Regeneron Pharmaceuticals reported that its investigational drug garetosmab delivered unprecedented efficacy in a pivotal Phase 3 trial for fibrodysplasia ossificans progressiva (FOP), an ultra-rare and debilitating genetic disorder. The OPTIMA trial in adults with FOP met its primary endpoint, with garetosmab reducing the formation of new abnormal bone lesions—heterotopic ossification—by more than 90% at 56 weeks compared to placebo.
This landmark outcome positions garetosmab as the first and only therapy to demonstrate such a dramatic reduction in FOP disease progression. FOP causes muscles, tendons, and ligaments to be gradually replaced by bone, leading to severe loss of mobility and eventual incapacitation. Experts estimate only about 900 people are diagnosed with FOP worldwide, underscoring the disease’s rarity.
Given the favorable safety profile, the trial’s independent monitoring committee recommended patients on placebo transition to active treatment. Regeneron plans to file for U.S. regulatory approval by year-end, with global submissions scheduled for 2026. The company also announced plans to expand research into pediatric FOP, aiming to make garetosmab available to children as well as adults.
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