Superior efficacy of dendritic cell-tumor fusion vaccine compared with tumor lysate-pulsed dendritic cell vaccine in colon cancer.

Dendritic cell (DC)-based tumor vaccine is a promising therapy for malignancies. Recent studies showed greater potency with DC/tumor fusion vaccines against acute myeloid leukemia and melanoma compared with lysate-pulsed DC vaccines. We compared these two vaccine strategies against murine colon cancer and investigated whether DC/tumor fusion cells continue to produce tumor antigens following fusion as a possible explanation for their increased potency. Using a mouse colon cancer model, CT26, we first showed that the DC/CT26 fusion vaccine is more effective in preventing tumor implantation than CT26 lysate-pulsed DC vaccine. Next, CT26 made to constitutively produce bioactive TGF-beta, a surrogate of tumor-derived products, was fused to DCs and found to produce bioactive TGF-beta 72 h after fusion. Our results suggest the DC/tumor fusion vaccine is more potent against colon cancer than the lysate-pulsed DC vaccine. These fusion cells have the distinct advantage of prolonged interaction with tumor antigens in vivo.