Suppression by thimerosal of ex-vivo CD4+ T cell response to influenza vaccine and induction of apoptosis in primary memory T cells.

International audienceThimerosal is a preservative used widely in vaccine formulations to prevent bacterial and fungal contamination in multidose vials of vaccine. Thimerosal was included in the multidose non-adjuvanted pandemic 2009 H1N1 vaccine Panenza. In the context of the analysis of the ex-vivo T cell responses directed against influenza vaccine, we discovered the in vitro toxicity Panenza, due to its content in thimerosal. Because thimerosal may skew the immune response to vaccines, we investigated in detail the ex-vivo effects of thimerosal on the fate and functions of T cells in response to TCR ligation. We report that ex-vivo exposure of quiescent or TCR-activated primary human T cells to thimerosal induced a dose-dependent apoptotic cell death associated with depolarization of mitochondrial membrane, generation of reactive oxygen species, cytochrome c release from the mitochondria and caspase-3 activation. Moreover, exposure to non-toxic concentrations of thimerosal induced cell cycle arrest in G0/G1 phase of TCR-activated T cells, and inhibition of the release of proinflammatory cytokines such as IFN gamma, IL-1 beta, TNF alpha, IL-2, as well as the chemokine MCP1. No shift towards Th2 or Th17 cells was detected. Overall these results underline the proapoptotic effect of thimerosal on primary human lymphocytes at concentrations 100 times less to those contained in the multidose vaccine, and they reveal the inhibitory effect of this preservative on T-cell proliferation and functions at nanomolar concentrations

Trial watch: Chemotherapy with immunogenic cell death inducers

The long-established notion that apoptosis would be immunologically silent, and hence it would go unnoticed by the immune system, if not tolerogenic, and hence it would actively suppress immune responses, has recently been revisited. In some instances, indeed, cancer cells undergo apoptosis while emitting a spatiotemporally-defined combination of signals that renders them capable of eliciting a long-term protective antitumor immune response. Importantly, only a few anticancer agents can stimulate such an immunogenic cell death. These include cyclophosphamide, doxorubicin and oxaliplatin, which are currently approved by FDA for the treatment of multiple hematologic and solid malignancies, as well as mitoxantrone, which is being used in cancer therapy and against multiple sclerosis. In this Trial Watch, we will review and discuss the progress of recent (initiated after January 2008) clinical trials evaluating the off-label use of cyclophosphamide, doxorubicin, oxaliplatin and mitoxantrone

Trial Watch: Adoptive cell transfer immunotherapy

During the last two decades, several approaches for the activation of the immune system against cancer have been developed. These include rather unselective maneuvers such as the systemic administration of immunostimulatory agents (e.g., interleukin-2) as well as targeted interventions, encompassing highly specific monoclonal antibodies, vaccines and cell-based therapies. Among the latter, adoptive cell transfer (ACT) involves the selection of autologous lymphocytes with antitumor activity, their expansion/activation ex vivo, and their reinfusion into the patient, often in the context of lymphodepleting regimens (to minimize endogenous immunosuppression). Such autologous cells can be isolated from tumor-infiltrating lymphocytes or generated by manipulating circulating lymphocytes for the expression of tumor-specific T-cell receptors. In addition, autologous lymphocytes can be genetically engineered to prolong their in vivo persistence, to boost antitumor responses and/or to minimize side effects. ACT has recently been shown to be associated with a consistent rate of durable regressions in melanoma and renal cell carcinoma patients and holds great promises in several other oncological settings. In this Trial Watch, we will briefly review the scientific rationale behind ACT and discuss the progress of recent clinical trials evaluating the safety and effectiveness of adoptive cell transfer as an anticancer therapy

A Phase II Study of Tg4010 (Mva-Muc1-Il2) in Association with Chemotherapy in Patients with Stage III/IV Non-small Cell Lung Cancer

BackgroundTG4010 is a recombinant viral vector expressing both the tumor-associated antigen MUC1 and Interleukine-2. This vector is based on the modified virus of Ankara, a significantly attenuated strain of vaccinia virus. TG4010 has been designed to induce or amplify a cellular immune response directed against tumor cells expressing MUC1.MethodsA multicenter, randomized phase II study has explored two schedules of the combination of TG4010 with first line chemotherapy in patients with stage IIIB/IV non-small cell lung cancer. In Arm 1, TG4010 was combined upfront with cisplatin (100 mg/m2 day 1) and vinorelbine (25 mg/m2 day 1 and day 8). In Arm 2, patients were treated with TG4010 monotherapy until disease progression, followed by TG4010 plus the same chemotherapy as in Arm1. Response rate was evaluated according to RECIST. Median time to progression and median overall survival were calculated according to the Kaplan–Meier method.ResultsSixty-five patients were enrolled, 44 in Arm 1 and 21 in Arm 2, in accordance with the two stage Simon design of the statistical plan. In Arm 1, partial response was observed in 13 patients out of 37 evaluable patients (29.5% of the intent to treat population, 35.1% of the evaluable patients). In Arm 2, two patients experienced stable disease for more than 6 months with TG4010 alone (up to 211 days), in the subsequent combination with chemotherapy, one complete and one partial response were observed out of 14 evaluable patients. Arm 2 did not meet the criteria for moving forward to second stage. The median time to progression was 4.8 months for Arm 1. The median overall survival was 12.7 months for Arm 1 and 14.9 for Arm 2. One year survival rate was 53% for Arm 1 and 60% for Arm 2. TG4010 was well tolerated, mild to moderate injection site reactions, flu-like symptoms, and fatigue being the most frequent adverse reactions. A MUC1-specific cellular immune response was observed in lymphocyte samples from all responding patients evaluable for immunology.ConclusionsThe combination of TG4010 with standard chemotherapy in advanced non-small cell lung cancer is feasible and shows encouraging results. A randomized study evaluating the addition of TG4010 to first line chemotherapy in this population is in progress

High Therapeutic Efficacy of a New Survivin LSP-Cancer Vaccine Containing CD4+ and CD8+ T-Cell Epitopes

The efficacy of an antitumoral vaccine relies both on the choice of the antigen targeted and on its design. The tumor antigen survivin is an attractive target to develop therapeutic cancer vaccines because of its restricted over-expression and vital functions in most human tumors. Accordingly, several clinical trials targeting survivin in various cancer indications have been conducted. Most of them relied on short peptide-based vaccines and showed promising, but limited clinical results. In this study, we investigated the immunogenicity and therapeutic efficacy of a new long synthetic peptide (LSP)-based cancer vaccine targeting the tumor antigen survivin (SVX). This SVX vaccine is composed of three long synthetic peptides containing several CD4+ and CD8+ T-cell epitopes, which bind to various HLA class II and class I molecules. Studies in healthy individuals showed CD4+ and CD8+ T-cell immunogenicity of SVX peptides in human, irrespective of the individual's HLA types. Importantly, high frequencies of spontaneous T-cell precursors specific to SVX peptides were also detected in the blood of various cancer patients, demonstrating the absence of tolerance against these peptides. We then demonstrated SVX vaccine's high therapeutic efficacy against four different established murine tumor models, associated with its capacity to generate both specific cytotoxic CD8+ and multifunctional Th1 CD4+ T-cell responses. When tumors were eradicated, generated memory T-cell responses protected against rechallenge allowing long-term protection against relapses. Treatment with SVX vaccine was also found to reshape the tumor microenvironment by increasing the tumor infiltration of both CD4+ and CD8+ T cells but not Treg cells therefore tipping the balance toward a highly efficient immune response. These results highlight that this LSP-based SVX vaccine appears as a promising cancer vaccine and warrants its further clinical development

Cancer immunotherapy

Tumor cells are recognized by the immune system, which controls the growth of some immunogenic tumors. Cancer immunotherapy is based on the stimulation of this natural defence against cancer. The use of recombinant cytokines (IL-2, IFN!…) and especially of antibodies has demonstrated the clinical efficacy of this approach. New immunotherapeutic strategies are being developed, based on the induction of anti-tumor T lymphocytes by cancer vaccines. The optimization of these vaccines is based on their validation in relevant preclinical and clinical models (spontaneous tumors in rodents and carnivore), on their association withmolecules able to inhibit the resistancemechanisms of tumours to immunotherapy, and on more clearly defined clinical indications.Des cellules tumorales peuvent être reconnues par le système immunitaire qui contrôle le développement de certaines tumeurs. L'immunothérapie anti-tumorale consiste à stimuler cette immunité naturelle contre les cancers. L'emploi de cytokines recombinantes (IL-2, IFNα...) et surtout d'anticorps a permis de démontrer l'efficacité clinique de cette approche. De nouvelles stratégies d'immunothérapie reposant sur l'induction de lymphocytes T anti-tumoraux par des vaccins sont en cours de développement. L'optimisation de ces vaccins repose sur leur validation dans des modèles cliniques pertinents (tumeurs spontanées des rongeurs et des carnivores), sur leur association à des molécules permettant de lever des mécanismes de résistance de la tumeur à l'immunothérapie et sur des indications cliniques mieux définies de ces vaccins

Comprehensive analysis of current approaches to inhibit regulatory T cells in cancer

CD4+CD25+Foxp3+ regulatory T cells (Treg) have emerged as a dominant T cell population inhibiting anti-tumor effector T cells. Initial strategies used for Treg-depletion (cyclophosphamide, anti-CD25 mAb…) also targeted activated T cells, as they share many phenotypic markers. Current, ameliorated approaches to inhibit Treg aim to either block their function or their migration to lymph nodes and the tumor microenvironment. Various drugs originally developed for other therapeutic indications (anti-angiogenic molecules, tyrosine kinase inhibitors,etc) have recently been discovered to inhibit Treg. These approaches are expected to be rapidly translated to clinical applications for therapeutic use in combination with immunomodulators

Vaccination-based immunotherapy to target profibrotic cells in liver and lung

Fibrosis is the final path of nearly every form of chronic disease, regardless of the pathogenesis. Upon chronic injury, activated, fibrogenic fibroblasts deposit excess extracellular matrix, and severe tissue fibrosis can occur in virtually any organ. However, antifibrotic therapies that target fibrogenic cells, while sparing homeostatic fibroblasts in healthy tissues, are limited. We tested whether specific immunization against endogenous proteins, strongly expressed in fibrogenic cells but highly restricted in quiescent fibroblasts, can elicit an antigen-specific cytotoxic T cell response to ameliorate organ fibrosis. In silico epitope prediction revealed that activation of the genes Adam12 and Gli1 in profibrotic cells and the resulting “self-peptides” can be exploited for T cell vaccines to ablate fibrogenic cells. We demonstrate the efficacy of a vaccination approach to mount CD8+ T cell responses that reduce fibroblasts and fibrosis in the liver and lungs in mice. These results provide proof of principle for vaccination-based immunotherapies to treat fibrosis

Mild dyslipidemia accelerates tumorigenesis through expansion of Ly6Chi monocytes and differentiation to pro-angiogenic myeloid cells

Cancer and cardiovascular disease (CVD) share common risk factors such as dyslipidemia, obesity and inflammation. However, the role of pro-atherogenic environment and its associated low-grade inflammation in tumor progression remains underexplored. Here we show that feeding C57BL/6J mice with a non-obesogenic high fat high cholesterol diet (HFHCD) for two weeks to induce mild dyslipidemia, increases the pool of circulating Ly6Chi monocytes available for initial melanoma development, in an IL-1β-dependent manner. Descendants of circulating myeloid cells, which accumulate in the tumor microenvironment of mice under HFHCD, heighten pro-angiogenic and immunosuppressive activities locally. Limiting myeloid cell accumulation or targeting VEGF-A production by myeloid cells decrease HFHCD-induced tumor growth acceleration. Reverting the HFHCD to a chow diet at the time of tumor implantation protects against tumor growth. Together, these data shed light on cross-disease communication between cardiovascular pathologies and cancer