FDA Approves Regeneron's Rare Bone Disease Drug Pasatru, Priced Up to $2.1 Million Annually

en.Wedoany.com Reported - On August 19, the U.S. Food and Drug Administration (FDA) approved Regeneron Pharmaceuticals' Pasatru (garetosmab-grts) for the treatment of fibrodysplasia ossificans progressiva (FOP) in adults. FOP is an ultra-rare genetic disease in which patients' muscles, tendons, ligaments, and other connective tissues are gradually replaced by abnormal bone tissue, forming a so-called "second skeleton," leading to progressive loss of mobility. Most patients require a wheelchair by age 30, with a median survival age of approximately 56 years. Approximately 900 people are diagnosed worldwide.

The approval was based on data from the Phase III OPTIMA trial. The trial enrolled 63 adult patients with FOP, who were randomized to receive Pasatru 10 mg/kg, 3 mg/kg, or placebo via intravenous infusion every 4 weeks for 56 weeks. Results showed that the 10 mg/kg group had a 90% reduction in new heterotopic ossification (HO) lesions (2 vs. 19 in placebo), and the 3 mg/kg group had a 94% reduction (1 vs. 19). Among key secondary endpoints, the 10 mg/kg group showed an 88% reduction in clinician-assessed disease flares (9 vs. 66). Serious treatment-related adverse events occurred in 2 patients in the 10 mg/kg group, 1 in the 3 mg/kg group, and 2 in the placebo group.

Pasatru is a fully human monoclonal antibody that targets and neutralizes activin A—a key driver of abnormal bone formation in FOP discovered by Regeneron scientists. The recommended starting dose is 10 mg/kg, administered as a 60-minute intravenous infusion every 4 weeks, which may be reduced to 3 mg/kg if not tolerated. Regeneron stated that the drug can be administered in various settings, including eligible home infusion.

The drug will compete with Ipsen's Sohonos, which was approved by the FDA in 2023 as the first FOP treatment. Regeneron expects the drug to be available "within days". The annual price ranges from $693,000 to $2.1 million depending on dose and body weight, with an approximate cost of $1.4 million based on the trial's average body weight at the 10 mg/kg dose. Regeneron plans to initiate the OPTIMA 2 trial within 2026 to evaluate Pasatru in pediatric and adolescent patients with FOP. The European Medicines Agency (EMA) is reviewing the marketing application, and submissions are also planned in countries such as Japan.