T cell depletion and no post transplant immune suppression allow separation of graft versus leukemia from graft versus host disease.

Allogeneic hematopoietic cell transplantation from a human leukocyte antigen (HLA) haplotype mismatched donor (haploidentical transplantation) was not feasible for the treatment of hematologic malignancies until the early 1990s, due to the high risk of rejection and graft-versus-host disease (GVHD). The first successful protocol of haploidentical transplantation was based on a highly myeloablative and immunosuppressive conditioning regimen and the infusion of a "mega-dose" of T-cell-depleted hematopoietic stem cells. More than 90% of patients engrafted and <10% developed GVHD. The protocol did not include post-transplant immunosuppression, which favored the graft-versus-tumor effect mediated by alloreactive NK cells and residual alloreactive T cells. However, donor post-transplant immune reconstitution was slow with a high risk of infection-related mortality. More recently, T-cell-depleted haploidentical transplantation has become the platform for innovative cell therapies that aim to enhance T-cell immunity while preventing adverse reactions against host tissues. One strategy is adoptive immunotherapy with conventional T cells and regulatory T cells. Preclinical studies and clinical trials have proven that regulatory T cells control GVHD caused by co-infused conventional T cells while the graft-versus-tumor effect is retained. The use of regulatory T cells in the absence of any other form of immune suppression allowed for a conventional T cell-mediated full eradication of disease in the vast majority of high-risk acute leukemia patients.

ADCC can improve graft vs leukemia effect after T- and B-cell depleted haploidentical stem cell transplantation in pediatric B-lineage ALL.

Posttransplant relapsed B-cell precursor ALL can be cured by 2nd hematopoietic stem cell transplantation (HSCT) in 20% of patients. The major cause of death after second HSCT is leukemic relapse. One reliable predictor for survival after 2nd-HSCT are posttransplant MRD levels. Patients with detectable or increase of MRD are likely to relapse. Patients in complete molecular remission show the best leukemia-free survival and lowest cumulative incidence (CI) of relapse. As patients who undergo second or subsequent HSCT are high-risk patients, we evaluated the prophylactic use of the chimeric Fc-optimized CD19-4G7SDIE-mAb. Posttransplant relapsed CD19+ BCP-ALL patients, who underwent a second or subsequent haplo-HSCT from a T- and B-cell depleted graft received posttransplant prophylactic CD19-4G7SDIE-mAb treatment on compassionate use in complete molecular remission, to increase the antileukemic activity of the new reconstituting immune system by recruiting Fc-expressing effector cells. NK cells recovered early and robust. The 3 year overall survival in 15 evaluable patients was 56%, the 3 year event-free survival was 55% and the CI of relapse 38%. Compared to a historical control group, the CI of relapse was markedly lower and consecutively the EFS higher. Posttransplant-targeted therapy may overcome the need for unspecific GvL effect of undesired GvHD, that can cause severe morbidity and mortality. Due to a low adverse event profile the CD19-4G7SDIE-mAb may be suitable for broad administration to consolidate posttransplant MRD negativity.

Administration of anti-CD20 mAb is highly effective in preventing but ineffective in treating chronic graft-versus-host disease while preserving strong graft-versus-leukemia effects.

Chronic graft-versus-host disease (cGVHD) is an autoimmune-like syndrome, and donor B cells play important roles in augmenting its pathogenesis. B cell-depleting anti-CD20 mAb has been administered before or after cGVHD onset for preventing or treating cGVHD in the clinic. Although administration before onset appeared to be more effective, the effect is variable and sometimes minimal. Here, we used 2 mouse cGVHD models to evaluate the preventive and therapeutic effect of anti-CD20 mAb. With the model of DBA/2 donor to MHC-matched BALB/c recipient, 1 intravenous injection of anti-CD20 mAb (40 mg/kg) the following day or on day 7 after hematopoietic cell transplantation when serum autoantibodies were undetectable effectively prevented induction of cGVHD and preserved a strong graft-versus-leukemia (GVL) effect. The separation of GVL effect from GVHD was associated with a significant reduction of donor CD4(+) T cell proliferation and expansion and protection of host thymic medullary epithelial cells. Anti-CD20 mAb administration also prevented expansion of donor T cells and induction of cGVHD in another mouse model of C57BL/6 donor to MHC-mismatched BALB/c recipients. In contrast, administration of anti-CD20 mAb after GVHD onset was not able to effectively deplete donor B cells or ameliorate cGVHD in either model. These results indicate that administration of anti-CD20 mAb before signs of cGVHD can prevent induction of autoimmune-like cGVHD while preserving a GVL effect; there is little effect if administered after cGVHD onset. This provides new insights into clinical prevention and therapy of cGVHD with B cell-depleting reagents.

Potent graft-versus-leukemia effect after reduced-intensity allogeneic SCT for intermediate-risk AML with FLT3-ITD or wild-type NPM1 and CEBPA without FLT3-ITD.

To investigate the role of reduced-intensity allogeneic (RIC-allo) stem cell transplant (SCT) as postremission therapy in adult intermediate-risk patients with acute myelogenous leukemia (AML) with FLT3-ITD or wild-type NPM1 and CEBPA without FLT3-ITD, we conducted a single-center retrospective study between January 2001 and December 2010. Sixty-six patients were included: 37 treated with RIC-alloSCT and 29 with nonallogeneic SCT therapies. Both groups were comparable concerning age, WBC count at diagnosis, gender, karyotype, genotype, and number of courses of chemotherapy to reach complete remission (CR1). Median follow-up after CR1 was 37 months (range, 11-112 months) and 48 months (range, 9-83 months) in the allo and no-allo groups, respectively. In the allo versus no-allo groups, the 3-year cumulative incidence of relapse (CIR) rates were 25% ± 8% versus 61% ± 9%; P = .005. The 3-year nonrelapse mortality (NRM), overall survival (OS), and relapse-free survival (RFS) were 22% ± 7% versus 4% ± 4% (P = .005), 52% ± 9% versus 44% ± 10% (P = .75), and 53% ± 9% versus 35% ± 9% (P = .28), respectively. Multivariate analysis indicated that CIR was reduced by allo (hazard ratio [HR], 0.32; P = .01). A landmark analysis performed at day 185 after CR1 confirmed a lower CIR after allo. RIC-allo reduces the risk of relapse, suggesting a potent graft-versus-leukemia (GVL) effect in these patients at a high risk of relapse.

In the absence of clinically significant graft vs. host disease, myeloablative conditioning may allow an effective graft vs. leukaemia effect.

In AML, prevention of GvHD leads to better tolerance of myeloablative therapy. 66 individuals with AML in CR underwent myeloablative conditioning and transplantation with allogeneic PBPC grafts. Median presentation age was 44.5 years. Karyotyping was intermediate in 48% and of unfavourable risk in 36%. For GvHD prophylaxis, PBPC harvests were incubated ex vivo with anti CD52 antibodies. TRM at day 100 and 1 year was 9% and 17%. At a median of 1018 days 65% are alive. Grade >1 GvHD was seen in 11%. GvHD and adverse karyotype were associated with treatment failure. In younger patients preservation of the dose intensity may improve cure rates.

Epigenomics in hematopoietic transplantation: novel treatment strategies.

Allogeneic hematopoietic stem cell transplantation is a high risk but curative treatment option for leukemia, myelodysplasia and other hematological malignancies. After high dose radio- or chemo-therapy, recipient's hematopoiesis is replaced by a new immunosystem and residual malignant cells are eliminated by the graft-versus-leukemia reaction. The benefit of this immunological effect is limited by the most frequent complication of hematopoietic stem cell transplantation: graft-versus-host disease. In addition to their well-known anti-tumor activity, epigenetic drugs mediate immunotolerance without reducing alloreactivity or even enhance graft-versus-leukemia effect without inducing graft-versus-host disease by regulating cytokine release, increasing the circulating number of regulatory T cells and interacting with natural killer cells. We focus on the use of epigenetic drugs in the allogeneic transplantation setting in relation to their anti-tumor and immunomodulatory potential.

The role of regulatory T cells during the attenuation of graft-versus-leukemia activity following donor leukocyte infusion in mice.

We investigated how the graft-versus-leukemia (GVL) effect is attenuated in the tumor microenvironment using a murine model of non-myeloablative allo-HSCT (NM-HSCT) plus delayed donor leukocyte infusion (DLI) in a haploidentical B6→F1 strain combination. In-line with aggravated leukemia growth, the proportions of effector T cells expressing IFN-γ (Teffs) in spleen were reduced and attenuated GVL activity was found to be accompanied by a rebound in CD4(+)Foxp3(+) regulatory T cells (Tregs) in tumor-draining lymph nodes and tumor tissues. DLI-derived Tregs and Teffs may be potential indicators of presence of leukemic progression after DLI in this GVL model.

Early human cytomegalovirus replication after transplantation is associated with a decreased relapse risk: evidence for a putative virus-versus-leukemia effect in acute myeloid leukemia patients.

The impact of early human cytomegalovirus (HCMV) replication on leukemic recurrence was evaluated in 266 consecutive adult (median age, 47 years; range, 18-73 years) acute myeloid leukemia patients, who underwent allogeneic stem cell transplantation (alloSCT) from 10 of 10 high-resolution human leukocyte Ag-identical unrelated (n = 148) or sibling (n = 118) donors. A total of 63% of patients (n = 167) were at risk for HCMV reactivation by patient and donor pretransplantation HCMV serostatus. In 77 patients, first HCMV replication as detected by pp65-antigenemia assay developed at a median of 46 days (range, 25-108 days) after alloSCT. Taking all relevant competing risk factors into account, the cumulative incidence of hematologic relapse at 10 years after alloSCT was 42% (95% confidence interval [CI], 35%-51%) in patients without opposed to 9% (95% CI, 4%-19%) in patients with early pp65-antigenemia (P < .0001). A substantial and independent reduction of the relapse risk associated with early HCMV replication was confirmed by multivariate analysis using time-dependent covariate functions for grades II to IV acute and chronic graft-versus-host disease, and pp65-antigenemia (hazard ratio = 0.2; 95% CI, 0.1-0.4, P < .0001). This is the first report that demonstrates an independent and substantial reduction of the leukemic relapse risk after early replicative HCMV infection in a homogeneous population of adult acute myeloid leukemia patients.

[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.

Comparison of Wilms' tumor antigen 1-specific T lymphocyte generation soon after nonmyeloablative allergenic stem-cell transplantation in acute and chronic leukemia patients.

Clinical studies have shown that NST has better therapeutic results with chronic myelogenous leukemia (CML) than acute leukemia (AL), but whether the generation of graft-versus-leukemia (GVL) effects is different between AL and CML patients early after NST has not yet been studied, so we used a pentamer-staining technique in combination with ICCS to detect WT1(+)CD8(+)CTL/WT1(+)Tc1 and WT1(+)Th1 cells in these two groups of patients. Results showed that the emergence time of WT1(+)CD(8) (+)CTL/WT1(+)Tc1 cells after NST in AL patients was similar to that in CML patients (P = 0.58), while the emergence time of WT1(+)Th1 cells after NST in AL patients was shorter than in CML patients (P = 0.047). Furthermore, the peak proportions of WT1(+)CD(8) (+)CTL/WT1(+)Tc1 (P > 0.05) and WT1(+)Th1 (P > 0.05) cells were similar between AL and CML patients, and the increased rates (P > 0.05) and elevated levels (P > 0.05) of WT1-specific T cells were not statistically different between the groups after G-CSF mobilized donor mononuclear cell infusion. In addition, the reconstruction of lymphocyte subsets (P > 0.05) and CD4/8 ratios (P > 0.05) in AL patients were not statistically different from those in CML patients within 180 days after NST. These results suggested that WT1 maybe induces similar GVL effects in both AL and CML patients early after NST.

PKCtheta is required for alloreactivity and GVHD but not for immune responses toward leukemia and infection in mice.

When used as therapy for hematopoietic malignancies, allogeneic BM transplantation (BMT) relies on the graft-versus-leukemia (GVL) effect to eradicate residual tumor cells through immunologic mechanisms. However, graft-versus-host disease (GVHD), which is initiated by alloreactive donor T cells that recognize mismatched major and/or minor histocompatibility antigens and cause severe damage to hematopoietic and epithelial tissues, is a potentially lethal complication of allogeneic BMT. To enhance the therapeutic potential of BMT, we sought to find therapeutic targets that could inhibit GVHD while preserving GVL and immune responses to infectious agents. We show here that T cell responses triggered in mice by either Listeria monocytogenes or administration of antigen and adjuvant were relatively well preserved in the absence of PKC isoform theta (PKCtheta), a key regulator of TCR signaling. In contrast, PKCtheta was required for alloreactivity and GVHD induction. Furthermore, absence of PKCtheta raised the threshold for T cell activation, which selectively affected alloresponses. Most importantly, PKCtheta-deficient T cells retained the ability to respond to virus infection and to induce GVL effect after BMT. These findings suggest PKCtheta is a potentially unique therapeutic target required for GVHD induction but not for GVL or protective responses to infectious agents.

Graft-versus-leukemia effects of transplantation and donor lymphocytes.

Allogeneic transplantation of hematopoietic cells is an effective treatment of leukemia, even in advanced stages. Allogeneic lymphocytes produce a strong graft-versus-leukemia (GVL) effect, but the beneficial effect is limited by graft-versus-host disease (GVHD). Depletion of T cells abrogates GVHD and GVL effects. Delayed transfusion of donor lymphocytes into chimeras after T cell-depleted stem cell transplantation produces a GVL effect without necessarily producing GVHD. Chimerism and tolerance provide a platform for immunotherapy using donor lymphocytes. The allogeneic GVL effects vary from one disease to another, the stage of the disease, donor histocompatibility, the degree of chimerism, and additional treatment. Immunosuppressive therapy before donor lymphocyte transfusions may augment the effect as well as concomitant cytokine treatment. Possible target antigens are histocompatibility antigens and tumor-associated antigens. Immune escape of tumor cells and changes in the reactivity of T cells are to be considered. Durable responses may be the result of the elimination of leukemia stem cells or the establishment of a durable immune control on their progeny. Recently, we have learned from adoptive immunotherapy of viral diseases and HLA-haploidentical stem cell transplantation that T-cell memory may be essential for the effective treatment of leukemia and other malignancies.

[Minor antigens - major impact. The role of minor histocompatibility antigens in allogeneic hematopoietic stem cell transplantation]. / Kleine Antigene - grosse Wirkung. Die Rolle von Minor-Histokompatibilitätsantigenen bei der allogenen Blutstammzelltransplantation.

Allogeneic hematopoietic cell transplantation (HCT) is often the only curative treatment option for patients with malignant and non-malignant hematological diseases. There is striking evidence that immunological Graft-versus-Leukemia (GvL)-reactions efficiently eradicate malignant cells after transplant. After HLA-matched HCT both the beneficial GvL-effect and the detrimental Graft-versus-Host Disease (GvHD) are mediated by donor derived T-cells specific for minor histocompatibility antigens (mHag) that differ between patient and stem cell donor. In addition, tumor-specific antigens can also be targeted and contribute to GvL-reactivity. This review summarizes the state-of-the-art knowledge on mHag and presents the potential therapeutical options on example of the mHag HA-1. HA-1 is currently the best characterized mHag and particularly attractive for immunotherapy due to the restricted expression on hematopoietic cells and on some solid tumors but not on cells involved during GvHD. This would allow amplifying the endogenous GvL-effect and selectively targeting malignant HA-1-positive cells without causing GvHD. HA-1-specific immunotherapy in eligible patient and donor pairs may range from vaccination with the immunogenic HA-1 peptide to the infusion of HA-1-specific cytotoxic T-cells (adoptive immunotherapy).

[Allogeneic stem cell transplantation in the management of acute myeloid leukemia]. / Die allogene Stammzelltransplantation im Therapiekonzept der akuten myeloischen Leukämie.

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.

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.

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.