CD274 and neoplasm: However, the PD-1 antibodies (Nivolumab and Pembrolizumab) used IgG4 isotype, which may be due to the PD-1 antibody only needing to block the interaction between PD-1 and PD-L1 to increase immune system function to produce anti-tumor activity, which is needed to avoid the toxicity to T cells from ADCC and CDC.