Differential Uptake of 68Ga-PSMA-HBED-CC (PSMA-11) in Low-Grade Versus High-Grade Gliomas in Treatment-Naive Patients

Abstract

Purpose of the Report Prostate-specific membrane antigen (PSMA) is a type II membrane glycoprotein, which is not only overexpressed in prostate cancers but also in variety of solid tumors including glioblastoma multiforme. The aim of the present study was to demonstrate PSMA expression in gliomas using 68Ga-PSMA-HBED-CC(PSMA 11) PET/CT. Patients and Methods Ten patients with initially MRI suspected and eventually histopathologically proven gliomas [8 males (age range 30–73 yr; mean age 51.8 yr); 2 females aged 39 and 55 years] were subjected preoperatively to regional brain PET scan with 68Ga-PSMA-11 and 18F-FDG PET/CT. Final histopathology of brain lesions, their MIB-1 proliferation index (MIB-1 PI) were compared with PSMA and FDG PET findings. Results FDG PET/CT showed distinct FDG uptake in high-grade gliomas, whereas low-grade gliomas were non-FDG-avid amidst physiological tracer uptake. In vivo PSMA expression was seen in all patients with glioma. Of these, the 7 patients of glioblastoma harboring 8 lesions showed significantly higher PSMA expression than those with low-grade gliomas, average SUVmax being 16.93 and 2.93, respectively. Similarly, average tumor-to-background ratios (13.95 and 3.42, respectively) and MIB-1 PI (17.31 and 3.3, respectively) were substantially more in high-grade versus low-grade gliomas. Conclusions The results of this pilot study show that 68Ga-HBED-CC-PSMA PET/CT can be used to characterize the PSMA expression in gliomas, high-grade ones demonstrating higher SUVmax, MIB-1 PI tumor-to-background ratio than the low-grade ones. With these results as basis, certain patients may benefit from potential PSMA-targeted radionuclide therapy.