Setrusumab Phase 3 Trials for Osteogenesis Imperfecta Fully Enrolled

Ultragenyx Pharmaceutical Inc. has reached a significant milestone in its clinical trials for setrusumab, a potential treatment for osteogenesis imperfecta (OI), a genetic disorder affecting bone metabolism. Enrollment is complete for the Phase 3 Orbit and Cosmic studies, which are focused on pediatric and young adult patients with the condition. The Orbit study has randomized 158 patients aged 5 to 25 years, while the Cosmic study has enrolled 66 patients aged 2 to less than 7 years.

Eric Crombez, Ultragenyx's chief medical officer, expressed gratitude to the OI community for their support and participation. He highlighted the interim Phase 2 results of the Orbit study, which showed a significant reduction in fracture rates and improvements in bone mineral density (BMD) among patients treated with setrusumab. The drug was well-tolerated with no serious adverse events reported.

Nick Bishop, a professor of pediatric bone disease, emphasized the importance of developing a treatment for children with OI, including very young children. He found the interim Phase 2 results encouraging and noted the rapid recruitment for the studies as a reflection of the clinical community's positive view of the therapy.

Setrusumab is a monoclonal antibody that inhibits sclerostin, a protein that regulates bone formation. By blocking sclerostin, setrusumab is expected to increase bone formation, density, and strength. In mouse models of OI, anti-sclerostin antibodies have been shown to improve bone mass and strength.

The Phase 3 program includes the global, seamless Phase 2/3 Orbit study, which is assessing the drug's effect on clinical fracture rates in patients aged 5 to 25 years. The pivotal Phase 3 portion of this study has enrolled 158 patients across 11 countries. The Phase 3 Cosmic study is an open-label, randomized, active-controlled trial for patients aged 2 to less than 7 years, comparing setrusumab to intravenous bisphosphonates therapy.

OI is a group of genetic disorders that affect approximately 60,000 people worldwide and is characterized by increased bone brittleness and a high rate of fractures. Currently, there are no globally approved treatments for OI.

Ultragenyx is a biopharmaceutical company dedicated to developing novel products for the treatment of serious rare and ultrarare genetic diseases. The company's strategy focuses on efficient drug development to deliver safe and effective therapies urgently.

Setrusumab's development is a collaborative effort between Ultragenyx and Mereo BioPharma, with a comprehensive late-stage program aimed at pediatric and young adult patients with OI sub-types I, III, and IV. The companies are working together to continue the development of setrusumab based on a collaboration and license agreement.