Stephanie van Hoppe

109 Brain accumulation of ponatinib and its active metabolite is limited by ABCB1 and ABCG2 For the transporter knockout mice, qualitatively similar results were obtained in an independent experiment where mice were sacrificed 2 h after oral administration of 10 mg/kg ponatinib (Figure 2B, Table 2). There were no significant differences in plasma ponatinib levels between the mouse strains, although it is worth noting that there was high interindividual variation during the first 2 to 4 h after administration in all mouse strains (see also Figure 2A), possibly due to variable rates of stomach emptying for this drug. Collectively, our data indicate that neither Abcg2 nor Abcb1a/1b has a direct impact on the oral availability of ponatinib in mice, but that Cyp3a does limit ponatinib oral availability. Ab c g2 and Ab c b1a / 1b, bu t no t Cy p3a , l imi t pona t i n i b b r a i n a c c umu l a t i on i n mi c e To investigate the impact of single and combined knockout of Abcg2 and Abcb1a/1b on ponatinib accumulation in the brain, we isolated mouse brains after termination of the 24-h and 2-h pharmacokinetic experiments. Figure 3A shows that only a low concentration of ponatinib accumulated in the brain of WT mice over 24 h after administration. Single absence of either Abcg2 or Abcb1a/1b resulted in a modestly Table 2 - Pharmacokinetic parameters of ponatinib and DMP at 2 h after oral administration of 10 mg/kg ponatinib to female wild-type, Abcg2 -/- , Abcb1a/1b -/- , and Abcb1a/1b;Abcg2 -/- mice. Parameter Genotype  Compound Wild-type Abcg2 -/- Abcb1a/1b -/- Abcb1a/1b;Abcg2 -/- Plasma AUC (0-2) , h.ng/mL Ponatinib 392 ± 303 142 ± 66 180 ± 85 265 ± 155 Fold increase AUC (0-2) 1.0 0.4 0.5 0.7 Cbrain, ng/g 258 ± 195 142 ± 63 247 ± 163 2896 ± 588*** Fold increase C brain 1.0 0.5 1.0 11 P brain (h -1 ) 0.68 ± 0.01 1.05 ± 0.28 1.28 ± 0.29** 12.3 ± 2.7*** Fold increase P brain 1.0 1.5 1.9 18 Plasma AUC (0-2) , h.ng/mL DMP 21 ± 11 13 ± 7 20 ± 11 39 ± 22 Fold increase AUC (0-2) 1.0 0.6 0.9 1.9 Cbrain, ng/g 7.2 ± 2.0 2.7 ± 0.5* 5.3 ± 3.3 55 ± 17*** Fold increase C brain 1.0 0.4 0.7 7.6 P brain (h -1 ) 0.39 ± 0.15 0.23 ± 0.83 0.27 ± 0.58 1.51 ± 0.31*** Fold increase P brain 1.0 0.6 0.7 3.9 AUC, area under the plasma concentration-time curve; C max maximum concentration in plasma; T max , the time after drug administration needed to reach maximum plasma concentration; C brain , brain concentration; P brain , brain accumulation (C brain divided by plasma AUC); C liver , liver concentration; P liver , liver accumulation (C liver divided by plasma AUC). *, P < 0.05; **, P < 0.01; ***, P < 0.001 compared to WT mice. Data are given as mean ± SD. All groups consisted of n = 3-5 mice