Calnexin dendritic vaccine and tumor vaccine for canine transmissible venereal tumor in the canine model

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Surgery and chemotherapy are standard treatments of canine cancers, but tumors commonly have a high rate of relapse. Dendritic cells (DC) vaccine and tumor vaccine are new treatment options for tumor diseases. Calnexin (CNX) is an endoplasmic reticulum chaperone and is identified as a protein involving in the production of MHC class I molecules. The antitumor efficiency of autologous DC and canine transmissible venereal tumor (CTVT) transduced with a lentiviral vector expressing CNX and were evaluated in a CTVT model. Four subcutaneous administration of CNX gene-modified DC and tumor cells led to marked tumor growth suppression with intratumoral lymphocytic infiltration. DC vaccine is more effective than tumor vaccine in the supression of established tumors. The surface expression of MHC I and II molecules of CTVT cells was significantly increased after these therapies. By ELISpot technique, the CNX therapy groups in DC or tumor vaccine therapy revealed a significantly greater frequency of tumor-specific T cells that released IFN-γ compared with the controls. The specific T-cell antitumor responses were significantly increased following the therapy but the innate natural killer antitumor responses were not. In addition, the DC vaccine and tumor vaccine therapies did not present with any apparent adverse effects. These results demonstrated that both DC and tumor vaccine for CTVT in vivo using calnexin were efficient in suppressing dog tumor and can be considered as another choice in treating canine cancers.