Chemical priming with 25KbPEI boosts mesothelin-targeting CAR-NK-92 activity by improving tumor trafficking and cytotoxic killing.

Chimeric antigen receptor-engineered natural killer (CAR-NK) cells offer a promising cancer immunotherapy, but their effectiveness against solid tumors is often hampered by poor tumor trafficking and compromised cytotoxic function within the tumor microenvironment (TME). Current strategies struggle to overcome these barriers, limiting CAR-NK cell penetration and sustained activity. This study explores a non-genetic chemical priming approach to enhance CAR-NK cell capabilities, addressing the critical need for improved CAR-NK cell efficacy in challenging tumor settings.

Mesothelin-targeting CAR-NK-92 cells were chemically primed with 25 kDa branched polyethylenimine (25KbPEI) based on prior findings. These primed cells were then compared against non-primed CAR-NK cells. Researchers evaluated migration, cytotoxicity, degranulation, perforin accumulation, and cytokine production. In vivo efficacy was assessed in a SKOV3 xenograft model, measuring tumor control and intratumoral infiltration, alongside safety profiles. Live-cell imaging was used to analyze killing dynamics and target engagement kinetics.

Chemical priming significantly enhanced cytotoxicity and degranulation against ovarian cancer cells without compromising cell viability. Primed CAR-NK cells showed increased CCR7 expression and improved tumor-directed migration. Additionally, chemical priming increased perforin accumulation and IFN-γ production. In the SKOV3 xenograft model, primed CAR-NK cells achieved superior tumor control and increased intratumoral infiltration compared with non-primed CAR-NK cells, while maintaining a favorable safety profile.

Live-cell imaging further revealed accelerated target engagement and shortened killing time, indicating enhanced cytotoxic kinetics.