Pharmacokinetics-Based Integration of Multiple Doses of Intravenous Pegaspargase in a Pediatric Regimen for Adults With Newly Diagnosed Acute Lymphoblastic Leukemia

Purpose Asparaginase treatment is standard in all pediatric acute lymphoblastic leukemia (ALL) regimens, whereas in adults, it is either excluded or administered for a shorter duration. Several adult ALL protocols are adapting pediatric regimens, but the optimal implementation of asparaginase is not well studied, considering its potential higher toxicity. We studied a pegaspargase dosing strategy based on its pharmacokinetic characteristics in adults. Patients and Methods Between 2004 and 2009, 51 adults age 18 to 57 years with newly diagnosed ALL were treated with a regimen adapted from a pediatric trial that included six doses of intravenous pegaspargase at 2,000 IU/m(2) per dose. Intervals between doses were longer than 4 weeks and rationally synchronized with other chemotherapy drugs to prevent overlapping toxicities. Pegaspargase was administered with steroids to reduce hypersensitivity. Asparaginase-related toxicities were monitored after 173 pegaspargase doses. Results The most common grade 3/4 asparaginase-related toxicities were lengthy hyperbilirubinemia and transaminitis, occasionally resulting in subsequent treatment delays. All toxicities resolved spontaneously. Forty-five percent of patients were able to receive all six doses of pegaspargase, and 61% received three doses. In only 20% of patients, the drug was discontinued after pegaspargase-related serious toxicity. Ninety-six percent achieved complete remission, almost all within 4 weeks, and a low induction death rate was seen. Seven-year disease-free and overall survival were 58% and 51%, respectively. Conclusion Our dose and schedule of pegaspargase, based on its pharmacokinetics, and our detailed toxicity profile could be applied for safer adaptation of pediatric ALL protocols in adults.