FDA approves Regeneron's garetosmab for fibrodysplasia ossificans progressiva
Regeneron's antibody treatment for fibrodysplasia ossificans progressiva — an ultra-rare genetic disorder in which bone forms progressively in soft tissue — has received FDA approval under the brand name Pasatru.
The United States Food and Drug Administration has approved garetosmab (brand name Pasatru), developed by Regeneron Pharmaceuticals, for the treatment of fibrodysplasia ossificans progressiva (FOP). Stat News reported the approval on 19 August 2026.
FOP is an ultra-rare autosomal dominant condition caused almost exclusively by a heterozygous gain-of-function variant in the *ACVR1* gene, which encodes the activin receptor type I (also known as ALK2), a bone morphogenetic protein receptor. The pathogenic variant — most commonly c.617G>A (p.Arg206His) — leads to aberrant BMP signalling and progressive ectopic bone formation in muscle, tendons, ligaments, and other soft tissues. The condition is severely disabling, with a cumulative effect that significantly restricts movement over time.
Garetosmab is a monoclonal antibody that targets activin A, a ligand that drives the aberrant signalling cascade in FOP. Phase 2 trial data published previously showed a reduction in new lesion formation compared with placebo.
FOP affects approximately one in two million people globally. The approval is relevant to clinical geneticists, genetic counsellors, and specialists in rare musculoskeletal disease who advise affected families. From a research perspective, the approval illustrates how precise molecular understanding of a single-gene disorder can underpin a targeted biological therapy.
Plain-language version
For patients, families, and general readers. Educational only — not medical advice.
The United States medicines regulator (the FDA) has approved a new medicine called garetosmab, sold under the name Pasatru, for a very rare genetic condition called fibrodysplasia ossificans progressiva, or FOP. FOP is caused by a fault in a gene called ACVR1. This gene fault makes the body wrongly produce new bone tissue in muscles and other soft tissues, which becomes progressively disabling over time. The condition affects roughly one in two million people. Garetosmab is an antibody — a type of protein — that targets a molecule called activin A, which drives the abnormal bone-forming process. By blocking this molecule, the medicine aims to slow or reduce the formation of abnormal bone. This approval relates only to treatment in countries where the FDA's decisions apply (primarily the United States), and availability in other countries would depend on separate regulatory processes. Researchers and clinicians who specialise in rare genetic disorders will be closely watching how the medicine performs in real-world use. This is an educational summary, not medical advice. If anything here raises questions for you, please speak with your GP or a clinical professional.
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Primary source Stat News · 2026-08-19STAT+: Regeneron drug for disease that causes dangerous bone growth earns FDA approval