This clinical trial is focused on studying a condition known as Osteogenesis Imperfecta, often referred to as brittle bone syndrome. This is a genetic disorder that causes bones to break easily, sometimes with little or no apparent cause. The study is testing a treatment called Setrusumab, which is a type of medication known as a monoclonal antibody. Monoclonal antibodies are proteins made in a lab that can bind to substances in the body, and in this case, Setrusumab is designed to target and neutralize a protein involved in bone breakdown.

The purpose of the study is to evaluate the safety and effectiveness of Setrusumab in reducing the rate of bone fractures in individuals with Osteogenesis Imperfecta. The study is divided into two phases. In the first phase, different doses of Setrusumab will be tested to find the most effective dose. In the second phase, participants will receive either Setrusumab or a placebo to compare the effects. The study will monitor participants over a period of time to see how the treatment affects their bone health and fracture rates.

Participants in the study will receive Setrusumab through an intravenous infusion, which means the medication is given directly into a vein. The study will involve regular visits to the clinic for these infusions and for monitoring the participants’ health and response to the treatment. The goal is to determine if Setrusumab can help reduce the number of fractures and improve the quality of life for those living with Osteogenesis Imperfecta.