Dasatinib Cellular Uptake and Efflux in Chronic Myeloid Leukemia Cells: Therapeutic Implications

Abstract

Purpose:The organic cation transporter OCT-1mediates active transport of imatinib.We recently showed that low OCT-1activity is a major contributor to suboptimal response in chronic myeloid leukemia (CML) patients treated with imatinib. The relevance of OCT-1activity and efflux pumps in determining intracellular uptake and retention (IUR) of dasatinib was assessed. Experimental Design: The effect of OCT inhibitors on [ 14 C]dasatinib and [ 14 C]imatinib IUR was compared using peripheral blood mononuclear cells from newly diagnosed CML patients. The role of efflux transporters was studied using ABCB1-and ABCG2-overexpressing cell lines and relevant inhibitors. Results: Unlike imatinib, there was no significant difference in the dasatinib IUR at 37jC and 4jC (P = 0.8), and OCT-1 inhibitors including prazosin did not reduce dasatinib IUR significantly. In CML mononuclear cells, prazosin inhibitable IUR was significantly higher for imatinib than dasatinib (6.38 versus 1.48 ng/200,000 cells; P = 0.002; n = 11). Patients with high OCT-1 activity based on their imatinib uptake had IC 50 dasatinib values equivalent to patients with low OCT-1acti-vity. Dasatinib IUR was significantly lower in ABCB1-overexpressing cell lines compared with parental cell lines (P < 0.05). PSC833 (ABCB1inhibitor) significantly increased the dasatinib IUR (P < 0.05) and reduced IC 50 dasatinib (from 100 to 8 nmol/L) in K562-DOX cell line. The ABCG2 inhibitor Ko143 significantly increased dasatinib IUR in ABCG2-overexpressing cell lines and reduced IC 50 dasatinib . Conclusion: Unlike imatinib, dasatinib cellular uptake is not significantly affected by OCT-1 activity, so that expression and function of OCT-1 is unlikely to affect response to dasatinib. Dasatinib is a substrate of both efflux proteins, ABCB1and ABCG2.

Gradient elution LC-MS determination of dasatinib in rat plasma and its pharmacokinetic study

“…In recent years, numerous laboratories have reported the use of high-throughput bioanalytical procedures for the quantification of antileukemia drugs [5,6], a small number of analytical methods have been reported for dasatinib based on high-performance thin-layer chromatography (HPTLC) or high-performance liquid chromatography (HPLC) or radioactive labeling methods [7][8][9] and a liquid chromatography-mass spectrometry (LC-MS) method for plasma determination of this agent [10][11][12][13]. As with most approaches used to quantify pharmaceuticals, analytical methods for measuring tyrosine kinase inhibitor levels have focused on each agent in isolation and generally have been applied to pharmaceutical analysis or plasma determination of the agent.…”

Seeking the causes and solutions to imatinib-resistance in chronic myeloid leukemia

“…Other TKIs, such as dasatinib and nilotinib, do not appear to be substrates for hOCT1, but whether this difference alone will lead to reduced resistance rates with these second-generation TKIs remains unknown. 55,57,64,65 …”

Hematopoietic Stem Cells in Chronic Myeloid Leukemia

“…Other TKIs, such as Dasatinib and, as just mentioned, Nilotinib, do not appear to be substrates for hOCT1, but whether this difference alone will lead to reduced resistance rates with these secondgeneration TKIs remains unknown [120]. An adequate balance between influx (hOCT1) and efflux (MDR1, ABCG2) transporters may be a critical determinant of intracellular drug levels and, hence, resistance to Imatinib.…”