Measurement and modeling of asparaginase activity in patient samples. The asparaginase activity of an acute lymphoblastic (ALL) patient enrolled in the TXVI protocol was measured before treatment and at 3, 5, 8, 12, and 37 days after a single dose of PEGylated E. coli asparaginase at 3,000 units/m2 during induction (○). The solid black line represents the best fit from the pharmacokinetic modelling.