Non-myeloablative transplantation

Very early lineage-specific chimerism after reduced intensity stem cell transplantation is highly predictive of clinical outcome for patients with myeloid disease

BACKGROUND

The importance of chimerism status in the very early period after hematopoietic stem cell transplantation is unclear. We determined PBMC and T-cell donor chimerism 50 days after transplantation and related this to disease relapse and overall survival.

METHODS

144 sequential patients underwent transplantation of which 90 had AML/MDS and 54 had lymphoma. 'Full donor chimerism' was defined as ≥99% donor cells and three patient groups were defined: 40% with full donor chimerism (FC) in both PBMC and T-cells; 25% with mixed chimerism (MC) within both compartments and 35% with 'split' chimerism (SC) characterised by full donor chimerism within PBMC and mixed chimerism within T-cells.

RESULTS

In patients with myeloid disease a pattern of mixed chimerism (MC) was associated with a one year relapse rate of 45% and a five year overall survival of 40% compared to values of 8% and 75%, and 17% and 60%, for those with SC or FC respectively. The pattern of chimerism had no impact on clinical outcome for lymphoma.

CONCLUSION

The pattern of lineage-specific chimerism at 50 days after transplantation is highly predictive of clinical outcome for patients with myeloid malignancy and may help to guide subsequent clinical management.

Clonal-level lineage commitment pathways of hematopoietic stem cells in vivo

While the aggregate differentiation of the hematopoietic stem cell (HSC) population has been extensively studied, little is known about the lineage commitment process of individual HSC clones. Here, we provide lineage commitment maps of HSC clones under homeostasis and after perturbations of the endogenous hematopoietic system. Under homeostasis, all donor-derived HSC clones regenerate blood homogeneously throughout all measured stages and lineages of hematopoiesis. In contrast, after the hematopoietic system has been perturbed by irradiation or by an antagonistic anti-ckit antibody, only a small fraction of donor-derived HSC clones differentiate. Some of these clones dominantly expand and exhibit lineage bias. We identified the cellular origins of clonal dominance and lineage bias and uncovered the lineage commitment pathways that lead HSC clones to different levels of self-renewal and blood production under various transplantation conditions. This study reveals surprising alterations in HSC fate decisions directed by conditioning and identifies the key hematopoiesis stages that may be manipulated to control blood production and balance.

The hematopoietic system in the context of regenerative medicine

Hematopoietic stem cells (HSC) represent the prototype stem cell within the body. Since their discovery, HSC have been the focus of intensive research, and have proven invaluable clinically to restore hematopoiesis following inadvertent radiation exposure and following radio/chemotherapy to eliminate hematologic tumors. While they were originally discovered in the bone marrow, HSC can also be isolated from umbilical cord blood and can be "mobilized" peripheral blood, making them readily available in relatively large quantities. While their ability to repopulate the entire hematopoietic system would already guarantee HSC a valuable place in regenerative medicine, the finding that hematopoietic chimerism can induce immunological tolerance to solid organs and correct autoimmune diseases has dramatically broadened their clinical utility. The demonstration that these cells, through a variety of mechanisms, can also promote repair/regeneration of non-hematopoietic tissues as diverse as liver, heart, and brain has further increased their clinical value. The goal of this review is to provide the reader with a brief glimpse into the remarkable potential HSC possess, and to highlight their tremendous value as therapeutics in regenerative medicine.

Non-myeloablative allogeneic hematopoietic transplantation for patients with hematologic malignancies: 9-year single-centre experience

Matched related and unrelated allogeneic nonmyeloablative hematopoietic transplantation (nmt) is increasingly being used in patients with hematologic malignancies. Conditioning regimens and indications for nmt vary considerably from centre to centre. Our institution uses intravenous fludarabine and cyclophosphamide, plus graft-versus-host disease (gvhd) prophylaxis with tacrolimus and mycophenolate mofetil. We retrospectively analyzed 89 consecutive patients who underwent nmt (65 related, 24 unrelated) at our institution from October 2002 to September 2011. The most frequent indications for nmt were acute myelocytic leukemia (high-risk in first complete or subsequent remission: n = 20, 22.5%) and relapsed follicular lymphoma (n = 18, 20.2%). The cumulative incidence of acute gvhd (grades 2-4) was 28.1% (n = 25), and rates were similar for related (n = 18, 28%) and unrelated (n = 7, 29%) nmt. At a median follow-up of 22.6 months, the cumulative incidence of chronic gvhd (limited and extensive) was 68% (n = 61): 68.5% (n = 44) for related and 71% (n = 17) for unrelated nmt. The 100-day transplant-related mortality rate was 2.2%: 1.5% for related and 4.2% for unrelated nmt. Of the 89 patients, 30 (33.7%) have relapsed: 41.5% after related and 12.5% after unrelated nmt. Relapse rates were similar in patients with myeloid and lymphoid malignancies (36.4% vs. 33.3%). The 3-year overall and progression-free survival rates were 50.0% and 43.4% respectively, with multivariate analysis showing that neither rate was affected by age, disease group, status at transplantation, or related compared with unrelated nmt. Our findings indicate that, despite its limitations, including the incidence of chronic gvhd, nmt is an important treatment modality for a selected subgroup of patients with hematologic malignancies.

The outlook for alemtuzumab in multiple sclerosis

Alemtuzumab is a humanized anti-CD52 monoclonal antibody. Treatment in humans results in a rapid, profound, and prolonged B- and T-cell lymphopenia. Subsequently, lymphocyte reconstitution by homeostatic mechanisms alters the composition, phenotype, and function of T-cell subsets, thus allowing the immune system to be 'reset'. One phase II and two phase III randomized, multicenter, single-blinded (outcomes assessor) clinical trials of alemtuzumab in relapsing-remitting multiple sclerosis have now been completed. Against an active comparator and the current first-line therapy for relapsing-remitting multiple sclerosis (interferon-beta), alemtuzumab showed a significant reduction in annualized relapse rate as well as a significant reduction in the accumulation of disability. These outcomes are sustained over at least 5 years following treatment. The most common adverse effects are mild infusion reactions, an increased incidence of mild-to-moderate severity infections and secondary autoimmunity. The latter is observed in a third of treated patients, commonly thyroid disease but other target cells have been described including cytopenias. Marketing authorization applications have been submitted for the use of alemtuzumab in multiple sclerosis to the Food and Drug Administration and the European Medicines Agency, with licensing expected in 2013. Here, we discuss the outlook for alemtuzumab in multiple sclerosis in light of the currently available therapies, outcomes of and lessons learnt from clinical trials, and the overall position of monoclonal antibodies in modern treatment strategies.

Post-transplant T cell chimerism predicts graft versus host disease but not disease relapse in patients undergoing an alemtuzumab based reduced intensity conditioned allogeneic transplant

In this multicentre retrospective study we have studied the impact of T cell chimerism on the outcome of 133 patients undergoing an alemtuzumab based reduced intensity conditioning allograft (RIC). The median age of the patients was 50 years (range 42-55 years). 77 patients were transplanted using an HLA identical sibling donor while 56 patients received a fully matched volunteer unrelated donor graft. 64 patients had a lymphoid malignancy and 69 were transplanted for a myeloid malignancy. 38 patients (29%) relapsed with no significant difference in risk of relapse between patients developing full donor and mixed donor chimerism in the T-cell compartment on D+90 and D+180 post transplant. Day 90 full donor T cell chimerism correlated with an increased incidence of acute GVHD according to NIH criteria (p=0.0004) and the subsequent development of chronic GVHD. Consistent with previous observations, our results confirmed a correlation between the establishment of T cell full donor chimerism and acute GVHD in T deplete RIC allografts. However our study failed to identify any correlation between T cell chimerism and relapse risk and challenge the use of pre-emptive donor lymphocyte infusions (DLI) in patients with mixed T cell chimerism transplanted using an alemtuzumab based RIC regimen.

Hematopoietic stem cell transplantation for chronic lymphocytic leukemia

PURPOSE OF REVIEW

Although hematopoietic stem cell transplantation (HSCT) is the treatment of choice for many aggressive hematologic malignancies, the role of HSCT in chronic lymphocytic leukemia (CLL) has remained controversial. Now in the era of improved conventional treatment and better prognostication of long-term outcome, a review of autologous and allogeneic HSCT in CLL treatment is warranted.

RECENT FINDINGS

Despite an improved disease-free survival in some patients, multiple, prospective, randomized autologous HSCT CLL trials fail to demonstrate an overall survival benefit as compared to conventional therapy. Allogeneic bone marrow transplantation, although limited by donor availability, can successfully eradicate CLL with adverse prognostic features. In the older CLL patients, nonmyeloablative allogeneic transplants are better tolerated than myeloablative transplants. Nonmyeloablative allogeneic transplants are less effective in heavily diseased burdened patients.

SUMMARY

Outside of a clinical protocol, autologous HSCT for CLL cannot be justified. Nonmyeloablative allogeneic transplantation should be considered in high-risk populations early in the disease process, when disease burden is most easily controlled. Alternative donor selection using haploidentical donors and posttransplantation cyclophosphamide has the potential to vastly increase the availability of curative therapy in CLL while retaining a low treatment-related toxicity.

Purified hematopoietic stem cell transplantation: the next generation of blood and immune replacement

Replacement of disease-causing stem cells with healthy ones has been achieved clinically via hematopoietic cell transplantation (HCT) for the last 40 years, as a treatment modality for a variety of cancers and immunodeficiencies with moderate, but increasing, success. This procedure has traditionally included transplantation of mixed hematopoietic populations that include hematopoietic stem cells (HSC) and other cells, such as T cells. This article explores and delineates the potential expansion of this technique to treat a variety of inherited diseases of immune function, the current barriers in HCT and pure HSC transplantation, and the up-and-coming strategies to combat these obstacles.

Purified hematopoietic stem cell transplantation: the next generation of blood and immune replacement

Replacement of disease-causing stem cells with healthy ones has been achieved clinically via hematopoietic cell transplantation (HCT) for the last 40 years, as a treatment modality for a variety of cancers and immunodeficiencies with moderate, but increasing, success. This procedure has traditionally included transplantation of mixed hematopoietic populations that include hematopoietic stem cells (HSC) and other cells, such as T cells. This article explores and delineates the potential expansion of this technique to treat a variety of inherited diseases of immune function, the current barriers in HCT and pure HSC transplantation, and the up-and-coming strategies to combat these obstacles.

Correlation of pretransplant and early post-transplant response assessment with outcomes after reduced-intensity allogeneic hematopoietic stem cell transplantation for non-Hodgkin's lymphoma

BACKGROUND

Chemotherapy sensitivity, defined simply as at least a partial response to chemotherapy, is an important outcome predictor for non-Hodgkin lymphoma (NHL) patients undergoing reduced-intensity allogeneic hematopoietic stem cell transplantation (allo-HCT). The authors hypothesized that further differentiation of chemotherapy sensitivity by specific response, complete remission (CR) versus partial remission (PR) versus stable disease (SD) versus progression of disease (PD), correlates with post-transplant outcomes.

METHODS

The impact of pretransplant and early (28 days) post-transplant disease response on transplant outcomes was analyzed in 63 NHL patients treated with reduced-intensity allo-HCT.

RESULTS

The 3-year event-free survival (EFS) and overall survival (OS) (median potential follow-up after reduced-intensity allo-HCT = 58 months) for all patients was 37% and 47%, respectively. The 3-year EFS based on pretransplant response was: CR = 50%; PR = 66%; SD = 18%; no patient with PD pretransplant reached 3-year follow-up. The 3-year OS based on pretransplant response was: CR = 63%; PR = 69%; SD = 45%. The 3-year EFS based on post-transplant response was: CR = 57%; PR = 32%; SD = 33%; no patient with PD post-transplant reached 3-year follow-up. The 3-year OS based on post-transplant response was: CR = 65%; PR = 43%; SD = 50%. In multivariate analyses, pretransplant response was the best predictor of EFS (P < .0001). Pretransplant response (P < .0001) and age (P = .0035) were jointly associated with OS.

CONCLUSIONS

These data suggest that NHL patients with pretransplant SD, generally considered inappropriate candidates, may benefit from reduced-intensity allo-HCT, and patients with pretransplant PD should only receive this therapy in clinical trials.

[Prospective evaluation of the efficacy of the combination of budesonide/formoterol in obstructive airway disease after allogeneic hematopoietic stem cell transplantation]

État des connaissances

La survenue d’un trouble ventilatoire obstructif au décours d’une allogreffe de cellules souches hématopoïétiques est attribuée à une réaction de greffon contre l’hôte pulmonaire et menace le pronostic des patients. La prise en charge thérapeutique consiste habituellement en une intensification du traitement immunosuppresseur systémique. Cette attitude non validée entraîne de nombreuses complications, notamment infectieuses, encourageant l’évaluation de traitements plus ciblés. Nous avons récemment rapporté de façon rétrospective notre expérience de l’efficacité du budésonide/ formotérol inhalés dans cette pathologie.

Méthodes

Il s’agit d’une étude prospective, multicentrique, randomisée, en double aveugle contre placebo qui évaluera l’efficacité de l’association budésonide/formotérol (400/12 µg 2 inhalations matin et soir) chez des patients ayant développé un trouble ventilatoire obstructif modéré à sévère après allogreffe de cellules souches hématopoïétiques. Le critère d’évaluation principal sera la variation absolue du VEMS après 1 mois de traitement. Les critères d’évaluation secondaires seront basés sur l’évolution de la symptomatologie clinique et de la fonction respiratoire après 6 mois de traitement.

Résultats attendus

L’hypothèse émise est que le traitement inhalé de budésonide/formotérol améliore de façon significative la fonction et les symptômes respiratoires dès le premier mois de traitement dans le groupe de patients étudié.

Epstein-Barr virus-associated enteritis with multiple ulcers after stem cell transplantation: first histologically confirmed case

The present case involves unique enteritis forming multiple ulcers associated with Epstein-Barr virus (EBV). A 57-year-old man had undergone a reduced intensity allogeneic stem cell transplantation for a relapse of multiple myeloma following sequential autologous peripheral blood stem cell transplantation. The ileum, resected for massive melena, showed multiple irregular ulcers with occasional cobblestone-like appearance. There was inflammation including numerous plasma cells in the ulcer bases and surrounding areas, where many EBV-infected plasma cells were detected by double staining with EBV-encoded small RNA-1 (EBER-1) in situ hybridization and CD79a, while EBV-infected epithelial cells were not noted. The number of EBER-1-positive cells in the ileum (mucosa, 1451 cells/mm(2); submucosa, 465 cells/mm(2)) was much larger than in control samples (malignant lymphoma or leukemia after allogeneic stem cell transplantation, n = 4, range 0-113 cells/mm(2); malignant lymphoma after chemotherapy, n = 14, range 0-0.89 cells/mm(2); colon cancer, n = 12, range 0-3.5 cells/mm(2)). In the mucosa near the ulcers, EBER-1-positive cells often surrounded and involved the glandular epithelium, forming lymphoepithelial-like lesions. The histological findings differ from post-transplant lymphoproliferative disorders or intestinal thrombotic microangiopathy, and this is the first case of EBV-associated enteritis with ulcers characterized by numerous plasma cells and lymphoepithelial-like lesions after stem cell transplantation.

Clonality analysis by sequence variation of the latent membrane protein 1 gene in patients with chronic active Epstein-Barr virus infection

Chronic active Epstein-Barr virus (EBV) infection is a severe systemic disease associated with high rates of mortality and morbidity. Recent studies suggest that the clonal expansion of EBV-infected T or natural killer cells plays a crucial role in the pathogenesis of chronic active EBV infection. However, it is not clear whether chronic active EBV infection is truly a monoclonal disorder that originates from one cell. The clonality of EBV was investigated by sequence variation of the latent membrane protein 1 (LMP1) gene, which has a high degree of sequence heterogeneity. Peripheral blood mononuclear cells were obtained from nine Japanese patients with chronic active EBV infection and four with infectious mononucleosis. A carboxyl-terminal region of the LMP1 gene was analyzed by polymerase chain reaction (PCR). The amplified PCR products were subcloned, and 18 clones from each sample were sequenced. Patients with chronic active EBV infection each had two to five different LMP1 nucleotide sequences, whereas patients with infectious mononucleosis each had one to seven different sequences. Patients with chronic active EBV infection and infectious mononucleosis both had one dominant sequence. Longitudinal analysis was performed in four patients with chronic active EBV infection, in whom the dominant strains were found to have remained unchanged for several years. The results suggest that EBV in patients with chronic active EBV infection was polyclonal, although clonal expansion may occur. Collectively, these findings are critical to clarify further the pathogenesis of chronic active EBV infection and aid in the development of effective treatment strategies.

The Role of Alemtuzumab in Nonmyeloablative Hematopoietic Transplantation

Nonmyeloablative stem cell transplants provide a viable therapeutic option for older patients or patients with comorbid conditions, who were previously deemed to be ineligible for transplantation. Despite improvements in clinical outcomes, graft-versus-host disease (GVHD) remains a significant and potentially lethal complication. One approach by which GVHD has been managed is through introduction of new agents, such as alemtuzumab, into the conditioning regimen. Alemtuzumab is a humanized monoclonal antibody that targets the CD52 antigen, which is highly expressed on both B and T lymphocytes. By depleting T cells in both the donor and the recipient, alemtuzumab has been shown to prevent development of both acute and chronic GVHD, without inhibiting the benefits associated with the graft-versus-leukemia effect. Clinical trials have shown that alemtuzumab is able to decrease the incidence of acute and chronic GVHD without impairing engraftment. Furthermore, in chronic lymphocytic leukemia therapy, alemtuzumab has been shown to purge malignant cells from the host to allow for harvesting for the purpose of autologous transplantation. Despite results showing that alemtuzumab can play an important role in managing GVHD, little information is available regarding a standardized dosing schedule. Greater insight into alemtuzumab's pharmacokinetic activity would assist in developing a schedule that can optimize alemtuzumab-mediated T-cell depletion to prevent GVHD, while retaining sufficient host T-cell activity to encourage the graft-versus-leukemia effect and prevent relapse.

Alemtuzumab, fludarabine and melphalan as a conditioning therapy in severe aplastic anemia and hypoplastic myelodysplastic syndrome--single center experience

BACKGROUND

Allogeneic hematopoietic stem cell transplantation is the treatment of choice in young patients with severe aplastic anemia. The main causes of failure after this procedure are graft versus host disease, infections and graft failure, often exacerbated by large numbers of transfusions and prolonged disease duration before transplant.

METHODS

We report the results of allografting following conditioning with fludarabine, alemtuzumab and melphalan in: five patients with severe aplastic anemia and one with hypoplastic myelodysplastic syndrome. All patients had matched sibling donors. Source of hematopoietic stem cell was: bone marrow-2, blood-3, bone marrow and blood-1. The age of recipients was 18-26 years. Four patients received their graft as the first line therapy and two after failure of cyclosporine and antithymocyte globulin treatment. Number of transfused units including red blood cells and platelets before transplantation was 8-100 (median: 22) and 10-32 (median: 11), respectively. All donors and recipients were CMV-seropositive. Conditioning consisted of: alemtuzumab 30 mg/d (day -7 to -5), fludarabine 30 mg/m(2) (days -7 to -3) and melphalan 140 mg/m(2) at the day -2.

RESULTS

The time to granulocytes and platelets recovery was 15 and 25 days, respectively. All patients achieved full donor chimerism on day +60. Only two patients needed ganciclovir as preemptive therapy. Recurrent parvovirus B19 infection with pure red cell aplasia and acute viral B hepatitis was observed in one case. Pure red cell aplasia was successfully treated with immunoglobulins and cyclosporine discontinuation. With a follow-up of 16-39 (median: 29) months all patients are alive, and neither graft failure nor graft versus host disease, or any no other severe complications, was observed.

CONCLUSIONS

Our study suggests that transplantation of hematopoietic stem cell using alemtuzumab, fludarabine and melphalan as a conditioning therapy is safe, inexpensive and effective treatment for patients with severe aplastic anemia, including multi-transfused adults having their disease for a long time.

Hematopoietic stem and progenitor cells: clinical and preclinical regeneration of the hematolymphoid system

A vast literature exists on the biology of blood formation and regeneration under experimental and clinical conditions. The field of hematopoiesis was recently advanced by the capacity to purify to homogeneity primitive hematopoietic stem and progenitor cells. Isolation of cells at defined maturational stages has enhanced the understanding of the fundamental nature of stem cells, including how cell fate decisions are made, and this understanding is relevant to the development of other normal as well as malignant tissues. This review updates the basic biology of hematopoietic stem cells (HSC) and progenitors, the evolving use of purified HSC as grafts for clinical hematopoietic cell transplantation (HCT) including immune tolerance induction, and the application of HSC biology to other stem cell fields.

Large-Scale Preparation of Human Anti—Third-Party Veto Cytotoxic T Lymphocytes Depleted of Graft-Versus-Host Reactivity: A New Source for Graft Facilitating Cells in Bone Marrow Transplantation

Induction of donor type chimerism in mildly prepared hosts without graft-versus-host disease (GvHD) is a most desirable goal in bone morrow transplantation. We have recently demonstrated in a mouse model that donor veto cytotoxic T lymphocytes (CTLs) can facilitate the induction of donor type chimerism in sublethally irradiated recipients without causing GvHD if they are effectively depleted of alloreactivity against host cells by means of stimulation against a third party. We extend this approach to human cells, by preparing CTLs in two major steps: primary culture in the absence of interleukin 2, leading to death by neglect of antihost clones, and addition of interleukin 2 and subsequent dilution of antihost clones as a consequence of the expansion of the anti-third-party clones. CTLs prepared in this way specifically suppress host cytotoxic T cells directed against antigens of the donor, but not against fourth-party antigens, as demonstrated in a standard (51)Cr release assay. We conclude that human anti-third-party CTLs afford a new source of veto cells that are depleted of potential graft-versus-host-reactive clones. The cells generated by this approach could potentially be used to facilitate engraftment of allogeneic hematopoietic stem cells.

Allogeneic immune replacement as cancer immunotherapy

The graft-versus-leukaemia (GVL) reaction that occurs after allogeneic haematopoietic cell transplantation (HCT) can cure patients with a variety of haematological malignancies. A heightened appreciation of the GVL effect has resulted in the development of reduced intensity transplant approaches, where antitumour effects occur predominantly as a consequence of the transplanted donor immune system. The recent success of these transplants in patients with acute and chronic leukaemias has led to trials investigating for graft-versus-tumour (GVT) effects in patients with treatment-refractory metastatic solid tumours. This review discusses evidence that immune replacement following allogeneic HCT is a potent form of cancer immunotherapy for patients with haematological and non-haematological malignancies.

Use of 18F-FDG positron emission tomography following allogeneic transplantation to guide adoptive immunotherapy with donor lymphocyte infusions

Fluorine-18 fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) provides valuable prognostic information in the management of lymphoma patients. However, the utility of (18)F-FDG PET following allografting is unclear. We analysed the use of (18)F-FDG PET after allogeneic reduced-intensity transplantation (RIT) performed in our institution. Between June 1998 and January 2002, 55 patients underwent RIT for either Hodgkin or non-Hodgkin lymphoma. At least one (18)F-FDG PET scan was performed during the post-transplant period (median five studies) in 15 (27.2%) of these 55 patients. PET scans were performed after re-staging computed tomography (CT) and were categorised depending on (18)F-FDG uptake. The first PET scan was informative in 11 of 15 patients (73%) and influenced the administration of donor lymphocyte infusions (DLI) in nine: leading to earlier DLI administration in two patients, earlier dose escalation in one, withholding of DLI administration in five and dose reduction in one. In addition, subsequent monitoring with (18)F-FDG PET scans documented a graft-versus-lymphoma effect in five patients (median post-DLI follow-up 33 months, range 13-36 months). These preliminary data suggest that (18)F-FDG PET has a role in guiding DLI administration and monitoring the immunotherapeutic effect in patients after allogeneic transplantation. This retrospective pilot study forms the basis for a prospective study to clarify the utility of (18)F-FDG PET/CT in these patients.

Relatively favorable outcomes of post-transplant pulmonary function in patients with chronic myeloid leukemia receiving non-myeloablative allogeneic hematopoietic stem cell transplantation

Pulmonary function tests were performed in 20 patients with chronic myeloid leukemia before and after human leukocyte antigen-matched allogeneic sibling hematopoietic stem cell transplantation (HSCT) to identify any conditioning treatment effects on post-transplant function from January 1995 to December 2002. Of 20 patients, eight received non-myeloablative conditioning treatment and 12 received conventional myeloablative conditioning treatment. Pulmonary function tests including forced vital capacity (FVC), forced expiratory volume in the first second (FEV1), and diffusion capacity for carbon monoxide (DLCO) were performed pretransplant, 6 and 12 months post-transplant. Possible pre-HSCT and post-HSCT risk factors were evaluated for association with pulmonary function. The results showed that myeloablative conditioning treatment had greater negative impact on FEV1, FVC, and DLCO than non-myeloablative conditioning therapy. We conclude that non-myeloablative allogeneic HSCT may apply a better transplant choice in patients who need special concern with post-transplant pulmonary function changes.

Tolerance induction by veto CTLs in the TCR transgenic 2C mouse model. I. Relative reactivity of different veto cells

Several bone marrow cells and lymphocyte subpopulations, known as veto cells, were shown to induce transplantation tolerance across major histocompatibility Ags. Due to the low frequency of the effector T cells against which the veto cells inhibitory activity is aimed, the fate of the effector cells was traditionally followed indirectly by functional limiting dilution assays, which are cumbersome and depend on numerous parameters. In the present study the fate of the effector T cells was monitored directly by FACS, using TCR transgenic mouse CD8(+) T cells in which the transgene is directed against H-2(d) (the 2C model). This assay is validated by demonstrating the potency, selectivity, radiation sensitivity, and contact dependency of anti-third-party CTLs previously demonstrated by the limiting dilution assay. In contrast to veto CTLs, nonactivated CD8(+) T cells lack veto activity. Comparison by FACS in the 2C model revealed a hierarchy of veto cells, in the order of veto CTLs activated NK cells, activated CD4(+) T cells, and activated B cells. The latter cells as well as nonactivated CD4(+) or NK cells were shown to be completely devoid of veto activity.

Allogeneic hematopoietic stem-cell transplantation: the next generation of therapy for metastatic renal cell cancer

The management of metastatic renal cell carcinoma (mRCC) remains a therapeutic challenge; less than 10% of patients survive for longer than 5 years. The resistance of renal cancer to chemotherapy may be explained by high levels of the multidrug resistance gene, MDR1. Immune-based treatments for renal cancer have been explored because of their unusual susceptibility to immunological assault. However, response rates to cytokines such as interleukin-2 and interferon-alpha have ranged from only 10% to 20%, prompting other immunotherapy approaches, such as allogeneic stem-cell transplantation, to be investigated. Several clinical trials have provided evidence of partial or complete disease regression in refractory mRCC following nonmyeloablative stem-cell transplantation. This effect is because of a donor antimalignancy effect mediated by immunocompetent donor T cells, called graft-versus-tumor effect. Unfortunately, less than 30% of patients who could have this procedure will have a human-leukocyte-antigen-compatible sibling, and attention is focusing on alternative donors such as matched unrelated donors and partially mismatched related donors. Despite the improved safety of nonmyeloablative conditioning regimens, transplant-related toxic effects (particularly graft-versus-host disease) remain obstacles to the safe and effective use of this treatment. Regardless of these limitations, innovative approaches have attempted to harness the potential of the graft-versus-tumor effect in mRCC and other solid tumors.

Graft-vs.-lymphoma effect in various histologies of non-Hodgkin's lymphoma

Generally, there is a significantly lower risk of lymphoma relapse following allogeneic than after autologous stem cell transplant. Factors contributing to this lower risk of relapse include an absence of the use of ablative conditioning, with a tumor-free graft, and the generation of a graft-vs.-tumor (GVT) immune response. Allogeneic transplantation, however, has the possibility of graft-vs.-host disease (GVHD). The use of autologous and conventional allogeneic hematopoietic stem cell transplantation (HSCT) in follicular lymphoma, diffuse large cell lymphoma, chronic lymphocytic leukemia and multiple myeloma is discussed. Due to a 1-year transplant-related mortality of 30-40% and complications caused by GVHD, conventional, myeloablative, allogeneic transplantation is a high-risk option for low-grade lymphoproliferative disorders. Novel applications of allogeneic HSCT are described that take advantage of a GVT effect while reducing the risk of GVHD. Minimally myelotoxic pretransplant conditioning regimens allow host antigen-presenting cells to persist, enabling presentation of host minor histocompatibility antigens to donor T cells, causing a GVT response. Although complications may arise due to GVHD, non-myeloablative HSCT can be offered to patients previously ineligible for conventional high-dose treatment. A protocol developed in Seattle using a low-dose total body irradiation (TBI)-based conditioning regimen with immunosuppression using mycophenolate mofetil in combination with cyclosporin has been used in a multicenter trial. To overcome the problem of graft rejection fludarabine was later added to the protocol. A second protocol from a smaller trial used a preparative, conventional-dose regimen of fludarabine, given with cyclophosphamide. Rituximab was also given to provide synergistic action with the chemotherapy to enhance tumor control in the early post-transplant period to allow time for the establishment of the GVT effect. Following transplantation, GVHD prophylaxis was given using tacrolimus with methotrexate. A trial of a further variation of allogeneic HSCT, tandem auto/allo transplants, is described. First, high-dose therapy with autologous PBSC rescue was used to cytoreduce the disease. This was followed by a reduced-intensity or non-myeloablative allogeneic graft. This procedure was devised to take advantage of high-dose therapy and allogeneic HSCT. Results for non-myeloablative allogeneic HSCT are particularly promising in low-grade NHL and the GVT effect may augment response and delay or prevent relapse. However, for aggressive disease, non-myeloablative regimens are only indicated for patients with minimal disease, as the non-myeloablative regimens are unable to control the tumor before the generation of a GVT effect, and/or lack the ability to control rapidly proliferating disease. Patients with relapsed disease may require a higher-dose regimen or tandem transplant approach.

[Auto-immune-like disease post-bone marrow transplantation]

INTRODUCTION

Bone marrow transplantation (BMT) is based on destruction of the patient's bone marrow with rescue of haematopoietic stem cells from a donor. Chronic graft-vs-host disease (GVH) is the major complication post-BMT and mimics some autoimmune diseases, such as scleroderma, sicca syndrome, primary biliary cirrhosis and an increased prevalence of various autoantibodies. Other autoimmune-like manifestations have been reported as case reports or short series. The most common are myasthenia gravis, polymyositis, autoimmune cytopenias and Graves' disease or autoimmune hypothyroidism.

CURRENT KNOWLEDGE AND KEY POINTS

These diseases occur mainly in association with chronic GVH. The pathophysiology of chronic GVH and other autoimmune-like diseases post-BMT remains poorly understood. Different mechanisms have been postulated. Most of the autoimmune events (either chronic GVH or more specific diseases) seem to be related to a poor or inadequate immunologic recovery post-BMT with an imbalance between autoregulatory and autoreactive lymphocytes. Microchimerism and molecular mimicry have been recently evocated. A minority of cases (autoimmune thyroid disorders) is attributed to the direct transfer of autoreactive cells from donor to patient (adoptive immunity).

FUTURE PERSPECTIVES

Despite physiopathologic uncertainty, these autoimmune-like disorders post-BMT are an interesting model for primary autoimmune diseases.

Mannose-binding lectin and infection following allogeneic hemopoietic stem cell transplantation

Major infection remains a major barrier to the success of allogeneic hemopoietic stem cell transplantation (SCT). There is growing interest in the importance of innate immunity in host defense, particularly when adaptive immunity is compromised. Furthermore, many host defense genes are polymorphic, and immunogenetic factors are known to influence the risk of other transplant complications, such as graft-versus-host disease. Mannose-binding lectin (MBL) has emerged as an important innate host defense molecule. MBL binds a wide range of pathogens independently of antibody and activates complement leading to lysis and phagocytosis. Genetically determined MBL deficiency is common and results in an increased risk of infection in a variety of clinical settings, especially in individuals already immunocompromised for other reasons. We conducted a retrospective study examining associations between polymorphisms in the gene encoding MBL, MBL2 and risk of major infection post-SCT in 96 related myeloablative transplants. This showed that "low-producing" MBL2 coding alleles, when present in the donor, were significantly associated with increased risk of major infection in the recipient following neutrophil count recovery. Furthermore, a "high-producing" MBL2 haplotype, HYA, when present in the recipient, was protective against infection. As MBL is under development as a therapeutic agent, these findings suggest that administration of MBL may reduce the risk of infection post-transplant. Prior to embarking upon trials of MBL replacement therapy in SCT, further work is required to confirm these results, to examine the kinetics of MBL synthesis peri-transplant, to correlate MBL2 genotype with blood MBL levels, and to examine the role of MBL in other settings, such as transplantation using reduced intensity conditioning regimens, and unrelated donor transplants. These results are the first report of a genetic determinant of risk of infection post-SCT, and highlight the importance of non-HLA genetic factors in determining the risk of transplant complications. Further studies examining other host defence genes are warranted, and are in progress.

Hematopoietic Cell Transplantation for Benign Hematological Disorders and Solid Tumors

Allogeneic hematopoietic cell transplantation (HCT) has been successfully used as replacement therapy for patients with aplastic anemia and hemoglobinopathies. Both autologous and allogeneic HCT following high-dose chemotherapy can correct manifestations of autoimmune diseases. The impressive allogeneic graft-versus-tumor effects seen in patients given HCT for hematological malignancies have stimulated trials of allogeneic immunotherapy in patients with otherwise refractory metastatic solid tumors. This session will update the status of HCT in the treatment of benign hematological diseases and solid tumors.

In Section I, Dr. Rainer Storb reviews the development of nonmyeloablative conditioning for patients with severe aplastic anemia who have HLA-matched family members. He also describes the results in patients with aplastic anemia given HCT from unrelated donors after failure of responding to immunosuppressive therapy. The importance of leuko-poor and in vitro irradiated blood product transfusions for avoiding graft rejection will be discussed.

In Section II, Dr. Guido Lucarelli reviews the status of marrow transplantation for thalassemia major and updates results obtained in children with class I and class II severity of thalassemia. He also describes results of new protocols for class III patients and efforts to extend HCT to thalassemic patients without HLA-matched family members.

In Section III, Dr. Peter McSweeney reviews the current status of HCT for severe autoimmune diseases. He summarizes the results of autologous HCT for systemic sclerosis, multiple sclerosis, rheumatoid arthritis, and systemic lupus erythematosus, and reviews the status of planned Phase III studies for autologous HCT for these diseases in North America and Europe. He also discusses a possible role of allogeneic HCT in the treatment of these diseases.

In Section IV, Dr. Richard Childs discusses the development and application of nonmyeloablative HCT as allogeneic immunotherapy for treatment-refractory solid tumors. He reviews the results of pilot clinical trials demonstrating graft-versus-solid tumor effects in a variety of metastatic cancers and describes efforts to characterize the immune cell populations mediating these effects, as well as newer methods to target the donor immune system to the tumor.

Hematopoietic Cell Transplantation for Benign Hematological Disorders and Solid Tumors

Allogeneic hematopoietic cell transplantation (HCT) has been successfully used as replacement therapy for patients with aplastic anemia and hemoglobinopathies. Both autologous and allogeneic HCT following high-dose chemotherapy can correct manifestations of autoimmune diseases. The impressive allogeneic graft-versus-tumor effects seen in patients given HCT for hematological malignancies have stimulated trials of allogeneic immunotherapy in patients with otherwise refractory metastatic solid tumors. This session will update the status of HCT in the treatment of benign hematological diseases and solid tumors.

In Section I, Dr. Rainer Storb reviews the development of nonmyeloablative conditioning for patients with severe aplastic anemia who have HLA-matched family members. He also describes the results in patients with aplastic anemia given HCT from unrelated donors after failure of responding to immunosuppressive therapy. The importance of leuko-poor and in vitro irradiated blood product transfusions for avoiding graft rejection will be discussed.

In Section II, Dr. Guido Lucarelli reviews the status of marrow transplantation for thalassemia major and updates results obtained in children with class I and class II severity of thalassemia. He also describes results of new protocols for class III patients and efforts to extend HCT to thalassemic patients without HLA-matched family members.

In Section III, Dr. Peter McSweeney reviews the current status of HCT for severe autoimmune diseases. He summarizes the results of autologous HCT for systemic sclerosis, multiple sclerosis, rheumatoid arthritis, and systemic lupus erythematosus, and reviews the status of planned Phase III studies for autologous HCT for these diseases in North America and Europe. He also discusses a possible role of allogeneic HCT in the treatment of these diseases.

In Section IV, Dr. Richard Childs discusses the development and application of nonmyeloablative HCT as allogeneic immunotherapy for treatment-refractory solid tumors. He reviews the results of pilot clinical trials demonstrating graft-versus-solid tumor effects in a variety of metastatic cancers and describes efforts to characterize the immune cell populations mediating these effects, as well as newer methods to target the donor immune system to the tumor.