Doctor of Philosophy, Universite De Montpellier (2014)
Imaging strategies to monitor chimeric antigen receptor (CAR) T-cell biodistribution and proliferation harbor the potential to facilitate clinical translation for the treatment of both liquid and solid tumors. Additionally, the potential adverse effects of CAR T-cells highlight the need for mechanisms to modulate CAR T-cell activity. The herpes simplex virus type 1 thymidine kinase (HSV1-tk) gene has previously been translated as a positron emission tomography (PET) reporter gene for imaging of T-cell trafficking in brain tumor patients. The HSV1-TK enzyme can act as a suicide gene of transduced cells through treatment with the prodrug ganciclovir (GCV). Here we report the molecular engineering, imaging, and GCV-mediated destruction of B7H3 CAR T-cells incorporating a mutated version of the HSV1-tk gene (sr39tk) with improved enzymatic activity for GCV. The sr39tk gene did not affect B7H3 CAR T-cell functionality and in vitro and in vivo studies in osteosarcoma models showed no significant effect on B7H3 CAR T-cell antitumor activity. PET/CT imaging with 9-(4-[18F]-fluoro-3-[hydroxymethyl]butyl)guanine [18F]FHBG of B7H3-sr39tk CAR T-cells in an orthotopic model of osteosarcoma revealed tumor homing and systemic immune expansion. Bioluminescence and PET imaging of B7H3-sr39tk CAR T-cells confirmed complete tumor ablation with intraperitoneal GCV administration. This imaging and suicide ablation system can provide insight into CAR T-cell migration and proliferation during clinical trials while serving as a suicide switch to limit potential toxicities.
View details for DOI 10.1158/0008-5472.CAN-19-3579
View details for PubMedID 32958548