Experimental and clinical approaches for optimization of the graft-versus-leukemia effect

Transitory Spontaneous Remission of Myelodysplasia in an Elderly Man while Receiving Intravesical Bacillus Calmette-Guérin for Bladder Cancer: A Case Report and Review of the Literature

Myelodysplasia is a clonal disorder characterized by progressive cytopenias. Intravescial BCG is standard immunotherapy for superficial bladder cancer. We present a patient with transfusion-dependent myelodysplasia whose blood counts normalized during treatment with intravesical BCG for bladder cancer. After finishing treatment, the patient became transfusion dependent once more. We discuss possible mechanisms to explain this case report.

Donor KIR Genotype Impacts on Clinical Outcome after T Cell-Depleted HLA Matched Related Allogeneic Transplantation for High-Risk Pediatric Leukemia Patients

Preliminary data suggest that ex vivo T cell-depleted matched related donor (MRD) hematopoietic stem cell transplantation (HSCT) is feasible and confers a clinically beneficial reduction in graft-versus-host disease. Classically, T cell-depleted grafts were associated with reduction of the graft-versus-leukemia (GVL) effect because of delayed T cell immune reconstitution. However, natural killer (NK) cell alloreactivity is also critical for an early GVL effect as well as for lymphocyte immune reconstitution. Here, we study the role of NK cells in MRD T cell-depleted HSCT, which is still poorly understood. Given that MRD ligands for inhibitory killer cell immunoglobulin-like receptors (KIRs) are matched, we focused on activating KIR receptors. We retrospectively analyzed KIR genotyping in patients and MRDs in 40 ex vivo T cell-depleted pediatric HSCTs. The log-rank test and Cox proportional risk test were performed to correlate genotype with clinical outcome (relapse rate, disease-free survival, and overall survival) and immune reconstitution. The statistical analysis revealed poorer overall survival when donors have a KIR-B content score of ≥2, a best/better subtype, or present the KIR2DS1 gene. The patient's relapse rate was higher when donors present the KIR2DL5A gene, as well as a poorer probability of disease-free survival when the donor is classified with a best/better subtype. Regarding immune reconstitution, donor KIR haplotype A or the presence of inhibitory KIR genes promote best recovery of T lymphocytes, whereas donor KIR haplotype B or the presence of activating KIR genes confer better expansion of NK cells. These findings suggest that the selection of MRDs with an inhibitory KIR phenotype improve T cell expansion as well as the clinical outcome after pediatric ex vivo T cell-depleted HSCT.

Adoptive therapy with donor lymphocyte infusion after allogenic hematopoietic SCT in pediatric patients

The aim of this study was to analyse the experience of Polish Pediatric Group for Hematopoietic Stem Cell Transplantation in respect to donor lymphocyte infusion procedure. The study included 51 pediatric patients with malignant (45) and non-malignant (6) diseases treated with DLI in the period 1993-2012. The indications for DLI were as follows: (1) increasing recipient chimerism after non-ablative hematopoietic SCT (18 patients); (2) immunomodulation after a reduced intensity conditioning regimen (2 patients); (3) increase in minimal residual disease detection (3 patients); and (4) relapse (28 patients). DLI was carried out at a median of 6 (0.5-79) months after SCT. DLI was administered as either a single-dose (in 19 cases) or in escalating-dose regimens (in 32 cases). The median total dose of CD3-positive T cells was 28.0 (0.1-730.0) × 10(6)/kg body weight. The time for assessment of DLI efficacy ranged from 0 to 70 (median 3) months. At evaluation, 18 patients experienced CR, 3 achieved PR, 19 showed relapse and 11 rejected the graft. DLI was found to be effective in 39% of cases. Complications of the procedure occurred in 18 patients; of these, 2 died. To sum up DLI shows efficacy in a significant percentage of children. Mortality related to the therapy adverse effects is low. However, this method requires standardization.

Recipient leukocyte infusion enhances the local and systemic graft-versus-neuroblastoma effect of allogeneic bone marrow transplantation in mice

Allogeneic hematopoietic stem cell transplantation and donor leukocyte infusion (DLI) may hold potential as a novel form of immunotherapy for high-risk neuroblastoma. DLI, however, carries the risk of graft-versus-host disease (GvHD). Recipient leukocyte infusion (RLI) induces graft-versus-leukemia responses without GvHD in mice and is currently being explored clinically. Here, we demonstrate that both DLI and RLI, when given to mixed C57BL/6→A/J radiation chimeras carrying subcutaneous Neuro2A neuroblastoma implants, can slow the local growth of such tumors. DLI provoked full donor chimerism and GvHD; RLI produced graft rejection but left mice healthy. Flow cytometric studies showed that the chimerism of intratumoral leukocytes paralleled the systemic chimerism. This was associated with increased CD8/CD4 ratios, CD8+ T-cell IFN-γ expression and NK-cell Granzyme B expression within the tumor, following both DLI and RLI. The clinically safe anti-tumor effect of RLI was further enhanced by adoptively transferred naïve recipient-type NK cells. In models of intravenous Neuro2A tumor challenge, allogeneic chimeras showed superior overall survival over syngeneic chimeras. Bioluminescence imaging in allogeneic chimeras challenged with luciferase-transduced Neuro2A cells showed both DLI and RLI to prolong metastasis-free survival. This is the first experimental evidence that RLI can safely produce a local and systemic anti-tumor effect against a solid tumor. Our data indicate that RLI may provide combined T-cell and NK-cell reactivity effectively targeting Neuro2A neuroblastoma.

The cancer antigenome

Cancer cells deviate from normal body cells in two immunologically important ways. First, tumour cells carry tens to hundreds of protein-changing mutations that are either responsible for cellular transformation or that have accumulated as mere passengers. Second, as a consequence of genetic and epigenetic alterations, tumour cells express a series of proteins that are normally not present or present at lower levels. These changes lead to the presentation of an altered repertoire of MHC class I-associated peptides. Importantly, while there is now strong clinical evidence that cytotoxic T-cell activity against such tumour-associated antigens can lead to cancer regression, at present we fail to understand which tumour-associated antigens form the prime targets in effective immunotherapies. Here, we describe how recent developments in cancer genomics will make it feasible to establish the repertoire of tumour-associated epitopes on a patient-specific basis. The elucidation of this 'cancer antigenome' will be valuable to reveal how clinically successful immunotherapies mediate their effect. Furthermore, the description of the cancer antigenome should form the basis of novel forms of personalized cancer immunotherapy.

Trafficking of CAR-engineered human T cells following regional or systemic adoptive transfer in SCID beige mice

Adoptive immunotherapy using chimeric antigen receptor-engrafted T cells is a promising emerging therapy for cancer. Prior to clinical testing, it is mandatory to evaluate human therapeutic cell products in meaningful in vivo pre-clinical models. Here, we describe the use of fused single-photon emission CT-CT imaging to monitor real-time migration of chimeric antigen receptor-engineered T cells in immune compromised (SCID Beige) mice. Following intravenous administration, human T cells migrate in a highly similar manner to that reported in man, but penetrate poorly into established tumors. By contrast, when delivered via intraperitoneal or subcutaneous routes, T cells remain at the site of inoculation with minimal systemic absorption-irrespective of the presence or absence of tumor. Together, these data support the validity of pre-clinical testing of human T-cell immunotherapy in SCID Beige mice. In light of their established efficacy, regional administration of engineered human T cells represents an attractive therapeutic option to minimize toxicity in the treatment of selected malignancies.

Impact on relapse of corticosteroid therapy after allogeneic hematopoietic stem cell transplantation for acute myeloid leukemia

Corticosteroids are often used following allogeneic hematopoietic stem cell transplantation (HSCT) to control complications such as graft-versus-host disease (GVHD). However, there is some concern that corticosteroids may suppress the graft-versus-leukemia effect and increase leukemia relapse. To evaluate the effect of corticosteroids on relapse, we analyzed 112 adult patients who received their first allogeneic HSCT for acute myeloid leukemia at our institution between 1997 and 2007. Fifty-seven patients (50.9%) received corticosteroid therapy. Patients who had corticosteroid therapy included higher proportion of patients who developed GVHD. In multivariate analysis, with corticosteroid administration entered as a time-dependent covariate, corticosteroid administration was not a risk factor for relapse (p = 1.00, hazard ratio [HR] 1.00, 95% confidence interval [CI] 0.53-1.88), but it was associated with higher non-relapse mortality (NRM) (p < 0.001, HR 55.5, 95% CI 7.42-416) and lower overall survival (p < 0.001, HR 2.68, 95% CI 1.56-4.61). The higher NRM associated with corticosteroid administration was mainly due to the increased deaths caused by the complications themselves, which required corticosteroid therapy. The findings of this study indicate the importance of controlling complications after allogeneic HSCT. The strategy of refraining from indispensable corticosteroid therapy because of the excessive concerns about relapse should be avoided.

Bispecific antibodies engage T cells for antitumor immunotherapy

INTRODUCTION

Although considerable evidence supports the hypothesis that T cells play a critical role in the immune response against cancer, the ability to mount and sustain tumor-specific cellular responses in vivo remains a challenge. A strategy that harnesses the cytotoxic advantage of T cell therapy is the use of bispecific antibodies designed to engage and activate endogenous polyclonal T cell populations via the CD3 complex, but only in the presence of a tumor antigen. While antibody constructs with dual specificity were first described as anticancer therapeutics over 25 years ago, it was not until recently that one subclass of bispecific single-chain antibody, the bispecific T cell engager (BiTE), emerged as superior to previous iterations in achieving efficacy in animal models and early clinical trials.

AREAS COVERED

The evolution of bispecific antibodies in antitumor immunotherapy is reviewed and the greatest hurdles impeding their clinical translation are discussed, specifically in the context of immunoprivileged sites as is the case for intracerebral malignancy.

EXPERT OPINION

The BiTE platform has great potential in the treatment of malignant disease. Despite burgeoning interest in bispecific antibodies and permutations thereof, the issues of stability and cost-effective production persist as obstacles.

Safety analysis of ex vivo-expanded NK and NK-like T cells administered to cancer patients: a phase I clinical study

The chimeric state after allogeneic hematopoietic stem cell transplantation provides a platform for adoptive immunotherapy using donor-derived immune cells. The major risk with donor lymphocyte infusions (DLIs) is the development of graft-versus-host disease (GvHD). Development of new DLI products with antitumor reactivity and reduced GvHD risk represents a challenging task in cancer immunotherapy. Although natural killer (NK) and NK-like T cells are promising owing to their antitumor activity, their low concentrations in peripheral blood mononuclear cells reduces their utility in DLIs. We have recently developed a system that allows expansion of clinical-grade NK and NK-like T cells in large numbers. In this study, the safety of donor-derived long-term ex vivo-expanded human NK and NK-like T cells given as DLIs was investigated as immunotherapy for cancer in five patients following allogeneic stem cell infusion. Infusion of the cells was safe whether administered alone or with IL-2 subcutaneously. No signs of acute GvHD were observed. One patient with hepatocellular carcinoma showed markedly decreased serum alpha-fetoprotein levels following cell infusions. These findings suggest that the use of ex vivo-expanded NK and NK-like T cells is safe and appears an attractive approach for further clinical evaluation in cancer patients.

T-cell immunotherapy for malignant glioma: toward a combined approach

PURPOSE OF REVIEW

Immunotherapies using T lymphocytes are now considered as promising approaches for treating malignant glioma patients. This review discusses how basic understanding of antitumor T-cell responses in the brain are now leading to the rational planning of such novel therapeutic modalities.

RECENT FINDINGS

Clinical trials show that therapeutic vaccination with defined glioma antigens or dendritic cells pulsed with glioma lysates is feasible and generally well tolerated, but clinical efficacy has yet to be demonstrated in randomized trials. Preclinical data have established that effector T cells can be engineered to more efficiently recognize tumor cells via high-affinity T-cell receptors or chimeric antibody-like receptors. Animal studies have demonstrated that glioma immunotherapy is enhanced if immunosuppressive molecules (including transforming growth factor-beta) and glioma infiltrating regulatory T cells are inactivated. Clinical trials are under way assessing transforming growth factor-beta2 antisense oligonucleotides and regulatory T cell depletion. Combination of any of the above approaches with chemotherapy or radiotherapy is strongly supported by animal and clinical observations.

SUMMARY

Future T-cell immunotherapies will combine different strategies to deliver potent T cells to the glioma bed. The synergy of immunotherapies with radiotherapy and chemotherapy requires optimization, but it is now clear that these modalities are partners and not enemies.

Nonhematopoietic antigen blocks memory programming of alloreactive CD8+ T cells and drives their eventual exhaustion in mouse models of bone marrow transplantation

Allogeneic blood or BM transplantation (BMT) is the most commonly applied form of adoptive cellular therapy for cancer. In this context, the ability of donor T cells to respond to recipient antigens is coopted to generate graft-versus-tumor (GVT) responses. The major reason for treatment failure is tumor recurrence, which is linked to the eventual loss of functional, host-specific CTLs. In this study, we have explored the role of recipient antigen expression by nonhematopoietic cells in the failure to sustain effective CTL immunity. Using clinically relevant models, we found that nonhematopoietic antigen severely disrupts the formation of donor CD8+ T cell memory at 2 distinct levels that operate in the early and late phases of the response. First, initial and direct encounters between donor CD8+ T cells and nonhematopoietic cells blocked the programming of memory precursors essential for establishing recall immunity. Second, surviving CD8+ T cells became functionally exhausted with heightened expression of the coinhibitory receptor programmed death-1 (PD-1). These 2 factors acted together to induce even more profound failure in long-term immunosurveillance. Crucially, the functions of exhausted CD8+ T cells could be partially restored by late in vivo blockade of the interaction between PD-1 and its ligand, PD-L1, without induction of graft-versus-host disease, suggestive of a potential clinical strategy to prevent or treat relapse following allogeneic BMT.

Donor lymphocyte infusion for leukemia relapse after hematopoietic stem cell transplantation

Leukemia relapse is a serious therapeutic challenge following hematopoietic stem cell transplantation (HSCT). In this retrospective study, 23 patients [15 (65.2%) AML, 8 (34.8%) ALL] who received DLI+/-reinduction chemotherapy for post-transplant relapse were reviewed. The overall response rate of DLI was 66.7% for AML and 50% for ALL. A total of 15 patients (65.2%) developed acute graft versus host disease (GVHD). Response rates were higher in patients with GVHD (80% versus 25%; p=0.01; OR: 12.0). The probability of OS was better in patients who respond to DLI (p=0.04). Further strategies are required to improve the anti-tumor properties of alloreactive donor lymphocytes and to obtain durable responses with DLI in patients with relapsed acute leukemia after allogeneic HSCT.

Influence of lymphocyte recovery on outcome of haploidentical transplantation for hematologic malignancies

Unmanipulated human leukocyte antigen (HLA)-mismatched/haploidentical blood and marrow transplantation is an established treatment for patients without HLA-matched related or unrelated donors. However, the prognostic significance of early lymphocyte recovery in this transplant setting is not defined. In this study, we investigated the association of day 30 absolute lymphocyte count (ALC-30) with outcome after unmanipulated HLA-mismatched/haploidentical transplantation. We prospectively analyzed the relationship between ALC-30 and transplant outcomes in 206 patients with hematologic malignancies receiving T-cell-replete transplantation from HLA-mismatched/haploidentical related donors. Multivariate analysis showed that ALC-30 above the cutoff value of 300 cells/microL was associated with improved overall survival (hazard ratio [HR], 0.258; 95% confidence interval [CI], 0.141-0.472; p < 0.0001); improved cancer-free survival (HR, 0.289; 95% CI, 0.166-0.501; p < 0.0001); reduced relapse (HR, 0.370; 95% CI, 0.161-0.853; p = 0.020); and decreased transplant-related mortality (HR, 0.211; 95% CI, 0.097-0.457; p < 0.0001). Our results suggest that the recovery of ALC-30 might have an influence on transplant outcomes following unmanipulated HLA-mismatched/haploidentical transplantation.

A meta-analysis of patients receiving allogeneic or autologous hematopoietic stem cell transplant in mycosis fungoides and Sézary syndrome

The survival outlook in advanced mycosis fungoides (MF) is poor. Autologous and allogeneic stem cell transplants (SCT) have been shown, in small case series and case reports, to have the potential for long-term remission or to alter disease course. Allogeneic SCT is thought to have a curative potential secondary to a graft-versus-lymphoma (GVL) effect. A patient-level meta-analysis was performed to compare the outcome of allogeneic versus autologous SCT in patients with MF/Sézary syndrome (SS) using 39 cases from the literature. There were a total of 20 allogeneic and 19 autologous transplant cases. The gender, age, and stage distribution was similar between the transplant groups. The allogeneic group received significantly more systemic therapies prior to transplant (P < .0005) and had longer follow-up after transplant. Overall survival (OS) results showed a more favorable outcome of patients who received allogeneic SCT (P = .027). Event-free survival (EFS) demonstrated a more durable response in patients who received allogeneic SCT (P = .002). In the allogeneic group, the majority (70%) of patients experienced persistent graft-versus-host disease (GVHD), mostly with mild to moderate severity, and 2 of 4 deaths were related to GVHD. Meanwhile, the majority of the deaths (8 of 10) in the autologous group were because of progressive disease. These results support the belief that allogeneic SCT offers a better survival and disease-free outcome versus autologous SCT in MF/SS, likely because of a GVL effect.

Thymocyte expansion and maturation: crosstalk of CD44v6 on thymocytes and panCD44 on stroma cells

Re-acquisition of immunocompetence after allogeneic bone marrow cell (BMC) transplantation depends on intrathymic maturation of the allogeneic T progenitor cells. We recently reported that CD44 promotes progenitor homing into the thymus and T-cell maturation and now elucidate the molecular mechanisms of CD44-supported thymocyte maturation. Lethally irradiated, tumor-bearing mice, allogeneically reconstituted with T-cell-depleted BMC and a small number of common lymphoid progenitor 2 cells (CLP2) from transgenic (TG) mice, that express ratCD44v4-v7 under the Thy1 promoter, showed accelerated immunocompetent T-cell recovery compared with mice reconstituted with non-transgenic (NTG) CLP2. In addition, graft-versus-host disease was strongly reduced after tumor vaccination. TG, but not NTG double-negative (DN) thymocytes showed high proliferative potential, accompanied by constitutive association of lck with CD44. Importantly, when thymocyte adhesion was strengthened by anti-CD44, co-cultures of DN thymocytes with thymic stroma supported DN thymocyte maturation. The close contact between DN thymocytes and thymic stroma promoted persisting activation of lck and ERK1/2, particularly in CD44v6(+) DN thymocytes. Thus, intrathymic T-cell maturation in allogeneically reconstituted, leukemia-bearing hosts can be considerably accelerated by high CD44v6 expression in early thymocytes, in which proliferation-supporting signals are initiated by a crosstalk between CD44v6 on thymocytes and panCD44 on the thymic stroma.

Use of tumour-responsive T cells as cancer treatment

The stimulation of a tumour-specific T-cell response has several theoretical advantages over other forms of cancer treatment. First, T cells can home in to antigen-expressing tumour deposits no matter where they are located in the body-even in deep tissue beds. Additionally, T cells can continue to proliferate in response to immunogenic proteins expressed in cancer until all the tumour cells are eradicated. Finally, immunological memory can be generated, allowing for eradication of antigen-bearing tumours if they reoccur. We will highlight two direct methods of stimulating tumour-specific T-cell immunity: active immunisation with cancer vaccines and infusion of competent T cells via adoptive T-cell treatment. Preclinical and clinical studies have shown that modulation of the tumour microenvironment to support the immune response is as important as stimulation of the most appropriate effector T cells. The future of T-cell immunity stimulation to treat cancer will need combination approaches focused on both the tumour and the T cell.

Allogeneic bone marrow transplantation and donor lymphocyte infusion in a mouse model of irradiation-induced myelodysplastic/myeloproliferation syndrome (MD/MPS): evidence for a graft-versus-MD/MPS effect

The role of graft-versus-malignancy reactivity in the effects of allogeneic hematopoietic stem cell transplantation and donor lymphocyte infusion (DLI) for myelodysplastic syndromes is as yet not well established. Clinical data are limited and animal models are scarce. Here, we report on the effects of allogeneic bone marrow transplantation (alloBMT) and DLI in a novel model of irradiation-induced murine myelodysplastic/myeloproliferation syndrome (MD/MPS). Total body irradiation with 8.5 Gy in SJL/J mice gave rise to a lethal wasting syndrome in 60% of mice, characterized by 1 degrees normocellular bone marrow with dysplastic features in erythroid, myeloid and megakaryocytic cell lineages, 2 degrees lymphosplenomegaly with spleens harboring a prominent extramedullary hematopoiesis with erythroid, myeloid and megakaryocytic lineages exhibiting dysplastic features, and foci of dysplastic hematomyelopoiesis in the liver, 3 degrees peripheral thrombocytopenia and 4 degrees evidence of disseminated infection or leukemic transformation in selected animals. This clinicopathological picture was consistent with a murine form of MD/MPS. Syngeneic or allogeneic (BALB/c) T cell-depleted BMT could not prevent the occurrence of lethal MD/MPS. In contrast, DLI at weeks 2-4 after BMT led to restoration of the dysbalanced hematomyelopoiesis. However, severe DLI-induced acute graft-versus-host disease occurred, precluding a survival advantage. We present evidence of the existence of a post-alloBMT DLI-induced graft-versus-MD/MPS effect in murine irradiation-induced MD/MPS.

Autologous and allogeneic hematopoietic stem cell transplantation for Multiple Sclerosis: perspective on mechanisms of action

Multiple Sclerosis (MS) is a frequent demyelinating immune-mediated disease of the central nervous system (CNS) that affects principally young adults and leads to severe physical and cognitive impairment. The current standard treatment makes use of the immune modulators beta-interferon, glatiramer acetate and natalizumab, or immunosuppressants such as mitoxantrone. However, these agents are only partially effective and in a number of patients fail to achieve satisfactory disease control. Autologous hematopoietic stem cell transplantation (HSCT) is being explored in the treatment of severe MS as a means of delivering high-dose immunosuppression followed by 'rescue' of the immuno-hematopoietic system with autologous HSC. The potential therapeutic benefit is based on the concept of so-called 'resetting' the immune system. The use of allogeneic HSCT as a possible therapeutic approach for severe MS is inspired by case reports of MS patients that underwent allogeneic HSCT for a concomitant hematological malignancy, and subsequently is supported by data from rodent models of MS. Allogeneic HSCT may offer specific therapeutic effects, such as the replacement of the autoreactive immune compartment by healthy allogeneic cells and the development of a graft-versus-autoimmunity (GVA) effect. Here, we review the currently available experimental and clinical evidence to support the role of autologous and allogeneic HSCT in MS.

Regression of human kidney cancer following allogeneic stem cell transplantation is associated with recognition of an HERV-E antigen by T cells

Transplanted donor lymphocytes infused during hematopoietic stem cell transplantation (HSCT) have been shown to cure patients with hematological malignancies. However, less is known about the effects of HSCT on metastatic solid tumors. Thus, a better understanding of the immune cells and their target antigens that mediate tumor regression is urgently needed to develop more effective HSCT approaches for solid tumors. Here we report regression of metastatic renal cell carcinoma (RCC) in patients following nonmyeloablative HSCT consistent with a graft-versus-tumor effect. We detected RCC-reactive donor-derived CD8(+) T cells in the blood of patients following nonmyeloablative HSCT. Using cDNA expression cloning, we identified a 10-mer peptide (CT-RCC-1) as a target antigen of RCC-specific CD8(+) T cells. The genes encoding this antigen were found to be derived from human endogenous retrovirus (HERV) type E and were expressed in RCC cell lines and fresh RCC tissue but not in normal kidney or other tissues. We believe this to be the first solid tumor antigen identified using allogeneic T cells from a patient undergoing HSCT. These data suggest that HERV-E is activated in RCC and that it encodes an overexpressed immunogenic antigen, therefore providing a potential target for cellular immunity.

Tumor-specific Th17-polarized cells eradicate large established melanoma

CD4+ T cells can differentiate into multiple effector subsets, but the potential roles of these subsets in anti-tumor immunity have not been fully explored. Seeking to study the impact of CD4+ T cell polarization on tumor rejection in a model mimicking human disease, we generated a new MHC class II-restricted, T-cell receptor (TCR) transgenic mouse model in which CD4+ T cells recognize a novel epitope in tyrosinase-related protein 1 (TRP-1), an antigen expressed by normal melanocytes and B16 murine melanoma. Cells could be robustly polarized into Th0, Th1, and Th17 subtypes in vitro, as evidenced by cytokine, chemokine, and adhesion molecule profiles and by surface markers, suggesting the potential for differential effector function in vivo. Contrary to the current view that Th1 cells are most important in tumor rejection, we found that Th17-polarized cells better mediated destruction of advanced B16 melanoma. Their therapeutic effect was critically dependent on interferon-gamma (IFN-gamma) production, whereas depletion of interleukin (IL)-17A and IL-23 had little impact. Taken together, these data indicate that the appropriate in vitro polarization of effector CD4+ T cells is decisive for successful tumor eradication. This principle should be considered in designing clinical trials involving adoptive transfer-based immunotherapy of human malignancies.