Sirolimus, Tacrolimus, Thymoglobulin and Rituximab as Graft-versus-Host-Disease Prophylaxis in Patients Undergoing Haploidentical and HLA Partially Matched Donor Hematopoietic Cell Transplantation

OBJECTIVES: Primary * Determine the incidence and severity of acute graft-vs-host disease (GVHD) in patients with hematologic malignancies undergoing donor peripheral blood stem cell transplantation who are receiving sirolimus, tacrolimus, anti-thymocyte globulin, and rituximab as GVHD prophylaxis. * Assess time to engraftment absolute neutrophil count (\> 0.5 x 10\^9/L for 3 consecutive days) and platelet count (\> 20 x 10\^9/L for 3 consecutive days) in these patients. * Determine the safety, as defined by serious adverse events and adverse events related to this immunosuppressive regimen, in the first 6 months after treatment. Secondary * Assess the incidence of chronic GVHD measured within 2 years after transplantation. * Assess overall and disease-free survival at 2 years after transplantation. * Examine the incidence of opportunistic infections including fungal infections, pneumocystis carinii pneumonia, and viral infections (cytomegalovirus, varicella zoster virus, herpes simplex virus, BK virus, Epstein-Barr virus, and post-transplant lymphoproliferative disorder). * Assess the incidence of thrombotic microangiopathy within 100 days of transplantation. * Perform immunocorrelative studies, including T-cell, B-cell, NK-cell, regulatory cell, and allo-reactive T-cell measurement studies via flow cytometry, at 30, 60, 90, and 180 days after transplantation. OUTLINE: Patients receive rituximab IV on days -7 and 3, tacrolimus IV continuously (may switch to orally when the patient is able to eat) and oral sirolimus beginning on day -3, and anti-thymocyte globulin IV over 6 hours on days -3 to -1. Tacrolimus and sirolimus are tapered at the discretion of the treating physician. All patients also receive a standard transplant-preparative regimen and undergo transplantation on day 0. Blood samples are collected before the preparative regimen and at 30, 60, 90, and 180 days after transplantation for correlative immunologic studies. After completion of study treatment, patients are followed up for 2 years.