To this day, PD-L1 expression remains the most used biomarker for ICIs in NSCLC patients and leads to major therapeutic differences between PD-L1 > 50% and <50% patients, with only the first subset having the possibility of first-line monotherapy with pembrolizumab and the latter being treated with either chemotherapy or a combination of ICIs and chemotherapy. The gene discussed is CD274; the disease is non-small cell lung carcinoma.