Detailed narrative
Rare Liver Disease Business Expansion
Mirum's rare liver disease business is entering a new growth phase, extending beyond its pediatric foundation into larger adult patient populations. The VISTAS study of volixibat in Primary Sclerosing Cholangitis (PSC) demonstrated a significant improvement in pruritus, positioning it as a potential first approved medicine for patients in the U.S.
Additionally, results from the Phase IIb portion of the AZURE 1 study for brelovitug in hepatitis delta further support its potential in a patient population with extremely limited treatment options. Both programs will be featured in late-breaking presentations at EASL later this month, highlighting their importance for future growth.
Zilurgisertib Acquisition and FOP Opportunity
Mirum is expanding its rare genetic disease business with the addition of zilurgisertib, an oral ALK2 inhibitor licensed from Incyte for fibrodysplasia ossificans progressiva (FOP). FOP is an ultra-rare, progressive condition affecting approximately 300 patients in the U.S. and 900 globally, leading to severe immobilization.
The NDA for zilurgisertib has been accepted for priority review by the FDA with a PDUFA date of September 26, 2026, and a U.S. launch is expected by year-end. This acquisition leverages Mirum's existing rare genetic disease team and is projected to reach peak sales of over $200 million globally.
Strong Commercial Performance
The first quarter of 2026 saw strong commercial execution, with total net product sales reaching $160 million. LIVMARLI sales were particularly robust, totaling $114 million ($84 million in the U.S. and $30 million internationally), driven by continued strong adoption in PFIC, especially among adult patients.
The bile acid medicines (CTEXLI and CHOLBAM) contributed $46 million, maintaining consistent growth through the identification of undiagnosed CTX patients. These dynamics are expected to continue, leading to a raised full-year revenue guidance.
Financial Overview and Investment Strategy
Mirum ended Q1 FY26 with $421 million in cash, cash equivalents, and investments, up from $391 million at the start of the year. The commercial business generated a mid-50s percent cash contribution margin, with cash flow from operations at $2 million.
Total operating expenses were $949 million, significantly impacted by a $761 million expense related to the Bluejay Therapeutics acquisition. R&D expense was $98 million, including $21 million for brelovitug development. The company expects to be operating cash flow positive next year, though GAAP profitability is projected to be pushed out until 2028 due to continued pipeline investments.
Sales Force Expansion for Future Growth
To support the expanding rare liver disease portfolio, Mirum plans to significantly expand its U.S. liver field commercial team. The team will grow from its current 20 personnel to approximately 60, enabling reach to over 4,000 liver healthcare professionals. This expansion, starting later this year and expected to be fully on board by early next year, will target adult liver settings, including GI liver providers, infectious disease specialists, and selected primary care providers, to maximize the commercial opportunity for volixibat and brelovitug.