Currently, the Precision Medicine Working Group from the European Society for Medical Oncology recommends TMB as a biomarker to select PD-1/PD-L1 therapy for well- and moderately differentiated neuroendocrine tumors and cervical, salivary, thyroid, and vulvar cancers [37]; however, no recommendations have been issued for gastric cancer. This evidence concerns the gene CD274 and neuroendocrine neoplasm.