Evaluation of 9-[(3-¹⁸F-fluoro-1-hydroxy-2-propoxy)methyl]guanine ([¹⁸F]-FHPG) in vitro and in vivo as a probe for PET imaging of gene incorporation and expression in tumors

Preparation of 9-[(3-¹⁸F-fluoro-1-hydroxy-2-propoxy)methyl]-guanine ([¹⁸F]-FHPG) for clinical use, and its evaluation as a positron emission tomography (PET) imaging agent for gene incorporation and expression in tumors are reported. In vitro studies in human colon cancer cells, HT-29, transduced with the retroviral vector G1Tk1SvNa and nontransduced (wild type) showed 4, 8, 12, and 15 times higher uptake of the probe in 1, 3, 5, and 7 h, respectively, in transduced cells compared with the controls. In vivo studies in tumor-bearing nude mice demonstrated that the tumor uptake of the radiotracer is three and six-fold higher in 2 and 5 h, respectively, in transduced cells compared with the control cells. These results suggest that [¹⁸F]-FHPG is a potential in vivo PET imaging agent for monitoring gene incorporation and expression in gene therapy of cancer.