Abstract
Cediranib is an orally active tyrosine kinase inhibitor that targets the vascular endothelial growth factor receptor family. Because of its potent antiangiogenic and antitumor activities, cediranib has been evaluated for therapy in glioma, a primary brain tumor. This study investigated the influence of two important efflux transporters at the blood-brain barrier, P-glycoprotein (P-gp) and breast cancer resistance protein (Bcrp), on the delivery of cediranib to the central nervous system. In vitro studies indicated that cediranib is a dual substrate for both P-gp and Bcrp. It is noteworthy that in spite of the in vitro data the in vivo mouse disposition studies conclusively showed that P-gp was the dominant transporter restricting the brain distribution of cediranib. The brain-to-plasma partitioning (AUC(brain)/AUC(plasma), where AUC is area under the curve) and the steady-state brain-to-plasma concentration ratio of cediranib were approximately 20-fold higher in Mdr1a/b⁻/⁻ and Mdr1a/b⁻/⁻Bcrp1⁻/⁻ mice compared with wild-type and Bcrp1⁻/⁻ mice. Moreover, there was no significant difference in brain distribution of cediranib between wild-type and Bcrp1⁻/⁻ mice and between Mdr1a/b⁻/⁻ and Mdr1a/b⁻/⁻Bcrp1⁻/⁻ mice. These results show that, unlike other tyrosine kinase inhibitors that are dual substrates for P-gp and Bcrp, Bcrp does not restrict the distribution of cediranib across the blood-brain barrier. We also show that inhibition of P-gp using specific or nonspecific inhibitors resulted in significantly enhanced delivery of cediranib to the brain. Concurrent administration of cediranib with chemical modulators of efflux transporters can be used as a strategy to enhance delivery and thus efficacy of cediranib in the brain. These findings are clinically relevant to the efficacy of cediranib chemotherapy in glioma.