FDA Approval of Pasatru and Entry into the Rare Disease Market

The U.S. Food and Drug Administration (FDA) has granted final approval to garetosmab-grts (brand name Pasatru) developed by Regeneron Pharmaceuticals (REGN) for the treatment of adult progressive fibrodysplasia ossificans progressiva (FOP). This approval follows the BLA 761508 marketing authorization application, and Pasatru has successfully entered the market with Orphan Drug designation. FOP is a fatal and extremely rare genetic disorder in which soft tissues such as muscles and ligaments turn into bone, leading to physical disability. Therefore, this approval holds significant humanitarian and commercial value by providing patients with a new therapeutic breakthrough.

Targeting Activin A and Overwhelming Clinical Efficacy

Pasatru is a fully human monoclonal antibody that selectively blocks Activin A, a protein responsible for abnormal bone formation. In the OPTIMA Phase 3 trial, which formed the basis of this approval, Pasatru demonstrated an overwhelming therapeutic effect, reducing the formation of heterotopic ossification lesions by 90% in the 10mg/kg dose group and 94% in the 3mg/kg dose group compared to the placebo group. With a convenient dosing schedule of intravenous infusion once every four weeks and excellent lesion inhibition rates, Pasatru is expected to gain high preference among healthcare professionals and patients.

Disruption of Monopoly and Intensifying Competitive Landscape

With this approval, Pasatru becomes the second drug in the U.S. market for treating FOP, following Ipsen's Sohonos (active ingredient: palovarotene). Despite Sohonos' exorbitant annual price of approximately USD 624,000, its commercial performance has been weak, with sales in H1 2026 reaching only USD 24,000,000 due to safety concerns and limited efficacy. Pasatru's superior data on heterotopic ossification reduction is expected to significantly disrupt the existing market dynamics and strongly capture market share from Sohonos.

Strengthening Rare Disease Portfolio and Financial Outlook

The global FOP treatment market is estimated to be valued at approximately USD 520,000,000 in 2025 and is projected to grow sharply to up to USD 2,800,000,000 by 2035, making it a high-value market. Regeneron has further solidified the commercial competitiveness of its rare disease pipeline through the approval of Pasatru. The market exclusivity granted through Orphan Drug designation and a high pricing strategy are expected to have a very positive impact on Regeneron's long-term revenue growth and profitability.