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Phenylketonuria, or PKU, is an autosomal recessive inborn error of phenylalanine metabolism resulting in a deficiency of the hepatic enzyme phenylalanine hydroxylase (PAH).



In classic PKU, there is less than 1% enzyme activity leading to an accumulation of phenylalanine (Phe). Untreated, it is characterised by irreversible intellectual disability, microcephaly, seizures, and other motor, neurocognitive and developmental deficits.

The prevalence of the disease is between 1 in 10,000 and 1 in 20,000 live births depending on geographic location. Evox is developing an exosome-delivered AAV encoding the PAH enzyme. Exosome-delivered AAV can significantly improve cellular delivery and increase transgene expression in animals, thereby lowering the AAV dose needed. Lastly, exosome-delivered AAV can evade pre-existing humoral immunity also possibly enable repeat dosing due to the generally non-immunogenic nature of exosomes.