PDCD1 and cancer: Antibodies blocking the PD-1/PD-L1 axis have been shown to induce durable clinical responses in numerous cancer types including malignant melanoma[22,23,32], non-small cell lung cancer (NSCLC)[33,34], urothelial carcinoma[35,36], head and neck squamous cell carcinoma, Hodgkin’s lymphoma and renal cell carcinoma (RCC)[32-34,37-39].