The FDA approved Regeneron’s garetosmab (branded Pasatru) for fibrodysplasia ossificans progressiva (FOP), giving patients a second cleared therapy for an ultrarare disorder that turns soft tissue into bone. The decision follows a Phase 3 Optima study in which Pasatru reduced new bone lesions and decreased clinician-assessed flare-ups in adults. Regeneron said the approval was based on randomized data from 63 adults with FOP who received every-four-weeks infusions of high- or low-dose Pasatru or placebo for 56 weeks. In the trial, both doses reduced new lesions by about 90% versus placebo, with high-dose Pasatru also producing a large reduction in painful inflammation episodes. The company positioned Pasatru for commercial availability in the U.S. for roughly 220 adult patients and highlighted the long development timeline behind the activin A antibody approach.