Phenotypic evolution of leukemic blasts after blinatumomab treatment. (A) L1/2 morphology of blasts (bone marrow) at the time of relapse, before blinatumomab (i); myelomonocytic morphology of cells in the bone marrow 11 days after blinatumomab treatment (ii) and 9 days after cessation of blinatumomab (iii). In each image pair, magnification is 1:1000 (left) and 1:500 (right) (Pappenheim staining). (B) Flow cytometry at the 2 respective time points: directly after blinatumomab treatment (left 2 columns) and 9 days later (right 2 columns). Staining shows CD45⁺ live cells.