Monitoring of treatment with L-asparaginase in children with acute lymphoblastic leukaemia, with a focus on silent inactivation and its influence on the treatment outcome.

Introduction: The aim of the study was to analyse the frequency of silent inactivation and allergic reaction to asparaginase (ASP) and its impact on treatment results in patients with lymphoblastic leukaemia. Material and methods: Seventy patients with acute lymphoblastic leukaemia treated with ASP were enrolled in the study. Asparaginase activity was monitored. The patients were switched to another ASP formulation after allergy or inactivation. The treatment results were analysed. Results: Silent inactivation of native E. coli ASP was diagnosed in 5 patients (7%) and allergy in 34 patients (49%), and these patients were switched to pegylated ASP (PEG-ASP). Silent inactivation of PEG-ASP occurred in 8 patients (23%) and allergy in 6 patients (17%). Eight children continued therapy with Erwinase, and 4 did not switch to Erwinase after inactivation of PEGASP. Allergy to Erwinase occurred in 2 patients (22%); there was no inactivation. No significant differences in outcome were found between the groups of patients with and without allergy or silent inactivation of ASP. Due to regular monitoring and switching to other ASP preparations after allergy or silent inactivation, therapeutic activity was ensured in almost all patients. Conclusions: Monitoring of ASP activity is crucial to recognize silent inactivation and to guarantee treatment effectiveness by switching to other ASP preparations. [ABSTRACT FROM AUTHOR]