Bone Marrow Transplant

Bone Marrow Transplant Hematology Phase IIA  Stem Cells & Bone Marrow Transplants Traditional Transplants     Types Therapeutic Mechanisms/ Rationale Potential risks and benefits Clinical Results Embryonic Stem Cells & Therapeutic Potential Umbilical Cord Stem Cells Somatic (Adult) Stem Cells  Stem Cell Plasticity    Types of Transplants  Autologous Transplant  Patient’s own stem cells  Allogeneic Transplant  Stem cells from someone else=donor stem cells Early Allogeneic Transplants Toxicity noted in early allogeneic studies:    “2° disease of diarrhea, liver necrosis & skin”  Versus Host Disease (GVHD) Now well recognized toxicity of alloBMT Termed Graft  GVHD pts had less leukemic relapse      in 1968, of 14 AlloBMT patients 10/20 died of GVHD w/o evidence of leukemia 4/20 had no GVHD, died of recurrent leukemia Same donor cells causing toxicity were anti-leukemic Termed the Graft Vs Leukemic Effect (GVL) Kaplan-Meier Probability of Survival of GVHD vs Non-GVHD 100 90 80 70 60 50 40 30 20 10 0 0 2 4 Years Post transplant 6 8 Prob of Survival Chr.GVHD A+C GVHD Ac GVHD NO GVHD GVL & GVHD is Immune Mediated  Donor Immune cells recognize Recipient cells as non-self  T-cell & NK cell response  Attack host cells: malignant and normal host cells  Balance of this immune response:  Minimize GVHD + Maximize GVL   1) Immunosuppressive Therapy with BMT 2) HLA-Match Donor & Recipient   Match major antigens to decrease GVHD Mismatch of minor antigens results in GVL  MHC-HLA MHC molecules discriminate self & non-self   In humans = HLA molecules function is Ag presentation to T-cells  Via Antigen Presenting Cells (Dendritic Cells)  T-Cells trained early in thymus to recognize this  Major HLA molecules (Class I & II) most important:   Class I (HLA-A, HLA-B) molecules interact with CD8 Cytotoxic T-cells Class II (HLA-DR) interact with CD4 Helper T-cells HLA Balance for alloBMT Major Class I & II HLA matched for allogeneic BMT  Decreases severe GVHD Minor HLA antigens not matched  Results in GVL and GVHD  Only recently being characterized   Types of Transplants  Allogeneic Transplants Stem cells donated from another  HLA match most important (HLA- A,B and DR)=6/6= match   Matched Sibling  Best match for major and minor antigens BMT bank now over 8 million donors  Matched Unrelated   Mismatched Single mismatch (5/6) or Haploidentical (3/6)  Least successful; most toxic  Types of Transplants  Syngeneic Transplants   Identical twins Not very successful: major AND minor HLA perfectly matched  No GVL effect   Types of Transplants Non-myeloablative or “Mini”allogeneic transplants  Non-myeloablative conditioning chemotherapy  Less toxic than full myeloablative traditional BMT’s    Takes advantage of the graft vs tumor effect Decreased mortality of transplant Allogeneic transplants now possible for elderly & medically compromised  Recent trials showing promising results  Donor Lymphocyte Injections (DLI)  Goal of alloBMT is to reach full chimerism of donor immune cells in recipient (100%)  Increases GVL, but also GVHD  Incomplete chimerisms (<90%) can be “topped up” with intermittent injections of more donor lymphocytes   Shown to improve remission rates More than two DLI’s shown to increase GVHD significantly   Peripheral Blood Stem Cells (PBSCT) Stem cells collected peripherally using apheresis (cell separator machine)  Types of Transplants Less invasive; less discomfort; less morbidity than BM     Outpatient procedure PBSCT results in more rapid hematopoietic recovery than BM No difference in treatment outcome Quickly replacing traditional BM    Using cytokine stimulation (G-CSF injections) BM releases large number CD34 stem cells into circulation Stem cells harvested via peripheral line  Stem Cell Collection and Transplant Procedure Autologous:         5 days of SC cytokine injections to mobilize stem cells from BM into PB (G-CSF) Day 5 & 6: PB collected and apheresed to separate/isolate CD34+ stem cells Volume 200 mL cryopreserved in dimethylsulfoxide (DMSO) and stored at -196º C using liquid nitrogen High dose chemotherapy +/- irradiation (TBI) given over 2-5 days 2-3 days later stem cells are thawed and infused through central line Stem cells “hone” in on BM and begin differentiation and BM recovery (2-3 weeks) Patient supported with transfusions (PLT<10;Hb<80) and given G-CSF until neutrophils recover Prophylactic antibiotics given; fevers or infections treated aggressively  Allogeneic      Similar except stem cells collected from donor same day as transplant and immediately infused to recipient Recipient given pre transplant chemo 2-3 days prior Donor can be harvested either peripherally (with GCSF mobilization); or donor taken to OR under general anasthesia, and multiple BM aspirates from bilateral iliac crests obtain the required stem cells Prophylactic antibiotics, antifungals and G-CSF given Immunosuppressive therapy also given   Cyclosporine, methotrexate, mycophenylate Prevents GVHD, but try not to decrease anti-tumor effect Adverse Effects   Autologous  Well tolerated/ low mortality rate (<1%) Graft Versus Host Disease (GVHD)   Allogeneic  Donor T lymphocytes recognize recipient as foreign and mount immune reaction 3 main organs affected: Skin, GI, Liver toxicities  Infections  Significant immune disruption can result in severe opportunistic infections (Fungal, Viral:CMV, bacterial)  Graft Rejection- very rare Autologous Stem Cell Transplant Advantages Lower Mortality (TRM)         Disadvantages Lower Cure   <1% No rejection No GVHD Less infections/ less immune suppression No Graft Vs Tumor Potential for tumor contamination    65-70 yo or older Allogeneic Transplants   Advantages   Disadvantages Graft Vs Tumor=CURE  Higher Mortality   Donor immune response against malignant cells GVHD Infections  With prophylactic abx, antifungals & immunosuppressive tx Now only 1% or less  Graft Rejection     <60 yo  Infections  Complications Early:    Potentially life threatening Main complication in first 30 days CMV infections have high mortality (so prophylaxis and early intervention important) Immune function takes 1 year (autologous) to 2 years (allogeneic) to fully recover Later opportunistic infections common, including pneumocystis carinii (PCP) and herpes zoster Prophylaxis required for 6-12 months  Late:    Complications (Con’d)  GVHD    Allogeneic complication Donor T cell response against recipient tissue cells Prophylaxis against GVHD begins day +1 with immunosuppressive agents  Cyclosporine, methotrexate, mycophenelate Skin, GI (especially diarrhea) or obstructive Liver dysfunction >60% develop Autoimmune manifestations of Skin especially, as well as GI, Liver and Lung 30-40% develop  Acute GVHD first 3-6 months:    Chronic GVHD develops 12-18 months post transplant:    Complications (Con’d) Veno-Occlusive Disease (VOD) Obstructive liver disease due to microthrombi in liver venules  Patients with previous liver disease at greater risk  No good treatments   Graft Rejection  Rare in present day (<1%)   Much improved due to opportunistic infection and GVHD prophylaxis TRM:   Mortality Autologous: <1% Allogeneic:  Matched Related: 5-10%  20%+ 10-15 yrs ago Mini-transplants proving to decrease TRM substantially Recent data shows comparable TRM for mini-MUD and full MRD transplants (5-10%)  Matched Unrelated or Mismatched: 20-30%   Treatments  Autologous Transplants: Non-Hodgkins Lymphoma  High Grade diseases  Salvage for relapsed DLBCL disease  60-65% LT survivals  Upfront for aggressive T-cell lymphomas  Hodgkins Disease  Salvage for relapsed or residual disease  Multiple Myeloma  First line therapy < 65 yo  Improves survival from 3 to 5-6 years  Treatments  Allogeneic Transplants (Matched Related)  Acute Myeloid Leukemia (AML)    All intermediate or high risk patients < 60 yo 75% cure for non-high risk patients 50-60% cure for higher risk patients  Acute Lymphoblastic Leukemia (ALL)   All patients < 60 yo Disappointing results with LT survivals 30-40% Controversial now with Gleevec 75-85% LT survival/cure for Chronic Phase CML  Chronic Myeloid Leukemia (?)    Allogeneic Transplants (con’d)  Myeodysplastic Syndrome  1-8 yr survival (depending on stage)  Pre-leukemic  No good treatments at all  alloBMT for ALL pts < 60 with match sibling  Aplastic Anemia  <20 yo highly successful, poor for >40yo  Consider for 20-40 yo with match sibling (less success)  Overall consider alloBMT for all patients up to age of 40 with match sibling Allogeneic Transplants (con’d)  Refractory Low Grade Non-Hodgkins Lymphomas  NO cure for these lymphomas  Disease may be controlled with chemo regimens for significant period of time  CLL, Follicular, Mantle Cell, etc  <60 yo with matched related donor: 50-60% LT CR  Transplant unresponsive or progressive symptomatic refractory disease Allogeneic Transplants (con’d)  Non-Malignant Diseases  Severe Autoimmune Diseases  Lupus, Crohn’s, MS  Severe Thalassemias  Severe Sickle Cell Anemias  Future Developments in BMT Minor MHC control    Minor HLA Ag’s responsible for GVL & GVHD Recent evidence beginning to characterize HA-2 linked to GVHD and HA-1 associated with decreased leukemic relapse or GVL Th1 T-cells and NK cells appear to be responsible for GVL whereas Th2 and CD8 cytotoxic T-cells with GVHD Specific cytokines now identified that initiate both immune pathways  Immune Modulation   Hematopoietic Stem Cells   All hematopoietic cells derived from this small population of primitive cells: Unlimited Self Renewal    High self-renewal capacity Give rise to identical daughter stem cells CD 34+ve cell surface marker Able to differentiate into committed progenitor cells Capacity to give rise to all lineages of blood cells Acquisition of specific growth factor receptors Myeloid Progenitor stem cell: committed progenitor of RBCs, WBCs and PLTs Lymphoid Progenitor stem cell: committed progenitor of B and T cell lymphocytes  Pluripotent / multipotential      Stem Cells and Transplantation  Rationale  High dose chemo/radiation rescue     A dose-response effect has been shown for many cancers ie: doubling of certain chemo agents may increase the cell kill by a factor of 10 Dose-intense treatment may improve response rates or result in cures, even those that have failed conventional doses of chemo Profound myeloablation would result in death without hematopoietic stem cell rescue  Actual killing of cancer cells by donor stem cell progenitors: Graft versus Tumor Effect   Donor immune cells attack recipient malignant cells Recognize recipient malignant cells as “foreign” Embryonic Stem Cells: Pluripotent Cells  Fertilization triggers first cell division of the embryo  At the 8-cell stage, the embryonic genome undergoes activation     The blastocyst includes the Inner Cell Mass (ICM), a small cluster of cells destined to give rise to all the tissues of the body  stage when embryonic stem cells are isolated ICM cells are pluripotent not totipotent  Can give rise to ALL tissue cells but NOT a new individual under appropriate support The yolk sac: lies closely apposed to the stem cells and plays a key role in dictating cell fate = commitment Commitment events gradually result in loss of pluripotentiality of most cells Pluripotent Stem Cell Definition:    Can undergo multiple self-renewing cell divisions (sustains the population) Single stem cell derived daughter cells differentiate into more than one cell type   HSC’s:myeloid,lymphoid Neural SCs: neurons,astrocytes,oligodendrocytes  Functionally repopulate the tissue of origin when transplanted in damaged recipient  HSC,Liver,NSC Therapeutic Potential of Embryonic Stem Cells  ES proliferate indefinitely in culture yet retain their potential to form ALL tissues of the developing organism  In culture ES cells maintain their undifferentiated pristine state    When removed from these conditions they undergo spontaneous differentiation Genes can be altered in ES cells identifying genetic programs responsible for development into blood, neurons, hepatocytes, cardiomyocytes and a host of other tissues Using MEF(mouse embryonic fibroblasts) + anti-differentiation cytokine LIF (leukemia inhibitory factor)  Using ES cells, are now identifying compounds that block or promote cell differentiation  ES as cell replacement therapy for degenerative diseases  Several groups have reported success in differentiating specific neuronal subtypes from mouse and human ES cells   Formed spinal motor neurons that successfully engrafted the embryonic spinal cord of the chick, extended axons, and formed synapses with target muscles In rodent models, improvement of Parkinson’s after transplant of undifferentiated ES cells into the striatum  Type 1 diabetes can be reversed by islet cell transplantation but there is an inadequate supply   Successful differentiation of murine and human ES cells into insulin secreting cells One group showed normalization of hyperglycemia in animal models  Stem cells are thought to be present in most adult tissues    Somatic Adult Stem Cells Responsible for replenishment of those tissues for life Best known are the HSC’s in the bone marrow Other lesser known SC’s in CNS,skin,liver  Somatic SC thought to be restricted in differentiation capacity, only able to generate cells of tissue from which they are derived    Preprogrammed during embryonic development Committed to specific differentiation Most tissues harbor a stem cell population that generally serves to replenish that tissue  Adult Stem Cell Plasticity Multipotential adult stem cells have been found after culture of bone marrow stromal elements   These multipotential adult progenitor cells have been reported to generate MOST cell types in vitro and in vivo after injection into mouse embryo blastocysts These cells have been isolated from both human and mouse bone marrow  Ability of tissue specific adult stem cells to differentiate into cells different from the tissue of origin    Recent published data suggests this, but not confirmed This lineage-switch defies established developmental biology and stem cell principles Tissues include skeletal, liver, cardiac muscle and neuronal     Orlic et al. Bone marrow cells regenerate infarcted myocardium Nature 1999;401:390-394 Jackson K, Majka SM et al. Regeneration of ischemic cardiac muscle and vascular endothelium by adult stem cells Journal of Clin Invest 2001;107:1395-1402 Woodbury D et al. Adult rat and human bone marrow stromal cells differentiate into neurons J Neurosci Res 2000;15: 364-370 Sanchez-Ramos J et al. Adult bone marrow stromal cells differentiate into neural cells in vitro Exp Neurol 2000;164:247-256 Adult (Somatic) Stem Cells  Adult stem cells appear to have greater differentiation potential than previously thought  Recent studies have shown that single cells may differentiate into cells of multiple different tissues   Krause DS et al. Multi-organ, multi-lineage engraftment by a single bone marrow derived stem cell Cell 2001;105:369-377 Schwartz RE et al. Multipotent adult progenitor cells from bone marrow differentiate into functional hepatocyte cells Journal Clin Inv 2002;96:1291-1302  Several in vitro studies have demonstrated that cells that apparently switch lineage acquire not only phenotypic but also functional characteristics of the new cell type Adult (Somatic) Stem Cells   If studies indicating that adult stem cells have greater differentiation potential can be confirmed and extended, adult stem cells, like their embryonic counterparts, may be used to treat degenerative or genetic disorders of many organs Whether they have the same longevity and in vivo functional differentiation potential as ES cells still needs to be proven in studies comparing both cell sources side by side    Queens University will soon have its second stem cell separator It is opening a stem cell research lab It will soon begin a bone marrow and stem cell transplant program  First stem cell transplant planned for this year