Prospective, real-time monitoring of pegylated Escherichia coli and Erwinia asparaginase therapy in childhood acute lymphoblastic leukaemia and non-Hodgkin lymphoma in Belgium

Asparaginase (ASNase) is an important anti-leukaemic drug in the treatment of childhood acute lymphoblastic leukaemia (ALL) and non-Hodgkin lymphoma (NHL). A substantial proportion of patients develop hypersensitivity reactions with anti-ASNase neutralising antibodies, resulting in allergic reactions or silent inactivation (SI), and characterised by inactivation and rapid clearance of ASNase. We report results of a prospective, real-time therapeutic drug monitoring of pegylated Escherichia coli (PEG-)ASNase and Erwinia ASNase in children treated for ALL and NHL in Belgium. Erwinia ASNase was given as second-line after hypersensitivity to PEG-ASNase. In total, 286 children were enrolled in the PEG-ASNase cohort. Allergy was seen in 11¸2% and SI in 5·2% of patients. Of the 42 patients treated with Erwinia ASNase, 7·1% experienced allergy and 2·4% SI. The median trough PEG-ASNase activity was high in all patients without hypersensitivity. After Erwinia administration significantly more day 3 samples had activities