Allogeneic transplantation using non-myeloablative transplant regimens

Recombinant Pregnancy-Specific Glycoprotein 1 Has a Protective Role in a Murine Model of Acute Graft-versus-Host Disease

Acute graft-versus-host disease (aGVHD) is an immune-mediated reaction that can occur after hematopoietic stem cell transplantation in which donor T cells recognize the host antigens as foreign, destroying host tissues. Establishment of a tolerogenic immune environment while preserving the immune response to infectious agents is required for successful bone marrow transplantation. Pregnancy-specific glycoprotein 1 (PSG1), which is secreted by the human placenta into the maternal circulation throughout pregnancy, likely plays a role in maintaining immunotolerance to prevent rejection of the fetus by the maternal immune system. We have previously shown that PSG1 activates the latent form of transforming growth factor β1 (TGF-β), a cytokine essential for the differentiation of tolerance-inducing CD4⁺FoxP3⁺ regulatory T cells (Tregs). Consistent with this observation, treatment of naïve murine T cells with PSG1 resulted in a significant increase in FoxP3⁺ cells that was blocked by a TGF-β receptor I inhibitor. We also show here that PSG1 can increase the availability of active TGF-β in vivo. As the role of CD4⁺FoxP3⁺ cells in the prevention of aGVHD is well established, we tested whether PSG1 has beneficial effects in a murine aGHVD transplantation model. PSG1-treated mice had reduced numbers of tissue-infiltrating inflammatory CD3⁺ T cells and had increased expression of FoxP3 in T cells compared with vehicle-treated mice. In addition, administration of PSG1 significantly inhibited aGVHD-associated weight loss and mortality. On the other hand, administration of PSG1 was less effective in managing aGVHD in the presence of an alloimmune reaction against a malignancy in a graft-versus-leukemia experimental model. Combined, this data strongly suggests that PSG1 could be a promising treatment option for patients with aGVHD following bone marrow transplantation for a nonmalignant condition, such as an autoimmune disorder or a genetic immunodeficiency.

The administration of polymerized human hemoglobin (pyridoxylated) to a jehovah's witness after submyeloablative stem cell transplantation complicated by delayed graft failure

A 55-yr-old woman with a history of B-cell lymphoma of the nasopharynx diagnosed in March 1999 eventually underwent submyeloablative allogeneic stem cell transplantation from a sibling donor in December 2002 after conventional treatment options were exhausted. The treatment approach was somewhat altered by the fact that the patient was a practicing Jehovah's Witness and refused blood-blood product transfusion. The course of her treatment was unremarkable until around day 100 posttransplant when she developed graft failure, leading to severe anemia. Blood transfusions were refused. Donor cells were re-infused. During this treatment period, the patient's hemoglobin dropped to a low of 2.7 g/dL, with the patient experiencing severe fatigue, dyspnea on exertion, headaches, and blurred vision. Polymerized human hemoglobin (pyridoxylated) (Poly- Heme, Northfield Laboratories Inc., Evanston, IL) was given under an emergency, compassionate use protocol and successfully bridged the patient's hemoglobin and relieved symptoms during her marrow recovery period.

Low incidence and severity of graft-versus-host disease after outpatient allogeneic peripheral blood stem cell transplantation employing a reduced-intensity conditioning

BACKGROUND

The prevalence and features of graft-versus-host disease (GVHD) in patients receiving allografts using peripheral blood stem cells (PBSCs) after a reduced-intensity conditioning (RIC) regimen are not well known. Several features of GVHD in patients at two institutions using RIC were assessed.

METHODS

We analysed the overall survival (OS) and prevalence of GVHD in patients who underwent outpatient allogeneic PBSC transplantation after RIC between October 1998 and July 2008.

RESULTS

We included 301 patients with a median age of 30 yrs (range, 1-71 yrs). In 37 cases, allogeneic peripheral blood stem cell transplantation was indicated for non-malignant disease, and in 264 for malignant disease. The median OS was 35 months. The estimated 3-yr OS was 48%. A total of 154 patients developed GVHD: there were 64 acute, 50 chronic and 40 cases that progressed from acute to chronic. Of the 104 patients with acute GVHD (aGVHD), 40% had grade I and 60% had grades II-IV. Of the 90 patients with chronic GVHD (cGVHD), 67% had limited and 33% had extensive forms. A total of 160 patients died, 40 as a result of GVHD (24 from aGVHD and 16 from cGVHD), 50 as a result of progressive disease and 70 from diverse causes.

CONCLUSIONS

The incidence of GVHD was lower than in other series using conventional myeloablative preparative regimens. Most importantly, the severity of GVHD did not significantly affect the long-term survival.

Vaccination strategies in lymphomas and leukaemias: recent progress

The successful identification of a range of leukaemia-specific and lymphoma-specific antigens in recent years has stimulated efforts to develop therapeutic vaccination strategies. A number of clinical trials have established the safety and immunogenicity of vaccination against tumour antigens, although there are limited data on the clinical efficacy of this approach in haematological malignancies. After encouraging results of phase I/II trials using idiotype vaccines in lymphoma, the outcome of the three phase III trials has been somewhat disappointing. Several other promising strategies are currently being developed to improve these results, including optimization of antigen delivery. In myeloid leukaemias, clinical trials of vaccination with peptides derived from a number of leukaemia antigens, including WT1, PR1, RHAMM and BCR-ABL, have shown evidence of immunogenicity, but limited data are available on the clinical efficacy of this approach. In this review, we focus on the results of clinical trials of vaccination in leukaemia and lymphoma, and discuss potential strategies to enhance the efficacy of immunotherapy in the future.

Non-myeloablative allogeneic hematopoietic stem cell transplantation

OBJECTIVE

To review the literature related to nonmyeloablative stem cell transplantation (SCT), and the unique characteristics and patient population to which it applies.

DATA SOURCES

Research studies, research and clinical reviews, clinical experience.

CONCLUSION

Nonmyeloablative SCT has demonstrated effective and safe application in a heterogeneous population not otherwise eligible for an allogeneic transplantation. Although many principles are based on those of conventional myeloablative transplantation, the engraftment kinetics, patient selection, and regimen-related complications are distinct.

IMPLICATIONS FOR NURSING PRACTICE

Nurses must be knowledgeable about nonmyeloablative SCT, including the provision of individualized care for a heterogeneous population. This can include non-traditional transplant indications, elderly cancer patients, and those with comorbidities.

Immune deficits in allogeneic hematopoietic stem cell transplant (HSCT) recipients

Immune deficits account for the high frequency of life threatening bacterial, viral, and fungal opportunistic infections seen in allogeneic HSCT recipients. Despite advances in infectious disease management, the integrity of host defenses remains the mainstay of defense. The intensity of the preparative regimen, degree of HLA matching, source of stem cells (marrow, blood, or cord), extent of T-cell depletion, and immunosuppressive therapy are some of the factors that impact the kinetics, characteristics, and quality of immune reconstitution. Graft-versus-host disease and its prophylaxis or treatment produce a host environment that is particularly vulnerable to infections. Mucosal disruption and prolonged severe neutropenia usually confine their impact to the early course of transplant. After initial engraftment, HSCT recipients remain at great risk for opportunistic infections and this is related to prolonged and severe T-lymphocyte dysfunction of a complex multifactorial nature. B cell dysfunction is less problematic clinically, but includes deficiencies of immunoglobulin subclasses and impaired ability to mount a vaccine response. Advances in understanding of these immune deficits have resulted in successful strategies including revaccination, growth factors, thymic protection, and adoptive cellular therapy with antigen-specific cells.

Chimerism in the immunohematology laboratory in the molecular biology era

Dual or multiple cell populations, induced by chimeras, have been the subject of many studies. This long-standing fascination with chimeras has revealed a good deal of knowledge about human inheritance. Although historically most chimeras were caused by natural events, certain current medical intervention therapies are increasing the number of situations that can lead to a mixed cell population, that is, the chimeric condition, in humans. Medical therapies such as transfusion, stem cell transplantation, kidney transplantation, and artificial insemination induce temporary and sometimes permanent chimeras. Such natural or therapeutically induced presentations of chimerism can present challenging issues to the clinical immunohematology laboratory with regard to interpretation of results and subsequent patient management. The purpose of this review was to highlight some of these chimeric states and hypothesize how testing DNA from various tissues can cause apparent discrepancies between phenotype and genotype results.

Health-related quality of life in patients receiving reduced-intensity conditioning allogeneic hematopoietic stem cell transplantation

Reduced-intensity conditioning allogeneic HSCT (RIC) has less regimen-related morbidity and mortality than myeloablative allogeneic HSCT (MT) offering allogeneic transplantation to patients otherwise excluded. Whether these advantages improve health-related quality of life (HRQL) is unknown. We examined the HRQL effects of RIC and MT in patients with hematological diseases pre-transplant (baseline), days 0, 30, 100, 1 and 2 years following HSCT. HRQL was measured using the Short Form-36 Health Survey and the Functional Assessment of Cancer Therapy - General and BMT. Data were analyzed using mixed linear modeling adjusting for baseline HRQL differences. Patients (RIC=41, MT=35) were predominately male (67%), in remission/stable disease (65%) with an Eastern Cooperative Oncology Group status <or=1 (97%). HRQL progressively improved (P<0.01) in both groups with higher scores at day 100 compared to days 0 and 30; there was no difference between groups during early recovery. At 2 years, all survivors (n=43) reported HRQL similar or better than baseline. Results suggest RIC and MT patients experience a similar pattern of HRQL improvement during early recovery. Two-year survivors report a return to baseline or better in HRQL by day 100, with the exception of physical health in MT patients.

Nonmyeloablative alternative donor transplants

The advent of nonmyeloablative preparative regimens and the expected lower regimen-related toxicities associated with them hold significant promise for extension of the use of allogeneic hematopoietic stem cell transplantation. Nonmyeloablative hematopoietic stem cell transplantation using human leukocyte antigen matched sibling donor, which carries a relatively low risk of transplant-related complications and can result in impressive antitumor responses, may benefit older patients and patients with preexisting organ impairment. However, more than 65% of patients in need of this procedure lack a human leukocyte antigen matched sibling donor. Therefore, attention has focused on alternative donors such as genotypically matched unrelated donors and partially mismatched related donors. Early clinical results suggest that the use of alternative donors is feasible, therefore potentially allowing full extension of the benefits of allografting to the group of patients in highest need.

New Developments in Allotransplant Immunology

After allogeneic stem cell transplantation, the establishment of the donor’s immune system in an antigenically distinct recipient confers a therapeutic graft-versus-malignancy effect, but also causes graft-versus-host disease (GVHD) and protracted immune dysfunction. In the last decade, a molecular-level description of alloimmune interactions and the process of immune recovery leading to tolerance has emerged. Here, new developments in understanding alloresponses, genetic factors that modify them, and strategies to control immune reconstitution are described.

In Section I, Dr. John Barrett and colleagues describe the cellular and molecular basis of the alloresponse and the mechanisms underlying the three major outcomes of engraftment, GVHD and the graft-versus-leukemia (GVL) effect. Increasing knowledge of leukemia-restricted antigens suggests ways to separate GVHD and GVL. Recent findings highlight a central role of hematopoietic-derived antigen-presenting cells in the initiation of GVHD and distinct properties of natural killer (NK) cell alloreactivity in engraftment and GVL that are of therapeutic importance. Finally, a detailed map of cellular immune recovery post-transplant is emerging which highlights the importance of post-thymic lymphocytes in determining outcome in the critical first few months following stem cell transplantation. Factors that modify immune reconstitution include immunosuppression, GVHD, the cytokine milieu and poorly-defined homeostatic mechanisms which encourage irregular T cell expansions driven by immunodominant T cell–antigen interactions.

In Section II, Prof. Anne Dickinson and colleagues describe genetic polymorphisms outside the human leukocyte antigen (HLA) system that determine the nature of immune reconstitution after allogeneic stem cell transplantation (SCT) and thereby affect transplant outcomethrough GVHD, GVL, and transplant-related mortality. Polymorphisms in cytokine gene promotors and other less characterized genes affect the cytokine milieu of the recipient and the immune reactivity of the donor. Some cytokine gene polymorphisms are significantly associated with transplant outcome. Other non-HLA genes strongly affecting alloresponses code for minor histocompatibility antigens (mHA). Differences between donor and recipient mHA cause GVHD or GVL reactions or graft rejection. Both cytokine gene polymorphisms (CGP) and mHA differences resulting on donor-recipient incompatibilities can be jointly assessed in the skin explant assay as a functional way to select the most suitable donor or the best transplant approach for the recipient.

In Section III, Dr. Nelson Chao describes non-pharmaceutical techniques to control immune reconstitution post-transplant. T cells stimulated by host alloantigens can be distinguished from resting T cells by the expression of a variety of activation markers (IL-2 receptor, FAS, CD69, CD71) and by an increased photosensitivity to rhodamine dyes. These differences form the basis for eliminating GVHD-reactive T cells in vitro while conserving GVL and anti-viral immunity. Other attempts to control immune reactions post-transplant include the insertion of suicide genes into the transplanted T cells for effective termination of GVHD reactions, the removal of CD62 ligand expressing cells, and the modulation of T cell reactivity by favoring Th2, Tc2 lymphocyte subset expansion. These technologies could eliminate GVHD while preserving T cell responses to leukemia and reactivating viruses.