PDCD1 and non-small cell lung carcinoma: A similar pattern has been reported [20] in non-small cell lung cancer (NSCLC) CD8+ tumor infiltrating lymphocytes (TILS), where PD-1-high cells are earlier stage CD27+ T cells, while KLRG1+ cells are later-stage CD27– T cells that are not PD-1-high (Figure 1C, 1D).