MPO and precursor B-cell acute lymphoblastic leukemia: But another study that demonstrated a higher frequency of isoMPO expression, identified similar aberrant expression of myeloid markers and similar or even better clinical outcomes (as indicated by minimal residual disease) in the MPO+ve and -ve B-ALL, suggesting that these cases are not necessarily high-risk as a group and remain best classified as B-ALL rather than a separate entity (McGinnis et al., 2020).