BIMG-06. RESPONSE ASSESSMENT OF BEVACIZUMAB THERAPY FOR GLIOBLASTOMA BY USING MULTIPLE PET TRACERS

OBJECTIVE Use of the positron emission tomography (PET), such as 18F-fluorodeoxyglucose (FDG), 11C-Methionine (MET), 18F- Fluorothymidine (FLT), and 18F-Fluoromisonidazole (FMISO), is expected to lead the way for novel applications aimed at achieving efficient malignancy grading and treatment of gliomas. The aim of this study was to assess FDG, MET, FLT, and FMISO PET studies to evaluate the biological effects induced by bevacizumab (BEV) therapy in glioblastoma patients. METHODS Seventy-one patients with glioblastoma were treated biweekly with BEV from July 2013 to November 2020. FDG, MET, FLT, and FMISO PET scans were obtained at baseline and at follow-up (4 weeks after treatment onset). Measures of FDG, MET, FLT, and FMISO avidity were recorded; the measures were SUVmax, metabolic tumor volume (MTV; volume of tumor with SUV>42% of SUVmax), SUVmean (within the MTV), tumor-to-normal ratio (TNR), tumor-to blood ratio (TBR), and total lesion avidity (TLA; calculated as MTV x SUVmean). The prognostic analysis was performed in relation to the response assessment by multiple PET tracers using progression-free survival (PFS) and overall survival (OS). RESULTS Under the assessment of the Cox proportional hazard model, increased changes of FDG SUVmax, MET TLA at follow-up, FLT TLA at follow up, increased changes of FLT TLA, increased changes of FMISO TBR and FMISO MTV were significant prognostic factor of PFS. Increase changes of FDG TLA and FLT TLA and increased changes of FMISO TBR were significant prognostic factor of OS. CONCLUSION Increased changes in FLT TLA and FMISO-PET after BEV therapy may be a useful biomarker for predicting PFS and OS in glioblastoma.