Cytotoxic T lymphocyte antigen-4 (CTLA-4) is a coinhibitory molecule expressed by activated T cells and a subset of regulatory T cells.5–7 CTLA-4 is of primary importance in maintaining immune homeostasis by down-regulating T-cell signaling to inhibit the CD28-B7 costimulatory pathway, limiting T-cell responses, and contributing to tolerance to self-antigens.8, 9 Therefore, blockade of CTLA-4 is thought to prevent down-regulation of T cells and can potentiate immune responses against antigens expressed on tumor cells.10–13. Here, CTLA4 is linked to neoplasm.