The FDA approved Regeneron’s activin A–targeting monoclonal antibody garetosmab, now branded Pasatru, for fibrodysplasia ossificans progressiva (FOP). The approval makes Pasatru the second FDA-cleared therapy for the ultrarare disorder and the first shown to reduce clinician-assessed flare-ups in adults. The decision was supported by Optima phase 3 data in 63 adults randomized to high-dose, low-dose, or placebo every four weeks. Regeneron reported major reductions in new bone lesions over 56 weeks and also reported large decreases in painful localized inflammation in the high-dose arm compared with placebo. Regeneron says Pasatru will be available to roughly 220 adult patients in the U.S. Regeneron’s approval also follows an earlier phase 3 victory reported by the company, setting up a broader commercial ramp for a patient community long limited to supportive care and one prior approved option.