Regeneron Pharmaceuticals (NASDAQ: REGN) Received FDA Approval Thursday August 20, 2026 for Pasatru (Garetosmab-Grts, an Anti-Activin A Monoclonal Antibody Administered as Subcutaneous Injection) for the Reduction of the Formation of New Heterotopic Ossification (HO) Lesions and Clinician-Assessed Flare-Ups in Adults With Fibrodysplasia Ossificans Progressiva (FOP), a Rare Genetic Disease in Which Skeletal Muscle and Connective Tissue Progressively Turn Into Bone Through Extra-Skeletal Ossification Triggered by Activin A Signaling; The Pasatru Approval Marks the Second FDA-Approved Therapy for FOP After Ipsen's Sohonos (Palovarotene) Approved in 2023, Extends Regeneron's Growing Rare-Disease Commercial Portfolio Alongside Eylea (Aflibercept), Dupixent (Dupilumab), and the Antibody-Drug Conjugate Programs in Development
Regeneron Pharmaceuticals (NASDAQ: REGN) received FDA approval Thursday August 20, 2026 for Pasatru (garetosmab-grts, an anti-activin A monoclonal antibody administered as subcutaneous injection) for the reduction of the formation of new heterotopic ossification (HO) lesions and clinician-assessed flare-ups in adults with fibrodysplasia ossificans progressiva (FOP). FOP is a rare autosomal-dominant genetic disease affecting roughly 1 in 2 million people globally (approximately 800 patients in the US) in which skeletal muscle and connective tissue progressively turn into bone through extra-skeletal ossification triggered by activin A signaling through mutated ACVR1 (activin receptor A type 1) receptors. Patients typically develop the first flare-ups in early childhood, with progressive immobilization by adulthood as ossification advances across major joints. Pasatru's mechanism: garetosmab binds activin A and blocks its signaling through the mutated ACVR1 receptors, reducing the flare-up frequency and slowing new HO lesion formation. The approval marks the second FDA-approved therapy for FOP after Ipsen's Sohonos (palovarotene, a retinoic acid receptor gamma agonist small molecule) approved in 2023. Pasatru offers a mechanistically distinct alternative for patients who cannot tolerate palovarotene or who need combination or sequential therapy. The Pasatru approval extends Regeneron's growing rare-disease commercial portfolio alongside Eylea (aflibercept for wet AMD), Dupixent (dupilumab for atopic dermatitis and asthma), and multiple antibody-drug conjugate programs in development. Pricing and launch details have not been publicly disclosed but rare-disease pricing typically runs $300,000-$500,000 per patient per year.