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Mirum Pharmaceuticals Launches with $120M to Advance Liver Drugs

Xconomy San Diego — 

Serial entrepreneur Mike Grey is launching a biotech enterprise with $120 million in new funding to advance two investigational liver disease drugs—one of which he has worked to develop before.

Called Mirum Pharmaceuticals, the startup is developing a compound, maralixibat, to treat Alagille syndrome (ALGS) and progressive familial intrahepatic cholestasis (PFIC), genetic liver disorders that affect primarily children. Mirum plans to move maralixibat, its lead drug, into a Phase 3 trial next year.

Mirum’s clinical trial development will be based out of the Bay Area, where the company’s headquarters are set to be located. Grey and some of his former Lumena colleagues, with whom he has co-founded Mirum, are in San Diego.

Mirum licensed maralixibat from Shire in exchange for an upfront payment plus potential milestone payments and royalties—and equity in the new company. Mirum didn’t share any further financial details of the deal.

For Grey, Mirum represents a second crack at maralixibat, which was the lead compound at San Diego-based Lumena Pharmaceuticals when the company was bought out for $260 million upfront by Shire (NASDAQ: SHPG) in 2014. Grey was president and CEO of the company from 2011 until it was acquired.

Maralixibat is being evaluated because it addresses frustrating and potentially dangerous symptoms associated with ALGS, PFIC, and other diseases. The drug may prevent the build up of bile and a condition known as pruritus—itching so intense some children with the disease injure themselves while scratching. Patients with such diseases face a choice of relief via off-label drugs, surgical intervention, or a liver transplant, according to the company.

Mirum said it will present results of a 48-week interim analysis from a Phase 2b study in people with ALGS at a liver disease meeting next year. More than 230 patients have to date taken the oral compound, which is believed to inhibit a “carrier protein” associated with bile acid, according to the company.

In 2016 another study of the drug, which Shire led, resulted in the FDA’s granting “breakthrough therapy” designation for maralixibat (then called SHP625) as a potential treatment for patients with the most common type of PFIC, which accounts for about half of all such cases. Some patients in the study saw a sustained improvement in their conditions with reduced bile build-up and lessened pruritus—some for more than two years, according to Shire.

Mirum said it also has other liver conditions, which affect both children and adults, in mind as potential targets.

Grey’s newly formed team includes executives who were formerly with Tobira, the South San Francisco-based company that was bought by Allergan (NYSE: AGN) in 2016 for $600 million up front and up to $1.7 billion total.

Tobira had been working on a treatment for nonalcoholic steatohepatitis (NASH), an increasingly common liver disease with no FDA-approved therapies, when the Dublin, Ireland-based pharma giant snapped it up. The investigational drug had failed to meet its primary endpoint in a Phase 2b trial a few months prior to the acquisition.

Chris Peetz, Mirum’s president, was chief financial officer and head of corporate development at Tobira during its initial effort to go public (a plan withdrawn in favor of a reverse merger with publicly traded Regado Biosciences) and its subsequent sale.

He was most recently an entrepreneur-in-residence at Mirum backer Frazier, of which Tobira was a portfolio company. At Frazier, Peetz launched Flashlight Therapeutics, a search company that focused on licensing other companies’ products and developing therapeutics.

Pamela Vig, Mirum’s chief scientific officer, was vice president of clinical research and discovery at Tobira. She is also Flashlight’s co-founder and CSO. Lara Longpre, Mirum’s chief development officer, is Flashlight’s operating officer.

Four of Grey’s former colleagues at Lumena, Alex Dorenbaum, Susan Dubé, Ciara Kennedy, and Niall O’Donnell, are Mirum co-founders and advisors.

As part of the Shire deal, Mirum also has the rights to volixibat, also considered an inhibitor of the carrier protein. Volixibat is being studied as a potential NASH drug.

New Enterprise Associates (NEA) led the financing. Deerfield Management, Frazier, Novo Holdings A/S, Pappas Capital, RiverVest Venture Partners, and Rock Springs Capital also invested. As part of the deal, the company added numerous people to its board of directors: O’Donnell, a managing director at RiverVest, NEA partner Ed Mathers, Frazier managing general partner Patrick Heron, Deerfield partner Jonathan Leff, and Novo Ventures partner Tiba Aynechi.