In Vitro and In Vivo Activity of a Lipid Nanoparticle System for the In Vivo Generation of CAR T Cells
Viktor Lemgart, Jennifer Richards, Laura Strauss, Jing Jiao, Brandon Quido, Laura Powers, Allison Caron, Eyoung Shin, Austin Boesch, Dharini Shah, Tiffany Le, Rasika Kunden, Samantha Stewart, Fazila Nasimi, Sampa Maiti, Mir Ali, Olga Lihoradova, Aaron Griset, Christopher M. Borges, William Kuhlman, Carla Lawendowski, Ulrik Nielsen, Valeria Fantin, Daryl Drummond, Donald Shaffer, Andrew J Sawyer
sciencedirect.com·2024
Background: CAR T-cells have shown impressive clinical responses in patients with hematologic malignancies, but barriers exist to broader patient access, these include personalized manufacturing, toxicity, and preconditioning chemotherapy. The current methods used to generate a CAR-T cell dose ex vivo are complex and hinder widespread application. Lipid nanoparticle technology has demonstrated the ability to deliver mRNA payloads to cells. A therapeutic platform based on that technology could provide an off-the-shelf option for generating therapeutic T cells in vivo, enabling broader patient access without costly personalized manufacturing. Here we share the key capabilities and data for a targeted lipid nanoparticle (LNP) encapsulating mRNA to reprogram circulating human T-cells in vivo, designed to overcome the significant limitations of current CAR T therapy.
Methods: The LNP consists of a proprietary ionizable lipid formulation containing an mRNA encoding a second-generation CAR against CD22. The ionizable lipid has been selected from a panel of candidate lipids for the efficient transfection of T cells. Transfection of T cells is then enabled by a CD8 targeting moiety attached to the surface. The LNPs were screened in vitro using cell lines and human primary T cells, and in vivo using PBMC humanized mice. Transfection specificity was examined in human whole blood assays and in PBMC humanized mice.
Results: LNPs made from a series of ionizable lipids were capable of in vitro transfection of human T cells to express reporter proteins (GFP, mCherry). LNP performance was dependent on ionizable lipid chemistry, including; chain length, branching, ester linkages, and head group. Untargeted lipid nanoparticles were not capable of transfecting T cells, indicating that the inclusion of a T cell targeting moiety was essential for transfection.