Volixibat Granted Breakthrough Therapy Designation for Cholestatic Pruritus in Primary Biliary Cholangitis

- Designation based on positive interim analysis of Phase 2b VANTAGE study

Mirum Pharmaceuticals, Inc. (Nasdaq: MIRM) today announced that the U.S. Food and Drug Administration (FDA) has granted Breakthrough Therapy Designation to volixibat as a potential treatment for cholestatic pruritus in patients with primary biliary cholangitis (PBC). The regulatory designation is based on the positive interim analysis of the Phase 2b VANTAGE study which showed statistically significant improvement versus placebo in pruritus for patients treated with volixibat. The confirmatory portion of the study is ongoing with completion of enrollment expected in 2026.

“Breakthrough Therapy Designation for volixibat in PBC underscores the importance and urgency for a treatment to address one of the most burdensome impacts of this rare liver disease,” said Joanne Quan, MD, chief medical officer at Mirum. “We look forward to advancing our VANTAGE study with the goal of making volixibat available to patients living with PBC-related itch as quickly as possible.”

The FDA’s Breakthrough Therapy Designation aims to expedite the development and review of drugs that are intended to treat serious or life-threatening diseases. To qualify for this designation, preliminary clinical evidence must indicate that the drug may demonstrate substantial improvement over existing therapy on at least one clinically significant endpoint.

About Volixibat

Volixibat is an oral, minimally absorbed agent designed to selectively inhibit the ileal bile acid transporter (IBAT). Volixibat may offer a novel approach in the treatment of adult cholestatic diseases by blocking the recycling of bile acids, through inhibition of IBAT, thereby reducing bile acids systemically and in the liver. Volixibat is currently being evaluated in Phase 2b studies for primary sclerosing cholangitis (VISTAS study), and primary biliary cholangitis (VANTAGE study). In June, Mirum announced positive interim results from the Phase 2b VANTAGE study showing statistically significant improvement in pruritus as well as meaningful reductions in serum bile acids and improvements in fatigue for patients treated with volixibat. No new safety signals were observed, and the most common adverse event was diarrhea with all cases mild to moderate.

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 two rare liver diseases affecting children and adults. It 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 other regions globally. It is also approved in the U.S. in cholestatic pruritus in PFIC patients 12 months of age and older; in Europe, it is approved for patients with PFIC three months of age and older. Mirum is also initiating the Phase 3 EXPAND study, a label expansion opportunity for LIVMARLI in additional settings of cholestatic pruritus. CHOLBAM is 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 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 2 VISTAS study for primary sclerosing cholangitis (PSC) and Phase 2b VANTAGE study for primary biliary cholangitis. Volixibat has been granted Breakthrough Therapy Designation for the treatment of cholestatic pruritus in patients with PBC. Lastly, chenodiol, has been evaluated in a Phase 3 clinical study, RESTORE, to treat patients with CTX, with positive topline results reported in 2023. Mirum has submitted a new drug application with the FDA for the approval of chenodiol to treat CTX in the U.S.

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

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 review and approval process by regulatory authorities of its product candidates. 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 “will,” “could,” “would,” “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 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. A further description of risks and uncertainties can be found in Mirum’s Annual Report on Form 10-K for the fiscal year ended December 31, 2023 and in its subsequent reports on Form 10-Q, including in the sections thereof captioned “Risk Factors,” as well as in its subsequent reports on Form 8-K, all of which are filed with the U.S. Securities and Exchange Commission and available at www.sec.gov.

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