Abstract SY15-01: Tumor agnostic dendritic cell vaccines

Abstract Dendritic cells (DCs) are specialized myeloid cells with the ability to uptake, process, and present antigens to T lymphocytes; they also generate cytokine and chemokine gradients that regulate immune cell trafficking, activation, and function. DCs pulsed with tumor antigens have been used as a platform for therapeutic vaccination in cancer. In a broadly tested clinical application called a DC vaccine, autologous monocyte-derived DCs (moDCs) are isolated from a patient with cancer, exposed to tumor antigens ex vivo (antigen loading), and matured before reinfusion to the patient. However, in spite of significant development and testing, DC vaccines based on antigen-loaded moDCs have delivered mixed clinical results. The suboptimal performance of DC vaccines may be due to the use of moDCs - a heterogenous population of non-professional antigen-presenting cells - and the artificial nature of the procedure used to "load" selected tumor antigens on moDCs ex vivo. To address both issues, we developed a DC vaccine that uses a population of mouse or human DC progenitors (DCPs) engineered to produce immunostimulatory cytokines. While not involving antigen loading, the new DC platform outperformed antigen-loaded moDCs in mouse models of cancer. Engineered DCPs produced professional cDC1 and cCD2 in mice, reprogrammed the tumor microenvironment to a form characterized by broad IFNg signaling, and inhibited tumors, including autochthonous models, in an antigen-agnostic fashion. In one application, engineered DCPs synergized with antigen-specific CAR-T cells to eradicate gliomas in mice. Citation Format: Michele De Palma. Tumor agnostic dendritic cell vaccines. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr SY15-01.