Flow cytometric immunophenotyping of acute lymphoblastic leukemia: is the time ready for consensus the guidelines?

Flow cytometry play a kery role in ALL subclassification. The majority of patients affected by B-cell acute lymphoblastic leukemia (B-ALL) will relapse after an initial response while approximately twenty percent will display primary resistant disease. Patients suffering from relapsed/refractory B-ALL display a very poor outcome. Allogeneic hematopoietic cell transplantation still represents the only approach with curative intent but is not so frequently feasible because of patient’s fitness, donor availability and the ability to achieve a remission. Estimated remission rates with conventional cytotoxic agents are around 30% but they are short-lived. These disappointing results led to the introduction of new immunologic-based treatments – Blinatumomab and Inotuzumab – that produced a substantial improvement in terms of response rates with the ability, in most cases to induce a minimal residual disease (MRD)-negative status. Ultimately, T cells engineered to express a CD19-specific chimeric antigen receptor (CAR-T) have produced sensational results among patients with relapsed/refractory B-ALL with unexpectedly high rates of MRD-negative complete remissions rates