Mirum Pharmaceuticals is no longer a single-asset pediatric liver story. The Foster City company now runs three approved rare-disease medicines and is using that cash engine to buy a late-stage pipeline that reaches adult cholestasis, hepatitis delta, and an ultra-rare bone disease. The second-quarter print raised full-year product-sales guidance and confirmed that Livmarli, the ileal bile acid transporter inhibitor sold for Alagille syndrome and progressive familial intrahepatic cholestasis, is still compounding. The investment debate is whether that commercial franchise can carry four concurrent development programs after the Food and Drug Administration told management that a successful mid-stage study is not, by itself, a filing package for volixibat in primary sclerosing cholangitis.
Livmarli remains the load-bearing product. Second-quarter product sales reached $176 million, with Livmarli contributing $129 million and bile-acid medicines the rest. Management lifted full-year product-sales guidance to a band of $680 million to $700 million, and that range still excludes any contribution from zilurgisertib if the late-September review lands as an approval. Cash, cash equivalents and investments stood at $561 million at mid-year after a $690 million zero-coupon convertible issue that also retired most of the older coupon notes. The commercial contribution margin sat in the high fifties, which is how a still-unprofitable company can keep funding a pipeline this wide without an immediate equity raise.
The counterweight is regulatory, not commercial. Volixibat's VISTAS study met its itch endpoint in May, and the agency still recommended a later-stage trial at the pre-filing meeting, pushing a possible submission into the first half of next year. Brelovitug, acquired with Bluejay Therapeutics in January, has two registration-enabling readouts still ahead. The next several quarters decide whether Mirum is a self-funding rare-disease platform or a commercial company that overpaid for optionality the regulator is not ready to credit.