FDA Approves Third Treatment for Fibrodysplasia Ossificans Progressiva

Action

The U.S. Food and Drug Administration (FDA) has approved Atebrioz (zilurgisertib) tablets to reduce the volume of total new heterotopic ossification (bone formation outside the skeleton) in adults and pediatric patients 12 years and older with fibrodysplasia ossificans progressiva (FOP). The recommended starting dosage is 100 mg orally once daily with or without food.

Disease or Condition

Fibrodysplasia ossificans progressiva (FOP) is a rare genetic disease caused by a mutation in activin A receptor-type 1, which controls new bone growth. As a result, connective tissues such as muscle, tendons, and ligaments gradually turn into bone, causing limited movement, deformities, severe disability, and early death.

Effectiveness

The effectiveness of Atebrioz was evaluated in a randomized, double-blind, placebo‑controlled trial (NCT05090891) in which 63 patients with FOP were randomly assigned to receive Atebrioz 100 mg or placebo once daily for 24 weeks followed by a 292-week, single-arm, open-label extension period during which patients received Atebrioz 100 mg daily.

Atebrioz’s efficacy was based on the change from baseline in volume of total new heterotopic ossification compared to placebo during the double‑blind period, assessed by whole body CT scans. At Week 24, the group of patients receiving Atebrioz had an average 3.2 cm³ decrease in volume of total new heterotopic ossification, whereas the placebo group had a 24.6 cm³ increase.

Safety Information

Atebrioz can cause fetal harm based on data from animal studies. Patients of reproductive potential should use effective contraception and should immediately discontinue Atebrioz and contact their healthcare provider if pregnancy occurs.

The most common side effects are headache, joint pain, upper respiratory tract infection, nosebleeds, and nausea. Atebrioz should not be taken with certain other medications, as described in the label.

Designations

Atebrioz received fast track, priority review and orphan drug designation for this indication.