Diagnostic impact of additional O-(2-[18F]fluoroethyl)-L-tyrosine (¹⁸F-FET) PET following immunotherapy with dendritic cell vaccination in glioblastoma patients

Abstract

Objective

Vaccination therapy using tumour antigen-loaded, autologous dendritic cells (DC) is a promising therapeutic approach alongside standard treatment for glioblastoma (GBM). However, reliable diagnostic criteria regarding therapy monitoring are not established. Here, we analysed the impact of additional ¹⁸F-fluoroethyl-tyrosine positron emission tomography (¹⁸F-FET PET) imaging following DC vaccination therapy.

Methods

We analysed data of GBM patients who received DC vaccination therapy. Following MRI diagnosis of tumour recurrence, additional static and dynamic ¹⁸F-FET PET imaging was performed. Vaccination was performed five times by intradermal injections, either weekly between concomitant radio/-chemotherapy and intermittent chemotherapy or after tumour recurrence, before re-radiation therapy. MRI and ¹⁸F-FET PET results were compared and correlated with clinical data.

Results

Between 2003 and 2016, 5 patients were identified who received DC vaccination and ¹⁸F-FET PET imaging (1 female/4 males; mean age: 44 ± 14 y). 3/5 patients showed congruent results of tumour progression. In three patients ¹⁸F-FET PET indicated treatment related changes, which was in contrast to MRI findings that indicated tumour progression. In these patients ¹⁸F-FET PET results could be confirmed by either neuropathological diagnosis or according to the RANO criteria

Conclusions

Despite the small patients number our results indicate an additional impact of ¹⁸F-FET PET for monitoring outcome following vaccination therapy.

Keywords:

• Glioblastoma multiforme
• dendritic cell vaccination
• 18F-FET PET
• pseudoprogression

Disclosure statement

No potential conflict of interest was reported by the authors.