Dasatinib Cerebrospinal Fluid Concentration and Plasma Pharmacokinetics: Potential for Central Nervous System Prophylaxis In Philadelphia Chromosome-Positive Leukemia

Takahashi, Naoto; Miura, Masatomo; Scott, Stuart; Saitoh, Hirobumi; Motegi, Mutsuhito; Fujishima, Naohito; Kameoka, Yoshihiro; Tagawa, Hiroyuki; Hirokawa, Makoto; Sawada, Kenichi

doi:10.1182/blood.V116.21.1807.1807

Abstract

Abstract 1807

Dasatinib (DA) is approved for use in imatinib-resistant or intolerant chronic myeloid leukemia (CML)/Philadelphia-positive acute lymphoid leukemia (Ph+ALL) and may also be useful for central nervous system (CNS) leukemia accompanied with CML/Ph+ALL; however, little is known about the relationship between DA pharmacokinetics and its ability to penetrate the blood-brain barrier. Consequently, we measured DA plasma and cerebrospinal fluid (CSF) levels by high-performance liquid chromatography in 20 samples obtained from 11 DA-treated patients (seven Ph+ALL and four lymphoid crisis CML). DA was detected in 10 CSF samples from five patients who were treated with 100 mg QD of DA (CSF C4h of detectable group; 3.526±2.604 ng/mL, 1.11–7.95 ng/mL), which was above the IC50 level for wild type BCR-ABL positive leukemia cells in vitro (0.8 nM = 0.39 ng/mL). However, DA was not detected in 10 CSF samples from 7 patients (CSF C4h of non-detectable group; <1.0 ng/mL). The concentration ratio of CSF to plasma was 3.90% (0.42-12.23%), which approached previously reported ratios for imatinib. There were significant differences in the AUC0-4 and the plasma C4h between the CSF detectable (D) and non-detectable (ND) patients (AUC0-4: 268.29±92.452 vs. 90.83±76.45, P=0.00019 by Student t-test, Figure 1; plasma C4h: 126.15±62.58 vs. 47.41±50.935, P=0.00637 by Student t-test). Moreover, there were significant correlations between CSF C4h and AUC0-4 (P<0.01, Figure 2) and between CSF C4h and plasma C2h (P<0.001), together suggesting that penetration of DA into the CSF may depend on DA plasma concentration. To investigate any influence of pharmacogenetic variation on CSF penetration, single nucleotide polymorphisms in genes involved in DA pharmacokinetics and transport (ABCB1, ABCG2, SLC22A1, SLC22A3, and CYP3A4/5) were interrogated; however, no significant correlation between CSF levels and genotype were observed. DA has a 325 fold greater potency than imatinib for inhibiting BCR-ABL tyrosine kinase, which undoubtedly influences the efficacy of DA for Philadelphia-chromosome positive CNS leukemia; however, our data suggest that clinical DA blood level monitoring may help estimate the penetration of DA to the CSF.