Early Monitoring Antiangiogenesis Treatment Response of Sunitinib in U87MG Tumor Xenograft by 18F-FLT MicroPET/CT Imaging

Aim. It was aimed to monitor early treatment response of Sunitinib in U87MG models mimicking glioblastoma multiforme by longitudinal F-18-FLT microPET/CT imaging in this study. Methods. U87MG tumor mice were intragastrically injected with Sunitinib at a dose of 80 mg/kg for consecutive 7 days. F-18-FLT microPET/CT scans were acquired on days 0, 1, 3, 7, and 13 after therapy. Tumor sizes and body weight were measured. Tumor samples were collected for immunohistochemical analysis of proliferation and microvessel density (MVD) with anti-Ki67 and anti-CD31, respectively. Results. The uptake ratios of tumor to the contralateral muscle (T/M) of F-18-FLT in the Sunitinib group decreased from baseline to day 3 (T/M 0 = 2.98 +/- 0.33; T/M 3 = 2.23 +/- 0.36; P < 0.001), reached the bottom on day 7 (T/M 7 = 1.96 +/- 0.35; P < 0.001), and then recovered on day 13. The T/M of F-18-FLT uptake in the control group remained around 3.0. There was no difference for the tumor size between both groups until day 11. F-18-FLT uptakes of tumor were correlated with Ki67 staining index and MVD. Conclusion. Early therapy response to Sunitinib could be predicted via F-18-FLT PET, which will contribute to monitoring antiangiogenesis treatment.