---
title: "Regeneron Secures FDA Approval For Ultra-Rare Bone Disorder Drug"
type: "News"
locale: "en"
url: "https://longbridge.com/en/news/296499413.md"
description: "Regeneron Pharmaceuticals secured FDA approval for Pasatru (garetosmab-grts), a novel monthly infusion therapy for adults with fibrodysplasia ossificans progressiva (FOP). The drug blocks Activin A to reduce heterotopic ossification lesions and flare-ups. Phase 3 trial results showed significant lesion elimination. Regeneron plans further global regulatory applications, including in Europe and Japan."
datetime: "2026-08-20T13:25:22.000Z"
locales:
  - [zh-CN](https://longbridge.com/zh-CN/news/296499413.md)
  - [en](https://longbridge.com/en/news/296499413.md)
  - [zh-HK](https://longbridge.com/zh-HK/news/296499413.md)
generator: "portal-rs"
---

# Regeneron Secures FDA Approval For Ultra-Rare Bone Disorder Drug

**Regeneron Pharmaceuticals, Inc.** (NASDAQ:REGN) secured approval from the U.S. Food and Drug Administration for Pasatru (garetosmab-grts), a novel therapy for adults battling fibrodysplasia ossificans progressiva (FOP).

The regulatory nod allows the drug to tackle the formation of new heterotopic ossification (HO) lesions and reduce clinician-assessed flare-ups associated with this ultra-rare condition.

## Understanding FOP And Treatment Administration

FOP progressively infiltrates muscles, ligaments, and tendons with abnormal bone growth. This severe dysfunction hinders essential actions like eating, speaking, and breathing.

With approximately 900 diagnosed cases worldwide, patients face a median survival age of 56 and often require wheelchairs by age 30.

Pasatru operates as a fully human monoclonal antibody that actively blocks Activin A, the protein responsible for developing these rogue bone lesions.

To accommodate patients facing significant mobility hurdles, healthcare providers can administer the monthly 60-minute intravenous infusions in home care settings.

The starting dose stands at 10 mg/kg, which doctors can lower to 3 mg/kg if patients struggle with tolerability.

 **Read Also: Eli Lilly, Regeneron Join FDA Pilot Designed To Accelerate US Manufacturing Readiness** 

## Clinical Efficacy And Future Regulatory Steps

The positive Phase 3 OPTIMA trial drove the FDA’s decision. After 56 weeks of treatment, CT scans showed the 10 mg/kg and 3 mg/kg doses eliminated new lesions by 90% and 94%, respectively, versus a placebo. Additionally, the 10 mg/kg dose decreased clinician-assessed flare-ups by 88%.

Following this U.S. milestone, the European Medicines Agency currently reviews the treatment, and Regeneron plans additional regulatory applications worldwide, including in Japan.

**REGN Stock Price Activity**: Regeneron Pharmaceuticals shares were up 0.44% at $844.52 during premarket trading on Thursday, according to Benzinga Pro data.

*Photo: Shutterstock*

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> **Disclaimer: This article is for reference only and does not constitute any investment advice.**