Mirum scoops $120M to take ex-Shire drug into phase 3

Mirum Pharmaceuticals has bought the rights to maralixibat from Shire and raised $120 million to take it into a pair of phase 3 trials next year. The deal reunites some of the management team and investor syndicate that worked on the liver disease drug at Lumena before selling out to Shire in 2014.

Back when Shire paid $260 million upfront for Lumena, maralixibat was tipped to rack up blockbuster sales and fuel its new owner’s growth. That vision soured fast. Maralixibat, then known as SHP625, failed a phase 2 trial in children with Alagille syndrome (ALGS) in 2015. And then went on to chalk up another midphase failure in primary sclerosing cholangitis.

Despite the setbacks, the drug never completely fell off the radar. Shire filed to run a phase 3 trial last year—but never started enrollment—and researchers continued to track patients in a midphase trial that was first discussed shortly after the Lumena buyout. 

Data from the midphase trial, dubbed ICONIC, have persuaded more people that maralixibat has a future. Neither Shire nor Mirum have shared the findings of the 48-week interim analysis of data on children with rare genetic disorder ALGS. But the impact of the analysis on the future of oral apical sodium dependent bile acid transporter inhibitor maralixibat is clear.

New Enterprise Associates (NEA) and supporting investors have given former Lumena CEO Mike Grey $120 million to buy back maralixibat and take it into phase 3. Mirum plans to start phase 3 trials in ALGS and progressive familial intrahepatic cholestasis next year. Shire let the drug go in return for an upfront fee, equity stake in Mirum and potential milestones and royalties. 

The financing round and Shire deal reunite some of the people who played starring roles in the story of maralixibat prior to the acquisition of Lumena. Months before the takeover by Shire, Lumena, led by Grey, raised $45 million in a series B round led by NEA. Pappas Capital, which founded Lumena, and RiverVest Venture Partners played supporting roles in the 2014 and 2018 funding rounds. 

In the near term, the syndicate’s support will enable Grey and the team of ex-Lumena and Tobira staffers he has put together to run the two phase 3 trials. Beyond that, Mirum has could look into the effect of maralixibat on children and adults with other forms of cholestatic liver disease.