278. Induction of Anti-Tumor Activity with Dendritic Cells Loaded with Tumor Cell Lysates or Adenoviral Vector-Encoding Tumor-Associated Antigens

A dendritic cell (DC) vaccine which is DC loaded with tumor-associated antigens (TAAs) has been considered as a promising candidate in cancer immunotherapy. Various approaches have been used to deliver TAAs to DCs, such as tumor lysates, viral vectors, and liposomes. In this study, we investigated the anti-tumor activity of DCs that were loaded with melanoma antigens such as MART-1 and tyrosinase using adenoviral vectors (Ad-MART and Ad-Tyr). Furthermore, we also investigated the efficacy of tumor cell lysate-pulsed DCs. In the prevention experiments, mice were immunized 2 times at 1-week intervals before challenging with B16F10 melanoma cells. Both adenovirus-transduced and tumor cell lysate-pulsed DCs could inhibit the growth of melanoma. In the therapeutic settings, mice bearing 3-day tumor were injected with antigen-loaded DCs. Mice treated with Ad-MART-transduced DC and Ad-Tyr-transduced DC showed a delay in tumor growth and an increase of IFN-g production. Simultaneous delivery of Ad-MART and Ad-Tyr to DCs showed therapeutic effects comparable to DCs transduced with single antigen. Tumor cell lysate-pulsed and mock-infected DCs failed to inhibit tumor growth in the established tumor model. These findings support the usefulness of Ad-TAA-transduced DCs in immunotherapy of cancer.