Limitations to the Field of Transplantation Drug treatment-related complications Chronic rejection Availability of organs
TOLERANCE Specific unresponsiveness to the donor of the recipient’s immune system. The donor is regarded as “self”. Therefore, no immunosuppressive drugs are needed to prevent rejection
Bone Marrow Induces Tolerance Animal studies >25 years ago showed that mixed bone marrow chimerism educates the immune system to make it tolerant of the donor We have aimed at making this approach less toxic and therefore clinically applicable
Bone Marrow Transplantation for Tolerance Induction: Requirements Recipient treatment must have minimal toxicity Must work for mismatched transplants Graft-versus-host-disease (GVHD) unacceptable. GVHD is the major complication of bone marrow transplantation, and precludes mismatched transplantation.
USING STEM CELLS TO INDUCE TOLERANCE 1)Treatments are given to block peripheral and intrathymic rejection of donor hematopioetic cells (e.g. anti-T cell mAbs, thymic RTX). Donor stem cells cells are given i.v. 2) Donor stem cells go to recipient marrow. Stem cells in the marrow send progeny to the recipient thymus. Blood cells are a mixture of donor and host (mixed chimera) 3) New T cells mature and become “educated” in the recipient thymus gland. Recipient Donor 4) The emerging T cells that repopulate the immune system are tolerant of donor and recipient. A donor organ is accepted and there is no GVHD.
BMT with T cell costimulatory blockade 3 Gy TBI day 0 anti-CD40L-mAb (0.5mg i.p., day 0) CTLA4Ig (0.5mg i.p., day +2) 15x10^6 B10.A bone marrow cells i.v. (fully MHC-mismatched, unseparated day 0) C57BL/6 Wekerle et al, JEM 1998,187:2037
n=14 third party donor 020406080100120140160 0 20 40 60 80 100 Percent Graft Survival Days post Skin-Grafting Donor-Specific Skin Graft Tolerance in Recipients of Non-Myeloablative BMT with Costimulatory Blockade
Bone Marrow/Stem Cell Transplantation The only known cure for many types of leukemia and lymphoma. Requires an HLA closely matched donor because of the complication of graft-versus-host disease (GVHD). Even with unrelated donors, about half of the patients whose only hope for cure is BMT do not have a donor.
GVHD Major complication of BMT Caused by donor T lymphocytes that see recipient antigens as “non-self” Disease of skin, liver, intestines Prevented by marrow T cell depletion, but this increases relapse rates, because donor T cells also eradicate leukemia cells
Our Goal To perform HLA mismatched transplants without GVHD. To use the GVH “response” (GVHR) to attack leukemia/lymphoma without producing GVHD. We have discovered that GVHR≠GVHD. This will allow even better cure rates than are seen with matched transplants.
Our Strategy Stimulate GVHR Confine GVHR to the tissues where leukemias and lymphomas reside (blood and lymphoid tissues). i.e. avoid migration of GVHR to skin, gut liver
Step 1: Bone marrow transplant with less toxic recipient treatment that includes antibodies. Donor marrow is T cell depleted Wait 1-2 months. Inflammation from preparative treatment subsides. Blood cells are a mixture of donor and host: Mixed chimerism is achieved without GVHR Step 2: Infuse donor T cells. Donor T cells interact with “presenting cells” of mixed chimera to maximize GVHR Tumor is killed Donor T cells are armed to kill tumor cells that express recipient antigens. They stay inside the blood and lymph, where tumor is. T cells don’t go to skin/gut/liver. There is no GVHD.
42 y.o. male with disseminated Hodgkin’s Disease, refractory to chemo and radiation therapy. Received a BMT with our protocol in Sept, 1999. Results: No GVHD, complete remission. 1yr post-transplant Pre-transplant
Rationale: Combined Matched Related Donor Bone Marrow and Kidney Transplantation in Multiple Myeloma With Kidney Failure Allogeneic BMT is the only known cure for MM. Complication rates are high with standard allogeneic BMT. Kidney failure is a common complication of MM, but the malignancy usually precludes kidney transplantation. Successful allogeneic BMT with less toxic conditioning induces transplantation tolerance (animal models). MGH investigators have developed a less toxic BMT protocol that is safe and effective in MM. Less toxic BMT combined with kidney transplantation from the same donor might induce tolerance while curing the myeloma.
Wait 1-2 months. Blood cells are a mixture of donor and host: Mixed chimerism and tolerance to the kidney is achieved. Step 2: Infuse donor T cells. Donor T cells interact with “presenting cells” of mixed chimera to maximize GVHR Tumor is killed Donor T cells are armed to kill tumor cells that express recipient antigens. Step 1: Bone marrow and kidney transplant with less toxic recipient treatment.
Combined Kidney and Bone Marrow Transplant: Patient 1 55-year-old woman presented in December, 1996 with ESRD due to multiple myeloma. Rx: Hemodialysis, chemotherapy September, 1998: combined kidney and bone marrow transplant from HLA-identical sister. 2005: pt in remission from myeloma; normal kidney function, off all immunosuppression since December, 1998.
Clinical course of patient 1 Days post-transplant CyA Discontinued
Applying our Strategy to Mismatched Transplants A greater challenge, because T cell depleted mismatched marrow is harder to engraft, especially when less toxic recipient treatment is given We have developed protocols achieving engraftment of mismatched, T cell-depleted marrow without GVHD. We have obtained proof of principle that our strategy can work in the mismatched setting.
GENETIC ENGINEERING OF PIGS AS XENOGRAFT DONORS Transgenics –Complement inhibition DAF CD46 CD59 –Fucosyl transferase –Growth factors pIL-3, pSCF Human GF receptors –MHC genes Class I (NK inhibition) Knock-outs – 1,3-galactosyl transferase Fertilized egg DNA
First GalT-KO miniature swine born November 2002 From: TBRC and Immerge BioTherapeutics, Boston
Anti-CD4 Anti-CD8 mAbs Days –6,-1, +7, +14 Normal mouse Thymectomize Day 0: Implant 1mm 3 fetal miniature swine thymus tissue under kidney capsule Reconstituted murine CD4 compartment. Tolerance to donor pig. Replacement of Recipient Thymus With a Xenogeneic Thymus in Thymectomized, T Cell-Depleted Mice
B134 kidney graft biopsy on POD60 x200 Normal kidney Kidney graft was pink No spot hemorrhage From: TBRC and Immerge BioTherapeutics, Boston
Summary of Heart and Kidney Transplants from the first available GalT-KO Pigs Do not undergo HAR Do not require antibody absorption nor complement inhibition With standard immunosuppression, organ survivals improved - modestly but consistently With kidney plus thymus tolerance strategy, survivals increased from maximum of 30 days to >83 days
A CKNOWLEDGEMENTS MGH BMT Unit (Spitzer, McAfee, Dey, Ballen, et al.) Transplant Unit (Cosimi, Kawai, Delmonico, Ko, Hertl, et al.) TBRC (Sachs, Sykes, Yamada, et al.) Pathology (Colvin, Saidman, et al.) Infectious Disease (Fishman, Basgoz, et al.) Renal (Rubin, Williams, Goes, Wong, et al.) Wellman Photomedicine Laboratories (Lin et al.) OUTSIDE ITN (NIH) Biotransplant/Immerge Medimmune
CONTRIBUTORS: MOUSE STUDIES BMT Section/ Transplantation Biology Research Center Ronjon Chakraverty Hyeon-Seok Eom Markus Mapara Thomas Fehr Yasuo Takeuchi Josef Kurtz Denise Pearson Juanita Shaffer Jennifer Buchli Tim Hogan Peter Cotter Guiling Zhao Richard Hsu Wellman Center for Photomedicine Daniel Cote Costas Pitsillides Charles Lin