Showing papers in "Cancer Immunology, Immunotherapy in 1999"

Tumor-induced immune dysfunction.

Abstract: Immune system-based approaches for the treatment of malignant disease over the past decades have often focused on cytolytic effector cells such as cytotoxic T lymphocytes (CTL), and natural killer (NK) cells. It has also been demonstrated that tumor-bearing mice can be cured using a wide variety of approaches, some of which involve cytokine-mediated enhancement of CTL and NK cell activity. However, the apparent success in mice stands in contrast to the current situation in the clinic, wherein only a minority of patients have thus far benefited from CTL- or NK cell-based antitumor approaches. The underlying causes of tumor-associated immune suppression of CTL and NK cell activity are discussed, and features of interest shared with HIV infection, leprosy, and rheumatoid arthritis are also be mentioned. Remarkable and very recent observations have shed more light upon the causes of dysfunctional alterations in CTL and NK cells often associated with these diseases, that in turn have suggested new immunotherapeutic approaches for cancer and infectious disease.

Signaling defects in T lymphocytes of patients with malignancy.

Abstract: In patients with cancer, alterations in the expression of T-cell receptor-associated molecules in tumor-infiltrating lymphocytes (TIL) as well as in circulating lymphocytes have been reported. By quantitative flow cytometry analysis, decreased or absent expression of the ζ chain in CD4+ or CD8+ T cells as well as in natural killer (NK) cells was demonstrated in patients with malignancies. Changes in the expression of ζ are biologically significant, because the absence or low expression of this signaling molecule in TIL of patients with stage III or IV head and neck cancer predicts a significantly shorter 5-year survival than that of patients with normal ζ expression in TIL. Preliminary evidence indicates that expression of ζ in TIL may not only influence survival but also predicts a favorable response to biologic therapies. Patients with cancer also show significantly greater spontaneous ex vivo apoptosis in peripheral blood mononuclear cells (PBMC) compared to normal controls, as measured by a terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) assay. While no correlation could be established between the proportions of cells with low ζ chain expression and those that spontaneously apoptose ex vivo, the ζ chain has been shown to be cleaved by caspases in T cells coincubated with tumor cells or with T cells exposed to CH-11 antibody, which induces apoptosis upon crosslinking Fas on the cell surface. The results suggest that low/absent ζ chain expression and lymphocyte apoptosis may be manifestations of negative effects of the tumor on the host immune system.

How tumors escape immune destruction and what we can do about it

Abstract: There is strong circumstantial evidence that tumor progression in cancer patients is controlled by the immune system. As will be detailed below, this conclusion is based on observations that tumor progression is often associated with secretion of immune suppressive factors and/or downregulation of MHC class I antigen presentation functions. The inference is that tumors must have elaborated strategies to circumvent an apparently effective immune response. Importantly, a tumor-specific immune response cannot be detected in most individuals. While this failure is in part technical, it also suggests that the magnitude of the immune responses to which tumors have to respond is low. This raises the concern, which is the underlying theme of this commentary, that a more robust immune response elicited by deliberate vaccination will exacerbate the rate of immune escape and nullify the potential benefits of immune-based therapies.

Analysis of Th1 and Th2 cytokine production by peripheral blood mononuclear cells as a parameter of immunological dysfunction in advanced cancer patients.

Abstract: Purpose: The presence of immunological dysfunction has not been well demonstrated in cancer patients. Recent studies have revealed that the immune response can be classified into types 1 and 2, and in the present work the immunological function of patients was studied from the perspective of these two types of response. Methods: Types 1 and 2 immune response were evaluated by monitoring the production of various cytokines by peripheral blood mononuclear cells from 38 patients with advanced cancer of various organs and 20 healthy subjects. The usual immunological parameters, differential cell leukocyte counts, the level of T cell subsets (CD4 and CD8) and natural killer activity were also examined. Results: The production of interleukin-2 (IL-2), interferon γ, IL-10, IL-12 and tumor necrosis factor α was found to be significantly lower in the patients (75 ± 57, 171 ± 205, 40 ± 34, 8 ± 8, 1450 ± 1010 pg/ml) than in healthy subjects (143 ± 99, 422 ± 296, 64 ± 34, 16 ± 10, 2550 ± 950 pg/ml); however, the mean level of IL-4 in the patients seemed to be higher. The correlations between different cytokine levels suggested that they were produced differently. Lymphocyte counts were significantly lower in patients, but there was no difference in the other usual immunological parameters. Conclusions: Patients with advanced cancer are deficient in monocytes and the type 1 immune response. The measurement of various cytokines reported in this study provides a more sensitive and valuable tool for evaluating the function of cell-mediated immunity in cancer patients than do the usual tests.

Vaccination with the extracellular domain of p185neu prevents mammary tumor development in neu transgenic mice.

Abstract: The HER2/neu oncogene product, p185HER2/neu, is overexpressed on the surface of many human breast cancers. Strains of transgenic mice have been developed that express the rat neu oncogene in mammary epithelial cells and develop spontaneous mammary tumors that overexpress p185neu. This model provides an ideal system for testing interventions to prevent tumor development. In this study, we immunized neu-transgenic mice with a vaccine consisting of the extracellular domain of p185neu (NeuECD). Immunized mice developed Neu-specific humoral immune responses, as measured by circulating anti-Neu antibodies in their sera, and cellular immune responses, as measured by lymphocyte proliferation to NeuECD in vitro. In addition, the subsequent development of mammary tumors was significantly lower in immunized mice than in controls and vaccine treatment was associated with a significant increase in median survival.

Homing of intravenously and intralymphatically injected human dendritic cells generated in vitro from CD34+ hematopoietic progenitor cells.

Abstract: Dendritic cells (DC) are professional antigen-presenting cells that can be generated in vitro from CD34+ peripheral blood progenitor cells by recombinant cytokines. These cells have potential implications for immunotherapeutic approaches in the treatment of cancer and other diseases. Physiologically, immature DC in the periphery capture and process antigens, then mature to interdigitating DC and migrate to lymphoid organs, where they activate lymphocytes. However, it is not known if DC generated in vitro have the capacity to traffic in vivo to the lymphoid tissues, such as spleen and lymph nodes. We have investigated whether human radiolabeled DC differentiated in vitro migrate and localize to lymphoid tissues after intravenous and intralymphatic injection. The distribution and localization of the DC were evaluated in five patients with malignant melanoma using serial whole-body gamma camera imaging. Intravenously infused DC demonstrated transient lung uptake followed by localization in the spleen and liver for at least 7 days. DC injected into a lymphatic vessel at the dorsal foot were rapidly detected in the draining lymph nodes where they remained for more than 24 h. These data suggest that DC differentiated in vitro localize preferentially to lymphoid tissue, where they could induce specific immune responses.

Selective MHC expression in tumours modulates adaptive and innate antitumour responses.

Abstract: Progress towards developing vaccines that can stimulate an immune response against growing tumours has involved the identification of the protein antigens associated with a given tumour type. Epitope mapping of tumour antigens for HLA class I- and class II-restricted binding motifs followed by immunization with these peptides has induced protective immunity in murine models against cancers expressing the antigen. MHC class I molecules presenting the appropriate peptides are necessary to provide the specific signals for recognition and killing by cytotoxic T cells (CTL). The principle mechanism of tumour escape is the loss, downregulation or alteration of HLA profiles that may render the target cell resistant to CTL lysis, even if the cell expresses the appropriate tumour antigen. In human tumours HLA loss may be as high as 50%, inferring that a reduction in protein levels might offer a survival advantage to the tumour cells. Alternatively, MHC loss may render tumour cells susceptible to natural killer cell-mediated lysis because they are known to act as ligands for killer inhibitory receptors (KIRs). We review the molecular features of MHC class I and class II antigens and discuss how surface MHC expression may be regulated upon cellular transformation. In addition, selective loss of MHC molecules may alter target tumour cell susceptibility to lymphocyte killing. The development of clinical immunotherapy will need to consider not only the expression of relevant CTL target MHC proteins, but also HLA inhibitory to NK and T cells.

Vascular endothelial growth factor in malignant pleural effusion associated with lung cancer.

Abstract: The presence of vascular endothelial growth factor (VEGF) was examined by enzyme immunoassay in 60 cytology-documented malignant pleural effusions associated with primary lung cancer and 51 other benign and malignant pleural effusions. Exudative pleural effusions contained significantly higher amounts of VEGF than transudative pleural effusions. Among exudative pleural effusions, levels of VEGF in malignant pleural effusions associated with lung cancer were significantly higher than those of benign exudative pleural effusions. There was no significant difference in pleural VEGF in patients with different histological types or clinical stages of lung cancer. Serial measurement of pleural VEGF levels was performed in six lung cancer patients treated with intrapleural instillation of recombinant interferon gamma, and reduction of pleural effusion was associated with decreasing pleural VEGF levels. These findings suggest that VEGF has a role in the accumulation of exudative pleural effusions, especially that of malignant pleural effusion associated with lung cancer.

Vaccines prepared with sialyl-Tn and sialyl-Tn trimers using the 4-(4-maleimidomethyl)cyclohexane-1-carboxyl hydrazide linker group result in optimal antibody titers against ovine submaxillary mucin and sialyl-Tn-positive tumor cells.

Abstract: Sialyl-Tn (STn) is an O-serine- or O-threonine-linked disaccharide [NeuAcalpha(2-->6)GalNAcalpha-O-Ser/Thr) expressed on mucins of most types of adenocarcinoma as single STn or clustered STn [STn(c)] epitopes. Though STn is expressed on some normal tissues it is relatively tumor-specific, especially in the clustered conformation. Clinical trials with STn-keyhole limpet hemocyanin (KLH) conjugate vaccines, prepared using reductive amination with a two-carbon linker group, have resulted in high titers against STn but lower titers against natural forms of STn (ovine submaxillary mucin, or tumor cells). To obtain antibodies of more appropriate specificity, we attempted to prepare STn(c)-KLH conjugates to establish their immunogenicity in mice in preparation for clinical trials; however, conjugation efficiency was poor when the same two-carbon linker was used, presumably because of steric hindrance. STn-KLH and STn(c)-KLH conjugates were prepared using the regular two-carbon or the recently developed more efficient longer heterobifunctional 4-(4-maleimidomethyl)cyclohexane-1-carboxyl hydrazide (MMCCH) linkers, and the resulting immunogenicities in mice were compared. The highest titers against STn were seen with the STn-KLH conjugate with the two-carbon linker, and the highest titers against STn(c) were seen with STn(c)-KLH with the MMCCH linker. Conjugation with MMCCH resulted in the highest conjugation efficiency (yield) and the highest titers against ovine submaxillary mucin and STn-positive tumor cells, and is the method of choice for the preparation of STn(c) vaccine for clinical trials.

Pharmacokinetics and stability of the ch14.18-interleukin-2 fusion protein in mice.

Abstract: The fusion protein formed from ch14.18 and interleukin-2 (ch14.18–IL-2), shown to exhibit antitumor efficacy in mouse models, consists of IL-2 genetically linked to each heavy chain of the ch14.18 chimeric anti-GD2 monoclonal antibody. The purpose of this study was to determine the pharmacokinetics of ch14.18–IL-2 in mice and assess its stability in murine serum. Following i.v. injection, the fusion protein was found to have a terminal half-life of 4.1 h. Detection of IL-2 following injection of the ch14.18–IL-2 fusion protein showed a similar half-life, indicating that the fusion protein prolongs the circulatory half-life of IL-2. Detection of human IgG1 following injection of ch14.18–IL-2 showed a terminal half-life of 26.9 h. These data suggested that the native fusion protein is being altered in vivo, resulting in a somewhat rapid loss of detectable IL-2, despite prolonged circulation of its immunoglobulin components. In vitro incubation of the ch14.18–IL-2 fusion protein in pooled mouse serum at 37 °C for 48 h resulted in a loss of its IL-2 component, as detected in enzyme-linked immunosorbent assay systems and in proliferation assays. Polyacrylamide gel electrophoresis and Western blot analysis of the fusion protein incubated in mouse serum at 37 °C indicated that the ch14.18–IL-2 is cleaved, resulting in a loss of the 67-kDa band (representing the IL-2 linked to the IgG1 heavy chain) and the detection of a band of more than 50 kDa, slightly heavier than the IgG1 heavy chain itself. This suggests that the fusion protein is being cleaved in vitro within the IL-2 portion of the molecule. These studies show that (1) ch14.18–IL-2 prolongs the circulatory half-life of IL-2 (compared to that of soluble IL-2) and (2) the in vivo clearance of the fusion protein occurs more rapidly than the clearance of the ch14.18 antibody itself, possibly reflecting in vivo cleavage within the IL-2 portion of the molecule, resulting in loss of IL-2 activity.

In situ T cells in melanoma.

Abstract: During the past decade new insights have been gained into the role of T lymphocytes in the host's immune response to cancer in general and to melanoma in particular. Several melanoma-associated antigens (MAA) recognized by T cells have been characterized, and a number of HLA class I- and class II-restricted peptides have been identified. These antigens can be divided into three different groups: tumor-associated testis-specific antigens, melanocyte differentiation antigens, and mutated or aberrantly expressed antigens. These proteins give rise to several antigenic peptides. The number of known melanoma-associated peptides that can induce killing by cytotoxic T-lymphocytes (CTL) exceeds 30 and is still increasing. In line with these findings, clinical data indicate that the immune system is essential in the control of tumor growth. A brisk infiltration of lymphocytes is associated with a favorable prognosis, and complete or partial regression of primary melanoma occurs quite frequently. Furthermore, immunomodulatory therapies have accomplished complete or partial tumor regression in a number of patients. However, the immune response is in most cases inadequate to control tumor growth as tumor progression often occurs. Hence, the coexistence of a cellular immune response in melanoma lesions, demonstrated by the presence of clonally expanded T cells, remains a major paradox of tumor immunology. In the present paper we review current knowledge regarding tumor infiltrating lymphocytes (TIL) in melanoma and discuss possible mechanisms of escape from immune surveillance.

Autoantibodies against the tumour-associated antigen GA733-2 in patients with colorectal carcinoma

Abstract: The tumour-associated antigen (TAA) GA733-2 is expressed as a non-secreted surface molecule on the majority of human colorectal carcinoma cells. The antigen has been used as a target for passive and active immunotherapy during the last decade. To determine the incidence of autoantibodies against this antigen, sera from 1068 patients with colorectal carcinoma were analysed for naturally occurring IgG antibodies against the baculovirus-produced GA733-2E protein. A total of 14.5% of the patients had IgG antibodies against the antigen. In 519 patients, sera were collected at the time of diagnosis and 15% of those patients had anti-GA733-2E IgG antibodies. There was a tendency to a higher frequency of patients with antibodies among those in the advanced Dukes stages: 11% in stage A and 32% in stage D respectively (P = 0.06). Antibodies could be detected for up to 10 years after the diagnosis. Patients with Crohn's disease or colitis ulcerosa (n = 20) did not elicit anti-GA733-2E antibodies. No healthy control donor (n = 45) had detectable antibodies against the antigen. The specificity of GA733-2E-reactive serum IgG was indicated by significant inhibition of mAb17-1A (originally used to define GA733-2) binding to the GA733-2E antigen. Sera of positive patients bound to the GA733-2-expressing human colorectal carcinoma cell line, SW948. No significant correlation was found between the presence of antibodies and survival in the present patient population. However, the high incidence of autoantibodies against this tumour antigen in colorectal carcinoma patients confirms its antigenicity in humans and supports the use of the GA733-2 antigen as a target for immunotherapy.

Synergistic antitumor effects of interleukin-12 gene transfer and systemic administration of interleukin-18 in a mouse bladder cancer model.

Abstract: We introduced the interleukin-12 (IL-12) gene into the mouse bladder cancer cell line (MBT2) to establish sublines that secrete bioactive IL-12 IL-12-secreting MBT2 (MBT2/IL-12) sublines were completely rejected when subcutaneously implanted into immunocompetent syngeneic C3H mice Although this antitumor effect did not change when IL-12-secreting cells were injected into immunodeficient mice whose CD8+ T or CD4+ T cells had been depleted by the corresponding antibody, it was abrogated when natural killer cells were depleted by anti-asialoGM1 antibody In addition, when parental MBT2 cells mixed with MBT2/IL-12 cells were subcutaneously injected into mice, admixed MBT2/IL-12 inhibited the growth of the parental tumor Furthermore, this antitumor effect was enhanced by systemic IL-18 administration This synergism was abrogated when the mice were treated with interferon-γ-neutralizing antibody in vivo In conclusion, local secretion of IL-12 led to effective antitumor activity that was enhanced by systemic administration of IL-18 Interferon-γ plays an important role in the synergism of IL-12 gene transduction and systemic administration of IL-18

A phase I study of a HER2/neu bispecific antibody with granulocyte-colony-stimulating factor in patients with metastatic breast cancer that overexpresses HER2/neu

Abstract: A phase I study of escalating doses of humanized bispecific antibody (bsAb) MDX-H210 with granulocyte-colony-stimulating factor (G-CSF) was conducted in patients with metastatic breast cancer that overexpressed HER2/neu. The main objectives of the study were to define the maximal tolerated dose (MTD) of MDX-H210 when combined with G-CSF, to measure the pharmacokinetics of MDX-H210 when administered with G-CSF, and to determine the toxicity, biological effects and possible therapeutic effect of MDX-H210 with G-CSF. MDX-H210 is a F(ab)′ × F(ab)′ humanized bispecific murine antibody that binds to both HER2/neu and the FcγR1 receptor (CD64), and was administered intravenously weekly for three doses followed by a 2-week break and then three more weekly doses. A total of 23 patients were treated, and doses were escalated from 1 mg/m2 to 40 mg/m2 with no MTD reached. The toxicity of the bsAb + G-CSF combination was modest, with no dose-limiting toxicity noted: 19 patients had fevers, 7 patients had diarrhea, and 3 patients had allergic reactions that did not limit therapy. The β-elimination half-life varied from 4 h to 8 h at doses up to 20 mg/m2. Significant release of cytokines interleukin-6, G-CSF, and tumor necrosis factor α was observed after administration of bsAb. Circulating monocytes disappeared within 1 h of bsAb infusion, which correlated with binding of bsAb, noted by flow-cytometric analysis. Significant levels of human anti-(bispecific antibody) were measured in the plasma of most patients by the third infusion. No objective clinical responses were seen in this group of heavily pre-treated patients.

Mechanisms of leukocyte-mediated tissue injury induced by interleukin-2.

Abstract: In this review we discuss the effects of interleukin-2 (IL-2) therapy on trafficking of leukocytes and platelets to normal organs. The use of animal models has allowed the elucidation of events leading to damage and/or dysfunction of normal tissues after IL-2 administration. These studies have shown that acute toxicity induced by IL-2 is mediated primarily by neutrophils. Chronic toxicity results from the adhesion and transmigration of activated lymphocytes into normal organs. Platelet-derived microvascular thrombosis also contributes to the vascular toxicity of IL-2. A better understanding of these mechanisms may lead to the development of interventions that will significantly improve the therapeutic efficacy of IL-2.

Cellular and humoral immune responses to MUC1 mucin and tandem-repeat peptides in ovarian cancer patients and controls

Abstract: The objective of this study was to demonstrate the presence of proliferative T cell responses to human polymorphic epithelial mucin (MUC1) and its tandem-repeat peptides in peripheral blood mononuclear cells (PBMC) from ovarian cancer patients and from controls and to correlate these cellular responses to a humoral response to MUC1. PBMC were obtained from 6 healthy women, from 13 women in the third trimester of pregnancy and from 21 ovarian cancer patients. Only 1 of the 6 healthy women showed a weak primary proliferative response (stimulation index, SI <2) to a 20-mer MUC1 tandem-repeat peptide in the presence of interleukin-2 (IL-2). In PBMC from 5/13 pregnant women (38%) a weak response could be induced by the 20-mer and/or 60-mer tandem-repeat peptides (SI < or =3.0) and in PBMC from 8/15 ovarian cancer patients (53%) 20-mer and/or 60-mer MUC1 tandem-repeat peptides induced primary responses (SI < or =5.4). MUC1 mucin purified from a breast tumor cell line and/or from urine of a healthy donor had a relatively strong stimulating effect (SI < or =19) on PBMC from 4 of 16 ovarian cancer patients (25%). In contrast, in PBMC of 9 ovarian cancer patients stimulated by the addition of a Candida albicans extract, MUC1 mucin strongly inhibited proliferation. This inhibition could partially be abrogated by the addition of IL-2. MUC1 (CA 15.3 assay) and free circulating MUC1 IgG and IgM antibodies (PEM.CIg assay) were determined in the plasma of all subjects. The MUC1 and the free circulating MUC1 IgG antibody plasma levels were significantly higher in the ovarian cancer patients than in the healthy women. Although no significant correlations were found between MUC1 mucin, MUC1 Ab plasma levels and the individual proliferative responses to the MUC1 antigens, an association may exist between them, since all three are significantly higher in the ovarian cancer patients than in the healthy women.

Granulocyte/macrophage-colony-stimulating factor released by adenovirally transduced CT26 cells leads to the local expression of macrophage inflammatory protein 1α and accumulation of dendritic cells at vaccination sites in vivo

Abstract: Antigen presenting cells (APC) play an essential role in the generation of tumor-specific immune responses. Dendritic cells are the most potent of APC, capable of activating both antigen-specific CD4+ and CD8+ T cells. Previously, we have described how vaccination of mice with irradiated tumor cells producing granulocyte/macrophage-colony-stimulating factor (GM-CSF) induces tumor-specific immunity capable of protecting mice from a subsequent tumor challenge. The present study extends these findings to examine the types of APC infiltrating vaccination sites and the chemokines responsible for their recruitment. GM-CSF released from genetically engineered tumor cells led to the local accumulation of dendritic cells in and around the vaccination site. Quantification revealed a significant ten-fold increase in the number of dendritic cells infiltrating GM-CSF-producing as opposed to β-galactosidase-producing (control) vaccination sites. Reverse transcription/polymerase chain reaction, enzyme-linked immunosorbent assay, and immunohistochemical analysis of vaccination sites revealed that MIP-1α may be responsible for dendritic cell infiltration into GM-CSF-producing tissues. These findings suggest that GM-CSF may indirectly recruit dendritic cells into vaccination sites through the local production of MIP-1α.

Tumour escape from the immune response: the last hurdle for successful immunotherapy of cancer?

Abstract: Over the last decade, since the pioneering work resulting in the molecular cloning of the ®rst human tumour antigen using tumour cell expression libraries selected by tumour-speci®c T cell clones [5], a large number of studies have identi®ed many potentially clinically exploitable target antigens. Clinical trials of active and more recently even adoptive immunotherapy are clearly showing the e€ectiveness of speci®c biological treatments for cancer. However, there are now de®nite cases where an initially undoubtedly e€ective therapy has lost ecacy because tumours develop resistance to immunological attack. This can happen for many di€erent reasons [4]. There are probably many more instances where clinical ecacy was never seen because tumours developed resistance even before a therapeutic e€ect could be noted. Tumour escape from the immune response may currently therefore be considered as the greatest impediment to the application of e€ective immunotherapy. To quote from the present author s recent report of an impressive collection of state-of-the-art presentations at a major cancer vaccine meeting during autumn 1998 [2]: This remarkable meeting concurrently illustrated both the great advances recently made in tumour immunology and the grave diculties met in applying this knowledge for clinically successful immunotherapy. Many tumour antigens have been identi®ed, many more are in the pipeline, and there is now a number of clinically well-tried approaches in both active and adoptive immunotherapy which do reproducibly result in the generation of e€ective antitumor immune responses. However, the major hurdle still to be overcome is the astounding capacity which tumours have for escaping from e€ective immune responses using numerous strategies and presenting themselves as real ``quick-change artists'' and regular ``Houdinis''. Finding ways of preventing tumour escape by multiple strategies will be the main challenge for immunotherapy in the next millennium. For this reason, a number of investigators active in this ®eld generously agreed to review their data and present their current views on the possible reasons for tumour escape, and how to go about preventing it in order to develop routinely successful immunotherapies for cancer. Whiteside discusses signalling defects in T cells induced by their residence in the tumour environment, and shows that certain of these are of prognostic signi®cance for disease progression and clinical outcome of treatment. She views the tumour-induced degradation of the zeta chain of the T cell receptor as associated with a tumour-induced apoptotic process, so that protection of the T cells against tumour-induced apoptosis should also be expected to ameliorate signalling defects and restore T cell ecacy. How this might be accomplished without non-speci®cally blocking the desired apoptosis of the tumour cells is presently unclear. One might possibly consider transferring antiapoptotic genes to T cells using T cell-tropic viruses in the future. Right now, it is clearly possible to remove the T cells and treat them ex vivo to restore activity (as well as induce apoptosis-resistance perhaps), and then re-infuse them adoptively. Whether they would be any more e€ective than before once they are again under the in ̄uence of the tumour environment is of course unCancer Immunol Immunother (1999) 48:343±345 Ó Springer-Verlag 1999

Isolation of MUC1-primed B lymphocytes from tumour-draining lymph nodes by immunomagnetic beads

Abstract: The humoral immune response against a tumour-associated antigen, polymorphic epithelial mucin (PEM, MUC1) in cancer patients was studied by isolating specific B cells primed for the antigen Human B lymphocytes from tumour-draining lymph nodes, obtained from 12 patients with epithelial cancers, were immunoselected with magnetic beads coated with a 60mer synthetic peptide corresponding to three tandem repeats of the protein core of the MUC1 antigen Short-term cultures of B cells were established utilizing interleukin-10 (IL-10), IL-4 and monoclonal antibody anti-CD40, and were maintained for a maximum of 3␣weeks B cell culture supernatants contained human anti-MUC1 antibodies, as detected by enzyme-linked immunosorbent assay, in 6/12 of the patients tested Five of these patients, all with early-stage cancer, also had high levels of circulating anti-MUC1 IgM antibodies in the serum A significant correlation was found (two-tailed P = 0041) between the presence of circulating anti-MUC1 antibodies and the ability to isolate PEM-specific B cells from tumour-draining lymph nodes The technique proposed provides a useful method for the analysis of natural immunity against defined tumour antigens

The role of monocytes and natural killer cells in mediating antibody-dependent lysis of colorectal tumour cells.

Abstract: Monocytes and natural killer (NK) cells are known to be important effector cell populations in mediating antibody-dependent cell-mediated cytotoxicity (ADCC). Purified monocyte and NK effector cell populations, from normal and colorectal cancer (CRC) patients, together with a number of murine (17-1A and 323/A3) and their chimaeric (c17-1A) or humanised (3622W94) equivalents, and chimaeric (c) SF25 were compared for their ability to mediate ADCC of colorectal tumour cells. The chimaeric and humanised antibodies were significantly better at mediating tumour lysis than their murine equivalents with all-effector populations. When effector cells from CRC patients were used the cSF25 antibody was significantly better than 3622W94 (P 80%), but 3622W94 bound to significantly more cells from primary tumour biopsies than cSF-25 (P = 0.001). Together, the results suggest that NK cells are the most important effector cell type mediating ADCC in vitro, that there is some impairment of NK function in CRC patients, and that cSF25 is the most potent antibody. For use in vivo the anti-Ep-CAM antibody 3622W94 would appear to be the most suitable reagent for further study.

Semiquantitative analysis of Th1 and Th2 cytokine expression in CD3+, CD4+, and CD8+ renal-cell-carcinoma-infiltrating lymphocytes.

Abstract: The mRNA expression of Th1 and Th2 cytokines was compared in freshly isolated CD3+ tumor-infiltrating lymphocytes (CD3+ TIL) and in autologous CD3+ peripheral blood lymphocytes (CD3+ PBL) obtained simultaneously from 20 patients with renal cell carcinomas (RCC). In addition cytokine expression was compared in CD4+ TIL and CD8+ TIL from another group of 20 patients with RCC. TIL were isolated from mechanically disaggregated tumor material and PBL from peripheral blood by gradient centrifugation and subsequent selection with anti-CD3, anti-CD4 or anti-CD8 magnetic beads. In these pure lymphocyte preparations the constitutive expression of interleukin-1 (IL-1), IL-2, IL-10, interferon γ (IFN), and tumor necrosis factor α (TNF) was determined by using a polymerase-chain-reaction-assisted mRNA amplification assay. In the CD3+ TIL, levels of mRNA for IFN, IL-10, IL-1 and TNF were significantly higher than in the autologous CD3+ PBL whereas IL-2 expression was rather low and did not differ in the two populations. Comparison of cytokine mRNA expression in CD4+ TIL and simultaneously obtained CD8+ TIL revealed a significantly higher expression of IFN in the CD8+ cells. These data reflect an in vivo activation of RCC-infiltrating lymphocytes at the mRNA level with respect to the Th1 as well as the Th2 immune response. Th1 activation seems to be most evident in the CD8+ TIL.

Function and dysfunction of CD4(+) T cells in the immune response to melanoma.

Abstract: A major difficulty for tumor immunotherapy derives from the phenomenon that the encounter of the immune system with an antigen does not necessarily result in activation, but may also be followed by the induction of tolerance either by anergy or physical deletion. It is well established that the immune system becomes alerted only in the face of danger, i.e. upon ligand recognition in the context of increased expression of costimulatory molecules, adhesion molecules, and MHC molecules on antigen-presenting cells (APC). The pivotal role of CD4+ T lymphocytes in this process has been established. However, encounter of CD4+ T cells with either MHC class II-expressing melanoma cells or certain tumor antigen-presenting APC has been reported to induce antigen-specific tolerance. Thus, as more is learned about the molecular regulation of immune responses and the role of CD4+ T cells in particular, additional strategies to block inhibitory pathways of T-cell activation will be developed. Such strategies are likely to be based on a modulation of the context in which antigen is encountered by the immune system, e.g. in situ cytokine therapy, induction of costimulatory molecules or the simulation of `danger' signals.

Cancer immunotherapy by antisense suppression of Ii protein in MHC-class-II-positive tumor cells.

Abstract: This study was aimed at creating a more effective tumor cell vaccine by suppressing Ii protein in the presence of MHC class II molecules within a cancer cell. Absence of the Ii protein, which normally blocks the antigenic-peptide-binding site of MHC class II molecules at synthesis in the endoplasmic reticulum, presumably increases the range of cancer-related epitopes presented to CD4+ helper T cells. Effective suppression of Ii protein was achieved with an antisense, phosphorothioate oligonucleotide, which was selected on the basis of (1) the RNase H activation assay, (2) an assay for Ii protein suppression, and (3) a test for potency with respect to the extent of base sequence (“sequence walking”). The SaI murine sarcoma, which is MHC-class-I+ and MHC-class-II−, Ii-protein−, upon transfection with genes for either interferon γ or the MHC class II transactivator, came to express MHC class II molecules and Ii protein. In each line of transfected tumor cells, the antisense oligonucleotide profoundly suppressed Ii protein in 35%–55% cells, without affecting expression of MHC class II molecules. Inoculation of mice with such Ii-protein-suppressed tumor vaccine cells, after either formaldehyde fixation or X-irradiation, led to much greater protection against challenge with the parental SaI sarcoma than did inoculation with untreated cells. This approach to cancer cell vaccination can be applied in a wide range of human tumors.

Restoration of expression of signal-transduction molecules in lymphocytes from patients with metastatic renal cell cancer after combination immunotherapy.

Abstract: A decrease in lymphocyte signal-transduction molecules, described in cancer patients and patients with chronic infectious diseases, has been proposed as a possible mechanism leading to an impaired immune response in cancer patients. Here we report the effects of combination immunotherapy on the levels of T cell receptor ζ chain and p56lck tyrosine kinase in a retrospective study of cryopreserved lymphocytes from 26 metastatic renal cell carcinoma patients treated with high-dose interleukin-2 (IL-2), interferon α(INFα) and ex vivo IL-2-activated lymphocytes. Of the 26 patients, 12 were responders (5 complete and 7 partial) and 14 were non-responders (6 stable and 8 with progressive disease). Prior to treatment, 21 of 26 patients (81%) and 13 of 21 patients (62%) respectively expressed ζ chain and p56lck at less than 50% of the levels observed in healthy controls. During therapy, this low ζ chain and p56lck expression increased to at least 50% of normal in 13 of the 21 patients (62%) and in 6 of the 13 patients (46%) respectively; in the remaining patients expression levels remained at 50% of normal or more, or declined. Although, in this limited study, pretreatment levels of ζ and p56lck did not show significant correlation with antitumor response, 4 of 5 patients that achieved a complete response (80%) corrected bothζ chain and p56lck levels to at least 50% of normal, while restoration of both signal-transduction molecules to such levels was only observed in 3 of 7 partial responders (43%), 1 of 5 patients with stable disease (20%) and 2 of 7 patients with progressive disease (29%). Thus, these results suggest that analysis of changes in signal-transduction molecules may a be useful tool for immunological monitoring of patients throughout immunotherapy, and could provide important information for designing new clinical trials that restore impaired signal transduction while activating T cell responses.

Treatment of medullary thyroid carcinoma by combined expression of suicide and interleukin-2 genes.

Abstract: Inherited medullary thyroid carcinomas (MTC) are aggressive and resistant to conventional chemo- and radiotherapies. We evaluated a novel strategy for treatment of MTC, combining “suicide” and interleukin-2 (IL-2) gene therapies. Tumors were produced in Wag/Rij rats by orthotopic injection of the rMTC 6–23 cell line, and/or derivatives expressing the herpes simplex virus 1 thymidine kinase (HSV1-TK) gene (rMTC-TK). Ganciclovir, a nucleoside analog selectively transformed to a toxic metabolite by HSV1-TK, totally eradicated rMTC-TK tumors in 60% of the animals. 1:1 rMTC and rMTC-TK mixed tumors were also strongly inhibited by ganciclovir (P < 0.05), indicating the occurrence of an efficient “bystander” effect in vivo. Double labelling of rMTC cell membranes and apoptotic nuclei revealed that, as with the TK+ cells, some TK− cells died by apoptosis. A 1:1 mixture of rMTC and rMTC-TK cells was administered to produce established tumors and then rMTC cells, transfected to express the IL-2 gene (rMTC-IL2), were inoculated. Combined ganciclovir and IL-2 treatment improved the inhibition of tumor growth compared to that following ganciclovir alone (86% compared to 54%, P < 0.05). This treatment also significantly enhanced macrophage activation and tumor infiltration by CD8+ and CD4+ T lymphocytes. These results open an avenue for combining suicide and immunoregulatory gene therapies for MTC management in man.

Effective cancer therapy with a single injection of interleukin-2 at the site of the tumour.

Abstract: Mice with a severe metastasized tumour burden can be cured with a single local injection of interleukin-2. Such a treatment can also be effective against ocular squamous cell carcinoma in cows and transmissible venereal tumours in dogs. We did not notice any toxic effects of this treatment.

Efficacy of repeated cycles of chemo-immunotherapy with thymosin alpha1 and interleukin-2 after intraperitoneal 5-fluorouracil delivery.

Abstract: We have used chemo-immunotherapy with 5-fluorouracil (5-FU), thymosin alpha1 (T alpha1) and interleukin-2 (IL-2) to treat multiple liver metastases from colorectal cancer induced by DHD/K12 cells in syngeneic BDIX rats, comparing one and two cycles of treatment, and different treatment combinations. 5-FU was delivered loco-regionally as a continuous infusion via an intraperitoneal (i.p.) catheter from a subcutaneously implanted mini-pump, a method we developed for this study. We show here that two cycles of a triple chemo-immunotherapy regimen significantly increased the average survival time compared to one cycle, and compared to untreated controls or those treated with two cycles of 5-FU alone. At 150 days, two rats treated with two cycles of triple therapy were cured, showing no signs of cancer at autopsy; all the other rats died before this time. Triple chemo-immunotherapy resulted in significantly fewer extra-hepatic metastases than in the controls and in those treated with 5-FU only. Further, we found that two cycles of triple treatment significantly increased the absolute number of peripheral T cells expressing IL-2 receptor, CD4 and CD8 compared to controls. We conclude that two cycles of chemo-immunotherapy with 5-FU, T alpha1 and IL-2 were superior to one cycle of treatment and to other treatments tested. Our results suggest that the triple therapy acts by increasing numbers of effector T cells. This method shows promise for the use of multi-cycle chemo-immunotherapy in the treatment of unresectable metastases of colorectal cancer in humans.

Humanisation and characterisation of PR1A3, a monoclonal antibody specific for cell-bound carcinoembryonic antigen

Abstract: Carcinoembryonic antigen (CEA) is highly expressed by most tumours of gastrointestinal origin, but its use as a target for tumour therapy is complicated by the high levels of soluble CEA that are found circulating in the blood of cancer patients. A monoclonal antibody PR1A3 has been prepared, which binds preferentially to cell-surface rather than soluble CEA, this cell selectivity should make PR1A3 an ideal candidate for antibody-targeted tumour therapy. PR1A3 has been humanised and shown to retain its cell-surface specificity and affinity. Stable expression of the humanised antibody from chinese hamster ovary (CHO) cells has been achieved after transfection and amplification. Since PR1A3 binds preferentially to cell-associated CEA, a cell-free enzyme-linked immunosorbent assay (ELISA) has been developed to allow characterisation and routine assay of the antibody. This assay was developed using a recombinant chimeric protein constructed by cloning the domain of CEA that is bound by PR1A3 (the B3 domain) into a hybrid gene containing the Fc portion of IgG and three domains of biliary glycoprotein. Stable expression of this hybrid protein has been achieved from CHO cells. In ELISA both humanised and murine PR1A3 bound strongly to this antigen but only at a minimal level to soluble CEA. Two binding sites for the antibody were found on the gastric carcinoma cell line MKN45, one of higher affinity (1 nM) and the other at lower affinity (60 nM). Similar affinities were found for both murine and humanised antibodies. The data presented make it unlikely that the differential binding to cell-surface as distinct from soluble CEA can be accounted for by low affinity of PR1A3 for CEA, and provides further support for the hypothesis that some conformational change takes place on CEA release from cells and that it is this change that blocks PR1A3 binding to its epitope.

Organ-specific pancreatic tumor growth properties and tumor immunity

Abstract: We established a model of orthotopic injection of a syngeneic pancreatic tumor cell line in C57BL/6 mice and evaluated the effects of organ site on induction of immunity to a tumor-specific antigen, MUC1. Mice were challenged with a syngeneic pancreatic adenocarcinoma cell line that expressed MUC1 (Panc02-MUC1) by orthotopic injection into the pancreas, or by subcutaneous injection. Tumor cells injected into the pancreas grew much faster than those injected subcutaneously. Mice challenged subcutaneously with Panc02-MUC1 rejected tumors or developed slowly growing tumors that were negative for MUC1 expression. In contrast, mice challenged orthotopically into the pancreas developed progressive tumors that were positive for MUC1 expression. Sera from mice that rejected PancO2-MUC1 (tumor-immune mice) showed no detectable IgG1 and IgM titers against the MUC1 tandem-repeat peptide, whereas mice with progressive tumor growth had significant titers of IgG1 and IgM specific for MUC1. This suggests that the humoral immune response was ineffective in mediating tumor rejection. The results show that the growth properties and immunological rejection of pancreatic tumors is affected by the organ site at which the tumor grows.

Generation of protective immunity against an immunogenic carcinoma requires CD40/CD40L and B7/CD28 interactions but not CD4(+) T cells.

Abstract: Interactions between CD40 and CD40L play a central role in the regulation of both humoral and cellular immunity. Recently, interactions between these molecules have also been implicated in the generation of protective cell-mediated tumor immunity. We have generated a tumor model in which a well-understood and clearly immunostimulatory antigen, influenza hemagglutinin has been transfected into the BALB/c-derived, MHC-class-I-positive, B7-deficient murine mammary carcinoma, MT901. In this model, expression of the influenza hemagglutinin antigen does not alter tumorigenicity in naive but serves as a tumor-rejection target in immunized mice. T-cell-depletion experiments indicate that successful tumor protection can occur following immunization in mice depleted of CD4+ but not CD8+ T cells, suggesting that tumor protection is largely CD8-mediated and CD4-independent. Interestingly, despite the ability of tumor protection to be generated in the absence of CD4+ T cells, effective immunization was clearly dependent on CD40/CD40L as well as CD28/B7 interactions.