Today, the U.S. Food and Drug Administration approved Ctexli (chenodiol) for the treatment of cerebrotendinous xanthomatosis (CTX) in adults. Ctexli is the first FDA-approved drug to treat CTX, a very rare lipid storage disease.

“The FDA is dedicated to supporting new drug development for rare diseases including very rare metabolic diseases like cerebrotendinous xanthomatosis,” said Janet Maynard, M.D., M.H.S., director of the Office of Rare Diseases, Pediatrics, Urologic and Reproductive Medicine, in the FDA’s Center for Drug Evaluation and Research. "CTX is a progressive multisystemic disorder that significantly impacts patients and previously lacked approved treatments. Today’s approval provides a safe and effective treatment option for CTX.”

CTX is a genetic metabolic disorder caused by a mutation in a gene called CYP27A1 resulting in a deficiency of the enzyme that is important in the body’s ability to break down fats. Due to reduced bile acid production in the liver, patients with CTX are unable to break down cholesterol in a normal way, resulting in deposition of atypical cholesterol metabolites (substances that result from the breakdown of cholesterol) in various places in the body including the brain, liver, skin and tendons, leading to damage to those organs and tissues. Ctexli works to replace deficient levels of one of the bile acids, reducing the abnormal deposits of cholesterol metabolites thought to be responsible for clinical abnormalities in CTX.

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 (e.g., stomach pain, nausea, fatigue, dark urine, bruising, yellowing of the eyes and skin, itching) 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 recommended dosage is 250 milligrams, taken orally three times a day.

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

The approval of Ctexli was granted to Mirum Pharmaceuticals Inc.