Vaccination of melanoma patients with an allogeneic, genetically modified interleukin 2-producing melanoma cell line

Advances in Cancer Vaccine Research

The use of cancer vaccines is considered a promising therapeutic strategy in clinical oncology, which is achieved by stimulating antitumor immunity with tumor antigens delivered in the form of cells, peptides, viruses, and nucleic acids. The ideal cancer vaccine has many advantages, including low toxicity, specificity, and induction of persistent immune memory to overcome tumor heterogeneity and reverse the immunosuppressive microenvironment. Many therapeutic vaccines have entered clinical trials for a variety of cancers, including melanoma, breast cancer, lung cancer, and others. However, many challenges, including single antigen targeting, weak immunogenicity, off-target effects, and impaired immune response, have hindered their broad clinical translation. In this review, we introduce the principle of action, components (including antigens and adjuvants), and classification (according to applicable objects and preparation methods) of cancer vaccines, summarize the delivery methods of cancer vaccines, and review the clinical and theoretical research progress of cancer vaccines. We also present new insights into cancer vaccine technologies, platforms, and applications as well as an understanding of potential next-generation preventive and therapeutic vaccine technologies, providing a broader perspective for future vaccine design.

Immunological and functional aspects of MAGEA3 cancer/testis antigen

Identification of ectopic gene activation in cancer cells serves as a basis for both gene signature-guided tumor targeting and unearthing of oncogenic mechanisms to expand the understanding of tumor biology/oncogenic process. Proteins expressed only in germ cells of testis and/or placenta (immunoprivileged organs) and in malignancies are called cancer testis antigens; they are antigenic because of the lack of antigen presentation by those specific cell types (germ cells), which limits the exposure of the proteins to the immune cells. Since the Cancer Testis Antigens (CTAs) are immunogenic and expressed in a wide variety of cancer types, CT antigens have become interesting target for immunotherapy against cancer. Among CT antigens MAGEA family is reported to have 12 members (MAGEA1 to MAGEA12). The current review highlights the studies on MAGEA3 which is a CT antigen and reported in almost all types of cancer. MAGEA3 is well tried for cancer immunotherapy. Recent advances on its functional and immunological aspect warranted much deliberation on effective therapeutic approach, thus making it a more interesting target for cancer therapy.

Genetically engineered mesenchymal stem cells: targeted delivery of immunomodulatory agents for tumor eradication

Cancer immunotherapy emerged as a novel therapeutic option that employs enhanced or amended native immune system to create a robust response against malignant cells. The systemic therapies with immune-stimulating cytokines have resulted in substantial dose-limiting toxicities. Targeted cytokine immunotherapy is being explored to overcome the heterogeneity of malignant cells and tumor cell defense with a remarkable reduction of systemic side effects. Cell-based strategies, such as dendritic cells (DCs), fibroblasts or mesenchymal stem cells (MSCs) seek to minimize the numerous toxic side effects of systemic administration of cytokines for extended periods of time. The usual toxicities comprised of a vascular leak, hypotension, and respiratory insufficiency. Natural and strong tropism of MSCs toward malignant cells made them an ideal systemic delivery vehicle to direct the proposed therapeutic genes to the vicinity of a tumor where their expression could evoke an immune reaction against the tumor. Compared with other methods, the delivery of cytokines via engineered MSCs is safer and renders a more practical, and promising strategy. Large numbers of genes code for cytokines have been utilized to reengineer MSCs as therapeutic cells. This review highlights the recent findings on the cytokine gene therapy for human malignancies by focusing on MSCs application in cancer immunotherapy.

Therapeutic effects of iNOS inhibition against vitiligo in an animal model

Nitric oxide (NO) is involved in several biological processes, but its role in human melanogenesis and vitiligo need further studies. Previous studies revealed that exposure to UVA and UVB were capable of the inducing nitric oxide production in keratinocytes and melanocytes through the activation of constitutive nitric oxide synthase, whereas inducible nitric oxide synthase overexpression has been reported to play an important role in hyperpigmentary disorders. The aim of this study was to evaluate iNOS inhibitor aminoguanidine (AG) as a therapeutic agent in our mouse model of vitiligo. In this study, male C57BL/6J Ler-vit/vit mice were purchased to evaluate the effect of iNOS inhibitor (aminoguanidine) (50 and 100 mg/kg) and L-arginine (100 mg/kg) in a mouse model of vitiligo induced by monobenzone 40%. Moreover, we used phototherapy device to treat the mice with NBUVB as a gold standard.The findings revealed that monobenzone was capable of inducing depigmentation after 6 weeks. However, aminoguanidine in combination with monobenzone was decrease the effect of monobenzone, while L-arginine play a key role in promoting the effect of monobenzone (P<0.001). Based on the phototherapy, the efficacy of phototherapy significantly increased by adding L-arginine (P<0.05). Taken together, we suggest that iNOS inhibitor can be a novel treatment for the prevention and treatment of vitiligo by combination of NBUVB therapy, furthermore; NO agents like L-arginine could also increase the effectiveness of phototherapy. Taken together, this pilot study showed significant repigmentation of vitiligous lesions treated with iNOS inhibitor plus NBUVB therapy, where other aspect including expression of an inducible iNOS, NO and TNF levels remained to be evaluated in mice model.

Blockade of Programmed Death 1 Augments the Ability of Human T Cells Engineered to Target NY-ESO-1 to Control Tumor Growth after Adoptive Transfer

PURPOSE

Tumor-infiltrating lymphocytes (TILs) become hypofunctional, although the mechanisms are not clear. Our goal was to generate a model of human tumor-induced TIL hypofunction to study mechanisms and to test anti-human therapeutics.

EXPERIMENTAL DESIGN

We transduced human T cells with a published, optimized T-cell receptor (TCR) that is directed to a peptide within the cancer testis antigen, NY-ESO-1. After demonstrating antigen-specific in vitro activity, these cells were used to target a human lung cancer line that expressed NY-ESO-1 in the appropriate HLA context growing in immunodeficient mice. The ability of anti-PD1 antibody to augment efficacy was tested.

RESULTS

Injection of transgenic T cells had some antitumor activity, but did not eliminate the tumors. The injected T cells became profoundly hypofunctional accompanied by upregulation of PD1, Tim3, and Lag3 with coexpression of multiple inhibitory receptors in a high percentage of cells. This model allowed us to test reagents targeted specifically to human T cells. We found that injections of an anti-PD1 antibody in combination with T cells led to decreased TIL hypofunction and augmented the efficacy of the adoptively transferred T cells.

CONCLUSIONS

This model offers a platform for preclinical testing of adjuvant immunotherapeutics targeted to human T cells prior to transition to the bedside. Because the model employs engineering of human T cells with a TCR clone instead of a CAR, it allows for study of the biology of tumor-reactive TILs that signal through an endogenous TCR. The lessons learned from TCR-engineered TILs can thus be applied to tumor-reactive TILs.

Vitiligo-like depigmentation in patients with stage III-IV melanoma receiving immunotherapy and its association with survival: a systematic review and meta-analysis

PURPOSE

Vitiligo-like depigmentation in patients with melanoma may be associated with more favorable clinical outcome. We conducted a systematic review of patients with stage III to IV melanoma treated with immunotherapy to determine the cumulative incidence of vitiligo-like depigmentation and the prognostic value of vitiligo development on survival.

METHODS

We systemically searched and selected all studies on melanoma immunotherapy that reported on autoimmune toxicity and/or vitiligo between 1995 and 2013. Methodologic quality of each study was appraised using adapted criteria for systematic reviews in prognostic studies. Random-effect models were used to calculate summary estimates of the cumulative incidence of vitiligo-like depigmentation across studies. The prognostic value of vitiligo-like depigmentation on survival outcome was assessed using random-effects Cox regression survival analyses.

RESULTS

One hundred thirty-seven studies were identified comprising 139 treatment arms (11 general immune stimulation, 84 vaccine, 28 antibody-based, and 16 adoptive transfer) including a total of 5,737 patients. The overall cumulative incidence of vitiligo was 3.4% (95% CI, 2.5% to 4.5%). In 27 studies reporting individual patient data, vitiligo development was significantly associated with both progression-free-survival (hazard ratio [HR], 0.51; 95% CI, 0.32 to 0.82; P < .005) and overall survival (HR, 0.25; 95% CI, 0.10 to 0.61; P < .003), indicating that these patients have two to four times less risk of disease progression and death, respectively, compared with patients without vitiligo development.

CONCLUSION

Although vitiligo occurs only in a low percentage of patients with melanoma treated with immunotherapy, our findings suggest clear survival benefit in these patients. Awareness of vitiligo induction in patients with melanoma is important as an indicator of robust antimelanoma immunity and associated improved survival.

Targeting the acute myeloid leukemic stem cell compartment by enhancing tumor cell-based vaccines

Harvesting the potential of the immune system in order to eradicate (residual) acute myeloid leukemia (AML) cells is the long pursued goal of immunotherapy in AML. Strategies using apoptotic tumor cell vaccines have been explored for many years, without significant clinical improvements. In recent years insight has been gained into the mechanisms activating and interfering with tumor-directed immunity. With the arrival of novel immune-modulating agents allowing for the interference with regulatory molecules and interaction with immune-propelling mechanisms, new doors are opening for increasing vaccination efficacy. Combined with advances in the design of apoptotic tumor-based vaccines, we are on the verge of creating an effective AML vaccine strategy, offering a much needed novel therapeutic option for this devastating disease.

Autologous versus allogeneic cell-based vaccines?

Devitalized tumor cells either autologous or allogeneic have been used as anti-cancer vaccines with the purpose of facilitating the induction of an immune response able to destroy growing tumor cells since the identification of tumor antigens was deemed not to be necessary, particularly in the autologous system. Such vaccines were tested first in animal models and then in the clinics as unmodified tumor cells or after insertion of genes coding for factors known to increase the immune response against tumors. These vaccines were usually given by subcutaneous injections along with different immunological adjuvants. Such immunization approaches were found to be effective in mice when carried out in a tumor preventive setting but significantly less in the therapeutic context, that is, in the presence of an established tumor. By analyzing several clinical trials of vaccination using either autologous or allogeneic unmodified and gene-modified tumor cells published in the last 10 to 15 years, we conclude for a lack of sufficient evidence for efficacy of this strategy in inducing both a strong immune response and a therapeutic response. A potential variant of this strategy is the direct intratumoral injection of immunostimulatory genes delivered by vectors in vivo. But even this approach failed to provide a statistically significant clinical benefit for the cancer patients.We also point out the inherent drawbacks of the tumor cell-based vaccine strategy that include (a) a limited frequency by which human tumor lines can be obtained from clinical samples, (b) the low number of available cells for vaccination, (c) the release of immune-suppressive factors by tumor cells, and (d) the cost and time necessary for standardization and collecting/expanding a number of cells according to the approved regulatory requirements. Thus, taking into consideration the new developments in cancer vaccines, we believe that tumor cell-based vaccines should be dismissed as anti-cancer vaccines unless a clear benefit could be demonstrated by the few ongoing trials of combination with new immunomodulating reagents (eg, anti-CTLA4, PD-1, chemotherapy).

Antigen-specific versus antigen-nonspecific immunotherapeutic approaches for human melanoma: the need for integration for optimal efficacy?

Due to its immunogenecity and evidence of immune responses resulting in tumor regression, metastatic melanoma has been the target for numerous immunotherapeutic approaches. Unfortunately, based on the clinical outcomes, even the successful induction of tumor-specific responses does not correlate with efficacy. Immunotherapies can be divided into antigen-specific approaches, which seek to induce T cells specific to one or several known tumor associated antigens (TAA), or with antigen-nonspecific approaches, which generally activate T cells to become nonspecifically lytic effectors. Here the authors critically review the different immunotherapeutic approaches in melanoma.

Advances in viral-vector systemic cytokine gene therapy against cancer

Current strategies for cancer gene therapy consist mainly of direct inhibition of tumor cell growth and activation of systemic host defense mechanisms. Cytokine gene-transduced tumor cells have been used as vaccines in clinical trials, which have shown good safety profiles and some local responses but substantial lack of systemic efficacy. Cytokines should be directed at the level of gene selection and delivery, in order to identify the optimal cytokine and achieve efficient and durable cytokine expression at the level of improving immune stimulation. In this review, we will summarize the current achievements of cytokine gene therapy, especially viral-vector, and their applications in cancer treatment. Additionally, we will also discuss and propose future perspectives about cancer gene therapy.

Cancer immunotherapy

Recent scientific advances have expanded our understanding of the immune system and its response to malignant cells. The clinical goal of tumour immunotherapy is to provide either passive or active immunity against malignancies by harnessing the immune system to target tumours. Monoclonal antibodies, cytokines, cellular immunotherapy, and vaccines have increasingly become successful therapeutic agents for the treatment of solid and haematological cancers in preclinical models, clinical trials, and practice. In this article, we review recent advances in the immunotherapy of cancer, focusing on new strategies and future perspectives as well as on clinical trials attempting to enhance the efficacy of immunotherapeutic modalities and translate this knowledge into effective cancer therapies.

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.

Evidence of systemic Th2-driven chronic inflammation in patients with metastatic melanoma

PURPOSE

Immunotherapeutic modalities are commonly used for treatment of patients with melanoma. The therapeutic success in preclinical models has not yielded the expected clinical results. To understand this discrepancy, we attempted to define immune homeostasis of 209 patients with melanoma across stages of disease relative to normal controls.

EXPERIMENTAL DESIGN

Peripheral blood mononuclear cells (PBMC) and plasma were collected from patients and healthy donors. PBMC were analyzed for frequencies of natural killer, dendritic, and T cells and their functional status. Matched plasma samples were analyzed for the concentrations of 27 cytokines, chemokines, and growth factors. RNA was isolated from 24 metastatic melanoma tumor biopsies and profiled by microarray analysis.

RESULTS

The frequency of natural killer, T, and dendritic cells in patients does not significantly change across stages of melanoma. However, plasma concentrations of Th2 cytokines [interleukin (IL)-4, IL-5, IL-10, and IL-13] in tumor-bearing patients were significantly higher than those with resected melanoma. Expression array analysis of metastatic melanoma revealed that the malignant melanocytes were not the source of the Th2 cytokines but did highly up-regulate vascular endothelial growth factor (VEGF) transcripts, consistent with plasma VEGF concentrations. In vitro VEGF exposure of normal PBMC lead to repolarization from Th1 to Th2 emulating the state of metastatic melanoma.

CONCLUSIONS

Patients with metastatic melanoma exist in a state of Th2-mediated "chronic inflammation" as a result of at least VEGF overproduction by malignant tumors. These data support prior observations regarding the effect of VEGF on immune cell function and suggests consideration of VEGF inhibitors in future cancer immunotherapy clinical studies in metastatic melanoma.

Tumour immunity: effector response to tumour and role of the microenvironment

Substantial evidence shows that inflammation promotes oncogenesis and, occasionally, participates in cancer rejection. This paradox can be accounted for by a dynamic switch from chronic smouldering inflammation promoting cancer-cell survival to florid, tissue-disruptive inflammatory reactions that trigger cancer-cell destruction. Clinical and experimental observations suggest that the mechanism of this switch recapitulates the events associated with pathogen infection, which stimulate immune cells to recognise danger signals and activate immune effector functions. Generally, cancers do not have danger signals and, therefore, they cannot elicit strong immune reactions. Synthetic molecules have been developed that mimic pathogen invasion at the tumour site. These compounds activate dendritic cells to produce proinflammatory cytokines, which in turn trigger cytotoxic mechanisms leading to cancer death. Simultaneously, dendritic cells capture antigen shed by dying cancer cells, undergo activation, and stimulate antigen-specific T and B cells. This process results in massive amplification of the antineoplastic inflammatory process. Thus, although anti-inflammatory drugs can prevent onset of some malignant diseases, induction of T cells specific for tumour antigen by active immunisation, combined with powerful activation signals within the cancer microenvironment, might yield the best strategy for treatment of established cancers.

Effective gene transfer to melanoma cells using bacterial ghosts

Bacterial ghosts (BG) are cell envelopes preparations of Gram-negative bacteria devoid of cytoplasmic content produced by controlled expression of PhiX174 plasmid-encoded lysis gene E. Eight melanoma cell lines were investigated for their capacity to bind and phagocyte BG derived from Escherichia coli NM522 and Mannheimia haemolytica A23. High capability to bind BG was observed in almost all of the analyzed cell lines, furthermore cells were able to take up BG independently of the used bacterial species. Further, transfection efficiency of BG loaded with DNA in vitro was measured. The Bowes cells exhibited a high expression level of GFP and the incubation of cells with plasmid loaded BG led up to 82% transfection efficiency.

Gene therapy in The Netherlands: highlights from the Low Countries

Gene therapy is an active research area in The Netherlands and Dutch scientists involved in fundamental and clinical gene therapy research significantly contribute to the progresses made in this field. This ranges from the establishment of the 293, 911 and PER.C6 cell lines, which are used worldwide for the production of replication‐defective adenoviral vectors, to the development of targeted viral vectors and T lymphocytes as well as of non‐viral vectors. Several milestones have been achieved in Dutch clinical gene therapy trials, including the first treatment worldwide of patients with adenosine deaminase deficiency with genetically corrected hematopoietic stem cells in collaboration with French and British scientists. Until now, about 230 patients with various diseases have been treated with viral and non‐viral gene therapy in this country. Ongoing and upcoming Dutch clinical trials focus on the translation of new developments in gene therapy research, including the restoration of genetic defects other than SCID, and the use of oncolytic adenoviruses and targeted T cells for the treatment of cancer. The growing commercial interest in Dutch clinical gene therapy is reflected by the involvement of two Dutch companies in ongoing trials as well as the participation of Dutch clinical centres in large phase III international multicenter immuno‐gene therapy trials on prostate cancer sponsored by an American company. Translational gene therapy research in The Netherlands is boosted at a governmental level by the Dutch Ministry of Health via a dedicated funding programme. This paper presents an overview on milestones in Dutch basic gene therapy research as well as on past, present and future clinical gene therapy trials in The Netherlands. Copyright © 2007 John Wiley & Sons, Ltd.

Treatment of vitiligo vulgaris with narrow-band UVB and oral Polypodium leucotomos extract: a randomized double-blind placebo-controlled study

BACKGROUND

The first choice treatment for vitiligo vulgaris is narrow-band UVB (NB-UVB), but no satisfactory treatment exists.

OBJECTIVES

To investigate if Polypodium leucotomos, an antioxidative and immunomodulatory plant extract, improves NB-UVB-induced repigmentation.

METHODS

Fifty patients with vitiligo vulgaris randomly received 250 mg oral P. leucotomos or placebo three times daily, combined with NB-UVB twice weekly for 25-26 weeks.

RESULTS

Repigmentation was higher in the P. leucotomos group vs. placebo in the head and neck area (44% vs. 27%, P = 0.06). Small repigmentation increases (P = n.s.) were observed for the trunk (6% increased repigmentation), extremities (4%), and hands and feet (5%) in the P. leucotomos group vs. placebo. Patients attending more than 80% of required NB-UVB sessions showed increased repigmentation in the head and neck area in the P. leucotomos group vs. placebo (50% vs. 19%, P < 0.002); no significant differences were seen in the other body areas. Patients with skin types 2 and 3 showed more repigmentation in the head and neck area in the P. leucotomos group vs. placebo (47% vs. 21%, P = 0.01), and no significant differences were seen in the other body areas. No conclusions could be drawn on skin types 4 and 5 due to low patient numbers.

CONCLUSION

There is a clear trend towards an increase in repigmentation of vitiligo vulgaris affecting the head and neck area when NB-UVB phototherapy is combined with oral P. leucotomos. This effect may be more pronounced in light skin types.

Angiogenesis meets immunology: Cytokine gene therapy of cancer

Delivery of cytokine genes at the tumor site in pre-clinical models has been shown to recruit host inflammatory cells followed by inhibition of tumor growth. This local effect is often accompanied by systemic protection mediated by the immune system, mainly by CD8(+) T and NK cells. On this basis, cytokine gene-transduced tumor cells have widely been used as vaccines in clinical trials, which have shown good safety profiles and some local responses but substantial lack of systemic efficacy. Are these findings the end of the story? Possibly not, if major improvements will be attained in the coming years. These should be directed at the level of gene selection and delivery, in order to identify the optimal cytokine and achieve efficient and durable cytokine expression, and at the level of improving immune stimulation, i.e. by co-administration of co-stimulatory molecules including B7 and CD40, or boosting the expression of tumor antigens or MHC class I molecules. Interestingly, some of the cytokines which have shown encouraging anti-tumor activity, including IFNs, IL-4, IL-12 and TNF-alpha, are endowed with anti-angiogenic or vasculotoxic effects, which may significantly contribute to local tumor control. Therapeutic exploitation of this property may result in the design of novel approaches which, by maximizing immune-stimulating and anti-angiogenic effects, could possibly lead to starvation of established tumors in patients.

Phase I clinical trial of a TGF-beta antisense-modified tumor cell vaccine in patients with advanced glioma

We performed a phase I clinical trial in grade IV astrocytoma to assess the safety of a whole-cell vaccine comprising autologous tumor cells genetically modified by a transforming growth factor-beta2 (TGF-beta2) antisense vector. Blocking secretion of the immunosuppressive molecule TGF-beta in this manner should inhibit one of the major mechanisms by which tumor cells evade immune surveillance and should lead to clinically effective antitumor immunity. Six patients with progressive WHO grade IV astrocytoma were enrolled in the trial. Patients received 2-7 subcutaneous injections of 5 x 10(6)-2 x 10(7) autologous tumor cells per injection. TGF-beta2 secretion by the tumor cells used to vaccinate patients was inhibited by 53-98%. Treatment was well tolerated with only low-grade, transient treatment-related toxicities reported. Two patients had partial regressions and two had stable disease following therapy. The overall median survival was 68 weeks. Median survival of the responding patients was 78 weeks, compared to a historic value of 47 weeks for glioma patients treated conventionally. There were indications of humoral and cellular immunity induced by the vaccine. These findings support further clinical evaluation of vaccines comprised of TGF-beta antisense-modified tumor cells.

Immunological and antitumor effects of IL-23 as a cancer vaccine adjuvant

The promising, but modest, clinical results of many human cancer vaccines indicate a need for vaccine adjuvants that can increase both the quantity and the quality of vaccine-induced, tumor-specific T cells. In this study we tested the immunological and antitumor effects of the proinflammatory cytokine, IL-23, in gp100 peptide vaccine therapy of established murine melanoma. Neither systemic nor local IL-23 alone had any impact on tumor growth or tumor-specific T cell numbers. Upon specific vaccination, however, systemic IL-23 greatly increased the relative and absolute numbers of vaccine-induced CD8(+) T cells and enhanced their effector function at the tumor site. Although IL-23 specifically increased IFN-gamma production by tumor-specific T cells, IFN-gamma itself was not a primary mediator of the vaccine adjuvant effect. The IL-23-induced antitumor effect and accompanying reversible weight loss were both partially mediated by TNF-alpha. In contrast, local expression of IL-23 at the tumor site maintained antitumor activity in the absence of weight loss. Under these conditions, it was also clear that enhanced effector function of vaccine-induced CD8(+) T cells, rather than increased T cell number, is a primary mechanism underlying the antitumor effect of IL-23. Collectively, these results suggest that IL-23 is a potent vaccine adjuvant for the induction of therapeutic, tumor-specific CD8(+) T cell responses.

Human cancer gene therapy with cytokine gene-modified cells

Cytokines can impede tumour growth and activate innate and adaptive immune responses, leading to elimination of cancer cells. For many years, it was believed that systemic administration of recombinant cytokines might become a standard treatment of different cancer types. However, due to a high toxicity of therapeutic doses and a low efficacy, even in combination with chemotherapy, this strategy is generally not accepted. On the other hand, cancer gene therapy approaches utilising cells modified with cytokine genes seem to represent a novel promising approach. For the last decade, numerous Phase I and II clinical trials evaluating different therapies based on cytokine gene-modified cells have been carried out. In the early studies, several strategies have been shown to improve clinical outcomes and induce strong antitumour immune responses. Recently, a few prospective, randomised, Phase III clinical trials have been initiated in order to finally determine the efficacy of particular cancer immunogene therapy strategies. This article reviews the present status and perspectives of clinical trials of cancer immunotherapies utilising cytokine gene-modified cells.

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.

Intratumoral immunotherapy: using the tumour against itself

Summary Diverse immunotherapy approaches have achieved success in controlling individual aspects of immune responses in animal models. Transfer of such immunotherapies to clinical trials has obtained some success in patients, with clinical responses observed or effective antigen specific immune responses achieved, but has had limited impact on patient survival. Key elements required to generate de novo cell-mediated antitumour immune responses in vivo include recruitment of antigen-presenting cells to the tumour site, loading these cells with antigen, and their migration and maturation to full antigen-presenting function. In addition, it is essential for antigen-specific T cells to locate the tumour to mediate cytotoxicity, emphasizing the need for local inflammation to target effector cell recruitment. We review those therapies that involve the tumour site as a target and source of antigen for the initiation of immune responses, and discuss strategies to generate and co-ordinate an optimal cell-mediated immune response to control tumours locally.

Cancer vaccine development: on the way to break immune tolerance to malignant cells

Exploiting a naturally occurring defense system, the immunotherapeutic approach embodies an ideal nontoxic treatment for cancer. Despite the evidence that immune effectors can play a significant role in controlling tumor growth either in natural conditions or in response to therapeutic manipulation, the cascade of molecular events leading to tumor rejection by the immune system remains to be fully elucidated. Nevertheless, some recent tumor immunology advancements might drastically change the way to design the next generation of cancer vaccines, hopefully improving the effectiveness of this therapeutic approach. In the present work, we will focus on three main areas of particular interest for the development of novel vaccination strategies: (a) cellular or molecular mechanisms of immune tolerance to malignant cells; (b) synergism between innate and adaptive immune response; (c) tumor-immune system interactions within the tumor microenvironment.

Antigen-based immunotherapy of melanoma: Canvaxin therapeutic polyvalent cancer vaccine

As yet there are no FDA-approved cancer vaccines for malignant melanoma, but encouraging response rates and low toxicities reported in phase I/II trials suggest that antigen-based active immunotherapy may complement current treatment modalities. The cumulative data for Canvaxin therapeutic polyvalent cancer vaccine represent the largest phase II clinical trial of any cancer vaccine. Univariate and multivariate analyses of these data have demonstrated the prognostic significance of this allogeneic whole-cell preparation as a postoperative adjuvant treatment for patients with stage III and IV melanoma. The vaccine has also been shown promising results after resection of stage II melanoma and in patients with regional in-transit disease. The consistent correlation between immune and clinical responses to the vaccine suggests that immune parameters may be used to monitor a patient's response to vaccine therapy.

Interleukin-2 improves tumour response to DNP-modified autologous vaccine for the treatment of metastatic malignant melanoma

This paper is a report of response rate (RR) and survival of 34 metastatic melanoma patients who received a dinitrophenyl (DNP)-modified autologous melanoma cell vaccine. In all, 27 patients started the vaccine as a primary treatment for metastatic melanoma and seven started it as an adjuvant, with no evidence of disease at the time, but had developed new metastases. Interleukin-2 (IL-2) was administered in 24 out of the 34 patients: 19 who progressed on vaccine alone and five who had the combination from start. Interleukin-2 was administered in the intravenous, bolus high-dose regimen (seven patients) or as subcutaneous (s.c.) low-dose treatment (17). Overall response for the entire group was 35% (12 patients out of 34), 12% having a complete response (CR) and 23% a partial response (PR). However, only two patients had tumour responses while on the vaccine alone, whereas the other 10 demonstrated objective tumour regression following the combination with IL-2 (two CR, eight PR), lasting for a median duration of 6 months (range 3–50 months). Of the 12 responding patients, 11 attained strong skin reactivity to the s.c. injection of irradiated, unmodified autologous melanoma cells. None of the patients with a negative reactivity experienced any tumour response. Patients with positive skin reactions survived longer (median survival – 54 months). The results suggest enhanced RRs to the combination of IL-2 and autologous melanoma vaccine. Skin reactivity to unmodified autologous melanoma cells may be a predictor of response and improved survival, and therefore a criterion for further pursuing of immunotherapeutic strategies.

Endocrine aspects of cancer gene therapy

The field of cancer gene therapy is in continuous expansion, and technology is quickly moving ahead as far as gene targeting and regulation of gene expression are concerned. This review focuses on the endocrine aspects of gene therapy, including the possibility to exploit hormone and hormone receptor functions for regulating therapeutic gene expression, the use of endocrine-specific genes as new therapeutic tools, the effects of viral vector delivery and transgene expression on the endocrine system, and the endocrine response to viral vector delivery. Present ethical concerns of gene therapy and the risk of germ cell transduction are also discussed, along with potential lines of innovation to improve cell and gene targeting.

Restimulation of tumour-specific immunity in a patient with AML following injection with B7-1 positive autologous blasts

Leukaemic blast cells lack co-stimulatory molecules such as B7, necessary for T-lymphocyte activation. We have used modified CD80+ (B7-1+) tumour cells, with autologous, IL-2 producing, stromal marrow cells in a series of subcutaneous vaccinations to provide a localised environment for the enhancement of cytotoxic T-lymphocytes (CTL) in a patient with acute myeloid leukaemia (AML). Localised inflammation was evident after the fifth and sixth injections with a reduction in the number of circulating blasts in the following 2 weeks. Peripheral blood in vitro CTL activity increased 36-47% after five injections.CD4 T-lymphocytes (5.7%) expanded from post-injection skin biopsies, expressed intracellular IFNgamma and perforin when exposed to autologous B7-1+ blasts and when co-cultured with either B7-1+ or unmanipulated autologous blast cells showed proliferative responses. In this patient, co-injection of B7-1+ tumour cells, together with a local source of sustained IL-2, resulted in an autologous anti-leukaemic in vitro immune response.

Induction of T lymphocytes specific to human gastric cancer using HLA-A matched allogeneic gastric tumor cells

Tumor-specific cytotoxic T lymphocytes (CTLs) from patients with early-stage tumors are usually more efficient at attacking tumor cells than CTLs from the progressing tumor stages. The authors investigated the antitumor activity of CTLs from gastric cancer patents and healthy donors. In this study, peripheral blood lymphocytes (PBLs) from gastric cancer patients and healthy donors were stimulated with HLA-A matched allogeneic gastric cancer cells such as KATO-3, MKN45, and SGC7901. Three different populations of lymphocyte, p5-CTL-KATO, h4-CTL-MKN45, and h4-CTL-KATO, were induced and expanded. Flow cytometry analyses showed that 85.2% to 97.8% of these cells were CD3-positive and 45.5% to 51.2% were CD8-positive. The induced CTLs efficiently kill HLA-A2 or HLA-A24 gastric cancer cells through CTL-mediated cytotoxicity. However, no effects were observed for other cancer cells or HLA-A2 negative gastric cancer cells. The specific cytotoxicity of the induced CTLs was further confirmed by cold-target inhibition and monoclonal antibody blockage. These results suggest that CTL-mediated cytotoxicity specific for tumor cells can be produced by stimulating PBLs from healthy donors using HLA-A matched tumor cells, which will lead to the development of new immunotherapeutic strategies to kill cancer cells.

[Gene therapy of melanoma: review of published clinical trials]

INTRODUCTION

Melanoma frequency increases. Conventional antitumoral treatments fail. Gene therapy for metastatic melanoma is studied in 17 phase I-II clinical trials. ACTUALITES ET POINTS FORTS: Sixteen use cytokine genes. These studies are heterogenous as far as methodology is concerned. Gene therapy clinical tolerance is acceptable. Security is rarely discuted. In these studies overall response rate is 8%, with histological complete responses.

PERSPECTIVES

Presently, three new studies are opened in United States.

Bcl-2 expression in metastatic malignant melanoma. Importance for the therapeutic efficacy of biochemotherapy

For the majority of patients with metastatic malignant melanoma the prognosis is poor. Immunotherapy and biochemotherapy have shown promise with a subset of durable responses, but there is still a great need for a better understanding of the mechanisms of action during treatment to optimize future treatment schedules. In the present study Bcl-2 expression was studied in biopsies from ten patients with metastatic malignant melanoma (five with regional disease and five with systemic disease) treated with biochemotherapy (cisplatinum 30 mg/m2 days 1-3, DTIC 250 mg/m2 days 1-3 i.v. and Interferon-alpha2b 10 MIU s.c. 3 days a week, on a 28-day cycle). The expression of Bcl-2 by the tumour cells was separately recorded in areas of histopathological regressive changes and in areas of unaffected tumour growth. Comparisons were made with biopsies from 14 untreated patients. In 10 of 10 treated patients a high expression of Bcl-2 by the tumour cells was found in areas of unaffected tumour growth. In contrast, only in 5 of 13 untreated patients was a high expression of Bcl-2 by the tumour cells found in these areas ( P=0.008). A significant difference was also found in the expression of Bcl-2 by the tumour cells between areas of unaffected tumour growth and areas of histopathological regressive changes ( P=0.03). The significantly higher expression of Bcl-2 by the tumour cells in areas of unaffected tumour growth in treated patients compared to untreated patients indicates that clones with a high expression of Bcl-2 may be present after therapy, preventing apoptosis and eventually in many patients resulting in progressive disease. Supporting this concept, a difference was also found between the expression of Bcl-2 in areas of unaffected tumour growth, i.e. in areas of treatment failure, and the expression in areas of histopathological regressive changes. Thus immunohistochemical analysis of tumour biopsies shortly after therapy seems to be a good surrogate endpoint that allows a detailed analysis of Bcl-2 expression. The high expression of Bcl-2 shown in unaffected tumour areas after therapy suggests the need for additional treatment, e.g. Bcl-2 antisense therapy.

Allogeneic breast cancer cell vaccines

Cancer vaccines are currently a major focus of immunotherapy research. The combination of specific targeting and low levels of toxicity makes vaccination an attractive approach. There are a variety of immunogens that can be employed to vaccinate patients in order to induce or enhance an antitumor response. The observation that most T-cell priming occurs via presentation of tumor antigens from tumor cells engulfed by host antigen-presenting cells, rather than by direct presentation by vaccine tumor cells themselves, provides the immunological rationale for an allogeneic tumor cell vaccine approach. Furthermore, there are practical advantages over an autologous tumor cell vaccine approach. We summarize herein the limited experience using allogeneic whole cell vaccines in patients with breast cancer. We also describe in vitro immunological results using peripheral blood mononuclear cells from women with stage IV breast cancer who were enrolled in a phase I trial employing a human leukocyte antigen-A2-matched, CD80-modified, allogeneic, whole cell vaccine. Clinical trials employing allogeneic tumor cell vaccines have achieved encouraging immunological and clinical effects in stage IV patients. Allogeneic tumor cell vaccines are safe, feasible, and associated with low toxicity, and the early clinical results suggest that they are worthy of further study

Melanoma vaccines

The identification of antigens on tumor cells has led to significant contributions to the field of immunotherapy. One of the most active areas under investigation in cancer immunotherapy is the development of vaccines against melanoma antigens. Induction of immunity against tumor antigens can follow multiple routes using different mechanisms. Crucial to the development of active immunization and other immunotherapies is the discovery and understanding of the molecular identity of antigens and the mechanisms involved in tumor immunity, as well as escape from immunity. In this review, we will discuss strategies to induce active immunity against melanoma.

Gene-based immunotherapy of skin cancers

Skin cancers continue to present a major therapeutic challenge to physicians. Recent advances in molecular genetics and improved understanding of immune responses to tumors have generated an interest in using gene-based immunotherapy for treating these malignancies. Two major forms of gene-based immunotherapy are currently being investigated. One focuses on genetic modification of some target cell populations of the host using immunostimulatory genes such as cytokines, in order to improve tumor immunogenicity and antitumor responses; the other is genetic immunization with the genes coding for melanoma-associated antigens recognized by cytotoxic T cells. This paper reviews these novel strategies and summarizes the most recent data recorded in either experimental studies or clinical trials.

Gene-based therapy of malignant melanoma

Melanoma continues to present a major therapeutic challenge to oncologists, oncologic surgeons, and dermatologists. Recent advances in molecular genetics and improvement in our understanding of immune responses to tumors have generated an interest in using gene-based treatment strategies to fight melanoma. Several basic strategies have emerged: (1) strengthening of the immune response against tumors by genetic modification of some target cell populations of the host using immunostimulatory genes such as cytokines and by genetic immunization with the genes coding for melanoma-associated antigens recognized by cytotoxic T cells; (2) interference with signaling cascades; and (3) suicide gene strategies. This article reviews these novel strategies and summarizes the most recent data generated by European groups either in experimental studies or in clinical trials.

Cytokine modified tumor vaccines

The immune system can recognize tumors, but may be actively tolerized to tumors during the tumorigenesis process. The identity of most tumor antigens remains unknown, but the number is growing due to new techniques. Most clinical trials using genetically modified tumor vaccines have shown immunological responses (DTH), but few clinical responses. Certain chemotherapeutic agents may enhance the immune effects of genetically modified tumor vaccines.

Therapeutic vaccines: realities of today and hopes for the future

Vaccines are by definition prophylactic, but in recent years an interest has developed in therapeutic vaccines for infectious diseases such as AIDS and tuberculosis, as well as gastric ulcers, cancer (with different approaches to combat various types of malignancy) and autoimmune diseases (a definite success was the development of a vaccine against multiple sclerosis) and there are potential vaccines in development for myasthenia gravis, lupus and diabetes. Therapeutic vaccines are also being developed against cognitive diseases such as Alzheimer's disease, prion diseases and Huntington's disease. All of these efforts are based on the therapeutic vaccine being closely related chemically to the etiological agent that causes the disease.

Enhanced inhibition of tumour growth and metastasis, and induction of antitumour immunity by IL-2-IgG2b fusion protein

Cytokine-immunoglobulin (Ig)-fusion proteins have attracted increasing interest as antitumour agents. Here, we have investigated the antimetastatic and antitumour responses elicited in vivo by mammary adenocarcinoma cells (TS/A) engineered to secrete interleukin (IL)-2-IgG fusion proteins. TS/A cells were transfected with DNA coding for IL-2-IgG2b, IgG2b or IL-2, and injected subcutaneously into syngeneic mice. Animals injected with TS/A-IL-2 or TS/A-IL-2-IgG2b both efficiently rejected tumours, whereas treatment with parental cells or TS/A-IgG2b was lethal. Interestingly, only mice vaccinated with IL-2-IgG2b fusion protein-secreting cells showed a long-lasting protective immunity against a later challenge with parental tumour cells. Moreover, the metastatic potential of TS/A-IL-2-IgG2b-transfected cells was dramatically decreased compared with TS/A-IL-2-cells, with a virtual absence of lung metastases after intravenous injection. Adenocarcinomas secreting IL-2-IgG2b exhibited a more prominent, early and persistent infiltration of CD4+, CD8+ and natural killer (NK) cells than TS/A-IL-2 cells. Therefore, upon transfection into adenocarcinoma cells, the IgG2b part of IL-2 fusion protein exerts intriguing added antitumour properties over IL-2 alone, thus contributing to a long-lasting tumour immunity, probably by the recruitment of specific immune effector cells. These findings suggest a promising new oncotherapeutic strategy for poorly immunogenic tumours: vaccination with tumour cells engineered to secrete IL-2-IgG2b fusion protein.

Tumour cell-based vaccines for the treatment of melanoma

Melanoma is generally resistant to chemotherapy and radiation therapy. Its unique immunological properties lend support to developing innovative new therapies via manipulation of the patient's own immune system. The use of whole-cell-based tumour vaccines, including autologous, whole-cell allogeneic and cytokine gene-modified vaccines, as well as tumour lysate vaccines, for active specific immunotherapy of melanoma, is discussed in detail with regard to rationale and available clinical data. Although phase II data on the use of melanoma vaccine in the adjuvant setting show promise, there is no randomised phase III trial demonstrating the efficacy of active specific immunotherapy for melanoma. The coming years will bring the results of several pivotal multicentre phase III trials testing the clinical utility of active specific immunotherapy in the management of melanoma.

Decreased intraindividual HLA class I expression is due to reduced transcription in advanced melanoma and does not correlate with HLA-G expression

The presentation of endogenously synthesized peptides in association with HLA class I molecules allows the activation of CD8(+) lymphocytes. Tumor cells often fail to present antigenic peptides resulting in the immune escape of metastasizing cells. The aim of this study was to elucidate possible molecular mechanisms leading to reduced antigen presentation in melanoma. Melanoma cell short-time cultures were genotypically and phenotypically HLA-typed by sequence-specific primer polymerase chain reaction and complement-mediated microlymphocytotoxicity assays, respectively. Flow cytometric analysis of HLA-A2 and HLA-A3 allospecificities were performed to confirm typing results. Transcriptional levels of classical HLA-A, HLA-B genes and nonclassical HLA-G genes were detected using quantitative real-time reverse transcriptase polymerase chain reaction (LightCycler). We found loss or downregulation of HLA proteins in 18% (for HLA-A) and 53% (for HLA-B) of all tested metastases. Genomic analysis, however, revealed the presence of the corresponding HLA class I gene in six out of seven cases. On the level of gene transcription we observed a differential regulation of HLA-A, HLA-B, and HLA-G mRNA expression. There was no correlation between classical and nonclassical HLA gene transcription, but the transcriptional levels of classical HLA corresponded to the protein expression levels. Furthermore, an overall reduced amount of HLA class I gene transcription was observed in melanoma metastases during disease progression in three individuals. We postulate that there is a transcriptional regulation of HLA class I gene expression in melanoma cells. These data suggest that treatment approaches aimed at activating specific cytotoxic T lymphocytes are most successful in early disease.

Cancer vaccines

Attempts to generate an anticancer immune response in vivo in patients with cancer have taken several forms. Although to date there have been relatively few published studies describing the effects of the approach in hematologic malignancy, that circumstance is expected to change rapidly during the next few years. In solid tumors, it is not known which, if any, of the approaches being explored will be able to produce responses of sufficient effectiveness and duration to be of general clinical value. Despite the documented increase in survival of patients developing an immune response to tumor immunization, no randomized clinical trial has been entirely convincing. As knowledge of the molecular basis of the immune response and of the immune defenses used by cancer cells improves, it is reasonable to expect to see increasing benefits from tumor vaccines, which are likely to complement, long before they replace, conventional therapies.

Genetically modified tumour vaccines: an obstacle race to break host tolerance to cancer

The development of genetically modified tumour vaccines (GMTV) has been prompted by a better understanding of antitumour immune responses and genetic engineering technologies, as well as the identification of numerous tumour antigens (TA) in several malignancies which occasionally induce spontaneous tumour regressions. Cellular vaccines are based on autologous or allogeneic tumour cells genetically engineered to secrete different cytokines, co-stimulatory molecules, or allogeneic HLA molecules in order to provide a strong stimulatory signal together with the presented TA. Another promising approach that is targeted towards breaking immune tolerance to TA, exploits dendritic cells (DC) loaded or genetically modified with TA (and sometimes cytokines). Effective nonviral and viral gene delivery systems have been constructed including a third generation of adenoviral, lentiviral and hybrid vectors. Studies in mice demonstrated that therapeutic, curative immune responses might be elicited by GMTV. Promising results from animal studies are rarely seen in human trials. Several reasons, such as numerous escape mechanisms of slowly evolving spontaneous tumours and immune incompetence of advanced patients, are major concerns. Improved monitoring of immune responses to GMTV is essential to distinguish between responders and non-responders in order to tailor immune therapy strategy to the individual patient.