Breakthrough: First FDA-Approved Treatment for CTX Announced

Introduction:

Chenodiol (Ctexli) was initially approved by the FDA in 1983 (as Chenix) for dissolving cholesterol gallstones—not for cerebrotendinous xanthomatosis (CTX). While chenodeoxycholic acid (CDCA) was used off-label for CTX, it lacked formal FDA approval.

CDCA  was first isolated from the bile of the domestic goose, which gives it the “cheno” portion of its name (Greek: χήν = goose). CDCA from geese has been useful in both traditional and modern medicine. Goose bile, rich in CDCA, was historically used to treat liver disorders, gallstones, and fevers. In Modern Medicine, CDCA (whether from geese or synthetic) is used for gallstone dissolution, cerebrotendinous xanthomatosis (CTX), and potential lipid regulation. Currently, synthetic CDCA is preferred for ethical and sustainability reasons, though TCM still utilizes goose bile.

In February 2025, the FDA officially approved Ctexli (chenodiol) for CTX, based on new clinical trial data demonstrating its safety and efficacy. This made it the first FDA-approved treatment for the disease.

The 2025 approval of chenodiol:

• Confirmed it is a safe and effective treatment for CTX.
• Made it easier for patients to get the medicine through insurance and as part of standard care.
• Provided clear instructions on how to take it and important safety warnings, especially about possible liver problems

CTX is a rare and serious disease where fats build up in the body. It’s caused by a change in the CYP27A1 gene, which reduces bile acid production. This leads to harmful cholesterol deposits in organs like the brain, liver, skin, and tendons, causing damage over time.

Ctexli, made by Mirum Pharmaceuticals, is the first approved treatment for CTX. It replaces the missing bile acids and helps lower harmful cholesterol levels. In studies, it reduced important disease markers in patients. However, Ctexli can cause liver problems, so regular liver tests are important. Common side effects include diarrhea, headache, stomach pain, and muscle weakness.

The FDA granted Ctexli Priority Review, Fast Track, and Orphan Drug designations, underscoring its importance in addressing this unmet medical need.

For patients and families affected by CTX, today’s approval represents a meaningful step forward.

Prevalence of Cerebrotendinous Xanthomatosis (CTX):

CTX is an ultra-rare genetic disorder, with prevalence estimates ranging from 1 per million to 3–5 per 100,000, depending on the population.

• Higher rates are seen in Moroccan Jews (1 in 108) and Asian populations (1 in 44,407 to 1 in 93,084).
• In European, American, and African populations, rates range from 1 in 70,795 to 1 in 233,597.
• In the U.S., despite estimates suggesting up to 8,400 cases, fewer than 100 are diagnosed, highlighting significant underdiagnosis.

Current Treatment Options for CTX

• FDA-Approved Treatment:
  • Ctexli (Chenodiol) was approved in February 2025 as the first FDA-approved therapy for CTX. It replaces deficient bile acids to reduce harmful cholesterol metabolites.
• Bile Acid Replacement Therapy (before FDA approval):
  • Chenodeoxycholic Acid (CDCA) was used off-label to normalize biochemical markers.
  • Cholic Acid has also been used, particularly in children, due to a lower risk of liver toxicity.
• Symptomatic and Supportive Care:
  • Surgical: Cataract surgery may be needed before age 50. CTX cataracts appear early due to lipid deposits in the lens. Without surgery, vision loss can happen well before age 50.
  • Medications: May include antidepressants, antiepileptics, levodopa, or botulinum toxin. These medications manage the neurological and psychiatric complications of CTX, which are common due to cholestanol accumulation in the brain. While they don’t treat the root cause, they relieve symptoms and improve quality of life.
  • Lifestyle: Dietary adjustments and physical therapy support quality of life.

Conclusion:

• Approved in 1983 for gallstones.
• Repurposed and approved in 2025 for CTX following new evidence and regulatory recognition.
• Early diagnosis and treatment are critical to prevent irreversible complications, with regular monitoring and multidisciplinary care recommended.

Disclaimer:
The information provided in this blog post is for educational and informational purposes only and is not intended as medical advice. It should not be used as a substitute for professional diagnosis, treatment, or medical care. Readers should consult their healthcare provider for any medical concerns or questions regarding diagnosis and treatment options, including the use of Ctexli (chenodiol). While every effort has been made to ensure accuracy, no guarantee is made regarding the completeness or reliability of the information presented. The mention of any pharmaceutical products does not constitute an endorsement. Always seek advice from a qualified healthcare professional before starting or changing any medication.