Population Pharmacokinetics of Blinatumomab in Pediatric and Adult Patients with Hematological Malignancies

Blinatumomab (BLINCYTO ® ) is a novel bispecific T cell engager (BiTE ® ) approved in the USA for the treatment of relapsed or refractory B cell precursor acute lymphoblastic leukemia (ALL) in children and adults, as well as minimal residual disease ALL in adults. This analysis characterized the population pharmacokinetics of intravenous blinatumomab in pediatric and adult patients. A total of 2417 serum concentrations of blinatumomab from 674 patients, including adult ( n = 628) and pediatric patients ( n = 46), from eight clinical studies were analyzed. The impact of covariates on pharmacokinetic parameters were explored, and significant covariates were further evaluated using a simulation approach. Blinatumomab pharmacokinetics were described by a one-compartment linear model with first-order elimination, a clearance (CL) of 2.22 L/h, and a central volume of 5.98 L. A statistically significant effect of body surface area (BSA) on CL was observed. The smallest BSA of 0.37 m 2 in the pediatric population was associated with a 63% reduction in blinatumomab systemic CL, relative to an adult patient with the median BSA (1.88 m 2 ), supporting the use of BSA-based dosing in patients of lower bodyweight. The BSA effect was minimal, with a ≤ 25% change in CL over the range of BSA in adults, supporting no need for BSA-based dosing. Blinatumomab pharmacokinetics were adequately described by a one-compartment linear model with first-order elimination. No covariates other than BSA on CL were identified as significant. BSA-based dosing should be considered for lightweight patients to minimize inter-subject variability in blinatumomab exposure.