It has been recently reported that 28% of patients with CUP present one or more predictive biomarkers to immune checkpoint inhibitors(ICI), such as programmed death-ligand 1 (PD-L1) expression on ≥ 5% cancer cells in 22.5%(≥ 1% in 34%) and lymphocytes in 58.7%, microsatellite instability (MSI)-high in 1.8% and tumour mutational burden (TMB) ≥ 17 mutations per megabase in 11.8%. Here, CD274 is linked to cancer.