Mirum Pharmaceuticals Reports P-IIb (VISTAS) Trial Data on Volixibat in Primary Sclerosing Cholangitis (PSC) Patients with Cholestatic Pruritus

Why It Matters

Effective itch relief addresses a major quality‑of‑life gap in PSC, positioning volixibat for potential first‑in‑class approval and expanding Mirum's rare‑disease franchise.

Key Takeaways

• Volixabat achieved primary endpoint with 2.72-point itch reduction vs placebo
• 55.6% of patients saw ≥2-point itch improvement, double placebo rate
• Effect observed within two weeks and maintained through twelve weeks
• Mirum plans FDA pre‑NDA meeting summer 2026, NDA H2 2026
• Phase IIb VANTAGE data for primary biliary cholangitis expected Q1 2027

Pulse Analysis

Primary sclerosing cholangitis (PSC) remains a therapeutic orphan, with cholestatic pruritus causing severe discomfort and impairing daily activities. Volixabat, an apical sodium‑dependent bile acid transporter (ASBT) inhibitor, reduces intestinal bile acid reabsorption, thereby lowering systemic bile acid concentrations that trigger itch receptors. By targeting the underlying pathophysiology rather than merely masking symptoms, volixabat offers a mechanistic advantage over antihistamines and opioid antagonists, which have limited efficacy in PSC‑related itch.

The VISTAS Phase IIb study enrolled 158 PSC patients, separating a primary cohort of 111 individuals with moderate to severe itch from a secondary group with milder symptoms. Volixabat produced a 2.72‑point improvement on the Adult ItchRO scale versus a decline of 1.08 points on placebo, with statistical significance achieved as early as week two and sustained through week twelve. Notably, more than half of the treated patients experienced a clinically meaningful ≥2‑point reduction, a benchmark that underscores the drug’s potential to meet regulatory expectations for symptom‑focused endpoints. Mirum’s upcoming pre‑NDA meeting in summer 2026 signals confidence in the data package and a clear pathway toward U.S. market entry.

Beyond PSC, Mirum is leveraging volixabat’s platform across cholestatic liver diseases. The Phase IIb VANTAGE trial in primary biliary cholangitis (PBC) is slated for topline results in Q1 2027, expanding the drug’s addressable market. Coupled with Mirum’s recent acquisition of Bluejay Therapeutics, which adds rare‑disease assets to its pipeline, the company is positioning itself as a specialist leader in bile‑acid‑mediated disorders. If approved, volixabat could capture a niche yet sizable segment, offering investors a differentiated growth story in the competitive hepatology space.