ASPG and acute lymphoblastic leukemia: We therefore explored mandatory monitoring of asparaginase enzyme activity (AEA) in patients with ALL aged 1–45 years treated according to the ALLTogether pilot protocol in the Nordic and Baltic countries to relate mean AEA to inactivation, to build a pharmacokinetic model to better characterize the pharmacokinetics of peg-asparaginase and assess whether an increased clearance relates to subsequent inactivation.