CD19 and neoplasm: CD19-targeting CAR T cells induce remission in approximately 70% of adults with relapsed/refractory B-cell ALL, but approximately 30% to 60% relapse due to loss of CD19 expression on tumor cells and/or limited CAR T-cell persistence.1,2 Bispecific constructs cotargeting CD19 and the alternative B-cell antigen CD223,4 may reduce antigen escape.