Paradoxically, the use of broadly immunosuppressive prophylactic regimens such as calcineurin and mechanistic target of rapamycin (mTOR) inhibitors to prevent acute GVHD can mediate endothelial damage (72, 73) and is associated with increased circulating levels of vWF, soluble thrombomodulin (sTM), and ICAM-1, predictive of VOD (72). This evidence concerns the gene MTOR and acute graft versus host disease.