Renal Allograft Tolerance Through Mixed Chimerism - SMC/MGH

Conditioning regimen .Patients will receive Rituximab, Fludarabine, Cyclophosphamide, Thymic irradiation and Thymoglobulin

Recipients will receive a conditioning regimen that includes rituximab on study days -7 and -2, fludarabine 10mg/m2/day on days -6 to -3 (4 doses), cyclophosphamide (22.5mg/kg/day) on days -5 and -4, followed by local thymic irradiation (7 Gy) on day -1 and Siplizumabon days -1, 0, and +1. Combined kidney and bone marrow transplant will be performed on study day 0. Methylprednisolone will be started at 250 mg/day on day 0 and tapered to prednisone 20mg by day 10 after which it will be continued until day 20. Prophylaxis will be provided for hemorrhagic cystitis, PCP, fungal infection, CMV, and perioperative infection. All patients who require any blood transfusion will receive only leukocyte-depleted and irradiated blood products for a period of at least 52 weeks following transplantation. The proportion of patients successfully weaned off immunosuppression without chimerism transition syndrome (CTS) will be assessed.