Mirum Pharmaceuticals (MIRM) Study result summary

Key study results and clinical insights

• Volixibat met the primary endpoint in the VISTAS Phase II-B study for PSC, showing a statistically significant and clinically meaningful placebo-adjusted reduction in pruritus of 1.64 points (p<0.0001), with improvements observed within two weeks and across both moderate/severe and mild itch cohorts.

• 55.6% of volixibat patients achieved a ≥2-point reduction in pruritus versus 26.3% for placebo (p=0.0019), and significant reductions in serum bile acids were observed.

• Safety profile was consistent with IBAT inhibitors, with diarrhea, abdominal pain, and nausea as the most common adverse events; diarrhea occurred in 40% of treated patients, and elevations in liver enzymes and bilirubin were more frequent, but no treatment-related serious adverse events were reported.

• AZURE-1 Phase II-B study of brelovitug in HDV met its primary endpoint, with 100% virologic response in the 300mg group and 75% in the 900mg group, ALT normalization in up to 45%, and a favorable safety profile.

• Both studies will have full results presented at EASL, with regulatory filings planned, including a pre-NDA meeting for volixibat with the FDA in summer 2026 and NDA submission in the second half of 2026.

Study design, patient population, and additional findings

• VISTAS was a randomized, double-blind, placebo-controlled 28-week study enrolling 158 PSC patients (111 moderate/severe, 47 mild pruritus), with well-balanced baseline characteristics and over 70% having concurrent IBD.

• Placebo response in pruritus was low, validating the study design and indicating persistent itch in PSC.

• Trends toward improvement in fatigue and sleep were observed, with nominal significance for sleep.

• Diarrhea events were mostly grade 1 or 2, with median onset and duration of a couple of weeks; no evidence of increased IBD exacerbation with volixibat.

• No significant impact of gender or baseline serum bile acids on efficacy; patients were selected based on pruritus severity.

Commercial, regulatory, and strategic outlook

• Volixibat is positioned as a potential first approved therapy for PSC-related pruritus, with plans for priority review and commercial launch preparations underway, including sales force expansion.

• The VANTAGE study in PBC and other pipeline programs are progressing, with topline data from VANTAGE expected in Q1 2027 and four potentially registrational topline readouts in the next 12 months.

• The VISTAS study population is considered representative of real-world PSC patients, supporting broad applicability of results.

• No difference in volixibat response based on background UDCA therapy was observed in initial analyses.

• 2026 net product sales guidance is $630-650M, with a cash flow positive outlook for 2027.