FcεR1γ-based Activating Chimeric Antigen Receptors enhanced Natural Killer cell function against HLA-E+ cells

Fc{varepsilon}R1{gamma} is a transmembrane adaptor protein regulating NKp30, NKp46, and CD16 expression and function in human NK cells. HLA-E expression by cancer cells suppresses NK cell function through interaction with NKG2A. Here, we engineered human NK cells to express a modified Fc{varepsilon}R1{gamma} with a 4-1BB co-stimulatory motif. Fc{varepsilon}R1{gamma}41BB expression led to upregulation of NKp30, NKp46, and CD16 expression and enhanced NKp30 and CD16-mediated target cell lysis. Against cells expressing HLA-E, Fc{varepsilon}R1{gamma}41BB improved NK cell lytic function relative to Fc{varepsilon}R1{gamma}. We then generated an CD19ScFv-CD8hinge-Fc{varepsilon}R1{gamma}41BB(TM-IC) CAR (FCRG10). Engineering human NK cells to express FCRG10 led to upregulation of NKp30 and CD16, and improved NK cell-mediated cytotoxicity against cells co-expressing B7H6, CD19, and HLA-E relative to NK cells expressing the conventional CD19CAR41BB-CD3{zeta} with a CD8 transmembrane domain. Our results indicate that modification of Fc{varepsilon}R1{gamma} enhanced NK cell lytic function mediated by several activating receptors and improved CAR NK cell response in conditions favoring NK cell suppression by HLA-E. Our work may contribute to NK cell-based cancer immunotherapy mediated by co-recognition of stress-induced ligands, antibody-coated cells, and tumor-associated antigens.