CTLA4 and neoplasm: Many studies have revealed that the immunity system has played a significant role in preventing tumorigenesis and tumor progression during the past decade.[5] Immunotherapy has ushered cancer treatment into a new era,[6] programmed death 1 (PD-1) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) inhibitors are particularly prominent in this field.