Mirum Pharmaceuticals MIRM announced that its oral pill zilurgisertib secured FDA approval for the treatment of fibrodysplasia ossificans progressiva (FOP) in patients aged 12 years and older. The drug will be marketed under the name Atebrioz.
Mirum Pharmaceuticals expects the drug to become commercially available in the United States in October through Mirum Access Plus, a patient support program designed to help navigate treatment access. It is currently under regulatory review for FOP indication in the European Union.
FOP is an ultra-rare genetic disease affecting about 300 people in the United States and 900 worldwide. It causes abnormal bone formation in soft tissues, which progressively restricts movement, mobility and daily activities.
Atebrioz is an oral activin receptor-like kinase 2 inhibitor and is recommended at a dose of 100 mg once daily for FOP. The drug is designed to reduce the volume of total new heterotopic ossification (HO). HO indicates the abnormal formation of extra bone tissue in muscles and other soft tissues where bone normally should not grow.
Mirum Pharmaceuticals obtained exclusive worldwide rights to Atebrioz from Incyte INCY in April 2026 for the drug’s development and commercialization. Under the agreement, Incyte received an upfront payment and remains eligible to receive additional development, regulatory and sales-based milestone payments, along with tiered royalties on worldwide net sales.
Year to date, MIRM shares have rallied 13.5% compared with the industry’s 8.3% growth.
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MIRM’s Atebrioz Approval for FOP Validates PROGRESS Data
The FDA approval for Atebrioz was supported by data from cohort 1 of the phase II PROGRESS study conducted by Incyte, which evaluated Atebrioz in adults and children aged 12 years and older with FOP. The study assessed the total new HO volume, including growth of existing bone lesions and development of new lesions.
After 24 weeks, patients treated with the drug achieved an average 3.2 cubic-centimeter reduction in total new HO lesion volume compared with a 24.6 cubic-centimeter increase in patients receiving placebo. The treatment benefit was sustained through week 48.
Atebrioz was generally well-tolerated, and the most common side effects were headache, joint pain, upper respiratory tract infection, nosebleeds and nausea.
The approval allows Mirum Pharmaceuticals to build a presence in the FOP market while it advances Atebrioz into younger pediatric patients. In this regard, the company is advancing cohorts 2 and 3 of the PROGRESS study. Enrollment has been completed in cohort 2 of children aged six to less than 12 years and cohort 3 is actively enrolling children aged two to less than 12 years with FOP.
MIRM’s Zacks Rank & Stock to Consider
Mirum Pharmaceuticals currently carries a Zacks Rank #3 (Hold).
Some better-ranked stocks in the biotech sector are Precigen PGEN and AC Immune ACIU carrying a Zacks Rank #2 (Buy) each. You can see the complete list of today’s Zacks #1 Rank (Strong Buy) stocks here.
Over the past 60 days, estimates for Precigen’s 2026 bottom line have improved from a loss of 2 cents to earnings per share of 24 cents. Over the same period, earnings estimates for 2027 have risen from 25 cents to 73 cents. PGEN shares have gained 85.4% year to date.
Precigen’s earnings beat estimates in three of the trailing four quarters and missed in the remaining one, with the average surprise being 108.96%.
Over the past 60 days, estimates for AC Immune’s 2026 loss per share have narrowed from 84 cents to 60 cents. Over the same period, earnings estimates for 2027 remained unchanged at 17 cents per share. ACIU shares have lost 19.8% year to date.
AC Immune’s earnings beat estimates in each of the trailing four quarters, with the average surprise being 33.25%.
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