Abstract A009: Optimizing lyophilization for long-term storage of a silicified cell-based cancer vaccine

Abstract Despite a strong rationale for immune therapy in ovarian cancer, to date, vaccines developed for the treatment of ovarian cancer have shown limited efficacy. In addition, the highly technical production requirements of these vaccines restrict their availability outside of specialized centers. This project leverages advances in materials science to construct a personalized tumor vaccine platform that is highly effective in the treatment of high-grade ovarian cancer. Moreover, the use of freeze-dried biomineralized tumor cells does not involve live cell ex vivo proliferation or differentiation, can be achieved in 24 hours, does not require cryo-preservation, and is a candidate for automation, amplifying the potential impact of this therapy. Cell silicification fixes tumor cells in a way that retains the cell’s innate structure and surface protein features. Furthermore, silicified cells are non-viable cells with adsorbent properties that enable surface functionalization with immunogenic ligands that attract and activate immune cells. In addition to the therapeutic advantages associated with silicification, condensation of orthosilicate into polymers on cellular surfaces displaces water and protects cell integrity during freezing and subsequent lyophilization. We have hypothesized that freeze-dried vaccine cells demonstrate long-term stability at room temperature that negates the need for cryopreservation and associated costs for liquid nitrogen, bulk tanks, 24/7 monitoring, and cold-storage shipping and monitoring. Sugar excipients such as trehalose, sucrose, and mannitol have been found to increase the structural stability of the lyophilization cake. In this study, we aim to find the optimal lyophilization and excipient conditions for fully dehydrating the vaccine while retaining long-term stability. We have developed an optimal procedure for lyophilization and have found trehalose to be the most desirable for creating a fluffy uniform vaccine “cake” that is able to easily resuspend into a homogenous mixture. We ensured no cellular viability in the cancer cells after lyophilization by utilizing a trypan blue live/dead test. The main objective of this study is to determine the optimal parameters for lyophilizing a silicified cell cancer vaccine for future clinical use. Citation Format: Kalpana R. Naranjo, Tyler J. Hipple, Rita E. Serda. Optimizing lyophilization for long-term storage of a silicified cell-based cancer vaccine [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Ovarian Cancer Research; 2025 Sep 19-21; Denver, CO. Philadelphia (PA): AACR; Cancer Res 2025;85(18_Suppl):Abstract nr A009.