Article
18F-FET PET imaging following immunotherapy with DC vaccination in glioblastoma patients
18F-FET PET Bildgebung im Verlauf einer Immuntherapie mit DC Vakzinierung bei Glioblastom-Patienten
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Authors
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Marion Rapp
- Universitätsklinikum Düsseldorf, Department of Neurosurgery, 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
- University Hospital Düsseldorf, Institute of Neuropathology, 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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Marcel A. Kamp
- Universitätsklinikum Düsseldorf, Department of Neurosurgery, Düsseldorf, 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, Department of Neurosurgery, Düsseldorf, Deutschland
| Published: | June 4, 2021 |
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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: Seventeen patients (n=10 vaccinated patients; n=7 control group, with temozolomide chemoradiation alone) received 23 additional 18F-FET PET scans (n=14 scans in vaccinated patients; n=9 scans in patients with standard therapy). In vaccinated patients, the median time between radiotherapy completion and progressive MRI was 6 months (range, 1-18 months). In contrast, in the control group, the median time to MRI progression was 2 months (range, 1-7 months).
In 8 18F-FET PET scans (performed in 4 vaccinated patients, and 4 patients with standard therapy) PET and MRI were congruent and indicated tumor progression. Further treatment of these patients: Vaccinated patients: 2 were referred to best supportive care, in two patients a re-resection was performed (NP diagnosis: 1: therapy induced changes; 1: recurrent tumor). Control group: one patient was referred to best supportive care, in 3 patients a re-resection was performed and tumor recurrence was confirmed.
In contrast to the corresponding MRI, findings of 15 18F-FET PET scans (performed in 10 vaccinated patients, and in 5 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.
