FDA approves Mirum and Incyte's Atebrioz for FOP; brelovitug hits Phase 3 HDV endpoint

Mirum Pharmaceuticals disclosed in an 8-K filing that on September 25, 2026, the company and Incyte Corporation announced that the FDA approved Atebrioz (zilurgisertib) tablets to reduce the volume of total new heterotopic ossification in adult and pediatric patients aged 12 years and older with fibrodysplasia ossificans progressiva.¹ Atebrioz was developed by Incyte and licensed to Mirum for worldwide development and commercialization.¹ The recommended dose is 100 mg administered orally, once daily.¹

Approval rested on Cohort 1 of the PROGRESS study. At Week 24, mean total new HO lesion volume decreased by 3.2 cm3 in patients receiving zilurgisertib compared with an increase of 24.6 cm3 in placebo-treated patients,¹ with treatment effects maintained through Week 48 of the open-label extension.¹ Atebrioz is expected to be commercially available in the U.S. in October, with eligible patients paying as little as $0 per month through Mirum Access Plus.¹

Separately, on September 28, 2026, Mirum announced that the primary endpoint was met in the Phase 3 portion of the AZURE-1 study evaluating brelovitug, an investigational fully human monoclonal antibody binding HBsAg, for chronic hepatitis delta virus.¹ At Week 24, 56% of patients in the 300 mg QW arm and 45% in the 900 mg Q4W arm achieved the combined endpoint of virologic response and ALT normalization, versus 0% in the delayed treatment arm (p<0.0001 for both).¹ Treatment with brelovitug was well tolerated across dose groups, with a safety profile consistent with previously reported AZURE-1 data.¹

Topline results from the Phase 3 AZURE-4 study are expected in the fourth quarter of 2026, with a BLA submission planned for the first half of 2027 and potential U.S. commercial launch in the fourth quarter of 2027.¹ Mirum estimated total annual revenue potential of brelovitug in HDV at more than $1 billion and of Atebrioz in FOP at greater than $200 million.¹