CAR T-cell behavior and function revealed by real-time imaging

Adoptivetransfer of T-cells expressing chimeric antigen receptors (CAR) has shown remarkable clinical efficacy against advanced B-cell malignancies. Nonetheless, the field of CAR T-cells is currently facing several major challenges. In particular, the CAR T-cell strategy has not yet produced favorable clinical responses when targeting solid tumors. In this context, it is of paramount importance to understand the determinants that limit the efficacy of T-cell-based immunotherapy. Characterization of CAR T-cells is usually based on flow cytometry and whole-transcriptome profiling. These approaches have been very valuable to determine intrinsic elements that condition T-cell ability to proliferate and expand. However, they do not take into account spatial and kinetic aspects of T-cell responses. In particular, in order to control tumor growth, CAR T-cells need to enter into the tumor, migrate within a complex tumor environment, and form productive conjugates with their targets. Advanced imaging techniques combined with innovative preclinical models represent promising tools to uncover the dynamics of CAR T-cells. In this review, we will discuss recent results on the biology of engineered T-cells that have been obtained with real-time imaging microscopy. Important notions have emerged from these imaging-based studies, such as the multi-killing potential of CAR T-cells. Finally, we will highlight how imaging techniques combined with other tools can solve remaining unresolved questions in the field of engineered T-cells.

Automated summary

Adoptive transfer of T-cells expressing chimeric antigen receptors (CAR) has shown significant clinical efficacy against advanced B-cell malignancies, but faces challenges in targeting solid tumors. Understanding the determinants that limit the efficacy of T-cell-based immunotherapy is crucial. Flow cytometry and whole-transcriptome profiling have been valuable in characterizing CAR T-cells, but fail to account for spatial and kinetic aspects of T-cell responses. Advanced imaging techniques can provide insights into CAR T-cell dynamics and uncover important notions, such as multi-killing potential. Imaging techniques combined with other tools have the potential to solve unresolved questions in the field of engineered T-cells.