Abstract 3484: Lipid nanoparticle-mediated <i>in vitro</i> transfection of microbubble-activated T cells

Abstract Immunotherapy of cancer has revolutionized approaches to controlling and curing cancer, with adoptive transfer of chimeric antigen receptor T cells (CAR-T cells) representing a potentially curative treatment for previously unresponsive tumors. CAR-T cell therapy consists of ex vivo expansion of autologous T cells, transfection with the chimeric antigen receptor (CAR) and transfer into the patient. The CAR allows those T cells to identify and kill any cells expressing the antigen of interest, typically a surface protein expressed abundantly and primarily by the tumor. While these methods are extremely effective in a subset of patients, there is opportunity for improvement that may broaden the efficacy of this type of therapy. First, the application of selection, activation and expansion microbubbles has been shown to result in a less “exhausted” phenotype of the T cells at the end of the expansion phase, resulting in better overall T cell responses. In addition, alternative methods of transfection such as lipid nanoparticles (LNPs) may improve both transfection efficiency and viability. LNP lipid components can be tuned to optimally encapsulate different cargo types and transfect different cell types. Therefore, we formulated a variety of different LNPs to encapsulate either mRNA or pDNA encoding a reporter gene and assessed the relative transfection efficiency in microbubble-activated T cells. Additionally, we evaluated the final activation/exhaustion profile of the transfected cells to determine how uptake of different LNPs may affect the killing effectiveness. These results may ultimately suggest process improvements that have the potential to expand the number of CAR-T recipients who have improved responses to therapy. Citation Format: Seeta Nyayapathy, Paige Gronevelt, Julie M. Rumble. Lipid nanoparticle-mediated in vitro transfection of microbubble-activated T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 3484.