On detailed analysis of other immune checkpoints (TIM-3, LAG-3 and CTLA-4) and the regulatory T cell marker FOXP3 on the T cells, we detected upregulation of TIM-3 but no significant changes in the other markers examined as compared with effusions from other lung cancer patients who had not been treated with PD-1-blocking antibodies (Fig. 4c, Supplementary Fig. 7a). Here, PDCD1 is linked to lung carcinoma.