PSMA- and GRPR-Targeted PET: Results from 50 Patients with Biochemically Recurrent Prostate Cancer

Abstract

Rationale: Novel radiopharmaceuticals for positron emission tomography (PET) are evaluated for the diagnosis of biochemically recurrent prostate cancer (BCR PC). Here, we compare the gastrin releasing peptide receptors (GRPR) -targeting 68 Ga-RM2 with the prostate specific membrane antigen (PSMA) -targeting 68 Ga-PSMA11 and 18 F-DCFPyL.Methods: Fifty patients had both 68 Ga-RM2 PET/MRI and 68 Ga-PSMA11 PET/CT (n=23) or 18 F-DCFPyL PET/CT (n=27) at an interval ranging from 1 to 60 days (mean±SD: 15.8±17.7).Maximum standardized uptake values (SUV max ) were collected for all lesions.Results: RM2 PET was positive in 35 and negative in 15 of the 50 patients. PSMA PET was positive in 37 and negative in 13 of the 50 patients. Both scans detected 70 lesions in 32 patients.Forty-three lesions in 18 patients were identified only on one scan: 68 Ga-RM2 detected 7 more lesions in 4 patients, while PSMA detected 36 more lesions in 13 patients.Conclusions: 68 Ga-RM2 remains a valuable radiopharmaceutical even when compared with the more widely used 68 Ga-PSMA11/ 18 F-DCFPyL in the evaluation of BCR PC. Larger studies are needed to verify that identifying patients for whom these two classes of radiopharmaceuticals are complementary may ultimately allow for personalized medicine.

68Ga-PSMA and 68Ga-DOTA-RM2 PET/MRI in Staging of High-risk Prostate Cancer Patients: a Prospective Pilot Trial

“…Few studies have investigated prostate cancer by using both 68 Ga-PSMA and 68 Ga-DOTA-RM2 PET so far, both in the staging [15] and restaging setting of the disease [18,19] In our cohort of patients, differently to all the other published papers, all subjects have been studied by using a hybrid PET/MRI scanner both for 68 Ga-PSMA and 68 Ga-DOTA-RM2 radiotracers [15,18,19].…”

“…They showed that 68 Ga-PSMA11 and 18F-DCFPyL might have a complementary role as they detect different sites of disease recurrence. Notably, the group used a PET/MR scanner only for 68 Ga-RM2 imaging and regarding PSMA PET/CT scans, 68 Ga-PSMA11 or 18F-DCFPyL were alternatively used [19].…”

“…Moreover, the possibility to simultaneously acquire a PET scan with two different radiotracers assessing different metabolic pathways provides additional information regarding primary tumor characteristics, together with a wholebody evaluation of the disease. Differently from other groups that investigated the dual tracer approach of 68 Ga-PSMA and 68 Ga-DOTA-RM2 in PCa staging, or restaging, using a PET/CT scanner [15,18,19], one of the most relevant patients' advantage in the present study relies on the possibility to have received a diagnostic MRI simultaneously acquired to the PET image acquisition.…”

“…Hybrid PET/MRI allows for the simultaneous acquisition of metabolic, structural, and functional imaging information regarding PCa status in a whole-body single session examination, thus representing an innovative imaging approach capable to overcome the pitfalls of conventional imaging and, potentially, helping clinicians in the management of PCa. Only few and preliminary studies have compared 68 Ga-PSMA and 68 Ga-DOTA-RM2-PET radiotracers in PCa by using PET/CT or PET/MRI so far, with promising results in both patients presenting with biochemical recurrence and in those with newly diagnosed intermediate-or high-risk prostate cancer [15,18,19].…”

In Vitro and in Vivo Comparative Study of a Novel 68 Ga-Labeled PSMA-Targeted Inhibitor and 68 Ga -PSMA-11

“…A great number of studies found that overexpression of transmembrane protein, namely prostate speci c membrane antigen (PSMA), also known as glutamate carboxypeptidase, dominates in over 90% prostate carcinoma and tumor-associated endothelium of various solid cancer tissue 9,10 . Along with other properties, such as over 94% amino acids of the transmembrane protein locating outside of membrane 11 , PSMA has become one of the most extensively studied drug targets and shows prominent promise in the prostate cancer cell detection [12][13][14] .…”