Organization and Description of Business	6 Months Ended
Jun. 30, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business Mirum Pharmaceuticals, Inc. (the “Company”) was incorporated in the State of Delaware on May 2, 2018, and is headquartered in Foster City, California. The Company is a biopharmaceutical company dedicated to transforming the treatment of rare diseases. The Company has three approved medicines: LIVMARLI® (maralixibat) (“Livmarli”), Cholbam® (cholic acid) capsules (“Cholbam”), and CTEXLI® (chenodiol) tablets (“Ctexli”). Livmarli is approved for the treatment of cholestatic pruritus in patients with Alagille syndrome (“ALGS”) in the United States (“U.S.”), the European Union (“EU”) and various other countries around the world and for cholestatic pruritus in patients with progressive familial intrahepatic cholestasis (“PFIC”) in the U.S. and certain other countries and for the treatment of PFIC in the EU. Cholbam is U.S. Food and Drug Administration (“FDA”) approved for the treatment of bile acid synthesis disorders due to single enzyme deficiencies and adjunctive treatment of peroxisomal disorders in patients who show signs or symptoms of liver disease. In February 2025, the Company received FDA approval for chenodiol tablets for the treatment of cerebrotendinous xanthomatosis in adults, which is commercialized under the brand name Ctexli. Prior to the approval of Ctexli, chenodiol tablets were commercialized under the brand name Chenodal under a medical necessity recognition from the FDA. Cholbam and Ctexli, collectively, are referred to as the “Bile Acid Medicines”. The Company’s development pipeline consists of the clinical-stage product candidate volixibat, MRM-3379, zilurgisertib and indication expansion opportunities for Livmarli. On January 23, 2026, the Company acquired Bluejay Therapeutics, Inc. (“Bluejay”). With the completion of the acquisition, the Company added worldwide rights to brelovitug, a late-stage, fully human monoclonal antibody for chronic hepatitis delta virus, a rare and severe liver disease. The Company commenced significant operations in November 2018. The Company views its operations and manages its business as one operating segment and has determined its operating segment on the same basis that it uses to evaluate its performance internally. Liquidity The Company has a limited operating history, has incurred significant operating losses since its inception, and the revenue and income potential of the Company’s business and market are unproven. As of June 30, 2026, the Company had an accumulated deficit of $1.5 billion and unrestricted cash, cash equivalents and investments of $561.3 million. The Company’s 4.00% convertible senior notes due 2029 (the “2029 Notes”) are convertible at the option of the holders during the third quarter of 2026. If holders of the 2029 Notes elect to convert, the Company may elect to settle such conversions in cash, common stock or a combination of the two. The Company’s 0.00% convertible senior notes due 2032 (the “2032 Notes”) are not convertible at the option of the holders during the third quarter of 2026. The Company believes that its unrestricted cash, cash equivalents and investments of $561.3 million as of June 30, 2026, provide sufficient capital resources to continue its operations for at least twelve months from the issuance date of the accompanying unaudited condensed consolidated financial statements.

Mirum Pharmaceuticals, Inc. (the “Company”) was incorporated in the State of Delaware on May 2, 2018, and is headquartered in Foster City, California. The Company is a biopharmaceutical company dedicated to transforming the treatment of rare diseases.

Livmarli is approved for the treatment of cholestatic pruritus in patients with Alagille syndrome (“ALGS”) in the United States (“U.S.”), the European Union (“EU”) and various other countries around the world and for cholestatic pruritus in patients with progressive familial intrahepatic cholestasis (“PFIC”) in the U.S. and certain other countries and for the treatment of PFIC in the EU.

Cholbam is U.S. Food and Drug Administration (“FDA”) approved for the treatment of bile acid synthesis disorders due to single enzyme deficiencies and adjunctive treatment of peroxisomal disorders in patients who show signs or symptoms of liver disease. In February 2025, the Company received FDA approval for chenodiol tablets for the treatment of cerebrotendinous xanthomatosis in adults, which is commercialized under the brand name Ctexli. Prior to the approval of Ctexli, chenodiol tablets were commercialized under the brand name Chenodal under a medical necessity recognition from the FDA. Cholbam and Ctexli, collectively, are referred to as the “Bile Acid Medicines”.

On January 23, 2026, the Company acquired Bluejay Therapeutics, Inc. (“Bluejay”). With the completion of the acquisition, the Company added worldwide rights to brelovitug, a late-stage, fully human monoclonal antibody for chronic hepatitis delta virus, a rare and severe liver disease.

The Company commenced significant operations in November 2018. The Company views its operations and manages its business as one operating segment and has determined its operating segment on the same basis that it uses to evaluate its performance internally.

The Company has a limited operating history, has incurred significant operating losses since its inception, and the revenue and income potential of the Company’s business and market are unproven. As of June 30, 2026, the Company had an accumulated deficit of $1.5 billion and unrestricted cash, cash equivalents and investments of $561.3 million. The Company’s 4.00% convertible senior notes due 2029 (the “2029 Notes”) are convertible at the option of the holders during the third quarter of 2026. If holders of the 2029 Notes elect to convert, the Company may elect to settle such conversions in cash, common stock or a combination of the two. The Company’s 0.00% convertible senior notes due 2032 (the “2032 Notes”) are not convertible at the option of the holders during the third quarter of 2026. The Company believes that its unrestricted cash, cash equivalents and investments of $561.3 million as of June 30, 2026, provide sufficient capital resources to continue its operations for at least twelve months from the issuance date of the accompanying unaudited condensed consolidated financial statements.