CD28 Costimulation Augments CAR Signaling in NK Cells via the LCK/CD3ζ/ZAP70 Signaling Axis

Area of Science:

• Immunology
• Cell Biology
• Cancer Research

Background:

• Chimeric antigen receptor (CAR) design critically impacts CAR T-cell function, particularly costimulatory signals.
• The role of costimulatory domains in CAR-engineered natural killer (NK) cells is understudied.
• NK cells are a promising platform for cancer immunotherapy.

Purpose of the Study:

• To investigate the impact of various costimulatory domains on CAR-NK cell activity.
• To evaluate the efficacy of CD28 costimulation in CAR-NK cells for cancer immunotherapy.

Main Methods:

• Engineered NK cells with a CD70-targeting CAR incorporating different costimulatory domains.
• Assessed CAR-NK cell activity in vitro and in vivo using xenograft models.
• Investigated downstream signaling pathways activated by costimulatory domains.

Main Results:

• CD28 costimulation significantly enhanced antitumor efficacy and long-term cytotoxicity of CAR-NK cells.
• CAR-NK cells exhibited improved persistence in both hematologic and solid tumor models.
• Mechanistically, CD28 recruitment of LCK and ZAP70 kinases initiated signaling cascades enhancing CAR-NK function.

Conclusions:

• CD28 costimulation is a key factor in enhancing CAR-NK cell-mediated antitumor responses.
• Incorporating CD28 into CAR constructs can improve NK cell-based cancer immunotherapy.
• This study elucidates the mechanism by which CD28 enhances CAR-NK cell function.