Mirum's Ctexli Scores FDA Approval for Rare Metabolic Disorder

The U.S. Food and Drug Administration (FDA) has granted approval to Mirum Pharmaceuticals' Ctexli (chenodiol) for the treatment of adults with cerebrotendinous xanthomatosis (CTX), marking a significant milestone in the management of this rare genetic metabolic disorder.

First FDA-Approved Treatment for CTX

Ctexli becomes the first drug specifically indicated to treat CTX in the United States. This approval comes nearly two years after Mirum's strategic $210 million acquisition of Travere Therapeutics' bile acid portfolio, which included chenodiol.

CTX is characterized by a genetic mutation that leads to a deficiency in the enzyme responsible for breaking down fats. As a result, patients with CTX cannot process cholesterol normally, leading to the accumulation of atypical cholesterol metabolites that can damage various organs, including the brain, liver, skin, and tendons.

Ctexli works by replacing low levels of one of the bile acids, thereby helping to clear out toxic cholesterol metabolite deposits. The drug's efficacy was demonstrated in a phase 3 clinical trial, where three daily doses of 250 mg Ctexli significantly reduced levels of two cholesterol metabolites that are typically elevated in CTX patients compared to placebo.

Safety Considerations and Market Implications

While the approval represents a breakthrough for CTX patients, the FDA has included a warning for liver toxicity. Patients are advised to undergo liver blood tests before initiating Ctexli treatment and annually thereafter to monitor potential risks.

The formal approval of Ctexli is expected to have significant market implications. JMP Securities analyst Jonathan Wolleben estimates that the drug could generate an additional $150 million to $200 million in revenue for Mirum. Moreover, the approval grants Ctexli seven more years of protection against potential generic competitors.

Chris Peetz, CEO of Mirum Pharmaceuticals, highlighted the potential impact of the approval on patient care. "We think that we'll be able to diagnose more undiagnosed patients," Peetz stated. "And by treating this disease earlier, you can prevent some of the accumulation of irreversible defects."

Expanding Mirum's Rare Disease Portfolio

The successful development and approval of Ctexli further solidifies Mirum's position in the rare disease market. Prior to acquiring the bile acid portfolio from Travere, Mirum's commercial presence was limited to Livmarli, a treatment for another rare liver disease.

With this latest approval, Mirum has demonstrated its ability to leverage acquired assets and bring much-needed treatments to market for underserved patient populations. As the company prepares to launch Ctexli, the pharmaceutical industry will be watching closely to see how this new treatment option impacts the lives of those affected by CTX.