CELL INTELLIGENCE · 肿瘤细胞治疗研究

PURPOSE: Chimeric antigen receptor (CAR) T cell therapy has achieved great success in treating hematologic malignancies. However, it is yet to prove effective in the treatment of solid tumors. Thus, it is necessary to develop appropriate methodology for the long-term, accurate, and quantitative evaluation of the distribution and activities of CAR T cells in solid tumors. In the present study, we engineered TfR PSMA CAR (CAR- PSMA) T cells, which targeted the transferrin receptor (TfR) expressed by tumor cells and could be tracked in vivo via a reporter gene encoding the truncated prostate specific membrane antigen ( PSMA). We then quantitatively monitored these CAR T cells in vitro and in vivo using [ 68 Ga]Ga-PSMA-617 positron emission tomography (PET)/computed tomography (CT). METHODS: The CAR- PSMA T cells were genetically engineered by transducing T cells with a lentiviral vector encoding TfR41BB -T2A- PSMA. Firstly, the target expression, activation, and cytotoxicity of CAR- PSMA T cells were validated in vitro. Secondly, the minimum thresholds of CAR- PSMA T cells detection for [ 68 Ga]Ga-PSMA-617 PET/CT were also determined in vitro and in vivo respectively. Lastly, the feasibility of monitoring the biodistribution and infiltration of CAR- PSMA T cells after systematic administration was evaluated in the breast cancer subcutaneous xenograft model. RESULTS: The CAR- PSMA T cells retained activation and tumor killing capacity after transduction of the PSMA-encoding reporter gene. Next, the CAR- PSMA T cells could be reliably tracked by [ 68 Ga]Ga-PSMA-617 PET/CT, the detection sensitivity of which was 250 cells/mm 3 in vitro and 100 cells/mm 3 in vivo. Next, the sequential imaging assays revealed that [ 68 Ga]Ga-PSMA-617 PET/CT could be used to specifically visualize PSMA + CAR T cells at the tumor site. The increase in the [ 68 Ga]Ga-PSMA-617 signal intensity over time allowed us to effectively detect CAR T cells in vivo. CONCLUSION: Our findings preliminarily confirmed that [ 68 Ga]Ga-PSMA-617 PET/CT could reliably detect CAR- PSMA T cells in vitro and in vivo in solid tumors, laying the foundation for the monitoring CAR T cell therapy in the future.