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; Download : Download high-res image (183KB) Download : Download full-size image Download : Download high-res image (136KB) Download : Download full-size image Disclosures: No relevant conflicts of interest to declare.