According to an announcement from Regeneronthe company's Phase 3 OPTIMA trial for garetosmab has yielded positive results. Garetosmab is a monoclonal antibody developed to treat the ultra-rare genetic disorder, Fibrodysplasia Ossificans Progressiva (FOP). This debilitating disease causes muscles, tendons, and ligaments to progressively be replaced by bone, leading to incapacitation. The OPTIMA trial, which enrolled 63 adults with FOP, met its primary endpoint, demonstrating that garetosmab is highly effective in preventing the formation of new, abnormal bone. At 56 weeks, the trial showed a remarkable 94% reduction in the number of new heterotopic ossification (HO) lesions in the 3 mg/kg dose group and a 90% reduction in the 10 mg/kg dose group, compared to the placebo. A post-hoc analysis further confirmed these findings, revealing that garetosmab prevented over 99% of the total volume of new HO lesions. the company's Phase 3 OPTIMA trial for garetosmab has yielded positive results. Garetosmab is a monoclonal antibody developed to treat the ultra-rare genetic disorder, Fibrodysplasia Ossificans Progressiva (FOP). This debilitating disease causes muscles, tendons, and ligaments to progressively be replaced by bone, leading to incapacitation. The OPTIMA trial, which enrolled 63 adults with FOP, met its primary endpoint, demonstrating that garetosmab is highly effective in preventing the formation of new, abnormal bone. At 56 weeks, the trial showed a remarkable 94% reduction in the number of new heterotopic ossification (HO) lesions in the 3 mg/kg dose group and a 90% reduction in the 10 mg/kg dose group, compared to the placebo. A post-hoc analysis further confirmed these findings, revealing that garetosmab prevented over 99% of the total volume of new HO lesions.

Regeneron scientists discovered that the Activin A protein is a key driver of HO lesions in FOP. Garetosmab works by neutralizing this protein. The trial's success marks a significant milestone, as garetosmab is the first and only investigational therapy to demonstrate such a dramatic reduction in both the number and volume of new bone lesions. The Independent Data Monitoring Committee (IDMC), based on these compelling efficacy and safety data, has recommended that all patients on the placebo arm be transitioned to garetosmab as soon as possible. Regeneron is now planning to submit garetosmab for regulatory approval in the U.S. by the end of 2025, with global submissions to follow in 2026. A Phase 3 trial for adolescents and children with FOP is also planned for the coming year.