Regeneron reports zero new bone lesions with Pasatru

Regeneron Pharmaceuticals announced positive 84-week results on October 12, 2026, from the Phase 3 OPTIMA trial evaluating Pasatru in adults with fibrodysplasia ossificans progressiva (FOP). The extended findings, presented at the American Society for Bone and Mineral Research Annual Meeting, showed that patients receiving Pasatru developed zero new heterotopic ossification lesions between weeks 56 and 84, compared with 9 new lesions observed in the placebo group.

The trial enrolled 63 participants aged 18 and older, with 58 completing the extension phase through at least 84 weeks. Patients received either 10 mg/kg of Pasatru, 3 mg/kg of Pasatru, or placebo intravenously every four weeks. In addition to halting new lesions, one lesion detected at week 56 in the 3 mg/kg group was no longer detectable at week 84. Clinician-assessed flare-ups dropped to 1 in the 10 mg/kg group and 14 in the 3 mg/kg group, compared with 17 in the placebo group.

Pasatru was recently approved by the US Food and Drug Administration to reduce new lesions and flare-ups based on 56-week data, which demonstrated a 90% or greater reduction in new lesions. Regulatory reviews remain underway in the European Union with the European Medicines Agency, with additional submissions planned globally, including Japan. Regeneron also plans to start OPTIMA 2, a Phase 3 trial in children and adolescents, later in 2026.

Safety remained consistent with earlier findings, with no deaths reported. Skin and soft tissue infections occurred in 33% of placebo patients, 53% on 3 mg/kg, and 78% on 10 mg/kg, all of which resolved with treatment without patient discontinuations. Common adverse events at week 84 included acne in the 10 mg/kg group and non-severe nosebleeds in the 3 mg/kg group.