Thus, targeting PD-1/PD-L1 interactions by immune checkpoint inhibitors (ICI) has been approved for systemic therapy in several tumor entities with clinical breakthrough during the last decade [3–5], whereby PD-L1 tumor proportion score (TPS) has been widely used to guide the selection of patients for immunotherapy in several cancer types [1, 6]. The gene discussed is PDCD1; the disease is neoplasm.