PDCD1 and lung cancer: In a previous study, the Th7R cluster, composed of CXCR3+CCR4−CCR6+ Th1/17 and CXCR3−CCR4−CCR6+ CCR6 single positive (CCR6 SP), was identified as a Th1-like CD4+ T-cell cluster predictive of the efficacy of PD-1 blockade therapy in advanced lung cancer, characterized by expression of IL7 receptor, TCF7, and granzyme K (GZMK), and distinct from Th1 in gene expression, epigenetics, and TCR clonotype (14).