Antigen loss is a common cause of resistance to CD19-targeted immunotherapy, but CD22 is also present in most B-ALL cases and is usually retained after CD19 loss.387 Therefore, CD22 is a promising candidate for antigen targeting by CAR T cells in patients with CD19 relapse.388 CD22 is mostly used as a supplement to CD19 or CD20 CAR T-cell therapy. This evidence concerns the gene CD19 and precursor B-cell acute lymphoblastic leukemia.