Sitagliptin for Prevention of Acute Graft Versus-Host Disease After Allogeneic Hematopoietic Stem Cell Transplantation

Primary Objective Evaluate the efficacy of sitagliptin in reducing the incidence of grade II-IV acute Graft Versus-Host Disease (GvHD) by day +100 post-transplant in patients undergoing allogeneic hematopoietic stem cell transplantation and receiving standard sirolimus and tacrolimus GvHD prophylaxis. Secondary Objectives The following descriptive secondary objectives will be studied: 1. Describe the tolerability and potential toxicity of sitagliptin. 2. Describe the cumulative incidence of grades II-IV acute GvHD by day +100. 3. Describe the cumulative incidence of grades III-IV acute GvHD. 4. Describe the engraftment kinetics of absolute neutrophil count and platelets. 5. Describe the incidence of infections occurring during the 100 days post-transplant. 6. Describe non-relapse mortality (NRM) at day +30, +100, and 1 year post-transplant. 7. Describe overall survival. 8. Describe the incidence of chronic GvHD. 9. Describe the cumulative incidence of relapse of the primary hematological malignancy.