Abstract B045: Antigen-free cancer vaccine to treat poorly immunogenic tumors

Certain chemotherapeutic drugs can elicit immunogenic death of tumor cells and enhance antitumor immune responses. Here we explore whether immunogenic chemotherapy can be utilized for the development of antigen-free cancer vaccines, by combining it with peritumorally injected biomaterial scaffolds that recruit dendritic cells (DCs) for subsequent antigen presentation and T-cell priming. Pore-forming alginate gels containing granulocyte-macrophage colony-stimulating factor (GM-CSF) and a doxorubicin-iRGD conjugate were found to efficiently induce the apoptosis of 4T1 triple-negative breast cancer cells in vivo, while recruiting large numbers of DCs. The co-encapsulation of CpG oligodeoxynucleotides in the gel significantly enhanced the immunogenic death of 4T1 cells, increased systemic tumor-specific CD8+ T-cells and tumoral infiltration of CD8+ T-cells, repolarized tumor-associated macrophages towards an inflammatory M1-like phenotype, and resulted in significantly improved antitumor efficacy. This in situ antigen-free gel vaccine shows promise for the treatment of poorly immunogenic tumors, and more broadly, may serve as a facile platform to enable in situ personalized cancer vaccination without requiring identification of tumor-specific antigens and manufacturing of personalized vaccines. Citation Format: Miguel C. Sobral, Hua Wang, Alexander J. Najibi, Aileen Li, Catia S. Verbeke, David J. Mooney. Antigen-free cancer vaccine to treat poorly immunogenic tumors [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B045.