RESUMO
B-cell acute lymphoblastic leukemia (B-ALL) is a diverse group of malignant blood disorders both with regard to the biological properties of the tumor and to therapeutic approaches. Immunophenotyping, molecular genetic techniques, whole-genome sequencing characterize B-ALL as a very diverse group for sensitivity to chemotherapy and prognosis. We present three clinical cases of patients with B-ALL and expected good response to standard therapy, in whom standard protocol treatment failured: refractoriness, persistence of minimal residual disease (MRD), and progression (MRD increase). The remission in these patients was achieved after chemotherapy change to immunological targeted therapy. Nowadays a unified therapeutic approach to all primary patients of the B-ALL is considered generally outdated. Great efforts are carrying out to develop molecular genetic classifications. The molecular dissection of subtypes of B-ALL goes on, and new protocols for selective treatment with targeting are clearly outlined for each subtype of B-ALL.