In Vitro Characterization of Axitinib Interactions with Human Efflux and Hepatic Uptake Transporters: Implications for Disposition and Drug Interactions

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 3 10 26 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 IC 50 values of 3 mM and 4.4 mM, 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 IC 50 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 [ 14 C]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.

Calibration of In Vitro Multidrug Resistance Protein 1 Substrate and Inhibition Assays as a Basis to Support the Prediction of Clinically Relevant Interactions In Vivo

“…This may result in a considerable overestimation of the intestinal concentration, particularly for poorly soluble compounds. Other groups have used fraction absorbed, absorption rate, and enterocyte blood flow, as well as built-in functions in physiologically-based pharmacokinetic (PBPK) models to estimate gut concentrations (Agarwal et al, 2013;Reyner et al, 2013). Further exploring the caveats of the static model, three main assumptions should be mentioned: 1) the victim drug absorption, elimination or brain distribution is driven by a single pathway; 2) the neglect of the dynamic nature of the involved processes; and 3) the intestinal, plasma, and extracellular concentrations used ( [I 2 ], [I 1 ], or IC 50 ) do not correspond to the intracellular MDR1 binding site.…”

The Nonspecific Binding of Tyrosine Kinase Inhibitors to Human Liver Microsomes

“…In particular, equilibrium was established in buffer-buffer and HLM-HLM controls for dialysis times ranging from 3 to 24 hours only with pazopanib, irrespective of whether we used conventional equilibrium dialysis (employing dialysis cells) or a commercial rapid equilibrium dialysis (RED) device. It has been reported that axitinib forms a supersaturated solution in buffers containing 0.5 or 1% dimethylsulfoxide (DMSO) (Reyner et al, 2013), and we surmised a similar situation may occur more generally with TKIs during the course of equilibrium dialysis experiments. Thus, we explored the use of a number of detergents to retain TKIs in solution without disrupting microsomal binding.…”

Individualized Dosing with Axitinib: Rationale and Practical Guidance

“…Furthermore, the properties of the drug itself mean there are inherent difficulties when measuring plasma concentrations; owing to the short half-life, axitinib concentrations rise and fall significantly during a dosing interval and there is minimal accumulation at steady state [13] (i.e., a concentration level that is therapeutically effective as long as regular doses are administered). In addition, axitinib degrades in the presence of light [35]; this could result in artefactual readings and the physician prescribing an incorrectly high dose of axitinib to the patient with resulting safety implications. With these limitations in mind, however, PK measurements could be considered on an individual basis, and only after checking the patient's level of compliance with treatment.…”