TLI, TBI, ATG & Hematopoietic Stem Cell Transplantation and Recipient T Regs Therapy in Living Donor Kidney Transplantation

Phase 1 Study of Total Lymphoid Irradiation, Total Body Irradiation, Anti-Thymocyte Globulin and Purified Donor CD34+, T-cell and Recipient T Regulatory Cell Transfusion in Human Leukocyte Antigen Mismatched Living Donor Kidney Transplantation

This study will determine whether a preparatory regimen including total lymphoid irradiation (TLI), total body irradiation (TBI), anti-thymocyte globulin (ATG) and infusion of the donor hematopoietic stem cells when given along with recipient regulatory T cells (Tregs) will allow for eventual discontinuation of anti-rejection drugs after living donor kidney transplantation.

It has been demonstrated that hematopoietic mixed chimerism or the coexistence of both donor and recipient immune cells can lead to tolerance to the graft in absence of graft versus host disease (GVHD). The goal of this pilot study is to determine if recipients of living donor kidney transplant can be successfully withdraw from immunosuppressive drugs. The patients will receive a preparatory regimen consisting of TLI and a low single dose of TBI and ATG following their kidney transplantation. Two weeks later, they will receive purified hematopoietic stem cells (CD34+) and Tcells that have been collected 6 weeks prior from their kidney donor. Regulatory T cells (Tregs) that have been collected from the recipient prior to the transplantation and expanded in vitro will be infuse the following day to enhance the chance of engraftment of the donor bone marrow cells. If chimerism develops and persists, the immunosuppressive drug will be tapered and stop. Mycophenolate mofetil (MMF) will be stopped 12 months after transplantation and if the chimerism remains stable, tacrolimus will be stopped 6 months later. The dose of Tregs will be escalated if the % of donor chimerism is not at least 25% during the first 60 days.

Inclusion Criteria:

1. All consenting adults who are 18 to 65 years, living donor renal transplant recipients at Stanford University Medical Center or Northwestern Medicine who have a haplotype matched (minimum single Human Leukocyte Antigen - DR locus (HLA-DR) and HLA-A or B match) living related or unrelated donor.
2. Patients who agree to participate in the study and sign an Informed Consent.
3. Patients who have no known contraindication to administration of rabbit ATG or radiation.
4. Males and females of reproductive potential who agree to practice a reliable form of contraception for at least 1 year posttransplant

Exclusion Criteria:

1. Previous treatment with rabbit ATG or a known allergy to rabbit proteins.
2. History of malignancy with the exception of non-melanoma skin malignancies.
3. Pregnant women or nursing mothers.
4. Serological evidence of HIV, Hepatitis B surface antigen positive (HBsAg+), or Hepatitis C infection. Epstein Barr Virus (EBV) positive to EBV negative.
5. Leukopenia (with a white blood cell count < 3000/mm3) or thrombocytopenia (with a platelet count < 100,000/mm3).
6. Panel Reactive Antibody (PRA) greater than 80% or demonstration of historic and/or current donor specific antibody (DSA)
7. Prior organ transplantation
8. High risk of primary kidney disease recurrence
9. Advanced coronary or vascular disease.