Monitoring of anti-L-asparaginase antibody and L-asparaginase activity levels in a pediatric patient with acute lymphoblastic leukemia and hypersensitivity to native Escherichia coli L-asparaginase during desensitization courses.

A patient with acute lymphoblastic leukemia who was hypersensitive to native Escherichia coli L-asparaginase (L-asp) underwent readministration of the L-asp without serious adverse effects for 11 doses using a desensitization protocol every time. Monitoring of anti-L-asp antibody and L-asp activity levels revealed that the serum L-asp activity was below the effective levels during the administration of first 6 to 7 doses because of extremely high levels of anti-L-asp IgG. Sustained L-asp activity was attained since the eighth dose was administered, when the antibody levels were <5 U/mL. L-asp activity levels in patients with L-asp hypersensitivity should be monitored during the desensitization courses to ensure a sufficient L-asp activity.