FDA Approves Breakthrough Therapy Designation to Ultragenyx for Setrusumab (UX143) in Treating Osteogenesis Imperfecta
Ultragenyx received Breakthrough Therapy Designation from the U.S. Food and Drug Administration (FDA) for setrusumab (UX143) as a treatment to reduce fracture risk in osteogenesis imperfecta (OI) Types I, III, and IV for patients aged two years and above.
This designation reflects the significant impact of OI on patients and highlights the positive outcomes observed in the Phase 2 Orbit study.
The FDA's decision is guided by initial clinical data, including encouraging 14-month findings from the Phase 2 Orbit study, which demonstrated a swift and significant decrease in fracture rates.
Findings from the completed Phase 2b ASTEROID study also contributed to this decision. Breakthrough Therapy Designation is intended to speed up the development and review process for treatments addressing serious or life-threatening conditions that show substantial improvement over existing therapies.
Osteogenesis Imperfecta (OI) is a genetic disorder affecting bone metabolism, mainly due to mutations in the COL1A1 or COL1A2 genes. These mutations result in reduced or abnormal collagen production, leading to brittle bones and frequent fractures.The condition is associated with poor bone density, fragility, bone deformities, spinal curvature issues, pain, limited mobility, and short stature.
Setrusumab is a fully human monoclonal antibody that blocks sclerostin, a protein that inhibits bone formation. By blocking sclerostin, setrusumab is expected to promote bone growth, improve bone mineral density, and enhance bone strength. Studies in mice with OI have shown that anti-sclerostin antibodies can improve bone mass and strength.
The ASTEROID study in adults with OI demonstrated that setrusumab led to a dose-dependent improvement in bone formation and density across multiple anatomical sites.
Ultragenyx and Mereo BioPharma are jointly advancing the global development of setrusumab, supported by a collaboration and license agreement, and have designed a comprehensive late-stage program targeting OI Types I, III, and IV in younger patients.
