PDCD1 and neoplasm: It has been reported repeatedly that many cancer cells express surface ligands for immune checkpoints to evade immune responses.58, 59 Due to this means of immune evasion in tumor cells, antibodies that target immune checkpoint components have been shown to significantly induce specific anti-tumor responses.58, 59 Among these immune checkpoints are three CD molecules that have been widely studied: CTLA-4, PD1, and TIM3.