PDCD1 and neoplasm: It has been reported that anti-PD-1 therapy often induces immune-related adverse events29 with fatal side effects such as type 1 diabetes mellitus.8,9 Moreover, there is an increasing number of reports indicating that the general administration of an anti-PD-1 antibody can induce tumour hyper-progression by augmenting regulatory T cells.30,31 Here we showed that the effects of NTP-GM-D17 were transient, and PD-1 expression in human PBMCs was restored to control levels on day 7 after the final treatment with the protein.