CD19 and graft versus host disease: The demonstration of a response in 8 of 11 patients with relapsed or refractory CD19-expressing B cell malignancies treated with these NK cells as part of a phase 1/2 trial, in conjunction with the lack of significant cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), or GVHD [27] will undoubtedly provide a strong impetus for further exploration of CAR-modified NK cells or NK/T cells.