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19th Aug, 2026 12:00 AM
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US FDA Approves Regeneron's Rare Bone Disorder Drug

Aug 19 - The U.S. FDA on Wednesday approved Regeneron's drug for a rare genetic disorder ⁠after it significantly reduced abnormal bone formation in certain soft tissues.

New York-based Regeneron's shares rose 4%.

The drug, garetosmab, branded ⁠as Pasatru, was approved for treating adults with fibrodysplasia ossificans progressiva — a condition where muscle, tendon ⁠and ligament tissue gradually turn ‌into bone, leading to a "second skeleton" that causes progressive loss of mobility and reduced life expectancy.

In a 56-week trial involving 63 participants, Pasatru reduced the development of new bone abnormalities by 94% in patients treated with a 3 mg per kg dose and by ‌90% in the case of a 10 mg per kg dose, when ​compared with ‌placebo.

Article Key Points
  • FDA approved garetosmab (Pasatru) for adult FOP.
  • FOP = progressive heterotopic ossification of muscle, tendon, ligament.
  • 56-week trial (n=63): new bone lesions ↓94% (3 mg/kg) vs placebo.
  • 56-week trial (n=63): new bone lesions ↓90% (10 mg/kg) vs placebo.
  • Garetosmab blocks Activin A; pediatric trial planned later this year.
What long-term outcomes improve in adult FOP treatment?
How does garetosmab compare with Sohonos in FOP?
What safety issues emerged in garetosmab FOP trials?

It works by blocking Activin A, ‌a protein involved in triggering abnormal bone growth in patients with FOP.

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Susan Rhee, a member of Regeneron's clinical ⁠team, told Reuters last week that the company ‌is planning to start a ⁠trial for children later this ​year.

The drug will compete with French ‌drugmaker Ipsen's oral treatment Sohonos, which in 2023 became the only other treatment to be approved by the U.S. Food and Drug Administration.

Incyte and partner Mirum Pharma as well ​as privately held Ashibio are also developing treatments for ‌the ‌condition.

In 2020, Regeneron paused dosing in a mid-stage trial of the drug after five patient ‌deaths, ultimately discontinuing the ​study and working with global regulators to design the late-stage trial, according to the company.

The condition affects roughly 1 in 2 million people worldwide, with ⁠around 800 to 900 active diagnosed cases globally, data from the ‌National Institutes of Health showed.

(Reporting by Bageshri Banerjee and Christy Santhosh in Bengaluru; ​Editing by Jonathan Ananda and Sahal Muhammed)

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