Tu164 - Development of Allogeneic Cmv-virus-specific CAR T Cells Targeting CD84 for Acute Myeloid Leukemia

Abstract Text: Allogeneic virus-specific T cells (VSTs) are a promising platform for off-the-shelf cell therapies due to their restricted T-cell receptor (TCR) repertoire, which has enabled their safe application as antiviral clinical therapies. CD84 is a surface antigen highly expressed on acute myeloid leukemia (AML), and CD84-targeted chimeric antigen receptor (CAR) T cells have demonstrated strong cytotoxic activity against AML in preclinical models. In this study, we engineered cytomegalovirus (CMV)-specific VSTs (CMV-VSTs) to express a CAR targeting CD84. The resulting CAR84-CMV-VSTs could not only target CD84 on AML through the CAR, but also recognize CMV antigens via their endogenous CMV-restricted TCR repertoire. Thus, we propose CAR84-CMV-VSTs as a potential off-the-shelf CART-cell therapy for the treatment of relapsed/refractory (R/R) AML.

We successfully expanded CMV-VSTs from healthy donor peripheral blood mononuclear cells (PBMCs) using CMV pp65 peptides. These VSTs demonstrated remarkable CMV specificity, with an average of 33% of CD4+ and 38% of CD8+ T cells responding to pp65 peptides, as shown by CD107a and IFNγ staining. Furthermore, CMV-VSTs exhibited robust functional activity, selectively lysing both autologous and allogeneic phytohemagglutinin-induced blasts presenting pp65 peptides. Subsequently, CAR84-CMV-VSTs were generated by transducing CMV-VSTs with a lentiviral vector encoding a CD84-directed second-generation CAR (antiCD84scFv-CD8αTM-4-1BB-CD3z). CAR84-CMV-VSTs exhibited potent cytotoxicity against CD84+ MOLM-13 cells (an AML cell line) in vitro, underscoring their therapeutic potential.

These findings support CMV-VSTs as a platform for developing allogeneic CAR T cell therapies. Optimizing transduction and expansion protocols will be critical to enable scalable, off-the-shelf production of CAR84-CMV-VSTs for clinical applications in R/R AML.