CD274 and non-small cell lung carcinoma: Immunohistochemical PD-L1 expression, routinely assessed on histological samples as tumor proportion score (TPS), is the most widely used predictor of ICI response until now, but its real-world applications are often limited by significant challenges, mainly including the need for invasive sampling methods, its heterogeneous expression in tumor tissue, reflecting the intratumoral heterogeneity of NSCLC, as well as the suboptimal standardization of the diagnostic assays employed and the variability of the scoring systems and cut-off values used [11,15,16].