Distinguished by the density of tumor-infiltrating lymphocytes (TILs), there are two causes of PD-L1 expression: (i) prior attack by immunity (adaptive resistance) and (ii) activation of the oncogenic pathway (intrinsic induction) [29] respectively predicting better and worse benefit from immune checkpoint inhibitors (ICIs) in non-small cell lung cancer [30]. The gene discussed is CD274; the disease is neoplasm.