Results Show Long-Lasting and Holistic Improvements in Children with AADC Deficiency Treated with PTC-AADC Gene Therapy

SOUTH PLAINFIELD, N.J. – PTC Therapeutics, Inc. (NASDAQ: PTCT) today presented a new analysis of five-year results that shows its novel gene therapy, PTC-AADC, leads to profound improvements in children with aromatic L-Amino acid decarboxylase (AADC) deficiency, a previously intractable, fatal and devastating rare disorder of the central nervous system. [1-4] Children treated with PTC-AADC developed motor function and cognitive skills not previously seen, such as holding up their head, sitting or standing with support and communicating, and these persisted for up to 10 years. [1]

“The transformations we are seeing in the children are remarkable, as they could not even lift their heads before treatment,” said Stuart W. Peltz, Ph.D., Chief Executive Officer, PTC Therapeutics. “Treatment with PTC-AADC is restoring dopamine production, which leads to the children now being able to sit, roll over, stand and walk. They are also able to communicate, and gain both weight and strength. We believe these results show its potential as a transformational therapy for the AADC patients and their families.”

The new, five-year results show that motor function improvements were sustained, demonstrating that the treatment effect of PTC-AADC is durable, which is highly important for a single administration therapy for a chronic, fatal disease. [1-2] Across three clinical trials, improvements in motor development were recorded in all children from as early as 3 months. [1] Cognitive and language skills were also reported to improve significantly from baseline, as measured by Bayley-III scores, with children able to understand their caregivers and express themselves. [2]

In addition, the rate of respiratory infection declined from an average of 2.4 episodes per year at 12 months to 0.6 episodes per year at 2 years and 0.3 episodes per year at 5 years. [3] Almost all treated children went from a baseline weight below the third percentile to making age-appropriate weight gains by 12 months following gene therapy treatment. [3]

There are currently no approved disease-modifying therapies for AADC deficiency, a fatal disorder caused by a defective gene that stops the body from producing the dopamine needed to develop and function normally. Delivering PTC-AADC gene therapy directly to the putamen, a site in the brain where dopamine is utilized, corrects this defect. [4]

“The impact that this one-time gene therapy has had on children with AADC deficiency in these trials is truly life-changing,” said investigator Paul Wuh-Liang Hwu, National Taiwan University Hospital. “We are encouraged by the strong safety profile and long-lasting effect seen with PTC-AADC, and how it has improved the lives of patients and their caregivers.”

PTC-AADC is currently under review by the European Medicines Agency’s Committee for Medicinal Products for Human Use with an opinion expected in the fourth quarter of 2021, and is an investigational new drug in the United States. A Biologics License Application is expected to be submitted to the U.S. Food and Drug Administration by the end of 2021.

About aromatic L-amino acid decarboxylase (AADC) deficiency
AADC deficiency is a fatal, rare genetic disorder that causes severe disability and suffering from the first months of life, affecting every aspect of life – physical, mental, and behavioral. The suffering of children with AADC deficiency is exacerbated by episodes of distressing seizure-like oculogyric crises, which can happen daily and last for hours, causing the eyes to roll up in the head, frequent vomiting, behavioral problems, difficulty sleeping, and life-threatening complications such as respiratory infections and gastrointestinal problems.

Current management options yield limited improvement for the majority of patients with AADC deficiency. Managing patients with AADC deficiency requires a multidisciplinary team of specialists and complex coordination of care to address significant health issues, including developmental delays, infections, orthopaedic and cardiac complications, and other comorbidities

While several diagnostic tests for AADC deficiency are available, the condition remains largely undiagnosed.

About PTC Therapeutics, Inc.
PTC Therapeutics is a science-driven, global biopharmaceutical company focused on the discovery, development and commercialization of clinically differentiated medicines that provide benefits to patients with rare disorders. PTC’s mission is to provide access to best-in-class treatments for patients with an unmet medical need, using its ability to globally commercialize products as the foundation to drive investment in a robust and diversified pipeline of transformative medicines. The Company’s strategy is to leverage its strong scientific expertise and global commercial infrastructure to maximize value for its patients and other stakeholders. To learn more about PTC, please visit us at and follow it on Facebook, on Twitter at @PTCBio, and on LinkedIn.


[1] Hwu PW-L, et al. Eladocagene Exuparvovec Gene Therapy Improves Motor Development in Patients With Aromatic L-Amino Acid Decarboxylase Deficiency. Poster presented at the CNS Annual Meeting; October 16-20, 2021.
[2] Hwu PW-L, et al. Gene Therapy With Eladocagene Exuparvovec Improves Cognition and Language in Patients With Aromatic L-Amino Acid Decarboxylase Deficiency. Poster presented at the CNS Annual Meeting; October 16-20, 2021.
[3] Hwu PW-L, et al. Eladocagene Exuparvovec Improves Body Weight and Reduces Respiratory Infections in Patients With Aromatic L-Amino Acid Decarboxylase Deficiency. Poster presented at the CNS Annual Meeting; October 16-20, 2021.
[4] Chien YH, et al. Efficacy and safety of AAV2 gene therapy in children with aromatic L-amino acid decarboxylase deficiency: an open-label, phase 1/2 trial. Lancet Child Adolesc Health. 2017;1(4):265-273.


Kylie O’Keefe
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Jane Baj
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