Regeneron Receives FDA Priority Review for Garetosmab in FOP, EMA Review for Cemdisiran in gMG
Regeneron announced FDA and EMA review acceptance for cemdisiran in generalized myasthenia gravis and FDA priority review acceptance for garetosmab in fibrodysplasia ossificans progressiva. The garetosmab BLA is supported by Phase 3 OPTIMA trial data showing 94% and 90% reductions in new bone lesions.
Regeneron Pharmaceuticals announced regulatory advancements for two rare disease treatments: U.S. and European regulators have accepted applications for its cemdisiran drug candidate in generalized myasthenia gravis, while the FDA has accepted for priority review its biologics license application for garetosmab to treat fibrodysplasia ossificans progressiva.
The FDA and the European Medicines Agency will review cemdisiran for adults with generalized myasthenia gravis (gMG) who are anti-acetylcholine receptor antibody-positive. The FDA has granted the application priority review, which shortens the review period, and has set a target action date in November. Regeneron expects a decision from the European Commission in the second half of 2027. Regeneron is developing cemdisiran under a licensing agreement with Alnylam Pharmaceuticals.
Separately, the FDA has accepted for Priority Review the Biologics License Application (BLA) for garetosmab for the treatment of adults with fibrodysplasia ossificans progressiva (FOP). The target action date for the FDA decision is August 2026. Garetosmab is a monoclonal antibody that blocks Activin A, a protein that Regeneron scientists discovered to be critical in the development of heterotopic ossification (HO) lesions in people with FOP. If approved, garetosmab would be the first and only available treatment shown to reduce the number and volume of new heterotopic bone lesions in adults with FOP.
The BLA is supported by efficacy and safety data from the positive Phase 3 OPTIMA trial evaluating garetosmab in adults with FOP. Both garetosmab doses (3 mg/kg and 10 mg/kg) evaluated in the trial were highly efficacious in reducing the total number and volume of new HO lesions at 56 weeks, compared to placebo. Regarding the primary endpoint analysis of reduction in total number of new HO lesions compared to placebo, those receiving the 3 mg/kg dose experienced a 94% reduction (1 lesion vs. 19 lesions; p=0.0274), while those receiving the 10 mg/kg dose experienced a 90% reduction (2 lesions vs. 19 lesions; p=0.0260). A post-hoc analysis also found both doses of garetosmab demonstrated a greater than 99% reduction in mean total volume (cm3) of new HO lesions compared to placebo.
At 56 weeks, among all 63 people with FOP aged 18 years and older who participated in the OPTIMA trial, serious treatment-emergent adverse events occurred in 1 patient treated with 3 mg/kg garetosmab, 2 patients treated with 10 mg/kg garetosmab, and 2 patients treated with placebo. The most common adverse reactions (incidence ≥30%) are epistaxis, increased hair growth, abscess, and acne.
Priority Review is granted to regulatory applications seeking approval for therapies that have the potential to provide significant improvements in the treatment, diagnosis, or prevention of serious conditions. The FDA previously granted Fast Track designation and Orphan Drug Designation for garetosmab for the prevention of HO in patients with FOP. Garetosmab has also been granted Orphan Designation in the European Union, and additional regulatory submissions are planned in countries around the world.