Navigating chimeric antigen receptor-engineered natural killer cells as drug carriers via three-dimensional mapping of the tumor microenvironment

Chimeric antigen receptor (CAR)-modified natural killer (NK) cells are recognized as promising immunotherapeutic agents for cancer treatment. However, the efficacy and trafficking of CAR-NK cells in solid tumors are hindered by the complex barriers present in the tumor microenvironment (TME). We have developed a novel strategy that utilizes living CAR-NK cells as carriers to deliver anticancer drugs specifically to the tumor site. We also introduce a time-lapse method for evaluating the efficacy and tumor specificity of CAR-NK cells using a twophoton microscope in live mouse models and three-dimensional (3D) tissue slide cultures. Our results demonstrate that CAR-NK cells exhibit enhanced antitumor immunity when combined with photosensitive chemicals in both in vitro and in vivo tumor models. Additionally, we have successfully visualized the trafficking, infiltration, and accumulation of drug-loaded CAR-NK cells in deeply situated TME using non-invasive intravital two-photon microscopy. Our findings highlight that tumor infiltration of CAR-NK cells can be intravitally monitored through the two-photon microscope approach. In conclusion, our study demonstrates the successful integration of CARNK cells as drug carriers and paves the way for combined cellular and small-molecule therapies in cancer treatment. Furthermore, our 3D platform offers a valuable tool for assessing the behavior of CAR cells within solid tumors, facilitating the development and optimization of immunotherapeutic strategies with clinical imaging approaches.

Automated summary

Chimeric antigen receptor-modified natural killer cells (CAR-NK cells) have been developed as potential immunotherapeutic agents for cancer treatment. However, the complex barriers in the tumor microenvironment hinder the efficacy and trafficking of CAR-NK cells in solid tumors. In this study, the researchers developed a strategy using living CAR-NK cells as carriers to deliver anticancer drugs specifically to the tumor site. They also introduced a time-lapse method to evaluate the efficacy and tumor specificity of CAR-NK cells using a two-photon microscope. The results showed enhanced antitumor immunity when CAR-NK cells were combined with photosensitive chemicals in both in vitro and in vivo tumor models. Additionally, the researchers successfully visualized the trafficking, infiltration, and accumulation of drug-loaded CAR-NK cells in the deeply situated tumor microenvironment using non-invasive intravital two-photon microscopy. This study demonstrates the successful integration of CAR-NK cells as drug carriers and provides insights for combined cellular and small-molecule therapies in cancer treatment.