In $86M IPO pitch, Mirum spells out plans to turn Shire discards into orphan liver drug successes
Mike Grey doesn’t have any time to waste. Having regained control of two liver disease drugs from Shire and positioned them for pivotal studies — five years after first handing them off in a deal to sell Lumena, where he was CEO — Grey is steering Mirum straight into an IPO with a $86 million ask.
Not that Mirum has spent much of its $120 million Series A cash since launching last November. According to the S-1, the Californian biotech has burned through $23.3 million as of March, but expects expenses to pick up once their clinical work gathers steam.
The filing also revealed that it only cost Mirum $7.5 million in cash upfront to bag maralixibat and volixibat, its two major assets. Shire — now part of Takeda — had wagered $260 million on Lumena largely on the promise of these two assets, which both target the apical sodium-dependent bile acid transporter, or ASBT (you might remember them as LUM001 and LUM002).
Mirum also issued $7.0 million worth of shares to Shire at the time, making them a principal stockholder (10.3%) behind NEA (20.8%), Frazier (17.3%), Deerfield (17.3) and alongside Novo Holdings (10.4%). Grey himself is keeping 5.5% of the stock while CEO Christopher Peetz claims 4.5%.
All told, milestones in the Shire deal are just shy of $200 million.
While maralixibat had failed mid-stage studies at Shire, Mirum believes better trial design and patient selection will deliver the wins they need. In Alagille syndrome (ALGS), that involves testing a higher dose — resulting in “statistically significant reductions in pruritus and sBA compared to placebo.” And for progressive familial intrahepatic cholestasis (PFIC), the team is zeroing in on the extreme itching associated with a particular, genetically defined subset of patients. Patient enrollment for the PFIC trial has begun while the ALGS study is slated for next year — all catering to pediatric patients.
Meanwhile, adults will be the core demographic for the volixibat program, which tests the hypothesis that blocking recycling of bile acids can reduce its harm systematically. Expect Phase II trials in primary sclerosing cholangitis and intrahepatic cholestasis of pregnancy in 2020, the company says, in a clear departure from a previous NASH focus.
If the public debut goes as planned, the team — comprising Lumena vets who followed the drugs — will have plenty of resources to execute all of that for two drugs they plan to eventually commercialize on their own in North America and Europe.
Mirum’s symbol of choice on the Nasdaq is $MIRM.