Abstract
Axitinib is an inhibitor of tyrosine kinase vascular endothelin growth factor receptors 1, 2, and 3. The ATP-binding cassette (ABC) and solute carrier (SLC) transport properties of axitinib were determined in selected cellular systems. Axitinib exhibited high passive permeability in all cell lines evaluated (Papp ≥ 6 × 10−6 cm/s). Active efflux was observed in Caco-2 cells, and further evaluation in multidrug resistance gene 1 (MDR1) or breast cancer resistance protein (BCRP) transfected Madin-Darby canine kidney cells type 2 (MDCK) cells indicated that axitinib is at most only a weak substrate for P-glycoprotein (P-gp) but not BCRP. Axitinib showed incomplete inhibition of P-gp-mediated transport of digoxin in Caco-2 cells and BCRP transport of topotecan in BCRP-transfected MDCK cells with IC50 values of 3 μM and 4.4 μM, respectively. Axitinib (10 mg) did not pose a risk for systemic drug interactions with P-gp or BCRP per regulatory guidance. A potential risk for drug interactions through inhibition of P-gp and BCRP in the gastrointestinal tract was identified because an axitinib dose of 10 mg divided by 250 mL was greater than 10-fold the IC50 for each transporter. However, a GastroPlus simulation that considered the low solubility of axitinib resulted in lower intestinal concentrations and suggested a low potential for gastrointestinal interactions with P-gp and BCRP substrates. Organic anion transporting polypeptide 1B1 (OATP1B1) and OATP1B3 transfected human embryonic kidney 293 (HEK293) cells transported axitinib to a minor extent but uptake into suspended hepatocytes was not inhibited by rifamycin SV suggesting that high passive permeability predominates. Mouse whole-body autoradiography revealed that [14C]axitinib-equivalents showed rapid absorption and distribution to all tissues except the brain. This suggests that efflux transport of axitinib may occur at the mouse blood-brain barrier.
Footnotes
- Received January 18, 2013.
- Accepted May 31, 2013.
↵1 Current affiliation: Genentech, Inc., South San Francisco, California.
↵2 Current affiliation: Dart NeuroScience, LLC, San Diego, California.
↵3 Current affiliation: Ardea Biosciences, San Diego, California.
↵4 Current affiliation: NSF International, Ann Arbor, Michigan.
↵5 Current affiliation: AstraZeneca, Macclesfield, Cheshire, United Kingdom.
↵6 Current affiliation: F. Hoffman La-Roche, Grenzacherstrasse, Basel, Switzerland.
↵7 Current affiliation: QPS DMPK Hepatic Biosciences, Research Triangle Park, North Carolina.
- Copyright © 2013 by The American Society for Pharmacology and Experimental Therapeutics
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