Mirum Pharmaceuticals (NASDAQ:MIRM) reported second-quarter net product sales of $176 million and raised its full-year 2026 product sales outlook to $680 million to $700 million, while outlining several upcoming clinical and regulatory milestones across its rare liver and rare genetic disease portfolios.
Second-quarter product sales rose from $128 million in the prior-year period. Chief Executive Officer Chris Peetz said the company’s commercial performance and strengthened capital structure provide capacity to invest in prospective launches, clinical development and business-development opportunities.
Commercial portfolio drives higher guidance
Mirum also said progressive familial intrahepatic cholestasis, or PFIC, remains a driver of LIVMARLI growth. Radovich pointed to increased awareness of later-onset PFIC among adult liver providers and more routine genetic testing. Based on claims data and two years of commercial experience, Mirum estimates an addressable adult PFIC population of at least 2,000 patients in the U.S., with a likely similar population in Europe.
The company’s bile acid medicines generated $48 million in quarterly net product sales. Mirum said its rare genetics business could expand with a potential fourth-quarter U.S. launch of zilurgisertib for fibrodysplasia ossificans progressiva, or FOP, if the product receives FDA approval.
Radovich said the FDA review of zilurgisertib was proceeding as expected following a late-cycle meeting, with a September PDUFA date. The company expects an initial launch, if approved, to focus on FOP patients aged 12 and older. Mirum plans to use its existing rare genetics commercial team, which markets Ctexli and CHOLBAM and already serves specialized treatment centers that manage FOP patients.
Chief Financial Officer Eric Bjerkholt said the updated $680 million to $700 million revenue guidance does not include potential FOP revenue. He said the company expects revenue from the potential product launch to begin more meaningfully in 2027.
PSC filing timeline pushed to first half of 2027
Mirum said the FDA granted breakthrough therapy designation to volixibat for cholestatic pruritus associated with primary sclerosing cholangitis, or PSC, following results from the VISTAS study. The study met its primary endpoint and showed statistically significant improvements in pruritus in the primary cohort, according to the company.
However, Peetz said a recent pre-NDA meeting resulted in an FDA recommendation to conduct a Phase III study. Mirum is not currently aligned with the agency on the proposed NDA package and has delayed its planned filing for volixibat in PSC to the first half of 2027.
Management maintained that the VISTAS data set is sufficient to support an application. Peetz said the trial was designed with FDA input and represents the largest randomized clinical study in PSC pruritus, with more than 180 randomized PSC patients and more than 100 patients with one-year safety exposure in the ongoing follow-up.
During the question-and-answer session, Peetz said the agency’s comments supporting another Phase III study were not specific and covered general efficacy and safety considerations. He said the company believes VISTAS addressed efficacy, gastrointestinal safety and liver-safety considerations. Mirum intends to use the breakthrough designation to support more frequent interactions with the FDA and expects an iterative dialogue before submission.
Peetz said the company may supplement the package with additional accumulated safety data, including longer-term follow-up, and could discuss post-marketing registry or monitoring requirements. He also stated that pruritus remains an approvable endpoint and that Mirum does not expect an accelerated-approval-style confirmatory study after approval.
Additional liver pipeline readouts ahead
Mirum said enrollment has been completed in the Phase III VANTAGE study of volixibat for pruritus associated with primary biliary cholangitis, or PBC, with more than 330 patients randomized. The company expects top-line results in the first quarter of 2027.
Management said it has received recent FDA feedback that VANTAGE can serve as a pivotal study if successful. Peetz said prior discussions related primarily to study size and the analysis plan for the pruritus endpoint, which the company addressed during the trial.
Elsewhere in the rare liver pipeline, Mirum expects top-line results later in the quarter from the Phase III portion of the AZURE-1 study of brelovitug. The company also expects four-year data in the fourth quarter and said those results could support a planned biologics license application submission in the first half of 2027. Peetz said the company expects a further Phase III readout, AZURE-4, over the remainder of the year.
Mirum also expects fourth-quarter top-line data from the Phase III EXPAND study of LIVMARLI in additional rare cholestatic conditions. Peetz said positive results could support a supplemental NDA next year. The company remains on track to report proof-of-concept data for MRM-3379 in Fragile X syndrome in 2027.
Capital structure and cash position
Cash, cash equivalents and investments totaled $561 million as of June 30, compared with $391 million at the start of the year. Bjerkholt said commercial cash contribution margin was in the high 50% range during the second quarter and first half, an improvement of about five percentage points from the previous year.
Operating expenses totaled $219 million during the quarter, including a $16 million in-process research and development charge tied to the upfront licensing payment for zilurgisertib. Operating cash flow was positive despite increased research and development spending, Bjerkholt said.
During the quarter, Mirum issued $690 million in aggregate principal amount of zero-coupon convertible notes due in June 2032, producing $672 million in net proceeds. The company used the transaction in part to settle 75% of its outstanding 2029 notes, adding $197 million of cash to its balance sheet and reducing interest expense, according to Bjerkholt.
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.
