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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
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.
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.
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.
BMT with T cell costimulatory blockade
3 Gy TBI day 0
15x10^6 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
1998,187:2037
Donor-Specific Skin Graft Tolerance in
Recipients of Non-Myeloablative BMT with
Costimulatory Blockade
Percent Graft Survival
100
80
donor
60
40
third party
20
0
0
20
n=14
40 60 80 100 120 140 160
Days post Skin-Grafting
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
Blood cells are a mixture of donor and
host: Mixed chimerism is achieved
without GVHR
Wait 1-2 months. Inflammation from
preparative treatment subsides.
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.
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.
Pre-transplant
1yr post-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.
Step 1: Bone marrow and kidney
transplant with less toxic recipient
treatment.
Blood cells are a mixture of donor and
host: Mixed chimerism and tolerance to
the kidney is achieved.
Wait 1-2 months.
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.
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
Kappa
mg/dl
Scr
CyA
mg/dl
5 ng/dl
500
4
3
2
Serum
CRE
CyA Levels
400
Kappa
Light
Chain
300
200
CyA
Discontinued
35
30
25
20
15
10
1
100
5
0
0
0
5 15 25 35 45 55 65 75 85 95 105 115 154 200 300 500 700 900
Days post-transplant
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.
POTENTIAL DONOR SPECIES
Swine
Advantages
Availability
Breeding Characteristics
Disadvantages
Phylogenetic distance
Natural (anti-GAL) antibodies
GENETIC ENGINEERING OF PIGS
AS XENOGRAFT DONORS
• Transgenics
DNA
Fertilized egg
– 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
First GalT-KO miniature swine born November 2002
From: TBRC and Immerge BioTherapeutics, Boston
Replacement of Recipient Thymus With a Xenogeneic
Thymus in Thymectomized, T Cell-Depleted Mice
Thymectomize
Days –6,-1, +7, +14
Anti-CD4
Anti-CD8
mAbs
Normal
mouse
Reconstituted
murine CD4
compartment.
Tolerance to
donor pig.
Day 0: Implant 1mm3 fetal miniature swine
thymus tissue under kidney capsule
Zhao et al, Nature Medicine 1996, 2:1211
Tolerance by Thymus Transplantation
2. Thymokidney transplantation
From: TBRC and Immerge BioTherapeutics, Boston
Cr(mg/dl)
Creatinine levels B134
(Thymokidney – Steroid free regimen)
10
9
8
7
6
5
4
3
2
1
0
KBx
0
7
14
21
28
35
42
49
laparotomy
56
63
POD
From: TBRC and Immerge BioTherapeutics, Boston
70
77
B134 kidney graft biopsy
on POD60
x200
Kidney graft was pink
No spot hemorrhage
Normal kidney
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
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
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