PET Imaging and Protein Expression of Prostate-Specific Membrane Antigen in Glioblastoma: A Multicenter Inventory Study

Sanne A. M. van Lith, Ilanah J. Pruis, Nelleke Tolboom, Tom J. Snijders, Dylan Henssen, Mark ter Laan, Maarten te Dorsthorst, William P. J. Leenders, Martin Gotthardt, James Nagarajah, Pierre A. Robe, Philip de Witt Hamer, Harry Hendrikse, Daniela E. Oprea-Lager, Maqsood Yaqub, Ronald Boellaard, Pieter Wesseling, Rutger K. Balvers, Frederik A. Verburg, Anita A. HarteveldMarion Smits, Martin van den Bent, Sophie E. M. Veldhuijzen van Zanten, Elsmarieke van de Giessen

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Upregulation of prostate-specific membrane antigen (PSMA) in neovasculature has been described in glioblastoma multiforme (GBM), whereas vasculature in nonaffected brain shows hardly any expression of PSMA. It is unclear whether PSMA-targeting tracer uptake on PET is based on PSMA-specific binding to neovasculature or aspecific uptake in tumor. Here, we quantified uptake of various PSMA-targeting tracers in GBM and correlated this with PSMA expression in tumor biopsy samples from the same patients. Methods: Fourteen patients diagnosed with de novo (n 5 8) or recurrent (n 5 6) GBM underwent a preoperative PET scan after injection of 1.5 MBq/kg [ 68Ga]Ga-PSMA-11 (n 5 7), 200 MBq of [ 18F]DCFpyl (n 5 3), or 200 MBq of [ 18F]PSMA-1007 (n 5 4). Uptake in tumor and tumor-to-background ratios, with contralateral nonaffected brain as background, were determined. In a subset of patients, PSMA expression levels from different regions in the tumor tissue samples (n 5 40), determined using immunohistochemistry (n 5 35) or RNA sequencing (n 5 13), were correlated with tracer uptake on PET. Results: Moderate to high (SUV max, 1.3–20.0) heterogeneous uptake was found in all tumors irrespective of the tracer type used. Uptake in nonaffected brain was low, resulting in high tumor-to-background ratios (6.1–359.0) calculated by dividing SUV max of tumor by SUV max of background. Immunohistochemistry showed variable PSMA expression on endothelial cells of tumor microvasculature, as well as on dispersed individual cells (of unknown origin), and granular staining of the neuropil. No correlation was found between in vivo uptake and PSMA expression levels (for immunohistochemistry, r 5 20.173, P 5 0.320; for RNA, r 5 20.033, P 5 0.915). Conclusion: Our results indicate the potential use of various PSMA-targeting tracers in GBM. However, we found no correlation between PSMA expression levels on immunohistochemistry and uptake intensity on PET. Whether this may be explained by methodologic reasons, such as the inability to measure functionally active PSMA with immunohistochemistry, tracer pharmacokinetics, or the contribution of a disturbed blood–brain barrier to tracer retention, should still be investigated.

Original languageEnglish
Pages (from-to)1526-1531
Number of pages6
JournalJournal of nuclear medicine : official publication, Society of Nuclear Medicine
Volume64
Issue number10
DOIs
Publication statusPublished - 1 Oct 2023

Keywords

  • PET
  • RNA sequencing
  • glioblastoma
  • immunohistochemistry
  • prostate-specific membrane antigen (PSMA)

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