CD8A and lung adenocarcinoma: TIM‐3 (also known as HAVCR2) is a co‐inhibitory receptor immune checkpoint protein, which was initially identified as expressed exclusively on the surface of differentiated T helper 1 (Th1) cells, IFNγ‐producing CD8+ T cells, and NK cells,[255] but it was also identified on lung cancer.[256] Compared with tumors lacking mutations in both KRAS and EGFR, EGFRmut lung adenocarcinomas had significantly lower TIM‐3.[256]