months, with specific statistical thresholds set for each study [4] Background on Osteogenesis Imperfecta - OI is a genetic disorder affecting bone metabolism, primarily caused by mutations in the COL1A1 or COL1A2 genes, leading to increased bone brittleness and a high rate of fractures [9] - Approximately 60,000 individuals are affected by OI in commercially accessible regions, with no globally approved treatments available [9] Mechanism of Setrusumab - Setrusumab is a fully human monoclonal antibody that inhibits sclerostin, which negatively regulates bone formation, potentially increasing bone mass and strength [10] - Previous studies have shown that anti-sclerostin antibodies can significantly improve bone formation and density in OI models [11] Company Profiles - Ultragenyx is focused on developing therapies for rare genetic diseases, with a portfolio aimed at addressing high unmet medical needs [13] - Mereo BioPharma is also dedicated to innovative therapeutics for rare diseases, with setrusumab as one of its key candidates [15]