The administration of the pembrolizumab molecule as first-line therapy to patients without genomic alterations in the genes EGFR, ALK, ROS1 and BRAF, and for whom 50 % of the tumor cells express PD-L1, has given back IHC a primordial role in the therapeutic care of patients with NSCLC [63]. The gene discussed is CD274; the disease is non-small cell lung carcinoma.