Mirum Pharmaceuticals Inc

The US FDA on Friday approved Mirum Pharmaceuticals and Incyte's Atebrioz, also known as zilurgisertib, as a treatment for the rare bone condition fibrodysplasia ossificans progressiva, or FOP. The oral activin receptor-like kinase 2 inhibitor is designed to reduce the volume of total new heterotopic ossification in adults and children 12 years and older. Approval was based on results from a cohort of the PROGRESS study that showed at week 24, mean total new heterotopic ossification lesion volume decreased by 3.2 cm³ in patients receiving Atebrioz compared with an increase of 24.6 cm³ in those on placebo, with benefits maintained through week 48 of the open-label extension. FOP is an ultra-rare, progressive genetic disease impacting approximately 300 people in the US and approximately 900 worldwide, characterized by heterotopic ossification in which bone forms in muscles, tendons, ligaments, and other soft tissues.

Mirum Pharmaceuticals reported a second-quarter 2026 loss of 80 cents per share, wider than the Zacks Consensus Estimate of a loss of 77 cents, while revenues of $176.2 million beat the $165 million consensus and grew 37.9% year over year. The company raised its full-year 2026 worldwide net product sales guidance to $680–$700 million from the prior $660–$680 million, driven by strong demand for Livmarli and bile acid products. Livmarli net product sales reached $128.7 million, up 46%, with $92 million in the United States and $37 million in ex-U.S. markets, and the FDA approved a new tablet formulation of Livmarli for the treatment of cholestatic pruritus in patients with Alagille syndrome and progressive familial intrahepatic cholestasis, launched in June 2025. Bile acid product sales, comprising Cholbam and Ctexli, rose 20% to $47.5 million. Mirum also provided pipeline updates, including completed enrollment in the phase III EXPAND study for Livmarli, expected top-line data from volixibat studies, and a Priority Review for zilurgisertib in fibrodysplasia ossificans progressiva with a target action date of September 26, 2026.

Mirum Pharmaceuticals has received US FDA priority review acceptance for its new drug application for zilurgisertib, a treatment for fibrodysplasia ossificans progressiva, with a decision expected in late September 2026. The acceptance follows positive pivotal phase II results from the PROGRESS study. This development adds a high-profile ultra-rare indication to Mirum's pipeline, potentially reducing its reliance on existing product Livmarli. The company's narrative projects $1.1 billion in revenue and $234.1 million in earnings by 2029, with some analysts modeling up to $1.3 billion in revenue and $436.2 million in earnings for the same year.

Mirum Pharmaceuticals shares rallied 5.5% in the last trading session to close at $123.77 on higher-than-usual volume. The move follows positive pivotal phase II data from Cohort 1 of the PROGRESS study evaluating zilurgisertib, an investigational oral ALK2 inhibitor, in patients with fibrodysplasia ossificans progressiva. The data showed a reduction in new heterotopic ossification lesions and improvements in secondary endpoints, and the FDA has accepted the new drug application under priority review with a decision expected on September 26, 2026. The stock has gained 17.8% over the past four weeks. Mirum is expected to report a quarterly loss of $0.77 per share on revenues of $164.76 million, and the consensus EPS estimate has been revised 9.5% lower over the last 30 days.

Five biotech stocks profiled by RTTNews reached new 52-week highs last week, with gains ranging from 105% to 235% since their respective publication dates. Twist Bioscience soared 235% to a high of $104.23, driven by strong revenue and an upcoming quarterly report. Biodesix climbed 124% to $23.34 following better-than-expected results, raised guidance, and positive clinical validation data. Mirum Pharmaceuticals rose 133% to $124.44 on consistent revenue growth, the Bluejay Therapeutics acquisition, and positive trial results for Brelovitug and Volixibat. Candel Therapeutics advanced 108% to $9.99 after extended survival data for Aglatimagene and a commercialization agreement with EVERSANA. Indivior Pharmaceuticals gained 105% to $42.81, supported by solid earnings, upbeat guidance, and real-world evidence favoring Sublocade.

Mirum Pharmaceuticals and Incyte Corporation reported positive pivotal phase II results for zilurgisertib in fibrodysplasia ossificans progressiva, and the FDA accepted the new drug application with Priority Review, setting a decision date of September 26, 2026. In the PROGRESS study, only 3.1% of patients on zilurgisertib developed new heterotopic ossification lesions at Week 24 versus 16.7% on placebo, an 81% reduction, with a 99.9% reduction in total volume of new lesions. Sustained benefit was seen through Week 48 with no new lesions in those continuing treatment, and the safety profile was favorable with mostly mild to moderate adverse events. Mirum licensed worldwide rights from Incyte, and year to date, Mirum shares have risen 28.5% and Incyte shares 1%, against a 1.4% industry decline.