Numerous studies have examined the role of PD-L1 expression as a predictive biomarker of tumor response; nonetheless, its predictive value remains unclear due to the different cut-off values (e.g., 1%, 5%, 10%, and 50%) reported for the definition of PD-L1 positivity or negativity, which is further compounded by the possibility of interlaboratory variation [23–25, 43]. The gene discussed is CD274; the disease is neoplasm.