Influence of Bevacizumab on Blood-Brain Barrier Permeability andO-(2-18F-Fluoroethyl)-l-Tyrosine Uptake in Rat Gliomas.
Restoration of the blood-brain barrier (BBB) after antiangiogenic therapy of gliomas with bevacizumab may result in a decrease in contrast enhancement on MRI despite tumor progression. This so-called pseudoresponse is difficult to differentiate from a true tumor response with conventional MRI. Initial patient studies have indicated that PET usingO-(2-18F-fluoroethyl)-l-tyrosine (18F-FET) may be helpful for solving this diagnostic problem. This study was performed to investigate the effects of bevacizumab on BBB permeability and18F-FET uptake in a human xenograft model.Methods:Human U87 glioblastoma cells were implanted into the striatum of immunodeficient RNU rats.18F-FET PET scans and ex vivo autoradiography were performed in animals receiving a single high dose of bevacizumab (45 mg/kg 2 d before PET;n= 9) or in animals receiving 2 lower doses (10 mg/kg 9 and 2 d before PET;n= 10) to evaluate short-term and long-term effects on the BBB, respectively, and in control animals without bevacizumab treatment (n= 8). Time-activity curves, slope, and tumor-to-brain ratios of18F-FET uptake (18-61 min after injection) were evaluated using a volume-of-interest analysis. After PET scanning, Evans blue dye (EBD) was injected into animals, and cryosections of the brains were evaluated by autoradiography, by histology, and for EBD fluorescence to assess BBB permeability.Results:Compared with the control, short-term bevacizumab therapy resulted in a trend toward BBB restoration (P= 0.055) and long-term therapy resulted in a significant decrease (P= 0.004) in BBB permeability, as assessed by EBD fluorescence. In contrast, no significant differences in tumor-to-brain ratios or slope of18F-FET uptake were observed in PET and autoradiography (P> 0.05).Conclusion:8F-FET uptake in glioblastomas seems to be largely independent of BBB permeability and reflects the viability of tumor tissue during antiangiogenic therapy more reliably than contrast-enhanced MRI.
Institute of Neuroscience and Medicine (INM-3, INM-4, INM-5, INM-11), Forschungszentrum Jülich, Jülich, Germany.
Carina
C
Stegmayr
Institute of Neuroscience and Medicine (INM-3, INM-4, INM-5, INM-11), Forschungszentrum Jülich, Jülich, Germany.
Dennis
D
Oliveira
Institute of Neuroscience and Medicine (INM-3, INM-4, INM-5, INM-11), Forschungszentrum Jülich, Jülich, Germany.
Nicole
N
Niemietz
Institute of Neuroscience and Medicine (INM-3, INM-4, INM-5, INM-11), Forschungszentrum Jülich, Jülich, Germany.
Antje
A
Willuweit
Institute of Neuroscience and Medicine (INM-3, INM-4, INM-5, INM-11), Forschungszentrum Jülich, Jülich, Germany.
Philipp
P
Lohmann
Institute of Neuroscience and Medicine (INM-3, INM-4, INM-5, INM-11), Forschungszentrum Jülich, Jülich, Germany.|Department of Neurology, University of Cologne, Cologne, Germany.
Norbert
N
Galldiks
Institute of Neuroscience and Medicine (INM-3, INM-4, INM-5, INM-11), Forschungszentrum Jülich, Jülich, Germany.|Department of Neurology, RWTH University, Aachen, Germany.|Jülich-Aachen Research Alliance (JARA)-Section JARA-Brain, RWTH Aachen University, Aachen, Germany; and.
N Jon
NJ
Shah
Institute of Neuroscience and Medicine (INM-3, INM-4, INM-5, INM-11), Forschungszentrum Jülich, Jülich, Germany.|Department of Nuclear Medicine, RWTH University Hospital, Aachen, Germany.
Johannes
J
Ermert
Institute of Neuroscience and Medicine (INM-3, INM-4, INM-5, INM-11), Forschungszentrum Jülich, Jülich, Germany k.j.langen@fz-juelich.de.|Department of Nuclear Medicine, RWTH University Hospital, Aachen, Germany.
Karl-Josef
KJ
Langen
D000818:Animals; D000068258:Bevacizumab / Q000008:administration & dosage*; D001812:Blood-Brain Barrier / Q000000981:diagnostic imaging / Q000187:drug effects*; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000378:metabolism*; D002199:Capillary Permeability / Q000187:drug effects*; D005910:Glioma / Q000000981:diagnostic imaging / Q000378:metabolism*; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D051381:Rats; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics
D019275:Radiopharmaceuticals; C545932:(18F)fluoroethyltyrosine; D000068258:Bevacizumab; D014443:Tyrosine
18F-FET PET; Evans blue dye; PET; bevacizumab; blood–brain barrier; glioblastoma