Garetosmab - (OPTIMA)

Aug. 19, 2026: Regeneron Pharmaceuticals (NASDAQ: REGN) said the FDA approved Pasatru (garetosmab-grts) to reduce new heterotopic ossification (HO) lesions and clinician-assessed flare-ups in adults with fibrodysplasia ossificans progressiva (FOP).

Approval was based on the Phase 3 OPTIMA trial in 63 adults with active FOP. At 56 weeks, both Pasatru dose arms met the primary endpoint versus placebo for reduction in total new HO lesions by CT: 10 mg/kg showed a 90% reduction (2 lesions vs. 19 for placebo; n=23 vs. n=21) and 3 mg/kg showed a 94% reduction (1 vs. 19; n=19 vs. n=21). For the key secondary endpoint of clinician-assessed flare-ups, the 10 mg/kg arm had 9 flare-ups (88% reduction vs. placebo), the 3 mg/kg arm had 53 (15% reduction), and placebo had 66. Patient-reported flare-ups were not significantly different versus placebo.

Serious treatment-emergent adverse events occurred in 2 patients on 10 mg/kg, 1 on 3 mg/kg, and 2 on placebo. Common adverse reactions included abscess, acne, increased hair growth, madarosis, oral ulcers, epistaxis, folliculitis, paronychia, and rash.

An EMA submission is under review, additional filings including Japan are planned, and Phase 3 OPTIMA 2 in adolescents and children is planned to start later this year.