PDCD1 and neoplasm: Several clinical trials have been initiated to test the safety and efficacy of CAR T cells that, in addition to targeting a specific tumour antigen, secrete either anti-PD-1 alone or anti-PD-1 in combination with anti-CTLA-4 or anti-PD-L1 antibodies (NCT03179007, NCT03182816, NCT03182803, NCT03030001, NCT02873390, NCT02862028, NCT03170141).