167 research outputs found
Disease stage variation in CD4+ and CD8+ T-cell reactivity to the receptor tyrosine kinase EphA2 in patients with renal cell carcinoma.
No full textWe have evaluated CD8+ and CD4+ T-cell responses against a new tumor-associated antigen, the receptor tyrosine kinase EphA2, which is broadly expressed in diverse cancer histologies and is frequently overexpressed in advanced stage/metastatic disease. We report herein that EphA2 is overexpressed in renal cell carcinoma (RCC) cell lines and clinical specimens of RCC, and rind that the highest levels of EphA2 are consistently found in the most advanced stages of the disease. We identified and synthesized five putative HLA class I-binding and three class II-binding peptides derived from EphA2 that might serve as targets for immune reactivity. Each peptide induced specific, tumor-reactive CD8+ or CD4+T-cell responses as measured using IFN-gamma enzyme-linked immunospot assays. The EphA2 peptides elicited relatively weak responses from CD8+ T cells derived from normal healthy volunteers or from RCC patients with active disease. In marked contrast, immune reactivity to EphA2-derived epitopes was greatly enhanced in CD8+ T cells that had been isolated from patients who were rendered disease-free, after surgery. Furthermore, enzyme-linked immunospot analyses demonstrated prominent EphA2-restricted T-helper 1-type CD4+ T cell activity in patients with early stage disease, whereas T-helper 2-type and T regulatory-type responses predominated in patients with more advanced forms of RCC. These data suggest that the immune system of cancer patients actively monitors EphA2-derived epitopes, and that the magnitude and character of T-cell responses to EphA2 epitopes may convey much-needed predictive information about disease stage and outcome
Engaging the Immune Response to Normalize the Tumor Microenvironment
No full textSolid tumors exist as heterogeneous populations comprised not only of malignant cells, but various other cell types, including cells that make up the vasculature, that can strongly influence tumorgenicity. Many forms of solid cancers are highly vascularized due to dysregulated angiogenesis. The tumor vasculature is classified by leaky, chaotic blood vessels consisting of several components including vascular endothelial cells and pericytes, as well vascular progenitors, resulting in vascular permeability and high interstitial pressure. As a result, the tumor vasculature limits the access of immune effector cells to the tumor, and may in part be responsible for the modest success observed in many current anti-cancer immunotherapies. Current first-line therapeutics in the advanced stage disease setting include anti-angiogenic small molecule drugs that have yielded high objective clinical response rates, however these responses tend to be transient in nature, with most patients becoming drug-refractory. Anti-tumor vasculature vaccines may promote the reconditioning of the tumor microenvironment by coordinately promoting a pro-inflammatory environment and the specific immune targeting of tumor-associated stromal cell populations that contribute to vasculature destabilization. Implementing a vaccine with these therapeutic effects is a promising treatment option that may extend disease-free intervals and overall patient survival. I show that vaccines specifically targeting tumor vasculature populations can “normalize” the tumor microenvironment, as shown by upregulation of proinflammatory molecules within the tumor as well as vascular remodeling promoting enhanced recruitment of CD8+ T cells, resulting in superior anti-tumor efficacy
Disease-associated bias in T helper type 1(Th1)/Th2 CD4(+) T cell responses against MAGE-6 in HLA-DRB10401(+) patients with renal cell carcinoma or melanoma
No full textT helper type 1 (Th1)-type CD4(+) antitumor T cell help appears critical to the induction and maintenance of antitumor cytotoxic T lymphocyte (CTL) responses in vivo. In contrast, Th2- or Th3/Tr-type CD4(+) T cell responses may subvert Th1-type cell-mediated immunity, providing a microenvironment conducive to disease progression. We have recently identified helper T cell epitopes derived from the MAGE-6 gene product; a tumor-associated antigen expressed by most melanomas and renal cell carcinomas. In this study, we have assessed whether peripheral blood CD4(+) T cells from human histocompatibility leukocyte antigens (HLA)-DRbeta1*0401(+) patients are Th1- or Th2-biased to MAGE-6 epitopes using interferon (IFN)-gamma and interleukin (IL)-5 enzyme-linked immunospot assays, respectively. Strikingly, the vast majority of patients with active disease were highly-skewed toward Th2-type responses against MAGE-6-derived epitopes, regardless of their stage (stage I versus IV) of disease, but retained Th1-type responses against Epstein-Barr virus- or influenza-derived epitopes. In marked contrast, normal donors and cancer patients with no current evidence of disease tended to exhibit either mixed Th1/Th2 or strongly Th1-polarized responses to MAGE-6 peptides, respectively. CD4+ T cell secretion of IL-10 and transforming growth factor (TGF)-beta1 against MAGE-6 peptides was not observed, suggesting that specific Th3/Tr-type CD4(+) subsets were not common events in these patients. Our data suggest that immunotherapeutic approaches will likely have to overcome or complement systemic Th2-dominated, tumor-reactive CD4(+) T cell responses to provide optimal clinical benefit
Mature dendritic cells pulsed with freeze-thaw cell lysates define an effective in vitro vaccine designed to elicit EBV-specific CD4(+) and CD8(+) T lymphocyte responses
No full textImmunotherapy trials targeting the induction of tumor-reactive T-cell responses in cancer patients appear to hold significant promise, Because nonmutated lineage-specific antigens and mutated idiotypic antigens may be coexpressed by tumor cells, the use of autologous tumor material to promote the broadest range of antitumor T-cell specificities has significant clinical potential in cancer vaccination trials. As a model for vaccination in the cancer setting, we chose to analyze the promotion of T-cell responses against Epstein-Barr virus (EBV)transformed B-lymphoblastoid cell line (B-LCL)-derived antigens in vitro. A series of bulk antigenic formats (freeze-thaw lysate, trifluoroacetic acid lysate, extracted membranes, affinity-purified MHC class I- and class Ii-presented peptides, acid-eluted peptides) prepared from EBV B-LCLs were tested for their ability to stimulate EBV B-LCL-reactive CD4(+) and CD8(+) T lymphocytes in vitro when pulsed onto autologous dendritic cells (DCs). DC presentation of freeze-thaw lysate material derived from (either autologous or allogeneic) EBV B-LCLs with an Mr of 10 kd or larger stimulated optimal anti-EBV B-LCL responsiveness from freshly isolated CD4(+) and CD8(+) peripheral blood T cells. These in vivo "memory" T-cell responses were observed only in EBV-seropositive donors. CD4(+) T-cell responses to lysate-pulsed DCs were Th1 type tie, strong interferon-gamma and weak interleukin-5 responses). While CD8(+) T-cell responses were also observed in interferon-gamma Elispot assays and in cytotoxicity assays, these responses were of low frequency unless the DC stimulators were induced to "mature" after being fed with tumor lysates, Optimal-length, naturally processed, and MHC class I- or class It-presented tumor peptides were comparatively poorly immunogenic in this model system. (C) 2000 by The American Society of Hematology
IL-12p70 and IL-18 gene-modified dendritic cells loaded with tumor antigen-derived peptides or recombinant protein effectively stimulate specific Type-1 CD4+ T-cell responses from normal donors and melanoma patients in vitro.
No full textAlthough CD4(+) Type-1T helper (Th1) cells secreting interferon-gamma (IFN-gamma) appear to play an essential role in promoting durable antitumor immunity, we have previously shown that patients with cancer exhibit dysfunctional Th1-type responses against epitopes derived from tumor antigens, such as MAGE-A6. Here, we engineered human dendritic cells (DCs) to secrete high levels of the IFN-gamma-inducing cytokines, interleukin (IL)-12p70 and IL-18, via recombinant adenoviral infection to generate an in vitro stimulus capable of promoting previously deficient patient Th1-type responses. Dendritic cells co- infected with Ad. IL-12 and Ad. IL-18 (DC. IL-12/18) were more effective at stimulating MAGE-A6-specific Th1-type CD4(+) T-cell responses than DCs infected with either of the cytokine vectors alone, control Ad. C5 virus or uninfected DCs. Furthermore, we show that DC. IL-12/18 loaded with recombinant MAGE-A6 protein (rMAGE) and used as in vitro stimulators promote Th1-type immunity that is frequently directed against multiple MAGE-A6-derived epitopes. The superiority of DC. IL-12/18-based stimulations in melanoma patients was independent of disease stage or current disease status. Based on these results, we believe this modality may prove clinically useful as a vaccine platform to promote the recovery of tumor antigen-specific, Th1-type CD4(+) T-cell responses in patients with cancer
gp100/pmel17 and tyrosinase encode multiple epitopes recognized by Th1-type CD4+T cells.
No full textCD4(+) T cells modulate the magnitude and durability of CTL responses in vivo, and may serve as effector cells in the tumour microenvironment. In order to identify the turnout epitopes recognized by tumour-reactive human CD4+ T cells, we combined the use of an HLA-DR4/peptide binding algorithm with an IFN-gamma ELISPOT assay. Two known and three novel CD4+ T cell epitopes derived from the gp 100/pmel17 and tyrosinase mefanocyte-associated antigens were confirmed or identified. Of major interest, we determined that freshly-isolated PBMC frequencies of Th1-type CD4+ T recognizing these peptides are frequently elevated in HLA-DR4+ melanoma patients (but not normal donors) that are currently disease-free as a result of therapeutic intervention. Epitope-specific CD4+ T cells from normal DR4+ donors could be induced, however, after in vitro stimulation with autologous dendritic cell pulsed with antigens (peptides or antigen-positive melanoma lysates) or infected with recombinant vaccinia virus encoding the relevant antigen. Peptide-reactive CD4+ T cells also recognized HLA-DR4+ melanoma cell lines that constitutively express the relevant antigen. Based on these data, these epitopes may serve as potent vaccine components to promote clinically-relevant Th1-type CD4+ T cell effector function in situ. (C) 2001 Cancer Research Campaign
MAGE-6 encodes HLA-DRbeta1*0401-presented epitopes recognized by CD4+ T cells from patients with melanoma or renal cell carcinoma
No full textCD4+ T cells modulate the magnitude and durability of CTL responses in vivo and may serve as potent effector cells within the tumor microenvironment. The current study was undertaken to define novel epitopes from the broadly expressed tumor antigen MAGE-6 that are recognized by CD4+ T cells. We have combined the use of a HLA-DR4/peptide binding algorithm with the IFN-gamma enzyme-linked immunospot assay to identify four nonoverlapping sequences derived from the MAGE-6 protein that served as CD4+ T-cell epitopes in HLA-DR4+ donors. Strikingly, patients with active melanoma or renal cell carcinoma failed to secrete IFN-gamma in response to MAGE-6-derived epitopes, whereas both normal donors and cancer patients with no current evidence of disease were responsive, particularly after short-term in vitro stimulations with peptide-pulsed dendritic cells. Importantly, peptide-specific CD4+ T cells also recognized HLA-DRbeta1*0401+ tumor cells that constitutively expressed the MAGE-6 protein and autologous HLA-DRbeta1*0401+ dendritic cells transfected with MAGE-6 cDNA-elicited CD4+ T cells that reacted against individual peptide epitopes in vitro. These data suggest that MAGE-6-derived epitopes could serve as useful vaccine candidate components and may provide an immune-monitoring index of clinically important Th1-type immunity in patients with renal cell carcinoma or melanoma
Mature dendritic cells pulsed with freeze-thaw cell lysates define an effective in vitro vaccine designed to elicit EBV-specific CD4(+) and CD8(+) T lymphocyte responses
No full textJAK3/STAT5/6 pathway alterations are associated with immune deviation in CD8 T cells in renal cell carcinoma patients.
No full textTo investigate the molecular mechanisms underlying altered T cell response in renal cell carcinoma (RCC) patients, we compared autologous and allogeneic CD8(+) T cell responses against RCC line from RCC patients and their HLA-matched donors, using mixed lymphocyte/tumor cell cultures (MLTCs). In addition, we analyzed the expression of molecules associated with cell cycle regulation. Autologous MLTC responder CD8(+) T cells showed cytotoxic activity against RCC cell lines; however the analysis of the distribution of CD8(+) T-cell subsets revealed that allogenic counterparts mediate superior antitumor efficacy. In RCC patients, a decreased proliferative response to tumor, associated with defects in JAK3/STAT5/6 expression that led to increased p27KIP1 expression and alterations in the cell cycle, was observed. These data define a molecular pathway involved in cell cycle regulation that is associated with the dysfunction of tumor-specific CD8(+) effector cells. If validated, this may define a therapeutic target in the setting of patients with RCC
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