Construction and characterization of a chimeric fusion protein consisting of an anti-idiotype antibody mimicking a breast cancer-associated antigen and the cytokine GM-CSF

Melanoma vaccines

Over the last century, vaccine studies have demonstrated that the human immune system, with appropriate help, can limit or prevent infection against otherwise lethal pathogens. Encouraged by these results, success in animal models and numerous well-documented reports of immune-mediated melanoma regression in humans, investigators developed melanoma vaccines. However, despite considerable laboratory evidence for vaccine-induced immune responses, clinical responses remain poor. Recent studies have elucidated several mechanisms that hinder or prevent the creation of successful vaccines and suggest novel approaches to overcome these barriers. Unraveling the mechanisms of autoimmunity, dendritic cell activation, regulatory T cells and Toll-like receptors will generate novel vaccines that, when used in conjunction with standard adjuvant therapies, may result in improved clinical outcomes. The objective of this review is to provide an overall summary of recent clinical trials with melanoma vaccines and highlight novel vaccine strategies to evaluate in the near future.

Characterization of cytokine-encapsulated controlled-release microsphere adjuvants

Controlled-release, injectable polymer microspheres provide a clinically feasible alternative to gene-modification for the local, sustained delivery of cytokines to tumors for cancer immunotherapy. Long-term release kinetics, bioactivity profiles, and stability of interleukin-2 (IL-2), interleukin-12 (IL-12), and granulocyte- macrophage colony-stimulating factor (GM-CSF)-encapsulated microspheres prepared by phase inversion nanoencapsulation (PIN) were evaluated. While all formulations released physiologically relevant quantities of cytokine for up to 30 days, the individual release kinetics were different. Recovery of specific activity after encapsulation was 40%, 60%, and 90%-that of pre-encapsulation levels for IL-2, GM-CSF and IL-12, respectively. Upon storage, the IL-12 microspheres rapidly lost activity, whereas IL-2 and GM-CSF microspheres remained stable for at least 9 weeks. These studies demonstrate that biochemical properties of microsphere formulations vary depending on the cytokine, and rigorous characterization of formulations is a prerequisite to in vivo testing.

A DNA vaccine encoding genetic fusions of carcinoembryonic antigen (CEA) and granulocyte/macrophage colony-stimulating factor (GM-CSF)

The anti-tumor immunologic effects of plasmid DNA vaccines encoding human carcinoembryonic antigen (CEA) fused to mouse granulocyte/macrophage colony-stimulating factor (GM-CSF) were examined. Immunization of C57BL/6 mice with the CEA-GMCSF fusion plasmids in a three injection, high-dose immunization schedule led to T cell and antibody responses specific for CEA. Mice injected with CEA-GMCSF fusion plasmids also developed IgG autoantibodies to GM-CSF. Tumor challenge with the CEA-expressing syngeneic mouse adenocarcinoma line, MC38-CEA-2, showed delayed tumor growth in mice immunized with the CEA-GMCSF fusion plasmids but complete protection in mice immunized with plasmid encoding CEA alone. In contrast, a single low-dose immunization with CEA-GMCSF fusion plasmids provided better tumor protection than low-dose CEA plasmid alone and resulted in lower titers of GM-CSF antibodies.

Monoclonal Anti-idiotype Antibody 6G6.C4 Fused to GM-CSF Is Capable of Breaking Tolerance to Carcinoembryonic Antigen (CEA) in CEA–Transgenic Mice

Internal image anti-idiotypic antibodies are capable of mimicking tumor-associated antigens and thus may serve as surrogate for vaccination strategies in cancer patients. The monoclonal antibody (mAb) 6G6.C4 mimics an epitope specific for the human carcinoembryonic antigen (CEA) and generates a CEA-specific response (Ab3) in various experimental animals. In humans, however, 6G6.C4 only yields a very limited humoral anti-CEA reaction presumably due to tolerance against the CEA autoantigen. In this study, we investigated the CEA-specific Ab3 response in mice transgenic for the human CEA and tested whether the antigen tolerance could be overcome by fusing a recombinant single-chain variable fragment of 6G6.C4 (scFv6G6.C4) to the murine granulocyte macrophage colony-stimulating factor (GM-CSF). Like mAb 6G6.C4, the fusion protein (scFv6G6.C4/GM-CSF) retained binding to the CEA-specific idiotype mAb T84.66. Also, scFv6G6.C4/GM-CSF was biologically active as measured by proliferation of the GM-CSF-dependent murine FDC-P1 cells in vitro. After immunization with the scFv6G6.C4/GM-CSF fusion protein, CEA-transgenic animals showed significantly enhanced Ab3 antibody responses to scFv6G6.C4 (P=0.005) and to CEA (P=0.012) compared with the scFV6G6.C4 alone. Sera from mice immunized with the fusion protein specifically recognized CEA in Western blot analyses with no cross-reaction to CEA-related antigens. Finally, the Ab3 antisera detected single CEA-expressing tumor cells in suspension as shown by flow cytometry. Taken together, these data show in a model antigenically related to the human system that vaccination with scFv6G6.C4/GM-CSF improves vaccination against an endogenous tumor-associated antigen resulting in a highly specific humoral Ab3 response in vivo that is capable of bind single circulating CEA-positive tumor cells.

Antibody-based vaccines for the treatment of melanoma

Malignant melanoma remains a difficult clinical problem. Chemotherapy is not effective and immunotherapy has long been contemplated as the preferred approach to this disease. Extensive passive and active immunotherapy trials have been conducted. Active vaccination with whole cells or defined antigens, administered with a panoply of techniques to increase immunogenicity, has yielded inconsistent results. The development of antibody-based vaccines has allowed vaccination without the need for tumor tissue material or purified antigens. The idiotype network theory originally proposed by Lindemann and by Jerne provided the basis for the development of anti-idiotype (anti-Id) antibody vaccines, which mimic the internal image of the epitope targeted for immunization. Preclinical and phase I clinical data are available for various malignancies. In melanoma, some of the anti-Id vaccines have targeted gangliosides. One of these vaccines, TriGem, has been successful in generating a robust and specific humoral immunity in melanoma patients. Phase II data suggest this anti-Id vaccine has clinical activity.

Production and characterisation of monoclonal anti-idiotype antibody to Vibrio anguillarum

Seven monoclonal anti-idiotype antibodies (mab2) were raised against mouse monoclonal antibody (mab1) 4A6. Identification of subclass showed that 1H5, 1D1, 2B12 and 2F12 belonged to IgG2b, 2H12 and 1H12 to IgG2a and lE10 to IgG3. The titres of these mab2 ascitic fluids ranged from 1 x 10(-4)-1 x 10(-6). The capacity of the mab2 to inhibit the binding between the corresponding rabbit antiserum and Vibrio anguillarum was investigated with the competitive inhibition ELISA. The results showed that mab2 1D1, 1E10, 1H5 and 1H12 were able to inhibit this binding. Another experiment demonstrated that mab2 1D1, 1E10 and 1H5 might induce Balb/c mice to produce Ab3 and these Ab3 competed the same antigen epitopes with Ab1. These results indicate that mab2 1D1, 1E10 and 1H5 are likely to represent an internal image of V. anguillarum and may thus be described as Ab2-beta anti-idiotype antibodies. In protection experiments, Japanese flounders vaccinated with mab21D1, 1E10 and 1H5 showed significantly enhanced survival from challenge with V. anguillarum. Thus. mab21D1, 1E10 and 1H5 may have use as idiotype vaccines for fish in aquaculture.

Short-term tumor cell lines from breast cancer for use as autologous tumor cell vaccines in the treatment of breast cancer

OBJECTIVE

We tried to establish short-term cultures of autologous tumors from patients with breast carcinoma for potential use as active specific immunotherapy (i.e., autologous vaccine) after resection of primary breast cancer, and/or for the treatment of metastases.

METHODS

Between 10/90 and 12/99 the cell biology laboratory of the Hoag Cancer Center attempted to establish short-term tumor cell lines from 115 breast cancer specimens from 56 primary breast lesions, 17 axillary nodes, 14 other lymph node/soft tissue sites, 10 chest wall recurrences, and 6 thoracentesis of malignant pleural effusions. Success was defined by growth of 5 x 10(7) viable cells whose malignant nature and breast cancer origin was confirmed by histology of the submitted tissue, cell morphology and antigenic phenotyping. Variables associated with successful growth of short-term cell lines were examined.

RESULTS

Expansion to 5 x 10(7) cells was achieved for only 8/115 samples [7%] including two from chest wall recurrences, and one each from a supraclavicular node, an umbilical node, liver, omentum, and pleural fluid. Two of the successful cell lines were established from tissue that originally had been cryopreserved; the others were initiated from fresh tumor. The success rate was better from regional/distant metastases 7/55 (13%) compared to primary tumors 1/56 (1.8%) (p = 0.063). The success rate for tumors harvested at Hoag Hospital was 4/97 (4%) compared to 4/14 from (31%) distant sites, but all but one of the tumors from a distant geographic site was a metastatic lesion. Tumor cell lines were successfully established from metastatic lesions ranging in size from < 1.0 g to 19 g. Four patients were treated with their autologous vaccine in the setting of chemotherapy-refractory metastatic disease without any significant toxicity.

CONCLUSIONS

We were unable to establish short-term cell lines for most patients with primary or metastatic breast cancer using this methodology. However, two long-term cell lines have been established and characterized. Treatment with the autologous irradiated cell product was not associated with acute toxicity.

Monoclonal antibody therapy for solid tumors

Monoclonal antibody therapy for solid tumors has many theoretical attractions and a long history. Until recently, with the approval and widespread use of rituximab (Rituxan) and trastuzumab (Herceptin), monoclonal antibody therapy for tumors had not had significant success. This article reviews basic theories behind antibody development and their clinical implementation as treatment for solid tumors. Medline was searched for articles over the past 15 years dealing with laboratory and clinical applications of antibody therapy for solid tumors. In addition, American Society of Clinical Oncology (ASCO) abstracts from the past 3 years were reviewed to complement the Medline search. This article focuses on treatment for common solid tumors, including breast, colon and lung cancers.

Uses of granulocyte-macrophage colony-stimulating factor in vaccine development

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a potent cytokine capable of inducing differentiation, proliferation, and activation of a variety of immunologically active cell populations. In addition to its effects on stimulating granulocytic hematopoiesis, it also facilitates development of both humoral and cellular mediated immunity. Accordingly, strategies involving the use of GM-CSF as a vaccine adjuvant have attracted considerable attention. These strategies include the systemic administration of soluble GM-CSF with an immunogen, and also its use as part of gene therapy approaches to immunization. Because of the potency of this cytokine as an immune adjuvant, particular interest has focused on its use to overcome poorly immunogenic antigens such as those associated with intracellular infections and cancer. This review focuses on recent advances in the use of GM-CSF as a vaccine adjuvant.

Exploring the feasibility of an anti-idiotypic cocaine vaccine: analysis of the specificity of anticocaine antibodies (Ab1) capable of inducing Ab2beta anti-idiotypic antibodies

Conventional vaccination with the cocaine molecule conjugated to a protein carrier is a new approach in the treatment of addiction. Experimentally, this strategy has been shown to alter the pharmacokinetics as well as the psychostimulant effect of a cocaine challenge. The purpose of this study was to investigate whether a more stable and less controversial molecule, an anti-idiotypic antibody, which mimics the configuration of the cocaine molecule (Ab2beta), could be successfully used instead of cocaine. Two cocaine conjugates that presented different areas of the cocaine molecule to the immune system were used to produce monoclonal antibodies specific for cocaine (Ab1). Several anti-idiotypic antibodies were then produced. Four were identified as Ab2beta, or internal images of the antigen; when injected into BALB/c mice, they elicited an anticocaine response. The anticocaine response elicited by one of the four Ab2beta (K1-4c) was sufficient to significantly reduce the level of cocaine that targeted the brain following cocaine challenge, compared with the level of cocaine found in the brain of control animals immunized with irrelevant antibody. In conclusion, the possibility of an anti-idiotypic vaccine seems to be worth pursuing.