Mirum wins FDA approval for Atebrioz

Posted by Stacy Sanders on Sep 28th, 2026

What happened

Mirum Pharmaceuticals, Inc. (NASDAQ: MIRM) said the FDA approved Atebrioz tablets for adults and children 12 years and older with FOP. The recommended dose is 100 mg administered orally once daily. Mirum said Atebrioz was developed by Incyte and licensed to the company for worldwide development and commercialization. The filing also said Atebrioz will be available through Mirum Access Plus.

Mirum said Atebrioz is expected to be commercially available in the U.S. in October. It said the approval was based on Cohort 1 of the PROGRESS study. At Week 24, mean total new HO lesion volume fell by 3.2 cm3 in patients taking zilurgisertib and rose by 24.6 cm3 in placebo patients. Treatment effects held through Week 48.

In the same filing, Mirum said the Phase 3 AZURE-1 study of brelovitug met its primary endpoint at Week 24. In the 300 mg QW arm, 56% of patients reached the combined endpoint, versus 45% in the 900 mg Q4W arm and 0% in the delayed-treatment arm. Mirum said brelovitug was well tolerated across dose groups. Most adverse events were mild or moderate, and none led to treatment stop or dose reduction.

Key numbers

Metric	Latest	Source
Atebrioz recommended dose	100 mg	SEC 8-K
Mean total new HO lesion volume, zilurgisertib	-3.2 cm3	SEC 8-K
Mean total new HO lesion volume, placebo	+24.6 cm3	SEC 8-K
Brelovitug primary endpoint response rate, 300 mg QW	56%	SEC 8-K
Brelovitug primary endpoint response rate, 900 mg Q4W	45%	SEC 8-K
Brelovitug annual revenue potential in HDV	more than $1 billion	SEC 8-K

Why it matters

The filing gives Mirum one approved FOP therapy and another positive readout for brelovitug. That matters for a rare-disease company built on product expansion. The clearest comparison is the 11 percentage point gap between the 300 mg QW arm and the 900 mg Q4W arm at Week 24.

Mirum also estimated annual revenue potential for brelovitug in HDV at more than $1 billion, and annual revenue potential for Atebrioz at more than $200 million. But these are trial results and revenue estimates, not sales. Brelovitug still needs a BLA before any possible launch.

What's next

Mirum said full AZURE-1 results will be presented at an upcoming medical congress. Topline results from AZURE-4 are expected in the fourth quarter of 2026. The company expects to submit a BLA to the FDA in the first half of 2027, with a possible U.S. launch in the fourth quarter of 2027. On-time AZURE-4 data and the BLA filing would strengthen the case. Delay would weaken it.