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Mirum Pharmaceuticals sells medicines that treat rare liver diseases in children and adults.
Mirum Pharmaceuticals is a drugmaker that focuses on rare liver diseases, the kind of conditions that are often diagnosed in babies and young children but can also affect adults. Its medicines are not everyday pharmacy products. They treat serious, sometimes life-threatening illnesses where few treatment options exist, which is exactly why a small company can build a real business around them.
Its best-known drug, Livmarli, treats a severe itching condition called cholestatic pruritus that comes with certain rare liver diseases, including Alagille syndrome and progressive familial intrahepatic cholestasis. The itching is not a minor annoyance. It can be so relentless that children scratch themselves raw and struggle to sleep, and it is one of the main reasons some families consider liver transplants. Livmarli works by blocking bile acids in the gut so less builds up in the body. Mirum also sells Chenodal, a tablet for a rare bile acid disorder called cerebrotendinous xanthomatosis, and Bylvay, another bile-acid drug for a different set of rare liver diseases. That gives it three approved products and a narrow but deep niche. The money comes from selling these drugs, mostly in the United States and Europe, paid for by insurers, health systems, and government programs. Rare-disease drugs can carry very high prices because the patient pool is tiny and the development costs are huge. That math cuts both ways: a small number of patients can generate a lot of revenue per patient, but the company has to keep finding those patients, getting diagnosed, and getting paid. Competition is thin. In Livmarli's main market the closest rival is another bile-acid drug from a larger drugmaker, Ipsen, so Mirum's edge rests on its clinical data and the relationships it builds with specialist doctors.
Mirum has grown fast by buying rather than inventing everything itself. It picked up Bylvay through its acquisition of Albireo Pharma in 2023, which roughly doubled its product lineup, and it has also licensed assets from other biotechs. These deals are how a young company assembles a rare-disease portfolio without spending a decade on early research. The risk is familiar to anyone who follows biotech: the stock swings on trial results, regulatory decisions, and how quickly new patients start treatment, and the company still spends heavily on research and sales to keep the pipeline and the revenue growing.
Saved answer 路 last researched 15 Nov 2026