Mirum Pharmaceuticals reported positive topline results on Monday from its Phase 3 EXPAND study evaluating LIVMARLI (maralixibat) for cholestatic pruritus in patients aged six months and older with ultra-rare liver conditions, including biliary atresia. Benzinga reported that the clinical trial met its primary endpoint while showing statistical significance across all five secondary measures.
Phase 3 EXPAND Trial Efficacy Results
The late-stage study evaluated 52 participants who received either a twice-daily dose of maralixibat at 285 µg/kg or a placebo. In the main pediatric analysis population, maralixibat generated a statistically significant reduction in itching compared to the placebo group.
Patients on maralixibat showed an average 1.81-point gain from baseline in their mean worst-daily ItchRO(Obs) severity score spanning Weeks 13 and 20. The placebo group recorded a 0.83-point improvement, marking a placebo-adjusted treatment difference of 0.98 points with a p-value of 0.0004.
Maralixibat also drove a 70.1% baseline drop in total serum bile acids, compared to a 3.5% reduction for the placebo cohort. Pediatric patients receiving the treatment achieved pruritus improvement on 86.0% of days, compared to 49.1% for the placebo group.
Biliary Atresia Subgroup Performance
Among patients with biliary atresia who retained their native liver, maralixibat delivered substantial clinical improvements. Patients taking the treatment achieved a 2.16-point reduction in severity score, compared to a 1.01-point drop for the placebo group, marking a 1.15-point difference.
These participants experienced pruritus relief on 96.4% of days, compared to 52.2% for the placebo group, with a p-value of 0.0045. Additionally, the maralixibat cohort achieved a 75.5% reduction in total serum bile acids, compared to 9.0% for the placebo group.
Safety Outcomes and Adverse Events
Safety outcomes mirrored previous clinical trials, and researchers identified no new safety concerns during the study. Pneumonia, pyrexia, large intestine infection, acute kidney injury, and viral infection with bronchiolitis were among the serious adverse events documented within the maralixibat group. Investigators determined none of these serious events were treatment-related.
Serious adverse events in the placebo group included pneumonia, pancytopenia, sepsis, forearm fracture, and cholangitis.
Market Response and Share Price Action
Following the announcement, Mirum Pharmaceuticals shares traded higher. Benzinga Pro data showed company shares were up 2.31% at $88.00 during premarket trading on Monday.
Questions About Maralixibat Treatment
What is the primary endpoint measured in the Phase 3 EXPAND study?
The trial evaluated the reduction of cholestatic pruritus, or severe itching, in individuals aged six months and older suffering from ultra-rare cholestatic liver conditions. The main pediatric analysis population measured a statistically significant reduction in itching using the ItchRO(Obs) severity score between Weeks 13 and 20.
What dosage of maralixibat was administered in the clinical trial?
Trial participants received either a twice-daily dose of maralixibat at 285 µg/kg or a matching placebo across the 52 total participants evaluated in the late-stage study.