Mirum Pharmaceuticals reports LIVMARLI met Phase 3 EXPAND endpoint
The treatment improved itch scores by 0.98 points more than placebo, with a supplemental U.S. drug application planned for the first half of 2027.
Theo Marchetti
Mirum Pharmaceuticals, Inc. NASDAQMIRM reported on Monday that LIVMARLI met the primary endpoint in its Phase 3 EXPAND trial, improving itch scores by 0.98 points more than placebo. The company plans a supplemental U.S. drug application in the first half of 2027 based on the results.
Mirum shares fell 2.7 per cent to US$83.67 on NASDAQMIRM as of 9:56 a.m. EDT on Monday, according to Google Finance.
The rare disease drugmaker tested LIVMARLI, also called maralixibat, in ultra-rare cholestatic liver diseases, including biliary atresia. EXPAND enrolled 52 patients, comprising 46 children and six adults, for a 20-week randomized, double-blind comparison against placebo.
The primary itch analysis covered pediatric patients and produced a p value of 0.0004. Mirum reported no new safety signals, although diarrhea occurred in 64.0 per cent of treated participants compared with 11.1 per cent on placebo.
The Primary Endpoint Measured Observer-Rated Itch
The primary analysis included 22 children receiving maralixibat and 24 receiving placebo. Participants received maralixibat at 285 micrograms per kilogram twice daily or placebo.
On an observer-rated itch scale running from zero to four, the treated group improved by 1.81 points from baseline. The placebo group improved by 0.83 points, with the endpoint measured over weeks 13 to 20.
Serum bile acids fell 70.1 per cent from baseline with maralixibat, compared with 3.5 per cent on placebo. Mirum reported a treatment effect of 69.0 per cent using log-transformed values, with a p value below 0.0001.
All five prespecified secondary endpoints reached statistical significance, including three in patients with biliary atresia who retained their native liver. That subgroup's itch analysis showed a 1.15-point improvement over placebo, with a p value of 0.0002.
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Serious treatment-emergent adverse events occurred in 20.0 per cent of maralixibat recipients and 18.5 per cent of placebo recipients. The company said none of the serious events in the treated group was related to the drug.
One treated participant discontinued the study because of an adverse event, compared with none on placebo. No treatment-emergent adverse events led to death.
"The improvements in pruritus and reductions in serum bile acids observed in EXPAND reinforce the potential for maralixibat to address this unmet need and benefit a broader population of patients living with ultra-rare cholestatic liver diseases," Mirum chief medical officer Rob Myers said.
LIVMARLI Already Generates Commercial Sales
Mirum's Aug. 5 financial update reported LIVMARLI net product sales of US$128.7 million in the second quarter of 2026, up 46 per cent from a year earlier. Unrestricted cash, cash equivalents and investments totalled US$561.3 million as of June 30.
That update listed U.S. approvals for cholestatic pruritus associated with Alagille syndrome and progressive familial intrahepatic cholestasis. EXPAND studied additional conditions for which LIVMARLI is not currently approved, according to Mirum's Oct. 12 release.
Ipsen S.A. EPAIPN OTCMKTSIPSEY announced FDA approval of Bylvay on June 13, 2023, for cholestatic pruritus in Alagille syndrome patients aged 12 months and older.
Mirum plans to submit the EXPAND results to the FDA through a supplemental New Drug Application in the first half of 2027.
