PDCD1 and neoplasm: Recent findings suggest that acquired resistance to PD-L1/PD1 blockade is associated with systemic T cell dysfunctionality and enhanced co-expression of PD1 and lymphocyte activation gene 3 (LAG3) in T cells [13–15], consistent with the well-accepted role of PD1 and LAG3 in the exhaustion of tumour-infiltrating T cells [13, 15–18].