Mirum Pharmaceuticals Inc. (NASDAQ: MIRM) announced that its experimental drug volixibat met the primary endpoint in a Phase 2b study for patients with primary sclerosing cholangitis, a rare liver disease.

The VISTAS study evaluated volixibat 20 mg twice daily versus placebo in 158 patients with primary sclerosing cholangitis. In the primary analysis cohort of 111 patients with moderate to severe itching, volixibat demonstrated a 2.72-point reduction from baseline in cholestatic pruritus, with a placebo-adjusted difference of 1.64 points (p<0.0001) as measured by the Adult ItchRO scale.

The study showed that 55.6% of patients treated with volixibat achieved at least a 2-point reduction in itching compared to 26.3% of placebo patients. Treatment effects were observed within two weeks and were also seen in a secondary cohort of patients with mild itching at baseline.

Safety data showed that 93.5% of volixibat-treated patients experienced treatment-emergent adverse events compared to 84.0% of placebo patients. The safety profile was characterized by gastrointestinal adverse events and elevations in liver laboratory parameters. Seven patients (9.1%) discontinued volixibat due to adverse events compared to two patients (2.5%) on placebo.

Mirum has scheduled a pre-New Drug Application meeting with the FDA for summer 2026, with a planned NDA submission in the second half of 2026. The company expects topline data from its VANTAGE Phase 2b study of volixibat in primary biliary cholangitis in the first quarter of 2027.

Primary sclerosing cholangitis is a rare, progressive liver disease affecting an estimated 30,000 patients in the United States. There are currently no approved therapies for the condition, according to the company's press release statement.