FDA approves first therapy for very rare lipid storage disorder
The U.S. Food and Drug Administration (FDA) has approved a first-of-its-kind drug to treat cerebrotendinous xanthomatosis (CTX)—a very rare lipid storage disease caused by a genetic mutation. The condition is characterized by a deficiency of an enzyme the body uses to break down fats.
Patients who suffer from CTX have a buildup of cholesterol in vital organs and tissues. However, the newly approved drug from Mirum Pharmaceuticals now offers a new treatment option. Ctexli (chenodiol), taken orally, helps the body produce a bile acid to break down those deposits and improve overall health.
In a placebo-controlled 24-week trial, the drug was shown to significantly reduce cholesterol metabolites in patients with CTX, demonstrated by a 20-fold reduction in bile alcohols. This means those who took Ctexli showed improved liver response in breaking down cholesterol, curbing the buildup elsewhere in the body.
That Phase II trial was the basis for the new therapy being fast-tracked by the FDA, which recommends a dosage of 250 milligrams three times a day to produce the desired results while limiting common side effects, which include diarrhea, headache, abdominal pain, constipation, hypertension, muscular weakness, and upper respiratory tract infection.
According to the FDA, before the approval of Ctexli, providers had virtually no other pharmaceutical treatments available for patients.
"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,” Janet Maynard, MD, director of the Office of Rare Diseases, Pediatrics, Urologic and Reproductive Medicine in the FDA’s Center for Drug Evaluation and Research, said in a statement.
“The FDA is dedicated to supporting new drug development for rare diseases, including very rare metabolic diseases like cerebrotendinous xanthomatosis,” she added.
The agency has included a warning for liver toxicity in the prescription information for the drug, as there is a risk of increased damage for patients with pre-existing disease or bile duct abnormalities. The FDA said patients should undergo liver blood tests before starting treatment and that blood work should continue on an annual basis to improve safety.
CTX was previously referred to as Van Bogaert–Scherer–Epstein syndrome. Less than 10,000 people in the U.S. are estimated to live with the disease.
Investment pays off for Mirum
The relative safety of the pharmaceutical chenodiol was already established, as it’s been used for decades to treat gallstones under the brand name Chenodal. This new approval by the FDA expands its potential use to CTX.
The green light from the FDA comes less than two years after Mirum Pharmaceuticals paid $210 million to acquire a portfolio of drugs from Travere Therapeutics, which included Ctexli.
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