Expression of B7.1 (CD80) in a renal cell carcinoma line allows expansion of tumor-associated cytotoxic T lymphocytes in the presence of an alloresponse

Low expression of CD80 predicts for poor prognosis in patients with gastric adenocarcinoma

AIM

To study the expression and prognostic significance of CD80 in patients with gastric adenocarcinoma. Materials & methods: Real-time quantitative PCR, western blot and immunohistochemistry were performed to detect the expression of CD80 in gastric cancer tissues and matched adjacent normal tissues. Double immunohistochemical staining was performed to preliminary examine the relationship between CD80⁺ cells and CD8⁺ cytotoxic T lymphocytes.

RESULTS

The expression of CD80 was downregulated in tumor tissues compared with normal tissues (p = 0.002). Immunohistochemistry analysis showed that 49 (39.8%) of 123 patients with gastric cancer demonstrated reduced CD80 expression, which was correlated with the tumor differentiation grade.

CONCLUSION

Our data suggest that reduced CD80 expression independently predicts a poor prognosis in patients with gastric adenocarcinoma.

MIDGE Technology for the Production of a Fourfold Gene-Modified, Allogenic Cell-Based Vaccine for Cancer Therapy

Gene modification of eukaryotic cells by electroporation is a widely used method to express selected genes in a defined cell population for various purposes, like gene correction or production of therapeutics. Here, we describe the generation of a cell-based tumor vaccine via fourfold transient gene modification of a human renal cell carcinoma (RCC) cell line for high expression of CD80, CD154, GM-CSF, and IL-7 by use of MIDGE(®) vectors. The two co-stimulatory molecules CD80 and CD154 are expressed at the cell surface, whereas the two cytokines GM-CSF and IL-7 are secreted yielding cells with enhanced immunological properties. These fourfold gene-modified cells have been used as a cell-based tumor vaccine for the treatment of RCC.

Immunotherapy of genitourinary malignancies

Most cancer patients are treated with some combination of surgery, radiation, and chemotherapy. Despite recent advances in local therapy with curative intent, chemotherapeutic treatments for metastatic disease often remain unsatisfying due to severe side effects and incomplete long-term remission. Therefore, the evaluation of novel therapeutic options is of great interest. Conventional, along with newer treatment strategies target the immune system that suppresses genitourinary (GU) malignancies. Metastatic renal cell carcinoma and non-muscle-invasive bladder caner represent the most immune-responsive types of all human cancer. This review examines the rationale and emerging evidence supporting the anticancer activity of immunotherapy, against GU malignancies.

Phase 1 trial of allogeneic gene-modified tumor cell vaccine RCC-26/CD80/IL-2 in patients with metastatic renal cell carcinoma

Preclinical studies showed that the allogeneic tumor cell line RCC-26 displayed natural immunogenic potential that was enhanced through expression of CD80 costimulatory molecules and secretion of interleukin-2. Here we report the study of RCC-26/CD80/IL-2 cells in a phase 1 vaccine trial of renal cell carcinoma patients with metastatic disease (mRCC). Fifteen patients of the HLA-A*0201 allotype, with at least one metastatic lesion, were included. Irradiated vaccine cells were applied in increasing doses of 2.5, 10, and 40 x 10(6) cells over 22 weeks. Primary study parameters included safety and toxicity. Sequential blood samples were analyzed by interferon-gamma enzyme-linked immunospot assays to detect tumor antigen-associated (TAA) effector cells. The vaccine was well tolerated and the designated vaccination course was completed in 9 of 15 patients. Neither vaccine-induced autoimmunity nor systemic side effects were observed. Delayed-type hypersensitivity skin reactions were detected in 11 of 12 evaluated patients and were particularly strong in patients with prolonged survival. In parallel, vaccine-induced immune responses against vaccine or overexpressed TAA were detected in 9 of 12 evaluated patients. No tumor regressions occurred according to RECIST (Response Evaluation Criteria in Solid Tumors) criteria; however, median time to progression was 5.3 months and median survival was 15.6 months, indicating substantial disease stabilization. We conclude that vaccine use was safe and feasible in mRCC. Clinical benefits were limited in these patients with advanced disease; however, immune monitoring revealed vaccine-induced responses against multiple TAAs in the majority of study participants. These results suggest that this vaccine could be useful in combination therapies and/or minimal residual disease.

Overview of Tumor Cell–Based Vaccines

Whole-cell tumor vaccines have been investigated for more than 20 years for their efficacy in both preclinical models and in clinical trials in humans. There are clear advantages of whole-cell/polyepitope vaccination over those types of immunotherapy that target specific epitopes. Multiple and unknown antigens may be targeted to both the innate and adaptive immune system, and this may be further augmented by genetic modification of the vaccine cells to provide cytokines and costimulation. In this review, we give an overview of the field including the preclinical and clinical advances using unmodified and modified tumor-cell vaccines.

NK-cell-mediated killing of target cells triggers robust antigen-specific T-cell-mediated and humoral responses

Previous work showed that administration of antigen-expressing apoptotic cells in vivo results in antigen-specific CD8+ T-cell responses independent of Toll-like receptor signaling. We report here that natural killer (NK) cells can serve a function directly upstream of this pathway and initiate robust adaptive immune responses via killing of antigen-expressing target cells. This pathway is highly sensitive, in that administration of as few as 10(4) target cells induced detectable antigen-specific CD8+ T-cell responses. Importantly, NK cell-mediated cytotoxicity of target cells could also induce robust antigen-specific CD4+ T-cell responses, which were critical for subsequent CD8+ T-cell priming and IgG responses. Unlike adaptive immune responses induced by gamma-irradiated cells, the NK-cell pathway required myeloid differentiating factor 88 (MyD88) and Toll/interleukin-1 receptor domain-containing adapter-inducing interferon-beta (Trif) signaling. NK cells have previously been shown to detect and kill pathogen-infected host cells, as well as neoplastic cells and tissue allografts. The present data provide further evidence that they also discharge a strong tie with their relatives in the adaptive immune system. We think that the recognition and killing of target cells by NK cells represents an important pathway for the generation of robust CD8+ T and humoral responses that may be exploited for vaccine development.

Identification of HLA-CW3, GNAS and IMPA as cytotoxic T-lymphocyte (CTL) target antigens using an allogeneic mixed lymphocyte tumor cell culture (MLTC) system and subsequent cDNA library screening

Allogeneic mixed lymphocyte tumor cell cultures (MLTCs) were established using lymphocytes from non-small-cell lung cancer (NSCLC) patient UKY-53 and HLA-A2+ NSCLC tumor cells (UKY-29). The tumor cells expressed the lymphocyte costimulatory molecule CD80 (UKY29.7). Cytolytic activity showed the cytotoxic T-lymphocytes (CTL) lysed UKY-29, but not K562 or Daudi. The CTL also lysed: HLA-A2+ and -A24+ tumor cell lines from a number of tumor histologies. The CTL also lysed Epstein Barr virus transformed (EBV) B-cells, UKY-29EBV, autologous to the stimulating cell line, UKY29TC. These data suggested the presence of both tumor-specific and allogeneic reactivities in the bulk CTL population. Subsequent cDNA cloning analysis and sequencing demonstrated that the bulk CTL population was recognizing: (i) allogeneic target HLA-CW3, and two minor histocompatibility antigens; (ii) guanine nucleotide-binding protein, G(S) (GNAS), and (iii) inositol myophosphatase (IMPA). All three antigens, we believe, were restricted by HLA-A2. Whereas the system described was initially intended to identify tumor-associated antigens recognized by CTL, the nature of the allogeneic system provides a unique opportunity for the identification of epitopes that confer both allo and minor antigen recognition.

Preclinical development of hybrid cell vaccines for multiple myeloma

Immunotherapy may provide alternative or supplementary treatment of multiple myeloma (MM). We propose that hybrid cells, formed by fusing professional antigen-presenting cells with malignant plasma cells, would induce immune responses capable of mediating tumour regression. The human B-lymphoblastoid cell line, HMy2, was fused in vitro with CD138+ bead-separated myeloma plasma cells from five patients with MM. The hybrid cell lines generated in these studies grew stably in tissue culture, and maintained their phenotypic and functional characteristics, providing self-renewing cell lines with potential for therapeutic vaccination. The hybrid cells stimulated allogeneic and autologous T-cell proliferative responses in vitro to a considerably greater degree than their respective parent myeloma plasma cells, and directly activated both CD4+ and CD8+ T-cell responses. The enhanced T-cell stimulation correlated with expression of CD80 on the hybrid cells, and was inhibited by CTLA4-Ig fusion protein. The hybrid cell lines expressed several tumour-associated antigens known to be expressed in myeloma. These data show that self-replicating cell lines with enhanced immunostimulatory properties and potential for therapeutic vaccination can be generated by in vitro fusion of ex vivo myeloma cells and B-lymphoblastoid cell lines.

Hybrid cells formed by fusion of Epstein - Barr virus-associated B-lymphoblastoid cells and either marrow-derived or solid tumour-derived cell lines display different co-stimulatory phenotypes and abilities to activate allogeneic T-cell responses in vitro

A panel of stable cell hybrids was generated by fusing a range of marrow-derived and solid tumour-derived human cell lines with the B-lymphoblastoid cell lines, HMy2 or KR4, and expression of immunologically relevant accessory and co-stimulatory molecules, and ability to stimulate allogeneic T-cell responses in vitro was investigated. Hybrid cell lines generated from three marrow-derived tumour cells consistently expressed both MHC class I and class II molecules, a range of accessory and T-cell co-stimulatory ligand molecules, including CD80 and CD86, and directly stimulated markedly enhanced T-cell proliferative responses in vitro, as compared with the parent tumour cell lines. The responses were blocked by addition of CTLA4-Ig fusion protein to the cultures, indicating a role of CD28/B7 interaction in induction of T-cell activation. By contrast, hybrid cells derived from three solid tumours only expressed MHC class II when the parent tumour cell line expressed MHC class II and consistently failed to express CD80 or CD86. These hybrid cells also stimulated greater T-cell proliferative responses in vitro than the parent tumour cell lines, although effective co-stimulation depended on the presence of responder non-T cells in the cultures. The expression of co-stimulatory ligand molecules and ability to directly stimulate strong allogeneic T-cell responses correlated with the EBV latency type of the hybrid cells. These data suggest that phenotypic and functional differences in fusion cells of professional antigen- presenting cells and tumour cells arise as a result of the parent tumour cell type.

An immune edited tumour versus a tumour edited immune system: Prospects for immune therapy of acute myeloid leukaemia

Cell based therapies for acute myeloid leukaemia (AML) have made significant progress in the last decade benefiting the prognosis and survival of patients with this aggressive form of leukaemia. Due to advances in haematopoietic stem cell transplantation (HSCT) and particularly the advent of reduced intensity conditioning (RIC), the scope of transplantation has now extended to those patients previously ineligible due to age and health restrictions and has been associated with a decrease in transplant related mortality. The apparent graft versus leukaemia (GvL) effect observed following HSCT demonstrates the potential of the immune system to target and eradicate AML cells. Building on previously published pre-clinical studies by ourselves and others, we are now initiating a Phase I clinical study in which lentiviral vectors are used to genetically modify AML cells to express B7.1 (CD80) and IL-2. By combining allogeneic HSCT with immunisation, using the autologous AML cells expressing B7.1 and IL-2, we hope to stimulate immune eradication of residual AML cells in poor prognosis patients that have achieved donor chimerism. In this report we describe the background to cell therapy based approaches for AML, and discuss difficulties associated with the deployment of a chronically stimulated, hence exhausted/depleted immune system to eradicate tumour cells that have already escaped immune surveillance.

Primary tumor cells resected from cancer patients and decorated with a novel form of CD80 protein serve as effective antigen-presenting cells for the induction of autologous T cell immune responses ex vivo

Vaccination with autologous tumor cells genetically modified to express costimulatory molecules has shown utility for cancer immunotherapy in preclinical and limited clinical settings. Given the complicated nature of gene therapy, a practical alternative approach has been designed that relies on modification of the cell membrane with biotin and its "decoration" with a chimeric protein composed of the functional portion of human CD80 and core streptavidin (CD80-SA). We tested whether primary tumor cells resected from cancer patients can be decorated with CD80-SA and whether such cells serve as antigen-presenting cells (APCs) to generate autologous T cell responses ex vivo. Tumors and peripheral blood lymphocytes (PBLs) were collected from 14 lung, 9 colon, and 2 breast "treatment-naive" cancer patients presenting various clinical stages of the disease. Tumors were mechanically processed, irradiated, decorated with CD80-SA or control streptavidin (SA) protein, and used as APCs in ex vivo autologous T cell-proliferative and cytotoxicity assays. All tumor samples were modified with CD80-SA, albeit with various degrees of decoration ranging from 21.8 to 100%. CD80- SA-decorated cells generated significant proliferative responses in autologous T cells from 9 of 16 evaluable patients (p < 0.05). Proliferative responses were CD80-SA specific and heterogeneous, with stimulation indices ranging from 0.25 to 45. In 15 of 15 evaluable patients, CD80-SA-specific cytotoxic T cell responses against autologous tumors were generated, 11 of which were significant, with specific killing ranging from 5 to 70%. Taken together, these data demonstrate that primary tumor cells can be effectively decorated with CD80-SA and that such cells serve as APCs to induce autologous antitumor T cell responses.

GPI-anchored TIMP-1 treatment renders renal cell carcinoma sensitive to FAS-meditated killing

The resistance of tumours to immune-mediated lysis has been linked to the biology of matrix metalloproteinases (MMPs), and specifically to the cell surface expression of MMPs by the tumour cell. The endogenous tissue inhibitors of metalloproteinases (TIMPs) exhibit diverse physiological/biological functions including the moderation of tumour growth, metastasis and apoptosis. These biologic activities are mediated in part by the stoichiometry of TIMP/MMP/cell surface protein interactions. A glycosylphosphatidylinositol (GPI) anchor was fused to TIMP-1 to focus defined concentrations of this inhibitory protein on the surface of three renal cell carcinoma (RCC) cell lines (RCC-26, RCC-53 and A498) independently of cell surface protein-protein interactions. Exogenously added TIMP-1-GPI efficiently inserted into the RCC cell membrane and dramatically altered the association of MMPs with the cell surface. TIMP-1-GPI treatment inhibited RCC proliferation and rendered the normally FAS-resistant RCC cells sensitive to FAS-induced apoptosis but did not alter perforin-mediated lysis by cytotoxic effector cells. The increased sensitivity to FAS-mediated apoptosis correlated with an alteration in the balance of pro- and antiapoptotic BCL-2-family proteins. By interfering with the proliferative capacity and inducing sensitivity to immune effector mechanisms GPI-anchored TIMP-1 may represent a more effective version of the TIMP-1 protein for therapeutic strategies.

A generic RNA-pulsed dendritic cell vaccine strategy for renal cell carcinoma

We present a generic dendritic cell (DC) vaccine strategy for patients with renal cell carcinoma (RCC) based on the use of RNA as a source of multiplex tumor-associated antigens (TAAs). Instead of preparing RNA from tumor tissue of each individual RCC patient, we propose to substitute RNA prepared from a well characterized highly immunogenic RCC cell line (RCC-26 tumor cells) as a generic source of TAAs for loading of DCs. We demonstrate here that efficient RNA transfer can be achieved using lipofection of immature DCs, which are subsequently matured with a cytokine cocktail to express high levels of MHC and costimulatory molecules as well as the chemokine receptor CCR7. Neither RNA itself nor the lipid component impacted on the phenotype or the cytokine secretion of mature DCs.

Following RNA loading, DCs derived from HLA-A2-positive donors were able to activate effector-memory cytotoxic T lymphocytes (CTLs) specific for a TAA ligand expressed by the RCC-26 cell line. CTL responses to RNA-loaded DCs reached levels comparable to those stimulated directly by the RCC-26 tumor cells. Furthermore, DCs expressing tumor cell RNA primed naïve T cells, yielding T cell lines with cytotoxicity and cytokine secretion after contact with RCC tumor cells. RCC-26 cell lines are available as good manufacturing practice (GMP)-certified reagents enabling this source of RNA to be easily standardized and adapted for clinical testing. In addition, well defined immune monitoring tools, including the use of RNA expressing B cell lines, are available. Thus, this DC vaccine strategy can be directly compared with an ongoing gene therapy trial using genetically-engineered variants of the RCC-26 cell line as vaccines for RCC patients with metastatic disease.

Cell-based vaccines for renal cell carcinoma: genetically-engineered tumor cells and monocyte-derived dendritic cells

Initial vaccine developments for renal cell carcinoma (RCC) have concentrated on cell-based approaches in which tumor cells themselves provide mixtures of unknown tumor-associated antigens as immunizing agents. Antigens derived from autologous tumors can direct responses to molecular composites characteristic of individual tumors, whereas antigens derived from allogeneic tumor cells must be commonly shared by RCC. Three types of cell-based vaccine for RCC have been investigated: isolated tumor cell suspensions, gene modified tumor cells and dendritic cells (DCs) expressing RCC-associated antigens. Approaches using genetic modification of autologous RCC have included ex vivo modification of tumor cells or modification of tumors in vivo. We have used gene-modification of allogeneic tumor cell lines to create generic RCC vaccines. More recently, emphasis has shifted to the use of DCs as cell-based vaccines for RCC. DCs have moved to a position of central interest because of their excellent stimulatory capacity, combined with their ability to process and present antigens to both naive CD4 and CD8 cells. The long impasse in identifying molecular targets for specific immunotherapy of RCC is now rapidly being overcome through the use of tools and information emerging from human genome research. Identification of candidate molecules expressed by RCC using cDNA arrays, combined with protein arrays and identification of peptides presented by MHC molecules, allow specific vaccines to be tailored to the antigenic profile of individual tumors, providing the basis for development of patient-specific vaccines.

Influence of CD80, interleukin-2, and interleukin-7 expression in human renal cell carcinoma on the expansion, function, and survival of tumor-specific CTLs

PURPOSE

A renal cell carcinoma (RCC) line, RCC-26, has been identified as a suitable candidate for development of an allogeneic tumor cell vaccine based on its expression of a variety of tumor-associated antigens (TAA). To improve immunogenicity, RCC-26 cells were genetically engineered to express CD80 alone or in combination with interleukin (IL)-2 or IL-7. The effect of these modifications on proliferation, function, and survival of autologous and allogeneic tumor-specific CTLs was assessed.

EXPERIMENTAL DESIGN

RCC-26 sublines expressing different transgenes were tested for their capacity to reactivate cytokine secretion and cytotoxicity in autologous tumor-infiltrating lymphocytes, to improve proliferation and survival of tumor-associated T cells present in autologous peripheral blood, and to induce tumor-associated responses in naive allogeneic lymphocytes. The expression of several common TAA was quantitated in the RCC-26 sublines using reverse transcription-PCR to identify surrogate markers for immune monitoring in clinical trials.

RESULTS

Gene-modified RCC-26 cells showed enhanced immunogenicity. CD80 expression was necessary to induce RCC-associated CTL in blood of healthy allogeneic donors. It also improved proliferation of autologous effector-memory T cells. Further enhancement was achieved with IL-2 through induction of the antiapoptosis protein Bcl-x(L). The candidate vaccine lines overexpressed several common TAA that are suitable markers for immune monitoring.

CONCLUSIONS

RCC-26 cells coexpressing CD80 and cytokine transgenes display improved immunogenic characteristics, supporting their use as allogeneic tumor cell vaccines for HLA-A2-matched patients with metastatic RCC.

Activated marrow-infiltrating lymphocytes effectively target plasma cells and their clonogenic precursors

A major limitation of adoptive immunotherapy is the availability of T cells specific for both terminally differentiated tumor cells and their clonogenic precursors. We show here that marrow-infiltrating lymphocytes (MILs) recognize myeloma cells after activation with anti-CD3/CD28 beads with higher frequency than activated peripheral blood lymphocytes from the same patients. Furthermore, activated MILs target both the terminally differentiated CD138+ plasma cells and the myeloma precursor as shown by profound inhibition in a tumor clonogenic assay. The presence of antigen in the marrow microenvironment seems to be important for the maintenance of tumor specificity. Taken together, these results highlight the intrinsic tumor specificity of MILs and describe a novel approach for the generation of tumor-specific T-cell populations suitable for adoptive immunotherapy of multiple myeloma.

A Novel Bispecific Tetravalent Antibody Fusion Protein to Target Costimulatory Activity for T-cell Activation to Tumor Cells Overexpressing ErbB2/HER2

Persistent activation of T-lymphocytes requires two signals: one is initiated by T-cell receptor binding to antigenic peptide presented by MHC molecules. In addition, binding of the B7 family members CD80 or CD86 on professional antigen presenting cells to CD28 on T cells is considered to provide an important costimulatory signal. Activation without costimulation induces T-cell unresponsiveness or anergy. To selectively localize costimulatory activity to the surface of tumor cells and enhance activation of tumor-specific T cells, we have developed a novel molecular design for bispecific costimulatory proteins with antibody-like structure. Within a single polypeptide chain we have assembled the IgV-like, CD28-binding domain of human CD86 (CD86(111)) together with hinge, CH2 and CH3 domains of human IgG1, and the scFv(FRP5) antibody fragment which recognizes the ErbB2 (HER2) protooncogene present at high levels on the surface of many human tumor cells. Upon expression in the yeast Pichia pastoris, the resulting CD86(111)-IgG-scFv(FRP5) protein could be purified as a homodimeric, tetravalent molecule from culture supernatants using single-step affinity chromatography. Bispecific binding of the molecule to ErbB2 on the surface of tumor cells and to the B7 counter receptor CTLA-4 was demonstrated by FACS analysis. Potent costimulatory activity of chimeric CD86(111)-IgG-scFv(FRP5) was confirmed by its ability to stimulate the proliferation of primary human lymphocytes pre-activated by low concentrations of anti-CD3 antibody. Our results suggest that such multivalent soluble proteins which combine specific targeting to tumor cells with costimulatory activity may become useful tools to elicit and/or improve T-cell mediated, tumor-specific immune responses.

A CD80-transfected human breast cancer cell variant induces HER-2/neu-specific T cells in HLA-A*02-matched situations in vitro as well as in vivo

Adjuvant treatment is still only working in a small percentage of breast cancer patients. Therefore, new strategies need to be developed. Immunotherapies are a very promising approach because they could successfully attack tumor cells in the stage of dormancy. To assess the feasibility of using an allogeneic approach for vaccination of breast cancer patients, we selected a CD80-transfected breast cancer cell line based on its immunogenic properties. Using CD80+ KS breast cancer cells and human leukocyte antigen (HLA)-A*02-matched peripheral blood mononuclear cells (PBMCs) of breast cancer patients in allogeneic mixed lymphocyte-tumor cell cultures (MLTCs), it was possible to isolate HLA-A*02-restricted cytotoxic T cells (CTLs). Furthermore, a genetically modified KS variant expressing influenza A matrix protein serving as a surrogate tumor-associated antigen (TAA) was able to stimulate flu peptide-specific T cells alongside the induction of alloresponses in MLTCs. KS breast cancer cells were demonstrated to express already known TAAs such as CEA, MUC-1, MAGE-1, MAGE-2, and MAGE-3. To further improve antigenicity, HER-2/neu was added to this panel as a marker antigen known to elicit HLA-A*02-restricted CTLs in patients with breast cancer. Thus, the antigen-processing and antigen-presentation capacity of KS cells was further demonstrated by the stimulation of HER-2/neu-specific CD8+ T cells in PBMCs of breast cancer patients in vitro. These results gave a good rationale for a phase I/II trial, where the CD80+ HER-2/neu-overexpressing KS variant is actually used as a cellular vaccine in patients with metastatic breast cancer. As a proof of principle, we present data from two patients where a significant increase of interferon-gamma (IFN-gamma) release was detected when postvaccination PBMCs were stimulated by allogeneic vaccine cells as well as by HLA-A*02-restricted HER-2/neu epitopes. In whole cell vaccine trials, monitoring is particularly challenging because of strong alloresponses and limited knowledge of TAAs. In this study, a panel of HER-2/neu epitopes, together with the quantitative real time (qRT)-PCR method to analyze vaccine-induced cytokines secreted by T cells, proved to be highly sensitive and feasible to perform an "immunological staging" following vaccination.

B7-1 and B7-2 act differentially in the induction of a T cell response: Their impact for a HLA-matched and HLA-mismatched anti-tumor immunotherapy

The efficacy of T cell-based immunotherapy is primarily due to efficient cellular activation that requires the engagement of 2 separate signals, i.e., via the T cell receptor complex and via co-stimulatory molecules the prototype of which is CD28. In cellular activation, the CD28 ligands B7-1 (CD80) and B7-2 (CD86) are thought to play nearly identical roles in T cell activation. We monitored the T cell response upon co-culture with HLA Class I-matched and mismatched renal carcinoma cells, respectively, that express different levels of B7-1 and B7-2, respectively. In a HLA Class I-mismatched co-culture, T cell proliferation, IFN-gamma and GM-CSF secretion equally depend on the levels of B7-1 and B7-2 on tumor cells. In contrast, in a HLA Class I-matched situation, B7-2 is more effective in the induction of IFN-gamma and GM-CSF secretion than B7-1, but both B7 molecules induce T cell proliferation equally efficient. B7-2 is more effective than B7-1 in inducing TNF-alpha and IL-10 secretion in both HLA Class I-matched and mismatched situations. The distinct patterns of cytokine induction by B7-1 and B7-2 obviously depend on the HLA Class I compatibility. These conclusions have substantial implications for the development of B7-based vaccines used for immunotherapies.

Necrotic death but not irradiation abolishes costimulation of T-cell effector functions and survival by CD80-expressing tumor cells

Tumor vaccination by the use of gene-modified cancer cells that provide costimulatory signals has been successfully applied in preclinical animal models and is currently evaluated in a variety of clinical settings. In previous work, we demonstrated the efficacy of B7.1/CD80 to promote tumor immunity in syngeneic murine models and to prevent deletion of activated T cells by activation-induced cell death (AICD). In clinical trials, tumor cell vaccines are generally inactivated to avoid transfer of live tumor cells, i.e., additional tumor burden. Previous data indicated, however, that inactivation of tumor cells by lethal ionizing irradiation abrogates tumor vaccination by CD80-expressing cells. Here, we compare living and irradiated allogeneic tumor cells regarding their capacity to induce T-cell effector functions and their propensity to interfere with T-cell deletion by apoptosis. Both lethally irradiated and nonirradiated tumor cells facilitated T-cell proliferation, tumor cell lysis, and interfered with T-cell AICD to a similar extent. In contrast, necrotic tumor cells failed to costimulate T-cell effector functions. Thus, irradiation does not seem to hamper tumor cell-mediated costimulation of T-cell effector functions. In contrast, necrosis of gene-modified tumor cells abrogates costimulation of T cells by CD80-expressing cells.

CD8+ cytotoxic T lymphocytes isolated from allogeneic healthy donors recognize HLA class Ia/Ib-associated renal carcinoma antigens with ubiquitous or restricted tissue expression

Allogeneic hematopoietic stem cell transplantation can induce considerable tumor remissions in metastatic renal-cell carcinoma (RCC) patients. The precise effector mechanisms mediating these graft-versus-tumor reactions are unknown. We studied RCC-directed CD8(+) T-cell responses in blood lymphocytes of healthy individuals matched with established RCC cell lines for HLA-class I. In 21 of 22 allogeneic mixed lymphocyte/tumor-cell cultures (MLTCs), RCC-reactive cytotoxic T-lymphocytes (CTLs) were readily obtained. From MLTCs, 121 CD8(+) CTL clones with memory phenotype were isolated. Their anti-RCC reactivity was restricted by multiple classical HLA-Ia molecules, in particular by HLA-A2, -A3, -B7, -B44, -Cw7, and by a nonclassical HLA-Ib determinant. Extensive cross-reactivity analyses on a broad target panel identified CTLs that recognize antigens with expression restricted to renal tissue or to renal and colon tumors. Other CTLs were directed against antigens with broader tissue distribution being expressed in various epithelial and nonepithelial tumors or, additionally, in hematopoietic cells. With microcapillary liquid chromatography and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF)/TOF mass spectrometry, we identified the HLA-A*0301-associated nonpolymorphic peptide KLPNSVLGR encoded by the ubiquitously expressed Eps15 homology domain-containing 2 gene as a CTL target. Defining human RCC antigens recognized by alloreactive CTLs may allow to improve the specificity and efficiency of allogeneic cell therapy (eg, specific donor-lymphocyte infusions or vaccination) in metastatic RCC patients.

Immunotherapy for urological malignancies

PURPOSE

For decades urologists have successfully used immunotherapy in the battle against cancer. Interleukin-2 in renal cell carcinoma and bacillus Calmette-Guerin in bladder cancer are standard primary and/or adjunctive therapies for these diseases. Recent advances in our understanding of mechanisms governing immune system activation have fostered a myriad of novel immunotherapeutic approaches that show great promise in vivo but have had limited success in human trials to date. This review highlights current immunotherapy strategies that may prove to be successful treatments for urological cancers.

MATERIALS AND METHODS

We performed a MEDLINE literature search for articles relating to immunotherapy in bladder, prostate and renal cell carcinoma in animals and humans. We included the most promising developments in this review.

RESULTS

In addition to combining existing therapies to improve their efficacy, novel approaches that attempt to exploit the immune system ability to identify, target and eradicate malignancies are now being developed. These therapies include the use of antitumoral monoclonal and bi-specific antibodies, manipulation of T-lymphocyte costimulatory molecules and the administration of newly discovered cytokines as well as the development of antitumor vaccines.

CONCLUSIONS

To date the full potential of immunotherapy for the treatment of urological malignancies has not been recognized. As our knowledge of the immune system expands, so too may our ability to manipulate it to affect tumor regression. This review describes the most recent and most promising developments in immunotherapy for urological malignancies.

Immunotherapy of cancer by active vaccination: does allogeneic bone marrow transplantation after non-myeloablative conditioning provide a new option?

The critical role of antigen-specific T cells in cancer immunotherapy has been amply demonstrated in many model systems. Though success of clinical trials still remains far behind expectation, the continuous improvement in our understanding of the biology of the immune response will provide the basis of optimized cancer vaccines and allow for new modalities of cancer treatment. This review focuses on the current status of active therapeutic vaccination and future prospects. The latter will mainly be concerned with allogeneic bone marrow cell transplantation after non-myeloablative conditioning, because it is my belief that this approach could provide a major breakthrough in cancer immunotherapy. Concerning active vaccination protocols the following aspects will be addressed: i) the targets of immunotherapeutic approaches; ii) the response elements needed for raising a therapeutically successful immune reaction; iii) ways to achieve an optimal confrontation of the immune system with the tumor and iv) supportive regimen of immunomodulation. Hazards which one is most frequently confronted with in trials to attack tumors with the inherent weapon of immune defense will only be briefly mentioned. Many question remain to be answered in the field of allogeneic bone marrow transplantation after non-myeloablative conditioning to optimize the therapeutic setting for this likely very powerful tool of cancer therapy. Current considerations to improve engraftment and to reduce graft versus host disease while strengthening graft versus tumor reactivity will be briefly reviewed. Finally, I will discuss whether tumor-reactive T cells can be "naturally" maintained during the process of T cell maturation in the allogeneic host. Provided this hypothesis can be substantiated, a T cell vaccine will meet a pool of virgin T cells in the allogeneically reconstituted host, which are tolerant towards the host, but not anergised towards tumor antigens presented by MHC molecules of the host.

Adenoviral transduction of tumor cells induces apoptosis in co-cultured T lymphocytes

Adenoviral gene transfer of immunmodulatory molecules has been employed successfully in tumor vaccination studies to induce rejection of transplanted syngeneic tumors. In contrast, the response observed when treating chemically induced murine tumors is rather limited. The same applies for human malignancies. A number of reasons including poor transduction efficiency or insufficient T cell infiltration have been held accountable for this lack of efficacy. However, little attention has been given to effects of the adenoviral transduction itself on the T cell system. Here, we show that T cells are sensitized for activation-induced cell death after co-culture with adenovirally infected tumor cells. The levels of CD95/Fas ligand or TNF-alpha, both known mediators of activation induced cell death, however were not affected by the presence of adenovirus-infected target cells. Furthermore, supernatant transfer from adenovirally transduced or non-infected tumor cell cultures did not result in increased T cell apoptosis. This suggests that cell contact rather than a soluble factor is responsible for the induction of T cell apoptosis upon co-culture with adenovirally transduced tumor cells. Interestingly, and in line with our previous observations, activation-induced cell death was partially inhibited if T cells were co-cultured with tumor cells adenovirally transduced to express IL-7 and CD80, both molecules having the capacity to prevent T cell apoptosis.

Phage display particles expressing tumor-specific antigens induce preventive and therapeutic anti-tumor immunity in murine p815 model

The efficacy of phage display particles expressing tumor antigen P1A35-43 in inducing protective and therapeutic anti-tumor immune responses were studied. A protective immune response against a lethal progressive P815 mastocytoma tumor cell challenge was established after subcutaneous injection of phage display particles. Furthermore, the vaccine suppressed growth of pre-existing tumors. Immunization with the hybrid phage particles elicited P1A(35-43) specific CTL responses and a Th1-dominated immune response with phage particle-specific secretion of IFN-gamma but not IL-4. Our results indicate that phage display particles might be a useful vaccine form for tumor-associated antigen epitopes in tumor immunotherapy.

Adoptive tumor therapy with T lymphocytes enriched through an IFN-gamma capture assay

Successful adoptive T-cell therapy has been demonstrated in viral disease and selected forms of cancer. However, it is limited by the difficulty to efficiently isolate and amplify autologous tumor-reactive T-cell clones. Tetramers of major histocompatibility complex (MHC) class I and peptide have facilitated the characterization of CD8+ T cells specific for tumor-associated antigens. However, for adoptive T-cell therapy, MHC-tetramers have limitations: they require knowledge of tumor antigens, which is often not available; they select T cells with a single specificity, thereby posing risk for selection of tumor escape variants; they do not select for function, so that T cells may be anergic when isolated from cancer patients; and they do not allow the isolation of CD4+ T cells that can be essential for tumor rejection. Because interferon (IFN)-gamma is essential for tumor rejection, we isolated live T cells based on their IFN-gamma production. IFN-gamma secreted by previously activated T cells is retained on the cell surface, allowing their specific isolation and expansion. We show here that IFN-gamma+ but not IFN-gamma- T cells from tumor-immunized mice are cytolytic and mediate tumor rejection upon adoptive transfer. Importantly, tumor-specific T cells can be enriched from lymphocytes infiltrating human renal cell carcinoma by the IFN-gamma capture assay.