Mirum Pharmaceuticals, Inc. announced new data from its LIVMARLI and volixibat programs presented at The Liver Meeting®, the American Association for the Study of Liver Diseases (AASLD) annual meeting in Boston, Massachusetts. Data were presented from the Phase 3 MARCH study and MARCH-ON extension evaluating the efficacy and safety of LIVMARLI in patients with progressive familial intrahepatic cholestasis (PFIC) as well as the Phase 2 OHANA study evaluating the efficacy and safety of volixibat in patients with intrahepatic cholestasis of pregnancy (ICP). MARCH was the largest and most genetically diverse trial of PFIC to date, enrolling patients with deficiencies of BSEP, FIC1, MDR3, TJP2, AND MYO5B, as well as those clinically diagnosed with PFIC but without a known genetic variant.

Poster 5048-C: Long-term maintenance of response and improved liver health with maralixibat in patients with progressive familial intrahepatic cholestasis (PFIC): 2-year data from the MARCH-ON study: The MARCH-ON extension study evaluated the long-term efficacy and safety of maralixibat in patients with PFIC who received maralixibat in the original MARCH study for 26 weeks and continued for up to two years and those who were on placebo who went on to receive maralixibat for up to one year. Significant and sustained improvements in pruritus severity, serum bile acid (sBA) levels, total bilirubin, and growth were observed with up to two years of maralixibat treatment across the broadest range of genetic PFIC types studied to date. The placebo-maralixibat group demonstrated rapid (as early as three weeks) and significant improvements in pruritus severity and sBA levels similar to those observed in the original MARCH maralixibat group.

No new safety signals were observed. The most common treatment emergent adverse events were GI, occurred early in treatment, and were mild and transient in nature. These data suggest overall improved liver health with maralixibat treatment in patients with PFIC that can be maintained long-term.

Poster 4602-C: Improvements in pruritus with maralixibat are associated with improved quality of life for patients with progressive familial intrahepatic cholestasis: Data from the MARCH-PFIC trial: Pruritus is known to be one of the most burdensome symptoms of PFIC, occurring in the majority of patients and leading to sleep disturbance, self-mutilation, and decreased school performance, further contributing to impaired quality of life. An exploratory endpoint in the MARCH study was to evaluate if a clinically significant reduction in pruritus following treatment with maralixibat was associated with an improvement in quality of life. These data demonstrated that clinically significant reductions in pruritus were associated with meaningful improvements in quality of life, as evaluated across several domains.

The maralixibat group demonstrated significant differences between pruritus responders and non-responders for PedsQL, PedsQL-SF, PedsQL-PF, and a trend toward significance with FI-T. Clinically meaningful improvements (MCID >4-5 points) across all HRQoL scales were experienced by maralixibat responders. The placebo group showed no significant differences between pruritus responders and non-responders in any of the assessments. These data suggest that benefits of maralixibat may extend beyond pruritus and yield meaningful improvements in quality of life as well.

Poster 4604-C: Maralixibat leads to significant improvement in cholestatic pruritus for children with progressive familial intrahepatic cholestasis due to TJP2 or MYO5B deficiency: Data from the MARCH-PFIC trial: The MARCH study assessed the broadest set of genetic types associated with PFIC. The most common causes of PFIC are deficiencies in BSEP (PFIC2), FIC 1, MDR3, TJP2, and MYO5B. Patients with TJP2 deficiency have a predisposition to developing hepatocellular carcinoma.

The goal of this analysis was to understand maralixibat?s potential to provide improvement across key markers of the disease in patients with these two rare genetic variants (TJP2, n=7, MYO5B, n=4). The results demonstrated that all patients with either a TJP2 or MYO5B deficiency receiving maralixibat achieved substantial improvements in pruritus and reductions in sBA while patients who received placebo experienced little benefit. Bilirubin levels were normalized in one participant with MYO5B deficiency who received maralixibat.

MARCH is the first trial demonstrating benefit of IBAT inhibition for TJP2 and MYO5B deficiencies and these data support the use of maralixibat in patients with these genetic types. Poster 4605-C: Maralixibat leads to significant improvements in cholestatic pruritus for children with progressive familial intrahepatic cholestasis without a genetic diagnosis: Data from the MARCH-PFIC trial: The MARCH study evaluated patients (n=8) with a PFIC clinical diagnosis without an identified genetic variant. The objective of this analysis was to understand the efficacy and safety of maralixibat treatment for patients clinically diagnosed with PFIC but without a known genetic variant.

Data demonstrated that maralixibat was associated with improvements in pruritus, sBA levels, total bilirubin, and direct bilirubin, as compared to placebo. No new safety signals were observed. These data demonstrate the utility of treating patients with PFIC but without a known genetic variant with maralixibat.

Poster 4547-C: Efficacy, safety and tolerability of volixibat in patients with intrahepatic cholestasis of pregnancy: A case series of 4 patients: Intrahepatic cholestasis of pregnancy (ICP) is a cholestatic liver disease impacting pregnant woman. ICP is characterized by elevated sBA and cholestatic pruritus, often impairing sleep and quality of life. Elevated sBAs pose significant risk to the unborn fetus.

A Phase 2 open-label study, OHANA, was conducted with volixibat, a minimally absorbed IBAT inhibitor, to evaluate the efficacy and safety in four patients with ICP. Volixibat demonstrated improvements in pruritus and sBA levels, signaling proof of concept for volixibat in cholestatic disease.No clinically meaningful changes in liver enzyme levels or hematology parameters were observed after volixibat treatment. The most common TEAEs were GI in nature, transient and moderate in severity.