Limitations to the Field of Transplantation

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Limitations to the Field of Transplantation

• Drug treatment-related complications
• Chronic rejection
• Availability of organs

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TOLERANCE

• Specific unresponsiveness to the donor of the
  recipients immune system.
• The donor is regarded as self.
• Therefore, no immunosuppressive drugs are needed
  to prevent rejection

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Bone Marrow Induces Tolerance

• Animal studies gt25 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

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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.

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USING STEM CELLS TO INDUCE TOLERANCE
3) New T cells mature and become educated in
the recipient thymus gland.
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.
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.
Blood cells are a mixture of donor and host
(mixed chimera)
2) Donor stem cells go to recipient marrow.
Stem cells in the marrow send progeny to the
recipient thymus.
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BMT with T cell costimulatory blockade
3 Gy TBI day 0
15x106 B10.A bone marrow cells i.v. (fully
MHC-mismatched, unseparated day 0)
C57BL/6
anti-CD40L-mAb (0.5mg i.p., day 0) CTLA4Ig (0.5mg
i.p., day 2)
Wekerle et al, JEM 1998,1872037
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Donor-Specific Skin Graft Tolerance in Recipients
of Non-Myeloablative BMT with Costimulatory
Blockade
100
80
donor
60
Percent Graft Survival
40
third party
20
n14
0
0
20
40
60
80
100
120
140
160
Days post Skin-Grafting
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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.

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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

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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.

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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

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42 y.o. male with disseminated Hodgkins
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
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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.

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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.

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Clinical course of patient 1
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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.

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POTENTIAL DONOR SPECIES
Swine
Advantages
Availability
Breeding Characteristics
Disadvantages
Phylogenetic distance
Natural (anti-GAL) antibodies
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GENETIC ENGINEERING OF PIGS AS XENOGRAFT DONORS
DNA

• 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
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First GalT-KO miniature swine born November 2002
From TBRC and Immerge BioTherapeutics, Boston
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Replacement of Recipient Thymus With a Xenogeneic
Thymus in Thymectomized, T Cell-Depleted Mice
Thymectomize
Reconstituted murine CD4 compartment. Tolerance
to donor pig.
Normal mouse
Day 0 Implant 1mm3 fetal miniature swine thymus
tissue under kidney capsule
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Zhao et al, Nature Medicine 1996, 21211
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Tolerance by Thymus Transplantation
2. Thymokidney transplantation
From TBRC and Immerge BioTherapeutics, Boston
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Creatinine levels B134 (Thymokidney Steroid
free regimen)
10
9
8
7
6
5
KBx
Cr(mg/dl)
laparotomy
4
3
2
1
0
0
7
14
21
28
35
42
49
56
63
70
77
POD
From TBRC and Immerge BioTherapeutics, Boston
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B134 kidney graft biopsy on POD60
x200
Normal kidney
Kidney graft was pink No spot hemorrhage
From TBRC and Immerge BioTherapeutics, Boston
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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 gt83 days

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ACKNOWLEDGEMENTS

• 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

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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