This issue arises considerable interest, given the strict relationship between MRD and outcome in adult ALL and the dramatically worse outcome of MRD+ CD20+ ALL as opposed to MRD− CD20+ ALL.25 Although the CD20 antigen is expressed in a relevant proportion of Ph+ ALL cases, there is no data on the therapeutic role of this MoAb in this subset. Here, MS4A1 is linked to acute lymphoblastic leukemia.