Beschreibung:
<jats:title>Abstract</jats:title>
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<jats:title>BACKGROUND</jats:title>
<jats:p>The REGOMA phase 2 trial showed an encouraging overall survival benefit of the multikinase inhibitor regorafenib in glioblastoma patients at first progression. We used O-(2-[18F]fluoroethyl)-L-tyrosine (FET) PET for the early assessment of response to regorafenib in patients with progressive glioma in an advanced disease stage.</jats:p>
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<jats:title>METHODS</jats:title>
<jats:p>Thirty patients with progressive glioma were treated according to the REGOMA trial and prospectively followed. FET PET and MRI were performed at baseline and after the second cycle of regorafenib. Static PET parameters such as maximum and mean tumor-to-brain ratios (TBRmax, TBRmean) and metabolic tumor volumes (MTV) were calculated. Threshold values of FET PET parameters to predict a response were established by ROC analyses using an overall survival of ≥ 6 months as reference. The predictive value of FET PET parameters and their changes concerning overall survival was subsequently evaluated using the Kaplan-Meier test. MRI changes were evaluated according to the RANO criteria.</jats:p>
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<jats:title>RESULTS</jats:title>
<jats:p>Up to now, 18 of 30 patients (glioblastoma, 83%; age range, 24-71 years) were eligible for data evaluation. The median number of tumor relapses before regorafenib was 2 (range, 1-4). During regorafenib (median cycles, 4; range, 2-9 cycles), CTCAE grade 3 or 4 side effects occurred in 56% and 11%, respectively. The median overall survival was 6 months (range, 3-18 months). After two cycles of regorafenib, a TBRmean reduction of 13% predicted a significantly longer overall survival (12 vs. 6 months; P=0.034). In contrast, MRI changes evaluated according to RANO criteria (i.e., Stable Disease or Partial Response vs. Progressive Disease) were not predictive (11 vs. 8 months; P=0.644).</jats:p>
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<jats:title>CONCLUSION</jats:title>
<jats:p>Data suggest that amino acid PET using the tracer FET may be clinically valuable for identifying responders to regorafenib early after treatment initiation.</jats:p>
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