Antibodies to immune checkpoint molecules on effector T cells such as programmed cell death-1 (PD1) and cytotoxic lymphocyte antigen-4 (CTLA-4) restores the effector T cell activity which is suppressed by ligands highly expressed on the cancer cells leading consequently to not only cancer cell death, but also death of regulatory T cells in the tumor environment. Here, PDCD1 is linked to neoplasm.