Mirum Pharmaceuticals’ marketed therapy, Livmarli (maralixibat), could be poised for a label expansion, after the drug secured a resounding success in a Phase III trial looking at its potential to treat itch linked to a range of ultra-rare liver diseases.
This potential addition to Livmarli’s label could come off the back of the positive results of the placebo-controlled EXPAND study (NCT06553768), in which Mirum explored the drug’s potential to reduce intense itching in 52 patients aged six months and up with a variety of ultra-rare liver conditions. A notable portion of the patient population in EXPAND had biliary atresia, which currently has no approved therapies.
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The trial met its primary endpoint as well as all five prespecified secondary endpoints, including three endpoints in patients with biliary atresia and a native liver.
During this trial, Livmarli triggered a significant 0.98-point, placebo-adjusted improvement in itch during weeks 13 to 20 in all 46 paediatric patients within this trial, while also prompting a 69% drop in blood bile acid levels versus placebo within the overall study population.
Livmarli’s itch-reducing effect was seen especially strongly in the population of patients who still had their own liver and were suffering from biliary atresia, with individuals in this subgroup experiencing a 1.15-point placebo adjusted improvement in itch scores.
Researchers also found Livmarli to be safe and effective within this patient population, as no new safety signals were observed during EXPAND.
With a new set of positive results in the bag for Livmarli, Mirum plans to submit a supplemental New Drug Application (sNDA) to US regulators in the first half of 2027, which could see the drug become the first therapy approved for biliary atresia – a condition where the bile ducts are scarred, blocked or entirely missing, leading to a potentially life-threatening buildup of bile acids in the blood.
In an investor call, Mirum’s president and COO, Peter Radovich, noted that a near-70% reduction in pruritus is “very clinically meaningful”, while the company’s CEO, Rob Myers, added that addressing itch in this context remains especially important due to the burden it can place on patients.
Livmarli is currently approved by the US Food and Drug Administration (FDA) for the treatment of itch in two rare liver conditions, Alagille syndrome (ALGS) and progressive familial intrahepatic cholestasis (PFIC).
While Livmarli’s mechanism of action (MOA) is not fully understood, researchers believe it acts by reversibly blocking the ileal bile acid transporter (IBAT) protein, which is normally linked to the recycling of bile acids from the gut into the liver.
According to analysts at GlobalData, the parent company of Clinical Trials Arena, sales of Livmarli will achieve sales of $876m in 2032, narrowly missing out on blockbuster status.
