Tumor PD-L1 expression has been established as a biomarker for patient selection for monotherapy with the anti-PD-1 monoclonal antibody pembrolizumab in multiple tumor types including advanced non-small-cell lung cancer (NSCLC), melanoma, cervical cancer, gastric cancer, head and neck squamous cell cancer and esophageal cancer [2,12–18], and MSI-H has been established as a tumor-agnostic biomarker for pembrolizumab monotherapy [2,19–21]. This evidence concerns the gene CD274 and neoplasm.