AUTHOR=Golinelli Giulia , Scholler John , Roussel-Gervais Audrey , Šakić Antonija , Ilmjärv Sten , Song Decheng , Gabunia Khatuna , Ji Mei , Fan Ting J. , Gupta Aasha , Deshmukh Mansi , Berjis Abdulla , Cuoghi Costantini Riccardo , Apodaca Kimberly , Sheppard Neil C. , Kili Sven , Dominici Massimo , Alessandrini Marco , June Carl H. , Levine Bruce L. 

TITLE=Multiplex engineering using microRNA-mediated gene silencing in CAR T cells

JOURNAL=Frontiers in Immunology

VOLUME=Volume 16 - 2025

YEAR=2025

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2025.1647433

DOI=10.3389/fimmu.2025.1647433

ISSN=1664-3224

ABSTRACT=BackgroundMultiplex gene-edited chimeric antigen receptor (CAR) T-cell therapies face significant challenges, including potential oncogenic risks associated with double-strand DNA breaks. Targeted microRNAs (miRNAs) may provide a safer, functional, and tunable alternative for gene silencing without the need for DNA editing.MethodsAs a proof of concept for multiplex gene silencing, we employed an optimized miRNA backbone and gene architecture to silence T-cell receptor (TCR) and major histocompatibility complex class I (MHC-I) in mesothelin-directed CAR (M5CAR) T cells. The efficacy of this approach was compared to CD3ζ and β2-microglobulin (β2M) CRISPR/Cas9 knockout (KO) cells. miRNA-expressing cassettes were incorporated into M5CAR lentiviral vectors, enabling combined gene silencing and CAR expression. Antitumor activity was evaluated using in vitro assays and in vivo pancreatic ductal adenocarcinoma models.ResultsSilenced (S) M5CAR T cells retained antitumor functionality comparable to, and in some cases exceeding, that of KO cells. In vivo, S M5CAR T cells achieved tumor control with higher persistence and superior metastasis prevention. In vitro assays demonstrated enhanced resistance to alloreactive natural killer (NK) cells and peripheral blood mononuclear cells (PBMCs).ConclusionsTitratable multiplex gene silencing via targeted miRNAs offers an alternative to gene editing for CAR T cells, with potential advantages in potency, persistence, metastasis prevention, and immune evasion for allogeneic products. This strategy may overcome tumor-induced immunosuppression while avoiding the risks associated with DNA double-strand breaks.