MTOR and graft versus host disease: On the other hand, various agents used for GvHD prophylaxis and treatment, such as post-transplantation cyclophosphamide, calcineurin and mammalian target of rapamycin (mTOR) inhibitors have been associated with the development of endothelial injury syndromes, such as HSCT-associated thrombotic microangiopathy (HSCT-TMA) [8,9].