FDA Approves First Treatment Rare Lipid Storage Disease CTX

Rare Daily Staff

The U.S. Food and Drug Administration approved Mirum Pharmaceuticals Ctexli to treat adults with cerebrotendinous xanthomatosis, a rare lipid storage disease.

Cerebrotendinous xanthomatosis (CTX) is an autosomal, recessive, progressive genetic disorder resulting from a deficiency of a key enzyme in the bile acid synthesis pathway. CTX is characterized by fatty yellow nodules (xanthomas) located in the connective tissues within the brain. These deposits can cause progressive damage to the brain and other areas of the body. As the clinical course progresses, irreversible neurological deterioration leads to premature death.

CTX is a synthetic oral form of chenodeoxycholic acid, a naturally occurring primary bile acid synthesized from cholesterol in the liver. The FDA previously approved the drug for the treatment of people with radiolucent stones in the gallbladder. Mirum acquired the drug from Travere Therapeutics in 2023.

The efficacy of Ctexli for the treatment of patients with CTX was evaluated in a double-blind, placebo controlled, randomized crossover withdrawal trial. The 24-week trial demonstrated that treatment with Ctexli, 250 milligrams three times per day, resulted in significant reduction in plasma cholestanol and urine 23S-pentol (cholesterol metabolites that are markedly increased in CTX patients) compared to placebo treatment.

The prescribing information for Ctexli includes a warning for liver toxicity in all patients with increased risk for liver damage in patients with pre-existing liver disease or bile duct abnormalities. Patients should obtain liver blood tests before starting treatment, annually while on treatment and as clinically indicated. If signs of liver toxicity occur, patients are advised to see their doctor and discontinue Ctexli.

The most common side effects of Ctexli are diarrhea, headache, abdominal pain, constipation, hypertension, muscular weakness and upper respiratory tract infection.

The FDA granted Ctexli Priority Review, Fast Track and Orphan Drug designations for this application.