Regulatory
FDA approves Mirum's oral drug Atebrioz for rare disease FOP
September 28, 2026
Biotech
Regulatory
Key Facts
Signal Type
Regulatory
Industry
Biotech
Companies
Mirum Pharma, Regeneron, Ipsen, Incyte, argenx
Date
September 28, 2026
The FDA approved Mirum Pharma's Atebrioz (zilurgisertib), an oral ALK2 inhibitor, for fibrodysplasia ossificans progressiva (FOP) in children aged 12 and over and adults. Atebrioz is the third drug cleared for FOP in the US, following Ipsen's Sohonos and Regeneron's Pasatru.
The approval was based on the phase 2 PROGRESS study, which showed a near-100% reduction in new bone lesions, a 3.2 cm³ reduction in new bone volume versus a 24.6 cm³ increase with placebo, and an 81% reduction in the number of patients developing new lesions. No treatment discontinuations or dose reductions were reported.
US patients with FOP, a life-shortening and highly debilitating disorder where heterotopic ossifications form in muscles, tendons, and ligaments, now have an additional daily pill option. Atebrioz is licensed by Mirum from Incyte and is also under review in the EU.
Mirum's launch will directly compete with Regeneron's recently approved Pasatru, an IV infusion given once monthly, and Ipsen's underperforming Sohonos. The FDA approval also earned Mirum a rare paediatric disease Priority Review Voucher, potentially worth $100 million to $200 million in a sale.
Pricing is expected to be a key competitive factor. Regeneron's Pasatru has an average annual list price of $1.4 million, with a weight-based range from roughly $700,000 to $2.1 million. Mirum has not revealed pricing, but analysts cited by Reuters speculate around $750,000 per year, which could generate peak sales of about $150 million.
Mirum's official pricing announcement and access strategy will determine how it positions against Pasatru's list price and payer contracts. Extended PROGRESS cohorts are testing Atebrioz in younger children (ages 6–11 and over-2), which could broaden the addressable population.
The EU review of Atebrioz remains pending, and Mirum may monetize the Priority Review Voucher. Updates from competitor Regeneron on Pasatru's launch traction and real-world safety will also shape the commercial landscape.
Source:
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