A combination hybrid-based vaccination/adoptive cellular therapy to prevent tumor growth by involvement of T cells

Cancer immunotherapy with dendritic cell-tumor cell fusion hybrids induces polyclonal stimulation against a variety of tumor antigens, including unknown antigens. Hybrid cells can prime CTLs, which subsequently develop antitumor responses. The aim of this study was to enhance the known antitumor effect of hybrid vaccination (HC-Vacc) and hybrid-primed adoptive T-cell therapy (HC-ACT) using the poorly immunogenic Lewis lung carcinoma (LLC1) model. The strategy used was a combination of a double HC-Vacc alternating with HC-ACT (HC-Vacc/ACT). Using flat-panel volumetric computer tomography and immunohistochemistry, we showed a significant retardation of tumor growth (85%). In addition, a significant delay in tumor development, a reduction in the number of pulmonary metastases, and increased survival times were observed. Furthermore, the tumors displayed significant morphologic changes and increased apoptosis, as shown by up-regulation of gene expression of the proapoptotic markers Fas, caspase-8, and caspase-3. The residual tumor masses seen in the HC-Vacc/ACT-treated mice were infiltrated with CD4+ and CD8+ lymphocytes and showed elevated IFNgamma expression. Moreover, splenic enlargement observed in HC-Vacc/ACT-treated mice reflected the increased functionality of T cells, as also indicated by increased expression of markers for CTL activation, differentiation, and proliferation (Cd28, Icosl, Tnfrsf13, and Tnfsf14). Our findings indicate that the combination therapy of dendritic cell-tumor cell HC-Vacc/ACT is a very effective and a promising immunotherapeutic regimen against poorly immunogenic carcinomas.