FDA Approves Mirum's CTEXLI™ for Treating Cerebrotendinous Xanthomatosis

Mirum Pharmaceuticals, Inc. has received approval from the U.S. Food and Drug Administration (FDA) for its drug CTEXLI™ (chenodiol) tablets. This medication is designed to treat adults suffering from cerebrotendinous xanthomatosis (CTX), a rare and progressive genetic disease. CTEXLI is notable for being the first and only medication approved for CTX, providing a new treatment option for those affected by this debilitating condition.

The approval of CTEXLI is grounded in the results of the Phase 3 RESTORE study. This study assessed the drug's safety and effectiveness by analyzing the levels of urine bile alcohols among adult patients with CTX. The findings were significant, showing a pronounced decrease in bile alcohols, specifically urine 23S-pentol, with a highly significant statistical measure (p<0.0001). At the conclusion of the study's double-blind withdrawal phase, patients treated with CTEXLI exhibited a 20-fold reduction in urine 23S-pentol levels compared to those receiving a placebo.

CTX is characterized by a deficiency in the bile acid chenodeoxycholic acid (CDCA), which results in the accumulation of bile alcohols and subsequently leads to a toxic buildup of cholestanol. This accumulation is a primary contributor to the symptomatic burden and progression of the disease, which includes irreversible neurological dysfunction. The RESTORE study demonstrated that CTEXLI treatment not only improved urine bile alcohol levels but also decreased serum cholestanol levels. Additionally, a larger number of patients on the placebo required rescue therapy, indicating the drug's substantial impact.

Chris Peetz, CEO of Mirum, expressed optimism about the FDA's approval, noting that it opens up opportunities for improved diagnosis and treatment of CTX in U.S. patients. He emphasized the importance of early diagnosis in potentially avoiding the severe symptoms associated with the disease. The approval is seen as a significant milestone, made possible by the contributions of clinicians, patients, and advocates involved in the research.

Dr. Ernst J. Schaefer, a professor of medicine, highlighted that CTX can lead to early-onset cataracts, tendon lipid deposits, and serious neurological issues. Early diagnosis and treatment with CTEXLI could prevent these severe outcomes by reducing levels of bile alcohols and cholestanol, thereby alleviating progressive symptoms. Jean Pickford, executive director of the CTX Alliance, expressed hope that with this approval, patients will receive earlier diagnoses, potentially avoiding irreversible disease progression and its associated symptoms.

Mirum is facilitating access to CTEXLI through its patient support program, Mirum Access Plus (MAP). Patients who are already on Mirum products or who have a prescription for CTEXLI can seek fulfillment support via MAP.

Cerebrotendinous xanthomatosis is an autosomal recessive genetic disorder caused by a deficiency in a key enzyme required for bile acid synthesis. This condition is marked by fatty yellow deposits, known as xanthomas, in the brain's connective tissues, leading to progressive brain damage and other bodily harm. Without effective treatment, the disease can advance to severe neurological deterioration and premature death. In the U.S., CTX affects approximately one to two thousand individuals.

CTEXLI, also known as chenodiol, is derived from CDCA, a naturally occurring bile acid. Originally approved for treating individuals with gallbladder stones, CTEXLI underwent evaluation in the Phase 3 RESTORE study, which was the only clinical trial conducted for CTX. This approval marks a critical advancement for those living with this rare condition, offering a new avenue for treatment and management of CTX.