CD274 and neoplasm: In this light, several biomarkers have been described, such as a minimal expression of PD-L1 by conventional IHC (62), a minimal level of tumor mutational burden (TMB) (63), and gene expression profiling (GEP) using the IPRES or IMPRES signatures (64, 65), but none of these have provided the required sensitivity and/or specificity to be implemented in the clinic.