PTC Therapeutics to Seek FDA Approval of AADC Gene Therapy

PTC Therapeutics is planning to request U.S. Food and Drug Administration (FDA) approval of PTC-AADC, its investigational gene therapy to treat aromatic l-amino acid decarboxylase (AADC) deficiency, the company announced in a corporate update.

The request will be made in the form of a biologics license application to the FDA in the second half of this year.

It will be similar to the application submitted to the European Medicines Agency (EMA) in January. PTC expects a final recommendation from the Committee for Medicinal Products for Human Use — CHMP, the EMA branch responsible for evaluating and issuing opinions, largely followed, on requests for new medicinal products in the European Union — by year’s end.

PTC-AADC is a candidate gene therapy designed to deliver a working version of the DDC gene — the faulty gene in patients with AADC deficiency — to nerve cells in a patient’s brain.

The one-time therapy delivers a functional DDC gene using an adeno-associated virus (AAV), a common and naturally occurring virus modified to work as a harmless delivery vehicle.

The aim is to increase production of the AADC enzyme, which is missing in patients due to their genetic defect, and would counter the symptoms caused by this deficiency.

PTC-AADC is injected via a surgical procedure into the putamen, a brain region fundamental for the production of neurotransmitters (chemicals that relay messages from neurons) such as dopamine and serotonin, which fail to be produced in patients because their neurons lack a working AADC enzyme.

A joint analysis reported data from three open-label clinical trials that enrolled a total of 26 children with AADC deficiency, ranging in age from 21 months to 8.5 years. Results, reported at the 48th Annual Meeting of the Child Neurology Society (CNS) in October 2019, showed that one-time treatment with PTC-AADC lowered the number of oculogyric crises (involuntary upward eye movement) over a five-year period.

Treatment also led to a recovery of the children’s weight, and improved their ability to sit, walk, and talk. Benefits in motor, language, and cognitive milestones were maintained for up to five years after treatment.

On its corporate report, PTC also offers an update on other therapeutic products on its pipeline.

But the company emphasizes that “due to the uncertainty with respect to the duration, nature and extent of impacts of the COVID-19 pandemic and responsive measures relating thereto, we cannot be certain that the pandemic will not cause us to experience further delays to the timelines set forth above or other negative additional impacts.”