ABSTRACT
Title
A newest Cetuximab-based bio-chemo-immunotherapy regimen enhances antigen presentation and cytotoxic T cell activity in advanced colorectal cancer patients
Authors
E. Bestoso1, C. Botta1, S. Apollinari1, L. Micheli2, G. Giorgi2, P. Correale1
1MedicalSchool Hospital “Santa Maria alle Scotte”, Oncology Unit,University of Siena
2Dep. of Neurological and Behavioural Science, “G.Segre” Pharmacology Unit, School of Medicine, University of Siena
1MedicalSchool Hospital “Santa Maria alle Scotte”, Oncology Unit,University of Siena
2Dep. of Neurological and Behavioural Science, “G.Segre” Pharmacology Unit, School of Medicine, University of Siena
Abstract
Introduction: Cetuximab (Erbitux) is a human/murine chimeric IgG1 monoclonal antibody (mAb) able to bind the epidermal growth factor receptor (EGFR). It is currently used in combination with chemotherapy in the treatment of patients with K-ras wild type metastatic colorectal cancer. Cetuximab may exert its antitumor activity through different mechanisms such as inhibition of EGFR pathways and FcγRs-mediated antibody dependent cell cytotoxicity (ADCC), phagocytosis and antigenic cross priming/cross-presentation. In previous studies we demonstrate that chemotherapy increases the expression of EGFR on tumor cells, making them highly susceptible to cetuximab dependent NK cells mediated ADCC. We also demonstrated that cetuximab ignites phagocytosis of tumor cells expressing EGFR by dendritic cells, enhances their ability to present antigens and, in turn, promotes the generation of a tumor-specific T lymphocyte response. This study intended to characterize the immunological activity of peripheral blood mononuclear cells (PBMCs) derived from patients with colon-rectal carcinoma in enrolled in our phase II clinical trial known as GILFCet (gemcitabine, 5-fluorouracil, Levofolenic acid, Irinotecan (GILF) + subcutaneous low dose aldesleukine and Cetuximab).
Material and Methods: The PBMCs of 20 patients enrolled in the GILFICet trial, were collected at baseline and after administration of 3 cycles of chemotherapy and evaluated for immune-phenotype change by flow cytometry. Colonspecific-T cell lines were also generated ex vivo from these samples, and subsequently characterized for immune-phenotype, functional activity and antigen specificity.
Results: Immune-phenotype PBMCs analysis revealed a significant treatment related increase in naïve and central memory T-cells (P<0.05), in activated cytotoxic T-lymphocytes, in NK/NKT cells and in mature activated DCs.T-celllines analysis revealed a treatment related increase in proliferating cytotoxic T lymphocytes (CD8+Ki67+; P<0.05) and a reduction in lymphocytes expressing a regulatory T cell (CD4+FoxP3+) in response to specific tumor antigens in vitro. Post treatment derivative T-cell lines, also showed a Th1-functional phenotype and a much greater precursor response through CEA and TS epytopes in IFN-ɣ Elispot assay.
Conclusion: Our results support the hypothesis that GILFICet regimen exerts substantial immune-modulating activity with potential antitumor effects.
Material and Methods: The PBMCs of 20 patients enrolled in the GILFICet trial, were collected at baseline and after administration of 3 cycles of chemotherapy and evaluated for immune-phenotype change by flow cytometry. Colonspecific-T cell lines were also generated ex vivo from these samples, and subsequently characterized for immune-phenotype, functional activity and antigen specificity.
Results: Immune-phenotype PBMCs analysis revealed a significant treatment related increase in naïve and central memory T-cells (P<0.05), in activated cytotoxic T-lymphocytes, in NK/NKT cells and in mature activated DCs.T-celllines analysis revealed a treatment related increase in proliferating cytotoxic T lymphocytes (CD8+Ki67+; P<0.05) and a reduction in lymphocytes expressing a regulatory T cell (CD4+FoxP3+) in response to specific tumor antigens in vitro. Post treatment derivative T-cell lines, also showed a Th1-functional phenotype and a much greater precursor response through CEA and TS epytopes in IFN-ɣ Elispot assay.
Conclusion: Our results support the hypothesis that GILFICet regimen exerts substantial immune-modulating activity with potential antitumor effects.