PTC Therapeutics has presented new long-term outcome data from its investigational gene therapy, PTC-AADC, in patients living with aromatic L-amino acid decarboxylase (AADC) deficiency.

The one-time gene therapy was found to give patients the ability to sit, walk, and talk, from data representative of up to five years of follow up post-treatment.

The new analysis evaluated outcomes of 26 patients with AADC deficiency across three separate clinical trials, and found that 12 months post-treatment with PTC-AADC, patients’ mean body weight had increased from 12.0 kg to 15.2 kg, and the frequency of oculogyric crises (involuntary upward eye movement) was reduced.

The data, presented at the Child Neurology Society 48th Annual Meeting, is a result of the most comprehensive analysis of patients treated with PTC-AADC to date.

Unfortunately, there are currently no approved therapies that address the underlying cause, and as such patients with severe AADC deficiency have a high risk of death during childhood.

The company is “excited to see the transformational effects in AADC deficiency patients in this long-term study as patients with severe AADC deficiency never achieve the ability to sit, walk or talk,” said Stuart Peltz, chief executive officer of PTC Therapeutics.

He also announced that PTC is “on track to submit a biologics license application (BLA) to the FDA by the end of the year and are proud to be on the verge of bringing the first commercial treatment for AADC deficiency patients, which is in line with our mission of bringing clinically differentiated treatments to patients with rare disorders.”

AADC deficiency is a rare genetic condition caused by a mutation in the dopa decarboxylase (DDC) gene, resulting in a lack of functioning AADC enzyme, which is responsible for the final step in the synthesis of key neurotransmitters dopamine and serotonin.

It results in delays or failure to reach developmental milestones such as head control, sitting, standing, walking, or talking, low muscle tone, severe, seizure-like episodes involving involuntary eye movement, autonomic abnormalities, and the need for life-long care.