BACKGROUND: As an attempt to develop a strategy to improve the protective immune response to GM-CSF-secreting CT26 (GM-CSF/CT26) tumor vaccine, we have investigated whether the apoptogenic treatment of GM-CSF/CT26 prior to vaccination enhances the induction of anti-tumor immune response in mouse model. METHODS: A carcinogen- induced mouse colorectal tumor, CT26 was transfected with GM-CSF gene using a retroviral vector to generate GM-CSF-secreting CT26 (CT26/GM-CSF). The CT26/GM-CSF was treated with gamma-irradiation or mitomycin C to induce apoptosis and vaccinated into BALB/c mice. After 7 days, the mice were injected with a lethal dose of challenge live CT26 cells to examine the protective effect of tumor vaccination in vivo. RESULTS: Although both apoptotic and necrotic CT26/GM-CSF vaccines were able to enhance anti-tumor immune response, apoptotic CT26/GM-CSF induced by pretreatment with gamma-irradiation (50,000 rads) was the most potent in generating the anti-tumor immunity, and thus 100% of mice vaccinated with the apoptotic cells remained tumor free for more than 60 days after tumor challenge. CONCLUSION: Apoptogenic pretreatment of GM-CSF-secreting CT26 tumor vaccine by gamma-irradiation (50,000 rads) resulted in a significant enhancement in inducing the protective anti-tumor immunity. A rapid induction of apoptosis of CT26/GM-CSF tumor vaccine at the vaccine site might be critical for the enhancement in anti-tumor immune response to tumor vaccine.
Animals ; Apoptosis ; Colony-Stimulating Factors* ; Colorectal Neoplasms ; Granulocyte-Macrophage Colony-Stimulating Factor ; Mice ; Mitomycin ; Vaccination ; Vaccines ; Zidovudine

BACKGROUND: Granulocyte-macrophage colony-stimulating factor (GM-CSF) gene- transduced tumor cell vaccines induce very potent systemic anti-tumor immunity in preclinical and clinical models. Our previous phase I clinical trial in patients with metastatic renal cell carcinoma (RCC) has demonstrated both immune cell infiltration at vaccine sites and T cell-mediated delayed-type hypersensitivity (DTH) response to whole tumor cell vaccines. METHODS: To investigate the immune responses to autologous genetically- modified tumor cell vaccines, tumor-specific CD8+ T cell lines were generated from peripheral blood lymphocytes (PBL) of a RCC patient 1.24 by repeated in vitro stimulation with either B7.1-transduced autologous RCC tumor cells or B7.1-transduced autologous tumor cells treated with interferon gamma (IFNgamma), and cloned by limiting dilution. RESULTS: Among several RCC-specific cytotoxic T lymphocytes (CTLs), a CD4+ /CD8+ double positive T cell clone (17/A2) appeared to recognize IFNgamma-treated autologous RCC restricted by HLA-B39. The 17/A2 also recognized other HLA-B39 positive RCC tumor cells after IFNgamma treatment. CONCLUSION: These results demonstrate that autologous RCC vaccination successfully generates the tumor-specific CTL 17/A2, and suggest that the presentation and recognition of the tumor antigen by the 17/A2 might be upregulated by IFNgamma.
Carcinoma, Renal Cell ; Cell Line ; Clone Cells ; Granulocyte-Macrophage Colony-Stimulating Factor* ; HLA-B39 Antigen ; Humans ; Hypersensitivity ; Interferons ; Lymphocytes ; T-Lymphocytes* ; T-Lymphocytes, Cytotoxic ; Vaccination ; Vaccines

The National Cancer Institute (NCI) Division of Cancer Prevention (DCP) convened the “Translational Advances in Cancer Prevention Agent Development (TACPAD) Workshop on Immunomodulatory Agents” as a virtual 2-day workshop on September 13 to 14, 2021. The main goals of this workshop were to foster the exchange of ideas and potentially new collaborative interactions among leading cancer immunoprevention researchers from basic and clinical research and highlight new and emerging trends in immunoprevention. The workshop included an overview of the mechanistic classes of immunomodulatory agents and three sessions covering the gamut from preclinical to clinical studies. The workshop convened individuals working in immunology and cancer prevention to discuss trends in discovery and development of immunomodulatory agents individually and in combination with other chemopreventive agents or vaccines.