Kebilidi gene therapy delivers big quality-of-life boost, study finds
Models indicate improvements in development and function
A new analysis makes a case for the value of Kebilidi (eladocagene exuparvovec-tneq), the first gene therapy approved for aromatic L-amino acid decarboxylase (AADC) deficiency.
While the one-time treatment has a high cost, it leads to significant improvements in a patient’s quality of life and survival compared to the best standard of care. Researchers determined that Kebilidi delivers these substantial gains — often measured in “quality-adjusted life-years” (QALYs) — at a much lower cost relative to many other recently approved gene therapies for rare disorders.
“Substantial QALY gains were achieved with [Kebilidi] at a lower cost relative to many other rare and/or one-time treatments, emphasizing the value of [Kebilidi] as an important treatment option for patients with AADC” deficiency, researchers wrote in a study, “Eladocagene Exuparvovec for the Treatment of Aromatic l-Amino Acid Decarboxylase Deficiency (AADCd): An Economic Evaluation from a US Perspective,” published in PharmacoEconomics.
The work was funded by PTC Therapeutics, the company that markets Kebilidi.
Understanding AADC deficiency and Kebilidi
AADC deficiency is a genetic disorder caused by mutations in the DDC gene, leading to low levels of certain signaling molecules in the brain. Kebilidi is a gene therapy administered in a one-time surgical procedure that introduces a healthy version of the DDC gene into the brain. The goal is to normalize brain signaling and ease symptoms.
In 2024, Kebilidi became the first treatment for AADC deficiency to gain approval in the U.S. It is approved in the European Union and in the U.K., where it is marketed under the name Upstaza.
Clinical trials have shown Kebilidi treatment can lead to substantial improvements in development and function for people with AADC deficiency. However, the therapy carries a list price of nearly $4 million for the single dose.
In this analysis, researchers built economic models using clinical trial data to compare the cost of caring for someone with AADC deficiency who receives Kebilidi against the cost of the best available standard of care.
Results showed overall costs were much higher for Kebilidi-treated patients, due primarily to the high price of the gene therapy itself. However, models also indicated that Kebilidi-treated patients would live longer and with better function.
To assess value, the researchers calculated the cost of each QALY, a metric used in medical economic studies that reflects one year of good health. Based on their models, Kebilidi was associated with roughly $200,000 in additional costs for each QALY gained.
The researchers highlighted that this cost-per-QALY is lower when compared to one-time gene therapies for other diseases that have recently been approved. In evaluations looking at 25 such cutting-edge treatments, the median cost-per-QALY gained was more than $900,000. “As such, within the context of these innovative treatments, [Kebilidi] provides substantial clinical improvements at a lower cost,” the researchers wrote.
They noted their findings are based on limited clinical trial data and that the analysis included only direct treatment costs. Real-world expenses for living with AADC deficiency may differ from what was captured in the model.
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