[Hematopoietic stem cell transplantation for hematologic disorders]

There have been a great progress in hematopoietic stem cell transplantation (SCT) for hematologic malignancies in various aspects including stem cell sources, supportive care, infrastructure, stem cell mobilization, etc., which has lead SCT from experimental therapy to standard medical practice. The most prominent is the advent of SCT with reduced-intensity conditioning (RIC) regimen. It has not only expanded the eligibility for SCT to patients of older age or with co-morbidities, but also highlighted the impact of graft-versus-tumor (GVT) effects in some malignant disorders such as follicular lymphoma, peripheral T-cell lymphoma, and chronic myeloid or lymphocytic leukemia. RIC will provide a possibility for myriads of newly developed molecular-targeted or antibody-based agents to be incorporated in SCT as pre- or post-SCT therapies.

[Allogeneic stem cell transplantation in the management of acute myeloid leukemia]

Allogeneic stem cell transplantation (SCT) is the most powerful treatment option for acute myeloid leukemia (AML). However, SCT is also complicated by a high risk for treatment-related morbidity and mortality. The antileukemic effect of SCT is based on the radio-/chemotherapy applied for conditioning, as well as on the allogeneic immune reaction, mediated by immunocompetent donor cells, the graft-versus-leukemia effect. The latter effect is of particular importance in the context of reduced-intensity conditioning regimens, that have enabled us to offer allogeneic SCT to a by far bigger part of patients suffering from AML. The indication for allogeneic SCT is based on the patient's individual risk profile. Biological and clinical characteristics of the leukemia contribute to this risk profile, as do extraleukemic conditions such as age and comorbidity. Allogeneic SCT represents the standard of care for all patients with AML < 65 years of age, who are beyond first complete remission (CR) or who have failed to respond to induction chemotherapy. In first CR, allogeneic SCT is a standard for patients with unfavorable karyotype disease or other risk factors, whereas for patients without specific risk factors it is just an option, in particular within clinical trials. In patients with a favorable leukemic karyotype, allogeneic SCT is usually not performed in first CR. Future developments in the field include transplant strategies specifically designed for biological AML subgroups, as well as the integration of new drugs into transplant regimens.

High PR3 or ELA2 expression by CD34+ cells in advanced-phase chronic myeloid leukemia is associated with improved outcome following allogeneic stem cell transplantation and may improve PR1 peptide-driven graft-versus-leukemia effects

The primary granule proteins elastase (ELA2) and proteinase 3 (PR3) both contain the nonapeptide PR1, which can induce cytotoxic T lymphocyte (CTL) responses against chronic myeloid leukemia (CML) cells. To investigate whether eradication of CML after allogeneic stem cell transplantation (SCT) was influenced by PR3 and ELA2 gene expression or PR1-specific CTL responses, we studied cells from 87 CML patients and 27 HLA-A*0201(+) donors collected prior to T-cell-depleted HLA-identical sibling SCT. For patients in advanced phase (AdP), a higher expression of both PR3 and ELA2 in CD34(+) progenitors before SCT was associated with a lower incidence of relapse-related death, improved leukemia-free survival (LFS), and overall survival (OS); in chronic phase patients, no differences were observed. PR1-CTL responses were detected in 7 of 27 HLA-identical sibling donors, and associated with improved LFS and OS after SCT on follow-up. PR1-CTL responses detected in 7 of 28 CML patients before transplantation were not predictive of outcome and correlated inversely with PR3 and ELA2 expression. These findings suggest that assessment of PR3 and ELA2 expression in leukemic progenitors is useful for predicting posttransplantation outcome in AdP patients undergoing SCT. The presence of a donor immune response against PR1 may be advantageous and could be exploited therapeutically.

Rapamycin Promotes Emergence of IL-10-Secreting Donor Lymphocyte Infusion-Derived T Cells Without Compromising Their Graft-Versus-Leukemia Reactivity

BACKGROUND

There are limited data examining the effects of pharmacological immunosuppression on the in vivo fate of donor lymphocyte infusions (DLI)-derived T cells, their function, and their antitumor efficacy.

METHODS

We addressed this question in a murine model in which DLI is given to stable mixed chimeras resulting in lymphohematopoietic graft-versus-host (LH-GVH) response. In this model, LH-GVH potency can be directly measured as the kinetics of conversion to full donor chimerism and can be correlated with associated graft-versus-leukemia (GVL) reactivity.

RESULTS

We found discordance in DLI-mediated LH-GVH reactivity depending on the timing of rapamycin (RAPA) administration. Delayed administration of RAPA in contrast to its early administration at the time of adoptive transfer did not interfere with conversion to full donor chimerism. Moreover, delayed administration of RAPA preserved the GVL reactivity of DLI. Analysis of the long-term chimeras showed that regardless of RAPA administration, adoptively transferred T cells mediating the LH-GVH response contribute minimally to the reconstitution of the peripheral T-cell compartment and exhibit profound hyporesponsiveness and decreased production of interleukin (IL)-2 on restimulation in vitro. However, we observed only in the RAPA-treated chimeras that the remaining hyporesponsive DLI-derived CD4+ T cells secrete large amounts of IL-10, a known immunoregulatory cytokine.

CONCLUSIONS

We conclude that delayed administration of RAPA after DLI does not interfere with their LH-GVH reactivity but promotes the emergence of IL-10-secreting DLI-derived CD4+ T cells that might contribute to the drug's known ability to promote bilateral donor host tolerance without interfering with GVL reactivity.

Combined immunoradiotherapy induces long-term remission of CNS relapse of peripheral, diffuse, large-cell lymphoma after allogeneic stem cell transplantation: case study

Relapse of peripheral non-Hodgkin's lymphoma (NHL) in the central nervous system commonly has a poor prognosis. Graft-versus-leukemia effects (GvL) contribute substantially to eradication of hematological malignancies after allogeneic stem cell transplantation. Few data are available describing GvL activity within the brain. We report the case of a man allografted for peripheral NHL. On day +83 after transplantation a CNS relapse of the lymphoma occurred. The brain was irradiated with 44 Gy, anti-CD20 antibodies were given, and the immunosuppression was withdrawn. Subsequently, limited-stage, chronic graft-versus-host disease occurred. The lymphoma regressed completely, and the patient has been in continuous complete remission for 30 months. The favorable course suggests substantial contribution of immunomodulation to excellent outcome.

Cellular adoptive immunotherapy after allogeneic stem cell transplantation

PURPOSE OF REVIEW

This review presents the role of donor lymphocyte infusion, natural killer cells, and dendritic cells in cellular immunotherapy after allogeneic stem cell transplantation.

RECENT FINDINGS

It becomes increasingly possible to infuse more specialized subsets of lymphocyte cells after transplantation. The infusion of natural killer cells, especially in non human leukocyte antigen-identical transplantation, may become an important tool in enhancing the graft-versus-tumor effect. Vaccination of patients after stem cell transplantation with autologous-derived dendritic cells merits further investigation.

SUMMARY

Stem cell transplantation has evolved to a specialized form of immunotherapy.

Donor APCs are required for maximal GVHD but not for GVL

Graft-versus-host disease (GVHD) is a major source of morbidity in allogenic stem cell transplantation. We previously showed that recipient antigen-presenting cells (APCs) are required for CD8-dependent GVHD in a mouse model across only minor histocompatibility antigens (minor H antigens). However, these studies did not address the function of donor-derived APCs after GVHD is initiated. Here we show that GVHD develops in recipients of donor major histocompatibility complex class I-deficient (MHC I(-)) bone marrow. Thus, after initial priming, CD8 cells caused GVHD without a further requirement for hematopoietic APCs, indicating that host APCs are necessary and sufficient for GHVD. Nonetheless, GVHD was less severe in recipients of MHC I(-) bone marrow. Therefore, once initiated, GVHD is intensified by donor-derived cells, most probably donor APCs cross-priming alloreactive CD8 cells. Nevertheless, donor APCs were not required for CD8-mediated graft-versus-leukemia (GVL) against a mouse model of chronic-phase chronic myelogenous leukemia. These studies identify donor APCs as a new target for treating GVHD, which may preserve GVL.

Inhibiting apoptosis of CTLL-2 cells to enhance their GVL effects via anti-Fas ribozyme

To investigate the inhibition role of anti-Fas hammerhead ribozyme on fas expression and Fas-mediated apoptosis of CTL cell line CTLL-2 cells, the cDNA of an anti-Fas hammerhead ribozyme was synthesized, its expression plasmid was constructed and transfected into CTLL-2 cells by electroporation. fas expression of CTLL-2 cells was detected by RT-PCR and Western blot. CTLL-2 cell viability was measured using MTT assay when co-cultured with mouse T cell leukemia cell line EL4 cells that highly expressed Fas ligand (FasL). Meanwhile, caspase-3 proteolytic activity was detected, and cell apoptosis was measured by flow cytometry and Hochest-PI double staining. Killing activity of CTLL-2 cells was detected by lactate dehydrogenase (LDH) releasing assay in vitro. Results showed that the expression of both Fas mRNA and protein in CTLL-2 cells were decreased after transfection of anti-Fas ribozyme. Compared with mock-transfected group and mutant ribozyme-transfected group, viability of CTLL-2 cells co-cultured with EL4 cells was increased significantly and cells killing activity was enhanced after transfected with anti-Fas ribozyme, while the caspase-3 activity and apoptosis rate was significantly decreased. The results demonstrated anti-Fas ribozyme could efficiently cleave Fas and inhibit Fas-mediated apoptosis of CTLL-2 cells to improve their viability. Our study made a basis for enhancing CTLL-2 cells anti-leukemia effect in DLI.

Juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia is an aggressive neoplasia of early childhood. Only allogeneic stem cell transplantation (SCT) offers long-term cure. In the absence of an HLA-matched family donor, early SCT from an unrelated donor is the treatment of choice for most children. With clear evidence of a graft-versus-leukemia effect and a high post-transplant relapse rate, the outcome of SCT depends, in part, on the management of immunosuppression during the procedure. The impact of pretransplant cytoreductive treatment, such as intensive chemotherapy, splenectomy, or 13-cis retinoic acid, is unclear. Hypersensitivity for granulocyte-macrophage colony-stimulating factor and pathologic activation of the Ras/MAPK pathway play an important role in the pathophysiology of juvenile myelomonocytic leukemia and provide the opportunity for several novel therapeutic approaches.

Effect of FK506 on donor T-cell functions that are responsible for graft-versus-host disease and graft-versus-leukemia effect

BACKGROUND

FK506 is a potent immunosuppressive agent that is used in human graft-versus-host disease (GvHD) prevention. However, the precise mechanisms for GvHD prevention and the effect on graft-versus-leukemia (GvL) activity are unknown. This study was undertaken to determine the effect of FK506, given at clinically relevant doses, on donor T-cell functions responsible for GvHD and GvL activity.

METHODS

The effect of FK506 on GvHD prevention and GvL activity was investigated using a murine model of allogeneic bone-marrow transplantation in which mice were injected with a P815 leukemic cell line. The regulatory role of FK506 on donor T cells was tested by analysis of donor T-cell expansions in the spleen and donor anti-host T-cell proliferative and cytotoxic responses. mRNA expression of type 1 T helper (Th1), Fas ligand (L), and granzyme B were also evaluated in target organs of GvHD.

RESULTS

FK506 significantly prolonged the survival of GvHD mice when given at the trough level of 17.6 ng/mL, whereas it also blocked GvL effect in P815-injected GvHD mice. FK506 reduced the expansion of donor CD8+ and, to a lesser extent, CD4+ T cells in the spleen and inhibited donor anti-host T-cell proliferative and cytotoxic responses. It also inhibited the induction of Th1, FasL, and granzyme B mRNA expression in target organs of GvHD.

CONCLUSIONS

FK506 inhibits both GvHD and GvL activity when given at clinical doses by inhibiting donor T-cell expansion, donor anti-host T-cell reactivity, and Th1 immune responses.

Janus kinase 3 inhibitor WHI-P131/JANEX-1 prevents graft-versus-host disease but spares the graft-versus-leukemia function of the bone marrow allografts in a murine bone marrow transplantation model

The purpose of the present study was to evaluate the effects of graft-versus-host disease (GVHD) prophylaxis with the Janus kinase 3 (JAK3) inhibitor WHI-P131/JANEX-1 on the graft-versus-leukemic (GVL) function of marrow allografts in mice undergoing bone marrow transplantation (BMT) after being challenged with an otherwise invariably fatal dose of BCL-1 leukemia cells. GVHD prophylaxis using WHI-P131 markedly improved the survival outcome after BMT. The probability of survival at 30 days after BMT was 11% +/- 6% for vehicle-treated recipients (median survival time, 25 days) versus 63% +/- 12% for recipients treated with WHI-P131 (median survival time, 36 days; P <.0001). Because WHI-P131 is devoid of antileukemic activity against BCL-1 leukemia cells, this marked improvement in survival outcome was due to reduced incidence of GVHD-associated fatalities combined with sustained GVL function of the allografts in the WHI-P131 group. Notably, adoptive transfer experiments demonstrated that the spleens of WHI-P131-treated allograft recipients contained less than 0.001% BCL-1 cells. Notably, GVHD prophylaxis with WHI-P131 plus methotrexate resulted in 100% survival of mice receiving allotransplants challenged with an otherwise invariably fatal dose of BCL-1 leukemia. Taken together, our results provide strong experimental evidence that GVHD prophylaxis using WHI-P131 does not impair the GVL function of the allografts and consequently contributes to an improved post-BMT survival outcome of the recipient mice.

[Study on graft-versus-leukemia effects of donor lymphocyte infusion after nonmyeloablative allogeneic bone marrow transplantation]

OBJECTIVE

To explore the graft-versus-leukemia effects of donor lymphocyte infusion(DLI) after nonmyeloablative allogeneic bone marrow transplantation while attenuating treatment-associated morbidity, mortality and graft-versus-host disease.

METHODS

615(H-2k) mice were loaded with L615 cells and 3 days later received total body irradiation (TBI) 5 Gy (60 Co gamma-ray) followed by allogeneic bone marrow transplantation (allo-BMT). The allo-grafts consisted of 3 x 10(7) bone marrow cells and 1 x 10(7) spleen cells from BALB/c (H-2d) donor mice. Two days after allo-BMT, the recipient mice were given 200 mg/kg of CTX. Afterwards these recipient mice were infused either donor spleen cells (2 x 10(7)) on d14 and d21 or hydrocortison (HC) and cyclosporine A (CsA) treated donor spleen cells (5 x 10(7)) on d14 post-BMT.

RESULTS

Survival time of mice received DLI on d21 and pretreated DLI on d14 post-BMT was longer than that of control group and d14 DLI group(P < 0.01) and without severe graft-versus-host disease.

CONCLUSION

Donor lymphocyte infusion after nonmyeloablative bone marrow transplantation could reduce transplantation-associated morbidity and mortality while strengthening graft-versus-leukemia effects.

Cytokines in graft-versus-host disease and the graft-versus-leukemia reaction

Graft-versus-host disease (GVHD) is the major complication after allogeneic hemopoietic stem cell transplantation. GVHD is destructive by itself and sets the stage for other sequelae, in particular, overwhelming infections. Recent investigations have improved our understanding of the underlying pathophysiology of GVHD. There are now compelling data on the role of host tissue destruction as the initial insult, extensive interactions of cellular donor and host components, a complex network of cytokines, adhesion molecules, and other components in the development of GVHD. The improved understanding of interactions among various signals is likely to allow for the development of new prophylactic strategies. A review of the data shows, however, that results are very dependent upon the models used. It is difficult or impossible to separate completely the discussion of cytokines that affect hemopoietic cells from discussion of cytokines that exert effects on immune cells. Furthermore, secondary effects on immune cells via hemopoietic cells complicate the picture. Application of the principles of cytokine signaling to the clinical setting may necessitate new trial design structures that take into consideration donor and host characteristics as well as the kinetics of GVHD development.

The role of interleukin-12 and interferon-gamma in GVHD and GVL

The production of interleukin (IL)-12 by antigen-presenting cells after antigen stimulation is a critical step for initiating antigen-specific cellular immune responses, and interferon (IFN)-gamma produced by natural killer cells and activated T cells is a potent mediator of IL-12 effect. However, recent studies have demonstrated that administration of exogenous IL-12 paradoxically inhibits antigen-specific immunity of T cells in vivo, including allogeneic, autoimmune, and viral antigen-initiated T-cell responses. Interestingly, these inhibitory effects are also mediated by IFN-gamma, whose production is induced by IL-12. Thus, IL-12, a potent immunostimulatory cytokine, can paradoxically lead to immunosuppression. Notably, this cytokine has been shown to preserve graft-versus-leukemia (GVL) effects of allogeneic CD8+ T cells while inhibiting graft-versus-host disease (GVHD) in murine allogeneic bone marrow transplantation models. This article will review recent studies concerning the effect of IL-12 and IFN-gamma on the development of GVHD and the induction of GVL effects, and discuss the possible mechanisms responsible for IL-12-mediated separation of GVL effects from the GVHD-promoting activity of allogeneic T cells.