Mirum Pharmaceuticals recently announced positive results from the Phase 2b VISTAS clinical trial evaluating volixibat, an investigational treatment for itch (pruritus) in people living with primary sclerosing cholangitis (PSC).
What Is Volixibat?
Volixibat is a medication designed to reduce the amount of bile acids circulating in the body. In PSC, bile acids can build up and are thought to contribute to symptoms like itching. By lowering bile acid levels, volixibat may help relieve this symptom.
Understanding the Study
The VISTAS study included 158 people living with PSC-related itch. Of these, 77 participants received volixibat and 81 received placebo (a non-active pill). The main goal of the study was to measure changes in itch using a tool called the Adult ItchRO, which asks patients to rate their itch on a scale from 0 to 10 (where 0 means no itch and 10 means the worst itch imaginable).
About 70% of participants had moderate to severe itch, and this group was the primary focus when evaluating how well the treatment worked.
Key Results
The study met its main goal:
- People taking volixibat experienced a meaningful reduction in itch compared to those taking placebo. Itch improved more with treatment
- Participants taking volixibat reported about a 2.7-point improvement in itch (on a 0–10 scale), compared to about a 1.1-point improvement with placebo.
More people experienced noticeable relief:
- About 55% of patients on volixibat had a meaningful improvement in itch (2 points or more), compared to about 26% on placebo.
Bile acid levels decreased:
- Patients taking volixibat also had reductions in bile acids, which may help explain the improvement in itch.
Safety
- Volixibat was generally well tolerated.
- The most common side effects were digestive issues such as diarrhea, nausea, or abdominal discomfort.
- Some changes in liver blood tests were observed and will continue to be monitored in future studies.
Why This Matters
Itch is one of the most common and challenging symptoms of PSC, often affecting sleep, daily activities, and quality of life. Currently, there are no approved treatments specifically for PSC-related itch.
These results are an important step forward and suggest that volixibat could become a potential treatment option if future studies and regulatory review are successful.
What’s Next?
Mirum plans to meet with the U.S. Food and Drug Administration (FDA) in 2026 and is preparing for a potential drug submission later this year. If Mirum submits and is approved, volixibat could become available as soon as 2027 or early 2028 in the U.S.
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