Recent advances in understanding of fundamental immunology have created new insights into the dynamic interactions between tumors and the immune system. This includes new understanding of T- and B-cell interaction, immune inhibitory mechanisms including the biology of T regulatory cells, myeloid suppressor cells, and dendritic cell subsets. Enhanced understanding of mechanisms underlying T-cell anergy such as arginine deprivation, immunosuppressive cytokines, defective innate and interferon response pathways, and NKG2D downregulation have all provided new insight into suppression of anti-tumors