Combined Treatment of Murine Fibrosarcoma with Chemotherapy (Paclitaxel), Radiotherapy, and Intratumoral Injection of Dendritic Cells

BACKGROUND New antitumor therapeutic strategies aim to combine different approaches that are able to induce tumor-specific effector and memory T cell responses that might control tumor growth. Dendritic cells (DCs) have the capacity to induce antigen-specific cytotoxic T lymphocytes. We have previously shown that the combined treatment of paclitaxel chemotherapy (Chemo) and injection of DCs led to complete tumor regression. OBJECTIVE The goal of this study was to evaluate synergistic antitumor effect of a triple combination treatment comprising radiotherapy, paclitaxel Chemo and intratumoral injection of syngeneic bone marrow-derived DCs on murine fibrosarcoma, compared to other single or double combination treatments. METHODS For the murine fibrosarcoma model, naïve C57BL/6 mice were inoculated intradermally with 2×10(3) MCA102 cells in the right upper flank. Mice were assigned to five groups (untreatedcontrol, RT alone, RT+Chemo, RT+DC, and RT+Chemo+DC), with eight mice in each group. In vitro cytotoxicity assays were performed to assess the immune activity. The persistence of tumor-specific immunity was determined by second tumor challenge in mice with complete tumor regression. RESULTS The triple combination treatment showed a significantly enhanced therapeutic efficacy by decreasing tumor size and inducing complete tumor regression, resulting in a cure of 50% of mice. The results of in vitro cytotoxicity assays and the second tumor challenge experiment strongly indicated the induction of a tumor-specific cytotoxic T lymphocyte response and acquisition of prolonged tumor immunity. CONCLUSION These findings suggest that the triple combination treatment can be a promising strategy for the treatment of murine fibrosarcoma.