IMG-40. PET-based imaging of high-grade gliomas using gallium-labeled prostate-specific membrane antigen (PSMA)

Humans with high-grade gliomas have a poor prognosis, with a mean survival time of just 12-18 months for patients who undergo standard of care tumor resection and adjuvant therapy. Currently, surgery and chemoradiotherapy serve as standard treatment for this condition, yet these can be complicated by the tumor location, growth rate and recurrence. Recurrent tumor can often be very difficult to distinguish using conventional gadolinium-based MRI imaging given its similarity in appearance to radiation-induced changes. Other imaging modalities, including PET (positron emission tomography), could play a significant role in the workup and treatment of these tumors. To this end, we must identify PET-based markers for use in imaging of high-grade gliomas. Gallium-labeled prostate-specific membrane antigen (68Ga-PSMA) has demonstrated success as an effective target for studying high-grade gliomas and will be evaluated in this study to diagnose these tumors. Patients in this pilot study will receive up to 3 doses of prostate-specific membrane antigen (PSMA) in conjunction with standard of care clinically-required serial MRI scans which are performed to monitor for tumor progression or recurrence. After images are obtained for all patients, they will be reviewed by a diagnostic radiologist at Carilion Roanoke Memorial Hospital. The primary outcome measures we will obtain are the sensitivity and specificity of MRI vs 68Ga-PSMA PET/CT in the diagnosis of high-grade gliomas and differentiation of tumor progression from treatment-related changes. Enrollment is nearly completed. PSMA scans have shown remarkable distinction in both pre-operative and recurrence scans, as well as internal controls, demonstrating, and the ability to label GBM specifically. Based on current analysis, PSMA is showing reliability as a marker to distinguish recurrent glioblastoma.