Chris Peetz, President and CEO of Mirum Pharmaceuticals, discusses the INDIGO phase 2 clinical trial testing maralixibat to treat progressive familial intrahepatic cholestasis (PFIC).

PFIC is a rare genetic disorder that causes progressive, life-threatening liver disease due to an inability to properly remove bile acids from the liver. The most common manifestation of PFIC is pruritus, which often results in a severely diminished quality of life. In many cases, this disease leads to cirrhosis and liver failure within the first 10 years of life, and nearly all PFIC patients require treatment before the age of 40 years. Currently, there are no drug therapies approved for PFIC, though the FDA is set to make an approval decision about odevixibat for children with PFIC patients by July 20, 2021.

As Mr. Peetz explains, the INDIGO trial was a phase 2, open-label study assessing the safety and efficacy of maralixibat as a treatment for children with PFIC. Primary outcome measures of the study included: 1) to evaluate the safety and tolerability of maralixibat in pediatric PFIC patients, 2) evaluate the effect of maralixibat on serum bile acids in pediatric PFIC patients, 3) evaluate the effect of maralixibat on pruritus in pediatric PFIC patients, and 4) evaluate the effect of maralixibat on biochemical markers of cholestasis and liver disease in pediatric PFIC patients. Results of the study demonstrated that only children with PFIC type 2 responded to treatment after 48 weeks. They found that for the subset that responded to treatment there was normalization or substantial reduction in serum bile acid levels, complete or substantial relief of pruritus, improvement in health related quality of life, and normalization of bilirubin and liver enzyme levels if they were originally elevated. More genetic research may help explain why children with PFIC type 1 did not respond to maralixibat.

To learn more about PFIC and other rare metabolic diseases, visit