To date, PD-L1 expression assessed by IHC remains the most widely used biomarker for predicting responses to ICIs in NSCLC, but its usefulness is tempered by technical and biological challenges [95]; its limitations include intra- and inter-tumor heterogeneity as well as the subjectivity inherent in pathologist interpretations [16]. The gene discussed is CD274; the disease is non-small cell lung carcinoma.