Pretreatment blast-to-lymphocyte ratio as a prognostic marker for CD19/CD3-bispecific T cell-engaging antibodies (blinatumomab) treatment against relapsed or refractory B-precursor acute lymphoblastic leukemia.

Blinatumomab is an immunotherapy drug approved for the treatment of acute lymphoblastic leukemia. Since not all patients respond to blinatumomab, markers are needed to predict the efficacy of blinatumomab in individual patients. We hypothesized that the pre-treatment blast-to-lymphocyte ratio would predict blinatumomab efficacy. To examine this possibility, we conducted a post hoc analysis using data from the TOWER Clinical Trials (NCT02013167). Multivariate analysis showed that, along with the treatment groups, each of the following was independently correlated with superior progression-free survival: salvage-treatment phase, allogeneic stem cell transplantation, and pre-treatment ratio of bone marrow blasts-to-peripheral blood lymphocytes < 25.