PDCD1 and neoplasm: Although tumour-infiltrating T cells from surgically resected primary NSCLCs (PT) showed variation in TIM-3 expression, the level of TIM-3 on CD4 and CD8 T cells in the effusion specimens from the two patients who progressed on anti-PD-1 therapy (resistant effusions: RE) was higher (mean of TIM-3 positivity was 22.10% and 37.85% in CD4 and CD8 T cells, respectively) than those from other NSCLC patients (mean of TIM-3 positivity was control effusions (CE):2.52% and PT:9.06% in CD4 T cells and 3.54% and PT:17.58% in CD8 T cells) (Fig. 4c).