Mirum's LIVMARLI Meets Phase 3 Goals for Rare Liver Diseases

Mirum Pharmaceuticals announced positive topline results from its Phase 3 EXPAND study evaluating LIVMARLI (maralixibat) in patients aged 6 months or older with ultra-rare cholestatic liver diseases, meeting its primary endpoint with plans for a U.S. regulatory submission in the first half of 2027.

The trial tested the oral medication against cholestatic pruritus, a severe itch caused by impaired bile flow, across a patient population that included individuals with biliary atresia. According to Mirum's investor relations announcement, the drug achieved statistical significance on its primary measures.

“These results are especially important because patients with ultra-rare cholestatic liver diseases continue to face a significant burden from pruritus,” said Rob Myers, M.D., Chief Medical Officer at Mirum Pharmaceuticals.

Clinical Efficacy and Biomarker Reductions

In the EXPAND study, maralixibat demonstrated a statistically significant reduction in cholestatic pruritus compared with placebo, marked by a p-value of 0.0004. Alongside symptom relief, the treatment achieved a 69.0% reduction in serum bile acids versus placebo, with a p-value below 0.0001.

For the specific subpopulation of patients with biliary atresia and a native liver, the medication similarly delivered a statistically significant reduction in cholestatic pruritus compared with placebo, registering a p-value of 0.0002. These biomarker and symptom drops indicate that the drug targets the underlying mechanism of bile acid accumulation rather than masking the itch.

“The magnitude and consistency of improvements in pruritus and serum bile acid levels observed in EXPAND are compelling, including for patients with biliary atresia,” said Jennifer Vittorio, M.D., FAASLD, Associate Professor of Pediatrics and Medical Director, Pediatric Liver Transplantation, NYU Langone Health.

Regulatory Timeline and Patient Impact

Building on the EXPAND data, Mirum Pharmaceuticals plans to submit a supplemental New Drug Application (sNDA) to the U.S. Food and Drug Administration in the first half of 2027. If approved, the filing would expand LIVMARLI's label to cover the broader ultra-rare cholestatic liver disease indications evaluated in the trial.

Biliary atresia is a rare condition in infants where the bile ducts inside or outside the liver are scarred or blocked, often requiring surgical intervention early in life. Cholestatic pruritus frequently persists even when patients retain their native liver, creating management challenges for pediatric patients and their caregivers.

“These results are meaningful for the biliary atresia community, where children and families continue to face significant challenges due to cholestatic pruritus,” said Jen Lau, MPH, Co-Founder and Executive Director of BARE, Inc. (Biliary Atresia Research and Education).