Immunotheranostics in Solid Tumors: Longitudinal Tracking of Human IL13Rα2 CAR-T Cells In Vivo

Chimeric antigen receptor (CAR)-T cell therapy has shown limited success in the treatment of solid tumors, reinforcing the need to elucidate the in vivo biodistribution of these engineered T cells. Here, we integrate the anti-DOTA huC825 reporter ("Thor") platform into newly developed human anti-interleukin-13 receptor α-2 (IL13Rα2)-single-cell fragment variable (scFv)-derived CAR-T cells and investigate its utility for mapping CAR-T cell distribution in a xenograft mouse model of melanoma. Methods: We engineered anti-IL13Rα2-scFv-derived CAR-T cells expressing huC825 (KLG3BBz-huC825), evaluated detection sensitivity, and monitored CAR-T cell biodistribution via weekly [⁸⁶Y]Y-aminobenzyl-DOTA PET/CT and therapeutic efficacy. Results: KLG3BBz-huC825 T cells demonstrated potent antigen-specific cytotoxicity and cytokine release in vitro. The Thor radiohapten capture platform offered exquisite detection sensitivity of only 3,000 engineered T cells and enabled prolonged spatiotemporal assessment of CAR-T cell kinetics up to 7 wk after infusion, corroborated by histopathology. Treatment with KLG3BBz-huC825 resulted in an overall survival benefit. Conclusion: The Thor platform offers a versatile and highly sensitive approach to study the real-time kinetics of CAR-T cells in vivo.