Distribution of gefitinib to the brain is limited by P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2)-mediated active efflux

Sagar Agarwal, Ramola Sane, Jose L. Gallardo, John R. Ohlfest, William F Elmquist

Research output: Contribution to journalArticlepeer-review

167 Scopus citations

Abstract

Gefitinib is an orally active inhibitor of the epidermal growth factor receptor approved for use in patients with locally advanced or metastatic non-small cell lung cancer. It has also been evaluated in several clinical trials for treatment of brain tumors such as high-grade glioma. In this study, we investigated the influence of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) on distribution of gefitinib to the central nervous system. In vitro studies conducted in Madin-Darby canine kidney II cells indicate that both P-gp and BCRP effectively transport gefitinib, limiting its intracellular accumulation. In vivo studies demonstrated that transport of gefitinib across the blood-brain barrier (BBB) is significantly limited. Steady-state brain-to-plasma (B/P) concentration ratios were 70-fold higher in the Mdr1a/b(-/-) Bcrp1(-/-) mice (ratio of approximately 7) compared with wild-type mice (ratio of approximately 0.1). The B/P ratio after oral administration increased significantly when gefitinib was coadministered with the dual P-gp and BCRP inhibitor elacridar. We investigated the integrity of tight junctions in the Mdr1a/b(-/-) Bcrp1(-/-) mice and found no difference in the brain inulin and sucrose space between the wild-type and Mdr1a/b(-/-) Bcrp1(-/-) mice. This suggested that the dramatic enhancement in the brain distribution of gefitinib is not due to a leakier BBB in these mice. These results show that brain distribution of gefitinib is restricted due to active efflux by P-gp and BCRP. This finding is of clinical significance for therapy in brain tumors such as glioma, where concurrent administration of a dual inhibitor such as elacridar can increase delivery and thus enhance efficacy of gefitinib.

Original languageEnglish (US)
Pages (from-to)147-155
Number of pages9
JournalJournal of Pharmacology and Experimental Therapeutics
Volume334
Issue number1
DOIs
StatePublished - Jul 2010

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