ROR1 and B-cell chronic lymphocytic leukemia: In order to optimize CAR T-cell products and to improve strategies to overcome the possible onset of resistance to therapy, today a variety of new constructs are being studied in numerous early-phase trials in CLL setting, including CARs that target alternative antigens, other than CD19 (e.g., CD20, CD22, ROR-1, Siglec-6), or that simultaneously target more than one antigen (e.g., CD19 and CD20, CD19 and CD22).