Abstract 4239: Immunomodulatory effects of topotecan augment the effectiveness of chemotherapy-immunotherapy combination

Combination therapy is a cornerstone of anticancer therapy, suggesting potential therapeutic benefit to nonresponders to single-agent treatment. BVAC, a B-cell-and-monocyte-based vaccine loaded with alpha-galactosylceramide(α-GC) and tumor antigen as reported in our previous studies, can be successfully combined with other treatments. Here we found out a novel synergistic regimen in TC-1 tumor model which combines BVAC with topotecan, a chemotherapeutic agent as a topoisomerase I inhibitor. We demonstrated some significant alteration in the immunoprofiles of topotecan-treated mice. We observed increased tumor recruitment of monocytes and CD8+ T cells, and decreased frequencies in regulatory T cells in tumor. Accordingly, we are currently investigating how topotecan-induced changes in immune cell composition could lead to improvement of antitumor effect. These data indicate that topotecan not only has cytotoxicity to tumor but can contribute to modulating tumor immune microenvironment. We anticipate that this study could provide a rationale for combination of cancer vaccine and chemotherapy and define future optimal treatment regimens in cancer patients. Citation Format: Jeong-Mi Lee, Kwang-Soo Shin, Choong-Hyun Koh, Insu Jeon, Tae-Seung Kang, Boyeong Song, Chang-Yuil Kang. Immunomodulatory effects of topotecan augment the effectiveness of chemotherapy-immunotherapy combination [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4239.