Assessment of PD-L1 expression by immunohistochemistry (IHC) is a predictive biomarker of response to anti-PD-1/PD-L1 treatment; across different tumor types, patients with PD-L1-negative tumors responded to PD-1/PD-L1 axis inhibitors in 0–17% of cases, while those with PD-L1-positive tumors responded in 44–100% of cases [11]. Here, PDCD1 is linked to neoplasm.