Pattern of CNS relapse in acute lymphoblastic leukemia BCR-ABL positive, the importance of characterization of ABL1 mutations in cerebrospinal fluid.

He incidence of central nervous system (CNS) relapse among; patients with BCR/ABL-positive acute lymphoblastic leukemia (ALL) is 8-17%. Although tyrosine-kinase inhibitors (TKI), especially imatinib, are included in; the first-line treatment in these patients, their concentration in CNS is too low; to effectively prevent CNS relapse, making CNS prophylaxis mandatory. Aims: To study the frequency, predictors and evolution of BCR-ABL positive; ALL patients with CNS relapse in two consecutive clinical trials of the PETHEMA; group using imatinib and chemotherapy. As secondary objective we proposed; the introduction of a new method for the study of variants of uncertain; significance (VUS) in kinase domain of the BCR-ABL from cDNA of cerebrospinal; fluid (CSF) blasts, in order to adapt the TKI used in relapse according; to the clonal evolution from bone marrow (BM) to CSF cells.N