Pegvaliase-induced immediate hypersensitivity reaction after the discontinuation of antihistamine therapy in a patient with phenylketonuria - Case report.

Phenylketonuria (PKU) is an autosomal recessive inborn error of phenylalanine (Phe) metabolism, resulting from the deficient activity of phenylalanine hydroxylase that converts Phe to tyrosine in the liver, leading to elevated levels of Phe. Pegvaliase is an innovative and effective enzyme replacement therapy for reducing Phe concentration, but it has been associated with severe drug-induced hypersensitivity adverse events (HAEs). Limited data is available on the management of these HAEs, thus, we aimed to present a case report of a successful management strategy.