In 2015, based on the results of the European Organisation for Research and Treatment of Cancer (EORTC) 18,071 phase III trial, the US Food and Drug Administration (FDA) approved ipilimumab, a cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4)-blocking monoclonal antibody (mAb), for the adjuvant treatment of stage III melanoma patients with regional lymph node metastasis of >1 mm after complete resection [2]. Here, CTLA4 is linked to cancer.