Mirum Pharmaceuticals NASDAQ: MIRM executives said the rare disease company is entering a catalyst-heavy period, with recent positive clinical updates, ongoing commercial momentum for LIVMARLI and additional business development activity expanding its portfolio.
Speaking at RBC Capital Markets’ 2026 Global Healthcare Conference, Peter Radovich, Mirum’s president and chief operating officer, described the company as a global rare disease business with about 430 employees and three approved medicines. He said LIVMARLI remains the foundation of the company’s commercial business, while additional assets acquired through business development have broadened Mirum’s rare disease strategy.
Radovich highlighted two recent clinical readouts: positive pivotal data from the VISTAS study of volixibat in primary sclerosing cholangitis, or PSC, and Phase 2b interim results from the company’s hepatitis delta program, which came through Mirum’s acquisition of Bluejay Therapeutics. He said the company is preparing for a pre-NDA meeting and an NDA submission for volixibat in the second half of the year, while full Phase 3 readouts from the AZURE-1 and AZURE-4 hepatitis delta studies are expected later this year.
LIVMARLI Growth Driven by PFIC Demand
RBC biotech analyst Lisa Walter noted that LIVMARLI generated $114 million in net sales in the first quarter of 2026, up 55% year over year, and that Mirum raised full-year guidance to $660 million to $680 million. Radovich said the key driver was demand, particularly in progressive familial intrahepatic cholestasis, or PFIC, where later-onset patients are increasingly being identified among adolescents and adults.
Radovich said international LIVMARLI sales were also stronger than expected in the quarter. He noted that the company typically expects a decline in the first quarter after some distributor and named-patient markets buy in bulk in the fourth quarter, but underlying demand remained strong.
In Alagille syndrome, Radovich said Mirum is about 50% penetrated into the addressable prevalent population and continues to see steady patient additions. In PFIC, he said the pediatric-onset population is likely more than 50% penetrated across the class, while the later-onset adult market remains in early development as more adult providers begin using genetic testing. He estimated that LIVMARLI’s U.S. market share in PFIC is roughly split 50/50 with BYLVAY, while Mirum has a higher share in Alagille syndrome.
Radovich also pointed to the Phase 3 EXPAND study as a potential growth driver for LIVMARLI. He said top-line data are expected in the fourth quarter and that Mirum views Alagille syndrome, PFIC and the EXPAND basket indication as roughly equal contributors to LIVMARLI’s stated peak potential of more than $1 billion. He said the pediatric opportunity in the EXPAND population is about 1,000 patients across the U.S. and Europe, with less visibility so far into the adult opportunity.
Volixibat Advances in PSC and PBC
Mirum executives said the VISTAS study met its primary endpoint with a statistically significant improvement in pruritus in PSC. The company said additional data to be presented at EASL would include responder rates and the time course of itch improvement, with the profile described as rapid and sustained, consistent with expectations for an IBAT inhibitor.
The company said the PSC results do not change its view that volixibat represents a potential opportunity of more than $1 billion across PSC and primary biliary cholangitis, or PBC.
Asked about placebo response in pruritus trials, Mirum said design elements such as screening and placebo run-in periods, along with training patients and sites on use of the ItchRO tool, appeared effective in both PSC and PBC. The company said screen failures in VANTAGE, its PBC study, are generally comparable to VISTAS and may be slightly higher in PBC, with fluctuating liver labs and diary compliance cited as common reasons.
Mirum executives said interim VANTAGE data increased confidence in the Phase 3 study, citing a clear separation between treatment and placebo in a 30-patient interim analysis. The company said it believes a pruritus benefit near the more than two-point improvement versus placebo seen at interim would be commercially differentiated.
Hepatitis Delta Program Readouts Expected Later This Year
Mirum also discussed brelovitug, its hepatitis delta candidate. Walter noted that the Phase 2b interim analysis showed a 100% virologic response in the 300 mg weekly dose arm and that 45% of patients at that dose achieved the primary endpoint of virologic response and ALT normalization, compared with no placebo responders.
Mirum said differences between the 300 mg weekly arm and the 900 mg monthly arm were likely due to small patient numbers and response kinetics, noting that exposures between the dosing regimens were broadly comparable. The company said the AZURE-1 interim results reinforced confidence in the full Phase 3 readouts expected in the second half of the year.
On competition in hepatitis delta, Mirum said multiple new treatment options would benefit patients, especially in the U.S., where interferon has been the main option. The company said it expects Gilead’s Hepcludex could help increase screening for delta among hepatitis B patients. Mirum said it sees potential advantages for brelovitug versus Hepcludex in efficacy, safety and convenience, describing brelovitug as a weekly self-administered subcutaneous monoclonal antibody.
The company said its previously outlined $750 million opportunity for brelovitug is a global number, but added that even the U.S. market could approach that scale under assumptions including 15,000 currently diagnosed patients, competitive market share and rare disease pricing.
Business Development Remains a Priority
Radovich said Mirum remains active but disciplined in business development, targeting assets with high unmet need, compelling biology and clinical data, and opportunities where Mirum can add value. He said a recent financing was mainly intended to address 2029 convertible notes by refinancing most of the principal at a 0% coupon, rather than changing the company’s BD approach.
Mirum recently acquired zilurgisertib from Incyte for fibrodysplasia ossificans progressiva, or FOP. Radovich described FOP as a devastating ultra-rare condition affecting about one in one million people, or roughly 300 patients in the U.S. He said Mirum believes zilurgisertib’s oral once-daily profile could be attractive in a market where intravenous administration can be challenging for patients.
Asked about balancing profitability with further investment, Andrew McKibben, senior vice president of strategic finance and investor relations, said Mirum’s focus is on value creation through its pipeline, commercial business and business development. He said profitability is not the company’s immediate goal, but that Mirum is in a strong financial position and intends to remain financially independent.
About Mirum Pharmaceuticals NASDAQ: MIRM
Mirum Pharmaceuticals, Inc is a late-stage biopharmaceutical company dedicated to the development and commercialization of innovative therapies for rare cholestatic liver diseases. The company's primary focus lies in addressing the unmet medical needs of patients suffering from genetic and progressive forms of pediatric liver disorders, where limited treatment options currently exist.
Mirum's lead product candidate, maralixibat (Livmarli), is an ileal bile acid transporter inhibitor designed to reduce systemic bile acid accumulation and alleviate associated pruritus and liver damage.
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