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DOI: 10.1055/s-0040-1708239
Imaging findings following regorafenib in malignant gliomas: FET PET adds valuable information to anatomical MRI
Publication History
Publication Date:
08 April 2020 (online)
Ziel/Aim Recent phase 2 data show promising effectivity of the antiangiogenic multikinase inhibitor regorafenib for glioblastoma treatment at first progression (1). Following antiangiogenic treatment, amino acid PET provides valuable additional diagnostic information regarding treatment-related changes on MRI (e.g., non-enhancing tumor progression). In contrast, only a little is known about regorafenib. The present prospective pilot study aimed to determine the value of O-(2-[18F]fluoroethyl)-L-tyrosine (FET) PET for the assessment of regorafenib-related treatment effects.
Methodik/Methods Fourteen patients (age range, 38-81 years) with progressive malignant glioma (median number of relapses, 2; range, 1-4) were enrolled. Seven of 14 patients were eligible for data evaluation and underwent regorafenib therapy (120-160 mg per day, 21 days on, 7 days off; median number of cycles, 2). FET PET and MRI was performed at baseline and after the second cycle. MRI response was evaluated according to RANO criteria (2). FET uptake 20-40 minutes p.i. was quantified by maximum and mean tumor-to-brain ratios (TBRmax, mean).
Ergebnisse/Results In 4 of 7 patients, FET PET provided clinically relevant additional information. In two patients with MRI improvement despite subsequent clinical progression, increasing FET uptake (range of relative TBRmax increase, 34-94 %) was consistent with pseudoresponse. In one patient, a FET uptake below a TBRmax < 1.6 despite progressive disease on MRI suggested pseudoprogression. In another patient, increasing FET uptake (relative TBRmax increase, 138 %) enabled an earlier diagnosis of tumor progression (time benefit, 5 weeks), in which MRI was unchanged.
Schlussfolgerungen/Conclusions Following regorafenib and in contrast to conventional MRI, FET PET was able to identify pseudoresponse and pseudoprogression, and to detect tumor progression earlier.