mRNA-based CAR T cell engineering: Unmodified mRNA enables high CAR expression without innate immune activation in T cells

Kahwaji N, Kotzian N, Prinz JM, Pu Y, Kath J, Picht S, Hiller AL, Klaas A, Dunne CM, Launspach M, Palmowski A, Kleyer A, Simon DN, Wagner DL, Pichon C, Krönke G, Schmueck-Henneresse M, Volk HD, Gossen M, Drzeniek NM (2026)

Publication Type: Journal article

Publication year: 2026

Journal

Molecular Therapy - Nucleic Acids Elsevier (Cell Press)

Book Volume: 37

Article Number: 102805

Journal Issue: 1

DOI: 10.1016/j.omtn.2025.102805

Abstract

Unmodified, uridine-containing mRNA is known to trigger antiviral immune responses, inflammatory signaling, and apoptosis in transfected cells. To avoid this and enable high expression, modified nucleosides such as N1-methylpseudouridine have become the gold standard for mRNA applications including T cell engineering, albeit at increased cost. Here, immune responses toward mRNA were evaluated across five primary human cell types. Remarkably, T cells, unlike other immune and non-immune cell types tested, exhibited no immune activation by unmodified mRNA. T cell viability and cytokine secretion remained unaffected, regardless of mRNA delivery method via lipid nanoparticles or electroporation. The absence of nucleotide modifications improved expression of chimeric antigen receptor (CAR) in activated T cells and CAR-T cell cytotoxic potency. By eliminating the need for mRNA-nucleoside modification in CAR-T cell engineering, our findings challenge existing paradigms and position mRNA as a non-inflammatory, minimally invasive and highly efficient tool for T cell engineering, while simplifying and reducing manufacturing cost.

Involved external institutions

Berliner Institut für Gesundheitsforschung in der Charité / Berlin Institute of Health at Charité (BIH) DE Germany (DE) Helmholtz-Zentrum Hereon DE Germany (DE) Charité - Universitätsmedizin Berlin DE Germany (DE) Pantherna Therapeutics GmbH DE Germany (DE) University of Orléans / Université d'Orléans FR France (FR)

How to cite

APA:

Kahwaji, N., Kotzian, N., Prinz, J.M., Pu, Y., Kath, J., Picht, S.,... Drzeniek, N.M. (2026). mRNA-based CAR T cell engineering: Unmodified mRNA enables high CAR expression without innate immune activation in T cells. Molecular Therapy - Nucleic Acids, 37(1). https://doi.org/10.1016/j.omtn.2025.102805

MLA:

Kahwaji, Nourhan, et al. "mRNA-based CAR T cell engineering: Unmodified mRNA enables high CAR expression without innate immune activation in T cells." Molecular Therapy - Nucleic Acids 37.1 (2026).

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