Mirum Pharmaceuticals Secures FDA Approval for Ctexli in Rare Metabolic Disorder

In a significant development for patients with cerebrotendinous xanthomatosis (CTX), the U.S. Food and Drug Administration (FDA) has approved Mirum Pharmaceuticals' Ctexli (chenodiol) for the treatment of adults with this rare genetic disorder. The approval, announced on February 21, 2025, marks a milestone as the first FDA-approved therapy specifically indicated for CTX in the United States.

Breakthrough for CTX Patients

CTX is an ultra-rare metabolic disorder affecting approximately one in a million people globally. The condition is caused by mutations in the CYP27A1 gene, leading to a deficiency in the enzyme responsible for breaking down cholesterol. As a result, patients experience toxic accumulations of cholesterol metabolites throughout the body, particularly in the brain and connective tissues.

Ctexli works by replenishing the body's insufficient levels of bile acids, thereby reducing the buildup of toxic metabolites that cause the disease. The drug's approval was supported by data from the Phase III RESTORE study, which demonstrated a significant reduction in plasma cholestanol and bile alcohols compared to placebo.

Janet Maynard, director of the FDA's Office of Rare Diseases, Pediatrics, Urologic and Reproductive Medicine, stated, "Ctexli provides patients and physicians with a safe and effective treatment option to address cerebrotendinous xanthomatosis."

Strategic Acquisition Pays Off

The approval of Ctexli stems from Mirum's strategic $210 million acquisition of Travere Therapeutics' bile acid portfolio in 2023. This deal included chenodiol, which was previously approved under the brand name Chenodal for the treatment of radiolucent gallstones.

Chris Peetz, CEO of Mirum Pharmaceuticals, expressed optimism about the approval's impact: "The FDA's approval of Ctexli is tremendous as it unlocks an opportunity to better identify and treat adult patients with CTX in the United States. Our hope is that patients are diagnosed sooner and have a chance to avoid some of the debilitating and lasting symptoms associated with CTX."

Expanding Mirum's Rare Liver Disease Portfolio

The approval of Ctexli further solidifies Mirum's position as a leader in rare liver diseases. The company's portfolio includes:

1. Livmarli: Approved in September 2021 for cholestatic pruritus in Alagille syndrome and expanded in March 2024 for familial intrahepatic cholestasis.
2. Volixibat: An investigational drug for primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC), which received Breakthrough Therapy designation for PBC in October 2024.

Mirum's focus on rare liver diseases has shown financial promise, with Livmarli securing $59.1 million in sales in the third quarter of 2024, accounting for more than half of the company's net product sales that quarter.

Looking Ahead

While Ctexli's approval represents a significant advancement for CTX patients, Mirum faces the challenge of increasing disease awareness and diagnosis rates. The company plans to leverage its patient support platform to facilitate access to the drug, with the majority of patients expected to pay $10 or less for treatment.

As Mirum continues to expand its rare disease portfolio, industry analysts anticipate that Ctexli could contribute an additional $150 million to $200 million to the company's revenue. With seven years of regulatory exclusivity granted for Ctexli's use in treating CTX, Mirum is well-positioned to capitalize on this latest approval and further strengthen its market presence in the rare liver disease space.