Aeglea BioTherapeutics has announced that their lead investigational therapy, pegzilarginase, has been granted Breakthrough Therapy designation for the treatment of arginase 1 deficiency (ARG1-D). 

ARG1-D is an inherited disease that causes arginine and ammonia to accumulate in the blood. The disease usually becomes evident around 3 years of age, with symptoms that may include slower growth, developmental delay, intellectual disability, seizures, and difficulty with balance and coordination. 

Pegzilarginase is an enhanced human arginase that is intended for use as an enzyme replacement therapy in patients to reduce elevated blood arginine levels. The Company is currently recruiting patients for a randomized, phase 3 trial which will evaluate the safety and efficacy of pegzilarginase in patients with ARG1-D. 

Results from a phase 1/2 trial demonstrated a statistically significant (P<.001) reduction in plasma arginine at 8 weeks and sustained lowering of plasma arginine in patients treated with pegzilarignase. The treatment was generally well-tolerated; serious adverse events included hypersensitivity and hyperammonemia. 

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“The emerging clinical data demonstrating favorable effects of pegzilarginase treatment on both plasma arginine levels and important disease manifestations has led to the FDA’s designation of pegzilarginase as a breakthrough therapy,” said Anthony G. Quinn, MB ChB PhD, President and CEO of Aeglea.

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