Mirum Pharmaceuticals Reports Second Quarter Financial Results and Provides Corporate Update

Mirum Pharmaceuticals Reports Second Quarter Financial Results and Provides Corporate Update

FOSTER CITY, Calif. August 28, 2019 Mirum Pharmaceuticals, Inc. (NASDAQ: MIRM), a biopharmaceutical company focused on

the development and commercialization of a late-stage pipeline of novel therapies for debilitating liver diseases, today reported financial results for the quarter ended June 30, 2019 and provided an update on its clinical programs.

With the advancement of maralixibat into Phase 3, the expansion of the team and the successful completion of our initial public offering, 2019 has been

a notable year for Mirum, said Chris Peetz, president and chief executive officer of Mirum. We are excited to have strengthened our capital position as we continue to build Mirum into a leading innovator in rare liver disease. We look

forward to further advancing maralixibat and achieving our goal of offering children with cholestasis a new treatment option that targets bile acid overload, a primary driver of liver damage and pruritus in these progressive diseases.

Key Operational Highlights

Second Quarter 2019 Financial Results

As of June 30, 2019, Mirum had cash, cash equivalents and investments of $100.3 million,

exclusive of the net proceeds of approximately $67.3 million from the IPO.

Upcoming Milestones and Expectations

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 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

(in thousands, except per share amounts)

Mirum Pharmaceuticals, Inc.

Selected Consolidated Balance Sheet Data

Heidi Chokeir, Ph.D.

Canale Communications