Mirum Pharmaceuticals Announces Data from EMBARK Phase 2b Study for Biliary Atresia

- Study did not meet primary or secondary endpoints.

- LIVMARLI was generally well-tolerated, with no new safety findings.

Mirum Pharmaceuticals, Inc. (Nasdaq: MIRM), today announced top-line results of the Phase 2 EMBARK study evaluating LIVMARLI® (maralixibat) oral solution versus placebo given as an adjuvant therapy to Kasai surgery in patients with biliary atresia. The study did not meet its primary endpoint of mean change in bilirubin from baseline to Week 26, or the key secondary endpoints. Baseline characteristics were well-balanced between the groups. LIVMARLI was generally well-tolerated, with no new safety findings.

“We are disappointed in the outcome of the study in this post-surgery, high-need disease setting,” said Chris Peetz, president and chief executive officer at Mirum. “We are grateful to the patients, families, and clinicians who participated in the study and advanced the science around this rare liver disease.”

About the EMBARK Study

The Phase 2b EMBARK study is a randomized, double-blind, placebo-controlled clinical trial evaluating the safety and efficacy of LIVMARLI® (maralixibat) oral solution in patients with biliary atresia who have undergone a Kasai surgery. Patients enrolled in the study were ≥21 days old and <90 days old at the time of the Kasai surgery and had a clinical diagnosis of biliary atresia; patients underwent a Kasai surgery within three weeks prior to randomization in EMBARK. The primary endpoint was mean change in total bilirubin through Week 26, followed by secondary endpoints including mean change in total serum bile acids, and proportion of patients who required liver transplant or had another liver related event over the 26 weeks.

IMPORTANT SAFETY INFORMATION

LIVMARLI can cause side effects, including:

Changes in liver tests. Changes in certain liver tests are common in patients with Alagille syndrome and can worsen during treatment with LIVMARLI. These changes may be a sign of liver injury and can be serious. Your healthcare provider should do blood tests before starting and during treatment to check your liver function. Tell your healthcare provider right away if you get any signs or symptoms of liver problems, including nausea or vomiting, skin or the white part of the eye turns yellow, dark or brown urine, pain on the right side of the stomach (abdomen) or loss of appetite.

Stomach and intestinal (gastrointestinal) problems. LIVMARLI can cause stomach and intestinal problems, including diarrhea, stomach pain, and vomiting during treatment. Tell your healthcare provider right away if you have any of these symptoms more often or more severely than normal for you.

A condition called Fat Soluble Vitamin (FSV) Deficiency is caused by low levels of certain vitamins (vitamin A, D, E, and K) stored in body fat. FSV deficiency is common in patients with Alagille syndrome but may worsen during treatment. Your healthcare provider should do blood tests before starting and during treatment.

Other common side effects reported during treatment were gastrointestinal bleeding and bone fractures.

US Prescribing Information

EU SmPC

Canadian Product Monograph

About Mirum Pharmaceuticals, Inc.

Mirum Pharmaceuticals, Inc. is a biopharmaceutical company dedicated to transforming the treatment of rare diseases affecting children and adults. Mirum has three approved medications: LIVMARLI® (maralixibat) oral solution, Cholbam® (cholic acid) capsules, and Chenodal® (chenodiol) tablets.

LIVMARLI, an IBAT inhibitor, is approved for the treatment of cholestatic pruritus in patients with Alagille syndrome in the U.S. (three months and older), in Europe (two months and older), and in Canada. Mirum has also submitted LIVMARLI for approval in the U.S. in cholestatic pruritus in PFIC patients three months of age and older and in Europe in PFIC for patients two months of age and older. Cholbam is FDA-approved for the treatment of bile acid synthesis disorders due to single enzyme defects and adjunctive treatment of peroxisomal disorders in patients who show signs or symptoms or liver disease. Chenodal has received medical necessity recognition by the FDA to treat patients with cerebrotendinous xanthomatosis (CTX).

Mirum’s late-stage pipeline includes two investigational treatments for debilitating liver diseases. Volixibat, an IBAT inhibitor, is being evaluated in two potentially registrational studies including the Phase 2b VISTAS study for primary sclerosing cholangitis and Phase 2b VANTAGE study for primary biliary cholangitis. Lastly, Chenodal, has been evaluated in a Phase 3 clinical study, RESTORE, to treat patients with CTX.

To learn more about Mirum, visit mirumpharma.com and follow Mirum on Facebook, LinkedIn, Instagram and Twitter.

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 Mirum’s clinical strategy, the therapeutic potential of IBATs in biliary atresia and any potential path forward for LIVMARLI in biliary atresia as well as the progress of Mirum’s ongoing and planned studies for its product candidates and the regulatory approval path for its product candidates globally. 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 “forward,” “planned,” “poised,”, “positioned” “potential”, “will” 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, the impact of the COVID-19 pandemic, 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 and are based on management’s assumptions and estimates as of such date. 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.

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