BTLA and cancer: A wide range of cancer cells has different inhibitory immunoreceptors, namely, PD‐1, CTLA‐4, LAG3, TIM3, TIGIT, BTLA, and so on, which are named as “immune checkpoint” and understanding of their dynamic role in cancer physiology subsequently brought to the discovery of new ICIs that radically revolutionize therapeutic battel of LC, especially NSCLC.303, 304