Article
Impact of 18F-FET PET imaging to differentiate tumour progression vs therapy induced changes following immunotherapy with DC vaccination in glioblastoma patients
Einfluss der 18F-FET-PET-Bildgebung zur Unterscheidung von Tumorprogression vs. therapieinduzierten Veränderungen nach Immuntherapie mit DC-Impfung bei Glioblastompatienten
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Authors
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Marion Rapp
- Universitätsklinikum Düsseldorf, Klinik für Neurochirurgie, Düsseldorf, Deutschland
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Angeliki Datsi
- Universitätsklinikum Düsseldorf, Institute for Transplantation Diagnostics and Cell Therapeutics, Düsseldorf, Deutschland
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Jörg Felsberg
- Universitätsklinikum Düsseldorf, Institut für Neuropathologie, Düsseldorf, Deutschland
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Caterina Quente
- Universitätsklinikum Düsseldorf, Klinik für Neurochirurgie, Düsseldorf, Deutschland
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Norbert Galldiks
- Research Centre Jülich, Institute of Neuroscience and Medicine, Jülich, Deutschland
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Karl-Josef Langen
- Research Centre Jülich, Institute of Neuroscience and Medicine, Jülich, Deutschland
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Rüdiger V. Sorg
- Universitätsklinikum Düsseldorf, Institute for Transplantation Diagnostics and Cell Therapeutics, Düsseldorf, Deutschland
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Michael Sabel
- Universitätsklinikum Düsseldorf, Klinik für Neurochirurgie, Düsseldorf, Deutschland
| Published: | May 25, 2022 |
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Outline
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Objective: In the ongoing phase-II GlioVax trial, patients with newly diagnosed glioblastoma are treated with DC vaccination as add-on to standard temozolomide chemoradiation after fluorescence-guided surgery. Due to the multimodal therapy including vaccination immunotherapy, the specificity of contrast-enhanced MRI to differentiate between tumor recurrence and treatment-related changes is low. We examined the diagnostic value of amino acid PET using O-(2-[18F]-Fluoroethyl)-L-Tyrosine (18F-FET) PET for this clinically important differentiation.
Methods: Patients enrolled in the GlioVax trial and with progressive MRI findings according to the RANO criteria underwent additional 18F-FET PET imaging. Treatment-related changes on 18F-FET PET were considered if the mean tumor-to-brain ratio was ≤ 2.0. Subsequently, MRI and 18F-FET PET findings were correlated with the clinicoradiological follow-up or neuropathological findings.
Results: 22 patients (n=13 vaccinated patients; n=9 control group) received 30 additional 18F-FET PET scans (n=19 scans in vaccinated patients). In vaccinated patients, the median time between radiotherapy completion and progressive MRI was 8 months (range, 1-18 months). In contrast, in the control group 5 months (range, 1-7 months).
In 10 18F-FET PET scans (performed in 5 vaccinated patients, and 5 patients with standard therapy) PET and MRI were congruent and indicated tumor progression. Further treatment of these patients: Vaccinated patients: 2 patients were referred to best supportive care; in 3 patients a re-resection was performed (neuropathological diagnoses: treatment-induced changes (n=1); recurrent tumor (n=2)). Control group: two patients were referred to best supportive care; in 3 patients a re-resection confirmed tumor recurrence.
In contrast to the corresponding MRI, findings of 20 18F-FET PET scans (performed in 13 vaccinated patients, and in 6 patients with standard therapy) were consistent with treatment-related changes and the patients remained stable for at least 3 months.
Conclusion: Following multimodal therapy including DC vaccination, treatment-related changes occurred more often and later than in patients undergoing standard therapy. Additional 18F-FET PET imaging is helpful to distinguish tumor progression from treatment-induced changes related to the applied multimodal therapy including DC vaccination.
