ovalbumin and Pancreatic-Neoplasms

Immunotherapies have shown great promise, but are not effective for all tumors types and are effective in less than 3% of patients with pancreatic ductal adenocarcinomas (PDAC). To make an immune treatment that is effective for more cancer patients and those with PDAC specifically, we genetically engineered Salmonella to deliver exogenous antigens directly into the cytoplasm of tumor cells. We hypothesized that intracellular delivery of an exogenous immunization antigen would activate antigen-specific CD8 T cells and reduce tumors in immunized mice.. To test this hypothesis, we administered intracellular delivering (ID) Salmonella that deliver ovalbumin as a model antigen into tumor-bearing, ovalbumin-vaccinated mice. ID Salmonella delivers antigens by autonomously lysing in cells after the induction of cell invasion.. We showed that the delivered ovalbumin disperses throughout the cytoplasm of cells in culture and in tumors. This delivery into the cytoplasm is essential for antigen cross-presentation. We showed that co-culture of ovalbumin-recipient cancer cells with ovalbumin-specific CD8 T cells triggered a cytotoxic T cell response. After the adoptive transfer of OT-I CD8 T cells, intracellular delivery of ovalbumin reduced tumor growth and eliminated tumors. This effect was dependent on the presence of the ovalbumin-specific T cells. Following vaccination with the exogenous antigen in mice, intracellular delivery of the antigen cleared 43% of established KPC pancreatic tumors, increased survival, and prevented tumor re-implantation.. This response in the immunosuppressive KPC model demonstrates the potential to treat tumors that do not respond to checkpoint inhibitors, and the response to re-challenge indicates that new immunity was established against intrinsic tumor antigens. In the clinic, ID Salmonella could be used to deliver a protein antigen from a childhood immunization to refocus pre-existing T cell immunity against tumors. As an off-the-shelf immunotherapy, this bacterial system has the potential to be effective in a broad range of cancer patients.

Topics: Animals; Antigens, Neoplasm; CD8-Positive T-Lymphocytes; Child; Humans; Mice; Mice, Inbred C57BL; Ovalbumin; Pancreatic Neoplasms; Salmonella; Vaccination

Adoptive T cell transfer (ACT) is currently under investigation for the treatment of metastatic cancer. Recent evidence suggests that the coinhibitory PD-1-PD-L1 axis plays a major role in ACT failure. We hypothesized that a new fusion receptor reverting PD-1-mediated inhibition into CD28 costimulation may break peripheral tolerance.. Different PD-1-CD28 fusion receptor constructs were created and retrovirally transduced into primary T cell receptor transgenic murine CD8(+) T cells specific for ovalbumin (OT-1). Cytokine release, proliferation, cytotoxicity, and tumor recognition were analyzed in vitro. Antitumor efficacy and mode of action were investigated in mice bearing subcutaneous tumors induced with the pancreatic carcinoma cell line Panc02 expressing the model antigen ovalbumin (Panc-OVA). For antitumoral efficacy, six to eight mice per group were used. All statistical tests are two-sided.. Transduction of the PD-1-CD28 receptor constructs mediated enhanced cytokine release, T cell proliferation, and T cell-induced lysis of target tumor cells. The PD-1-CD28 receptor function was dependent on two of the CD28-signaling motifs and IFN-γ release. Treatment of mice with established Panc-OVA tumors with fusion receptor-transduced OT-1 T cells mediated complete tumor regression. Mice rejecting the tumor were protected upon subsequent rechallenge with either ovalbumin-positive or -negative tumors, indicative of a memory response and epitope spreading in nine of 11 mice vs none of the six naïve mice (P < .001). Treatment efficacy was associated with accumulation of IFN-γ-producing T cells and an increased ratio of CD8(+) T cells to immunosuppressive myeloid-derived suppressor cells in the tumors.. Transduction of T cells with this new PD-1-CD28 receptor has the potential of breaking the PD-1-PD-L1-immunosuppressive axis in ACT.

Topics: Adoptive Transfer; Animals; B7-H1 Antigen; CD28 Antigens; CD8-Positive T-Lymphocytes; Cell Line, Tumor; Epitopes; Immunosuppression Therapy; Interferon-gamma; Lymphocyte Count; Mice; Mice, Transgenic; Ovalbumin; Pancreatic Neoplasms; Programmed Cell Death 1 Receptor; Signal Transduction; Transduction, Genetic; Treatment Outcome

Multiple studies have shown that dendritic cell (DC)-based vaccines can induce antitumor immunity. Previously, we reported that gemcitabine enhances the efficacy of DC vaccination in a mouse model of pancreatic carcinoma. The present study aimed at investigating the influence of gemcitabine on vaccine-induced anti-tumoral immune responses in a syngeneic pancreatic cancer model.. Subcutaneous or orthotopic pancreatic tumors were induced in C57BL/6 mice using Panc02 cells expressing the model antigen OVA. Bone marrow-derived DC were loaded with soluble OVA protein (OVA-DC). Animals received gemcitabine twice weekly. OVA-specific CD8(+) T-cells and antibody titers were monitored by FACS analysis and ELISA, respectively.. Gemcitabine enhanced clinical efficacy of the OVA-DC vaccine. Interestingly, gemcitabine significantly suppressed the vaccine-induced frequency of antigen-specific CD8(+) T-cells and antibody titers. DC migration to draining lymph nodes and antigen cross-presentation were unaffected. Despite reduced numbers of tumor-reactive T-cells in peripheral blood, in vivo cytotoxicity assays revealed that cytotoxic T-cell (CTL)-mediated killing was preserved. In vitro assays revealed sensitization of tumor cells to CTL-mediated lysis by gemcitabine. In addition, gemcitabine facilitated recruitment of CD8(+) T-cells into tumors in DC-vaccinated mice. T- and B-cell suppression by gemcitabine could be avoided by starting chemotherapy after two cycles of DC vaccination.. Gemcitabine enhances therapeutic efficacy of DC vaccination despite its negative influence on vaccine-induced T-cell proliferation. Quantitative analysis of tumor-reactive T-cells in peripheral blood may thus not predict vaccination success in the setting of concomitant chemotherapy.

Topics: Adenocarcinoma; Animals; Antibody Specificity; Antimetabolites, Antineoplastic; B-Lymphocytes; Cancer Vaccines; CD8-Positive T-Lymphocytes; Cell Line, Tumor; Combined Modality Therapy; Dendritic Cells; Deoxycytidine; Drug Screening Assays, Antitumor; Enzyme-Linked Immunosorbent Assay; Female; Gemcitabine; Immunity, Cellular; Immunity, Humoral; Immunosuppression Therapy; Mice; Mice, Inbred C57BL; Mice, Transgenic; Ovalbumin; Pancreatic Neoplasms; Peptide Fragments; Tumor Escape

Vaccines based on immune stimulatory complexes (ISCOM) induce T-cell responses against tumor antigen (Ag). However, immune responses are impaired in pancreatic cancer patients. We investigated the efficacy of an ISCOM vaccine in a murine pancreatic carcinoma model. Panc02 cells expressing OVA as a model Ag were induced subcutaneously or orthotopically in the pancreas of C57BL/6 mice. Treatment consisted of an OVA containing ISCOM vaccine, either used alone or in combination with the TLR9 agonist CpG. The ISCOM vaccine effectively induced Ag-specific CTL capable of killing tumor cells. However, in mice with established tumors CTL induction by the vaccine was inefficient and did not affect tumor growth. Lack of efficacy correlated with increased numbers of Treg. Depletion of Treg with anti-CD25 mAb restored CTL induction and prolonged survival. Adding low-dose CpG to the ISCOM vaccine reduced Treg numbers, enhanced CTL responses and induced regression of pancreatic tumors in a CD8(+) T cell-dependent manner. Mice cured from the primary tumor mounted a memory T-cell response against wild-type Panc02 tumors, indicative of epitope spreading. Combining ISCOM vaccines with TLR agonists is a promising strategy for breaking tumor immune evasion and deserves further evaluation for the treatment of pancreatic carcinoma.

Topics: Adenocarcinoma; Animals; Antigen-Antibody Complex; Antigens, Neoplasm; Cancer Vaccines; Cell Line, Tumor; Disease Models, Animal; Enzyme-Linked Immunosorbent Assay; Female; Flow Cytometry; Humans; Immune Evasion; Immunization; Immunotherapy; Lymphatic Metastasis; Lymphocyte Activation; Mice; Mice, Inbred C57BL; Oligodeoxyribonucleotides; Ovalbumin; Pancreatic Neoplasms; Survival Rate; T-Lymphocytes, Cytotoxic; T-Lymphocytes, Regulatory; Toll-Like Receptor 9; Tumor Cells, Cultured