The cancer vaccine therapy using DCs derived from iPS cells (iPSDCs) expressing TAA gene.

768 Background: Dendritic cells (DCs) are potent antigen-presenting cells (APCs) that play a critical role in the initiation of anti-tumor immune responses. Many cancer patients have previously been treated by the cancer vaccine therapy using DCs worldwide. We have employed a study of a cancer vaccine therapy using genetically modified DCs expressing tumor-associated antigen (TAA) gene. Clinically DCs are generated from the peripheral blood monocytes of patients. Thus the number of monocytes and potential of them are limited, so they are serious obstacle. Recent studies have revealed that induced pluripotent stem (iPS) cells can be generated from murine fibroblasts. Furthermore, it has been reported that DCs can be successfully derived from murine iPS cells (iPSDCs). If the therapeutic efficacy of iPSDCs is equivalent to that of naive DCs, then the above-mentioned problems may be solved. Methods: We have induced iPSDCs from murine iPS cells by 4 steps and examined the efficacy as APCs of iPSDCs compared with naive DCs. We also examined whether a vaccine therapy using genetically modified iPSDCs can induce strong therapeutic antitumor immunity compared with naive DCs. Next, we examined the therapeutic antitumor immunity of iPSDCs expressing CEA gene compared with that of naive DCs in pre-clinical study with CEA transgenic mice. Results: We have clarified that genetically modified iPSDCs have an equal efficacy as APCs and TAA-specific therapeutic antitumor immunity, equivalent to naive DCs. And we also have clarified that genetically modified iPSDCs expressing CEA gene have a TAA-specific therapeutic antitumor immunity. Conclusions: This vaccine strategy using genetically modified iPSDCs has an equal capacity with naive DCs in terms of a therapeutic efficacy. Now, we are engaging another pre-clinical study with human, in an effort to apply in a clinical setting.