Restricted brain penetration of the tyrosine kinase inhibitor erlotinib due to the drug transporters P-gp and BCRP.
OBJECTIVE
Erlotinib (Tarceva®, OSI-774) is a small molecule inhibitor of the epidermal growth factor receptor (EGFR) tyrosine kinase. As high-grade gliomas frequently show amplification, overexpression and/or mutation of EGFR, this drug has been tested in several clinical trials with glioblastoma patients, but unfortunately, with little success. As erlotinib is a known substrate of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) we have investigated the effect of these ABC-transporters on the brain penetration of erlotinib.


METHODS
Erlotinib (50 mg/kg) was given by i.p. administration to wild-type (WT), Mdr1ab(-/-) (single P-gp knockout), Bcrp1(-/-) (single Bcrp1 knockout) and Mdr1ab(-/-)Bcrp1(-/-) (compound P-gp and Bcrp1 knockout) mice. Drug levels in plasma and tissues were determined by reversed-phase high-performance liquid chromatography.


RESULTS
Relative to Mdr1ab(-/-)Bcrp1(-/-) mice that are deficient for both drug transporters, the area under the concentration time curve in brain tissue (AUC)(brain) of erlotinib decreased significantly by 1.6-fold in Mdr1ab(-/-) mice where Bcrp1 is present (49.6 ± 3.95 versus 31.1 ± 1.7, μg/g*h; P < 0.01). In Bcrp1(-/-) mice, were P-gp is present, a more pronounced 3.8-fold decrease to 13.0 ± 0.70, μg/g*h (P < 0.01) was observed, which is close to the 4.5-fold decrease in the AUC(brain) of erlotinib found in WT mice where both drug transporters are present (11.0 ± 1.35, P < 0.01). The plasma clearance of erlotinib was similar in mice deficient for P-gp and/or Bcrp1 compared with wild-type mice. In all other tissues the differences between the genotypes were negligible.


CONCLUSIONS
Both P-gp and Bcrp1 reduce the brain penetration of erlotinib. Although P-gp appears to be the most effective factor limiting the brain penetration of erlotinib, the highest brain accumulation was observed when Bcrp1 was also absent. Strategies to inhibit P-gp/BCRP in patients to improve delivery of (novel molecular-targeted) substrate agents, such as erlotinib, to the brain may be required for treatment of intracranial malignancies.
de Vries
Nienke A
NA
Department of Clinical Chemistry, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
Buckle
Tessa
T
Zhao
Jin
J
Beijnen
Jos H
JH
Schellens
Jan H M
JH
van Tellingen
Olaf
O
D018435:ATP Binding Cassette Transporter, Subfamily B / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001812:Blood-Brain Barrier / Q000378:metabolism*; D002199:Capillary Permeability; D002851:Chromatography, High Pressure Liquid; D056148:Chromatography, Reverse-Phase; D000069347:Erlotinib Hydrochloride; D005260:Female; D007274:Injections, Intraperitoneal; D008657:Metabolic Clearance Rate; D051379:Mice; D018345:Mice, Knockout; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D011799:Quinazolines / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D014018:Tissue Distribution; D000097202:ATP-Binding Cassette Sub-Family B Member 4
D018435:ATP Binding Cassette Transporter, Subfamily B; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; D000069347:Erlotinib Hydrochloride; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D000097202:ATP-Binding Cassette Sub-Family B Member 4; C501412:Abcg2 protein, mouse; C095122:multidrug resistance protein 3