While the use of nivolumab and ipilimumab (humanized anti-CTLA-4 IgG1 mAb) in the post allo-SCT relapse setting in hematologic malignancies has demonstrated potent anti-tumor effects, significant immune-related adverse events (irAE) have also been reported (Table 1) [31, 49, 50]. This evidence concerns the gene CTLA4 and hematologic disorder.