Pharmacokinetics of very prolonged PEGasparaginase and Erwinia asparaginase use. (A) Serum PEGasparaginase activity levels (mean ± SEM) of children with or without allergy to or silent inactivation of PEGasparaginase (2500 IU/m2 every other week) (n = 62). (B) Serum Erwinia asparaginase activity levels (mean ± SEM) of children without allergy to Erwinia asparaginase (20 000 IU/m2 2-3 times per week) (n = 57). In panel B, 3 curves are shown in the first 2 weeks of Erwinia asparaginase therapy. The upper curve (white open circles) shows 19 children who had high Erwinia asparaginase levels (72-hour levels ≥100 U/L) and were switched to infusions 2 times per week after the first 2 weeks of Erwinia asparaginase therapy. The lower curve (gray blocks) shows 38 children who had low Erwinia asparaginase levels (72-hour levels <100 U/L) and continued infusions 3 times per week after the first 2 weeks of Erwinia asparaginase therapy. The middle curve (closed circles) shows analysis of variance estimates of all 57 children receiving Erwinia asparaginase 3 times per week in the first 2 weeks.
