Imaging , Diagnosis , Prognosis Treatment Response Evaluation Using 18 F-FDOPA PET in Patients with Recurrent Malignant Glioma on Bevacizumab Therapy

Purpose: This study compares the value of 3,4-dihydroxy-6-[F]-fluoro-L-phenylalanine (F-FDOPA) positron emission tomography (PET) and MRI in assessing outcome during antiangiogenic treatment in patients with recurrent high-grade gliomas. Experimental Design: Thirty patients were prospectively studied with F-FDOPA PET scans immediately before, and two and six weeks after start of bevacizumab therapy. F-FDOPA metabolic tumor volumes (MTV) as well asmax andmean standardized uptake values (SUV) within thisMTVwere obtained. MRI treatment response was assessed at six weeks. The predictive ability of F-FDOPA PET and MRI response assessmentwere evaluatedwith regard to progression-free survival (PFS) and overall survival (OS). Results: A total of 30, 28, and 24 F-FDOPA PET scans at baseline, two weeks, and six weeks, were available for analysis, respectively. F-FDOPA PET SUVs as well as their changes through therapy were not predictive of outcome. However, MTV parameters such as MTV changes were highly prognostic. Interestingly, absoluteMTV at the first follow up scan provides themost significant prediction for increasedOS (P < 0.0001) as well as PFS (P 1⁄4 0.001). This surprising result was scrutinized with cross-validation and simulation analysis. Responders based on F-FDOPA PET data survived 3.5 times longer (12.1 months vs. 3.5 months, median OS, P < 0.001) than nonresponders (17 patients vs. 11 patients, respectively). In comparison, responders based on MRI data lived 1.5 times longer (11.4 months vs 7.7 months, P 1⁄4 0.03) than nonresponders (22 patients vs. 7 patients, respectively). Conclusions: F-FDOPA PET identifies treatment responders to antiangiogenic therapy as early as two weeks after treatment initiation. Clin Cancer Res; 20(13); 3550–9. 2014 AACR.