Comparison of somatostatin receptor expression in patients with neuroendocrine tumours with and without somatostatin analogue treatment imaged with [18F]SiTATE

Ralf S Eschbach; Markus Hofmann; Lukas Späth; Gabriel T Sheikh; Astrid Delker; Simon Lindner; Klaus Jurkschat; Carmen Wängler; Björn Wängler; Ralf Schirrmacher; Reinhold Tiling; Matthias Brendel; Vera Wenter; Franziska J Dekorsy; Mathias J Zacherl; Andrei Todica; Harun Ilhan; Freba Grawe; Clemens C Cyran; Marcus Unterrainer; Johannes Rübenthaler; Thomas Knösel; Tanja Paul; Stefan Boeck; Christoph Benedikt Westphalen; Christine Spitzweg; Christoph J Auernhammer; Peter Bartenstein; Lena M Unterrainer; Leonie Beyer

doi:10.3389/fonc.2023.992316

Comparison of somatostatin receptor expression in patients with neuroendocrine tumours with and without somatostatin analogue treatment imaged with [¹⁸F]SiTATE

Front Oncol. 2023 Jan 30:13:992316. doi: 10.3389/fonc.2023.992316. eCollection 2023.

Authors

Ralf S Eschbach¹, Markus Hofmann¹, Lukas Späth¹, Gabriel T Sheikh¹, Astrid Delker¹, Simon Lindner¹, Klaus Jurkschat², Carmen Wängler³, Björn Wängler⁴, Ralf Schirrmacher⁵, Reinhold Tiling¹, Matthias Brendel¹, Vera Wenter¹, Franziska J Dekorsy¹, Mathias J Zacherl¹, Andrei Todica^{1

6}, Harun Ilhan^{1

6}, Freba Grawe^{1

7}, Clemens C Cyran⁷, Marcus Unterrainer⁷, Johannes Rübenthaler⁷, Thomas Knösel^{6

8}, Tanja Paul^{6

8}, Stefan Boeck^{6

9}, Christoph Benedikt Westphalen^{6

9}, Christine Spitzweg^{6

10}, Christoph J Auernhammer^{6

10}, Peter Bartenstein^{1

6}, Lena M Unterrainer¹, Leonie Beyer^{1

6}

Affiliations

¹ Department of Nuclear Medicine, University Hospital, LMU Munich, Munich, Germany.
² Fakultät für Chemie und Chemische Biologie, Technische Universität Dortmund, Dortmund, Germany.
³ Biomedical Chemistry, Clinic of Radiology and Nuclear Medicine, Medical Faculty Mannheim of Heidelberg University, Mannheim, Germany.
⁴ Medical Faculty Mannheim of Heidelberg University, Molecular Imaging and Radiochemistry, Clinic of Radiology and Nuclear Medicine, Mannheim, Germany.
⁵ Department of Oncology, Division of Oncological Imaging, University of Alberta, Edmonton, AB, Canada.
⁶ ENETS Centre of Excellence, Interdisciplinary Center of Neuroendocrine Tumours of the GastroEnteroPancreatic System at the University Hospital of Munich (GEPNET-KUM), University Hospital of Munich, Munich, Germany.
⁷ Department of Radiology, University Hospital, LMU Munich, Munich, Germany.
⁸ Institute of Pathology, LMU, Munich, Germany.
⁹ Department of Internal Medicine 3, University Hospital, Munich, Germany.
¹⁰ Department of Internal Medicine 4, University Hospital, LMU Munich, Munich, Germany.

Abstract

Purpose: Somatostatin analogues (SSA) are frequently used in the treatment of neuroendocrine tumours. Recently, [¹⁸F]SiTATE entered the field of somatostatin receptor (SSR) positron emission tomography (PET)/computed tomography (CT) imaging. The purpose of this study was to compare the SSR-expression of differentiated gastroentero-pancreatic neuroendocrine tumours (GEP-NET) measured by [18F]SiTATE-PET/CT in patients with and without previous treatment with long-acting SSAs to evaluate if SSA treatment needs to be paused prior to [18F]SiTATE-PET/CT.

Methods: 77 patients were examined with standardised [18F]SiTATE-PET/CT within clinical routine: 40 patients with long-acting SSAs up to 28 days prior to PET/CT examination and 37 patients without pre-treatment with SSAs. Maximum and mean standardized uptake values (SUVmax and SUVmean) of tumours and metastases (liver, lymphnode, mesenteric/peritoneal and bones) as well as representative background tissues (liver, spleen, adrenal gland, blood pool, small intestine, lung, bone) were measured, SUV ratios (SUVR) were calculated between tumours/metastases and liver, likewise between tumours/metastases and corresponding specific background, and compared between the two groups.

Results: SUVmean of liver (5.4 ± 1.5 vs. 6.8 ± 1.8) and spleen (17.5 ± 6.8 vs. 36.7 ± 10.3) were significantly lower (p < 0.001) and SUVmean of blood pool (1.7 ± 0.6 vs. 1.3 ± 0.3) was significantly higher (p < 0.001) in patients with SSA pre-treatment compared to patients without. No significant differences between tumour-to-liver and specific tumour-to-background SUVRs were observed between both groups (all p > 0.05).

Conclusion: In patients previously treated with SSAs, a significantly lower SSR expression ([18F]SiTATE uptake) in normal liver and spleen tissue was observed, as previously reported for 68Ga-labelled SSAs, without significant reduction of tumour-to-background contrast. Therefore, there is no evidence that SSA treatment needs to be paused prior to [18F]SiTATE-PET/CT.

Keywords: NET; PET/CT; [18F]SiTATE; molecular imaging; somatostatin analogues; somatostatin receptor.

Copyright © 2023 Eschbach, Hofmann, Späth, Sheikh, Delker, Lindner, Jurkschat, Wängler, Wängler, Schirrmacher, Tiling, Brendel, Wenter, Dekorsy, Zacherl, Todica, Ilhan, Grawe, Cyran, Unterrainer, Rübenthaler, Knösel, Paul, Boeck, Westphalen, Spitzweg, Auernhammer, Bartenstein, Unterrainer and Beyer.

Grants and funding

LB and LU were funded by the Munich-Clinician-Scientist-Program (LMU Munich).