PDCD1 and B-cell chronic lymphocytic leukemia: Simon et al. showed feasibility and improved antitumor function in vitro of T cells following electroporation of multiple mRNA encoding for either TCR/CARs, and siRNAs allowing significant knockdown of checkpoint molecules (programmed cell death 1 [PD-1], CTLA4).56 Other immune cells can also be used as effectors, such as NK cells electroporated with CAR-encoding RNA with even higher transfection efficiency and cytotoxicity in a CLL model.57