Exhibit 99.1

Mirum Pharmaceuticals Reports Third Quarter Financial Results and Provides Corporate Update

Breakthrough Therapy Designation for Maralixibat for the Treatment of Pruritus Associated with Alagille Syndrome Granted

Cash, Cash Equivalents and Investments Balance of $153.6 million

FOSTER CITY, Calif. – November 6, 2019 – Mirum Pharmaceuticals, Inc. (NASDAQ: MIRM), a biopharmaceutical company focused on the development and commercialization of novel therapies for debilitating liver diseases, today reported financial results for the quarter ended September 30, 2019 and provided an update on its clinical programs.

“The first nine months of 2019 have seen great progress towards bringing maralixibat to market for Alagille syndrome and progressive familial intrahepatic cholestasis,” said Chris Peetz, president and chief executive officer of Mirum. “The granting of breakthrough designation by the Food & Drug Administration and an oral late breaking presentation at the Liver Meeting are testimony of the tremendous potential of maralixibat for Alagille syndrome. The next 12 months are poised to be a transformational year as we prepare for commercialization and complete the MARCH-PFIC Phase 3 study.”

Key Operational Highlights

Third Quarter 2019 Financial Results

As of September 30, 2019, Mirum had cash, cash equivalents and investments of $153.6 million.

Upcoming Milestones and Expectations

About Maralixibat

Maralixibat is a novel, minimally-absorbed, orally administered investigational drug being evaluated in several rare cholestatic liver diseases for pediatric populations. Maralixibat inhibits the apical sodium dependent bile acid transporter, which results in more bile acids being excreted in the feces, leading to lower levels of bile acids systemically, thereby potentially reducing bile acid mediated liver damage and related effects and complications. More than 1,500 individuals have received maralixibat, including more than 100 children who have received maralixibat as an investigational treatment for Alagille syndrome (ALGS) and progressive familial intrahepatic cholestasis (PFIC). In a Phase 2 PFIC study, a genetically defined subset of BSEP (bile salt export pump) deficient, or PFIC2, patients responded to maralixibat, which led to maralixibat receiving Breakthrough Therapy designation from the U.S. Food and Drug Administration for PFIC2. In a Phase 2b ALGS study, patients taking maralixibat had significant reductions in bile acids and pruritus compared to placebo. Maralixibat was generally well-tolerated throughout the studies. The most frequent adverse events were diarrhea, abdominal pain and vomiting.

About Mirum Pharmaceuticals

Mirum Pharmaceuticals, Inc. is a clinical-stage biopharmaceutical company focused on the development and commercialization of a late-stage pipeline of novel therapies for debilitating liver diseases. The company’s lead product candidate, maralixibat, is an investigational oral drug in development for progressive familial intrahepatic cholestasis (PFIC) and Alagille syndrome (ALGS). For more information, visit MirumPharma.com. Follow Mirum on Twitter, Facebook and LinkedIn.

Forward-Looking Statements

Statements contained in this press release regarding matters that are not historical facts are “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Such forward-looking statements include statements regarding, among other things, the results, conduct, progress and timing of Mirum’s clinical trials, and the regulatory approval path for maralixibat. Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. Words such as “plans”, “will”, “believes,” “anticipates,” “expects,” “intends,” “goal,” “potential” and similar expressions are intended to identify forward-looking statements. These forward-looking statements are based upon Mirum’s current expectations and involve assumptions that may never materialize or may prove to be incorrect. Actual results could differ materially from those anticipated in such forward-looking statements as a result of various risks and uncertainties, which include, without limitation, risks and uncertainties associated with Mirum’s business in general, and the other risks described in Mirum’s filings with the Securities and Exchange Commission. All forward-looking statements contained in this press release speak only as of the date on which they were made. Mirum undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made, except as required by law.

Mirum Pharmaceuticals, Inc.

Selected Consolidated Statement of Operations Data

(Unaudited)

(In thousands, except per share amounts)

Mirum Pharmaceuticals, Inc.

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Media Contact:

Heidi Chokeir, Ph.D.

Canale Communications

619-203-5391

heidi@canalecomm.com

Investor Contact:

Ian Clements, Ph.D.

650-667-4085

ir@mirumpharma.com