PDCD1 and neoplasm: In a recent ex vivo precision cut tumour slice (PCTS) model study [39], we observed that patient ID 168 and 141 had differential checkpoint receptor expression in PCTS based on gene expression analysis, with patient 141 displaying a higher expression of programmed cell death protein 1 (PD-1) compared to patient 168, which may relate to an implicit difference in immune efficiency in the two subjects.