FDA Approves PTC's Ultra-Rare Disease Gene Therapy for More Patients Than Europe

PTC Therapeutics has received FDA clearance for its gene therapy, Kebilidi, designed to treat Aromatic L-Amino Acid Decarboxylase (AADC) deficiency. This ultra-rare condition affects nerve cells and the brain. Kebilidi, generically known as eladocagene exuparvovec, has been approved for a broad range of patients, including both children and adults, regardless of the severity of their disease. In other regions, including the European Union, the United Kingdom, and Israel, this therapy is marketed under the name Upstaza and is indicated for children as young as 18 months who suffer from severe AADC deficiency.

The initial authorization for this gene therapy was granted in the EU and the UK in 2022. In the UK, the therapy's list price is approximately £3 million, or $3.8 million. However, PTC Therapeutics has not yet publicized the list price for Kebilidi in the United States.

Clinical trials involving 26 patients demonstrated that the therapy significantly enhanced both motor and cognitive functions. According to the 2022 published results, these improvements were sustained for over five years in those who had long-term follow-up evaluations. In the United States, it is estimated that fewer than 1,000 individuals suffer from AADC deficiency. This genetic disorder results in insufficient dopamine production, leading to developmental delays, sleep disorders, and various motor and behavioral issues.

Kebilidi functions by introducing a functional copy of the mutated DDC gene into the patient's brain, thus promoting dopamine production. This gene therapy is notable for being the first of its kind to receive FDA approval for direct administration to the brain.

In addition to Kebilidi, PTC Therapeutics is awaiting FDA decisions regarding two other treatments it has in its pipeline. One is Translarna, a drug for Duchenne muscular dystrophy, which faced rejection in the US in 2016 and 2017 and is anticipated to lose its EU market authorization soon. The other is sepiapterin, a treatment for phenylketonuria (PKU).