FDA Approves Second Drug for Ultra-Rare Bone Disease FOP

The FDA approved garetosmab (Pasatru) to reduce new heterotopic ossification lesions and disease flares in adults with fibrodysplasia ossificans progressiva (FOP). In a phase III trial, the monoclonal antibody reduced new bone lesions by 90-94% and flares by up to 88% compared with placebo. This is the second approved treatment for FOP, following palovarotene in 2023.

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FOP arises from a mutation in the activin A receptor-type 1 gene, driving progressive bone formation within muscles, tendons, and ligaments. The condition affects fewer than 500 Americans, with most patients requiring wheelchairs by age 30 and facing shortened lifespans due to complications like cardiorespiratory failure. Garetosmab's approval follows palovarotene in 2023, giving clinicians two distinct therapeutic options.

The OPTIMA trial enrolled 63 adults and demonstrated substantial reductions in new bone lesions on CT imaging, with the higher 10 mg/kg dose showing greater flare suppression. Common adverse events included nosebleeds, skin infections, and oral ulcers. Regeneron