PSMA, EpCAM, VEGF and GRPR as Imaging Targets in Locally Recurrent Prostate Cancer after Radiotherapy

Abstract

In this retrospective pilot study, the expression of the prostate-specific membrane antigen (PSMA), the epithelial cell adhesion molecule (EpCAM), the vascular endothelial growth factor (VEGF) and the gastrin-releasing peptide receptor (GRPR) in locally recurrent prostate cancer after brachytherapy or external beam radiotherapy (EBRT) was investigated, and their adequacy for targeted imaging was analyzed. Prostate cancer specimens were collected of 17 patients who underwent salvage prostatectomy because of locally recurrent prostate cancer after brachytherapy or EBRT. Immunohistochemistry was performed. A pathologist scored the immunoreactivity in prostate cancer and stroma. Staining for PSMA was seen in 100% (17/17), EpCAM in 82.3% (14/17), VEGF in 82.3% (14/17) and GRPR in 100% (17/17) of prostate cancer specimens. Staining for PSMA, EpCAM and VEGF was seen in 0% (0/17) and for GRPR in 100% (17/17) of the specimens’ stromal compartments. In 11.8% (2/17) of cases, the GRPR staining intensity of prostate cancer was higher than stroma, while in 88.2% (15/17), the staining was equal. Based on the absence of stromal staining, PSMA, EpCAM and VEGF show high tumor distinctiveness. Therefore, PSMA, EpCAM and VEGF can be used as targets for the bioimaging of recurrent prostate cancer after EBRT to exclude metastatic disease and/or to plan local salvage therapy.

Bombesin related peptides/receptors and their promising therapeutic roles in cancer imaging, targeting and treatment

“…In early studies using 99m Tc-labeled-BnR-agonists[133,178,179] involving 4–10 patients with proven/suspected prostate-cancer, specific-uptake by the probe was seen in 25% in one study[133] and in 100% of patients in the other two studies[178,179], for both the primary tumor and lymph node metastases(Table 1). A recent study[180] investigated the expression of various proteins used for imaging prostate-cancer or reported to be overexpressed and potentially useful for imaging (PSMA, EpCAM, VEGF and GRPR), in recurrent prostate-cancer in patients after surgery or radiotherapy. This study[180] in 17 patients prostate-cancer samples found in the tumor the PSMA; EpCAM; VEGF; GRPR positivity was; 100; 82; 82;100% and in the surround nontumor, stromal tissue it was 0 ;0; 0; 100%.…”

“…A recent study[180] investigated the expression of various proteins used for imaging prostate-cancer or reported to be overexpressed and potentially useful for imaging (PSMA, EpCAM, VEGF and GRPR), in recurrent prostate-cancer in patients after surgery or radiotherapy. This study[180] in 17 patients prostate-cancer samples found in the tumor the PSMA; EpCAM; VEGF; GRPR positivity was; 100; 82; 82;100% and in the surround nontumor, stromal tissue it was 0 ;0; 0; 100%. This led the authors to conclude that to evaluate recurrent prostate-cancer after therapy, GRPR should not be a target for bio-imaging and that,PSMA, EpCAM; VEGF should be considered[180].…”

Near Complete Response to 177Lu-PSMA-DKFZ-617 Therapy in a Patient with Metastatic Castration Resistant Prostate Cancer

“…Prostate speci ic membrane antigen (PSMA) is a membrane bound protein that is more avidly expressed in primary as well as in metastatic prostate cancer [4][5][6]. Extensive research is going on to develop PSMA ligands.…”

Cocktail Therapy of 177Lu-PSMA-617 and 177Lu-EDTMP in Patients With mCRPC

“…Prostate specific membrane antigen (PSMA) is a membrane bound protein that is more avidly expressed in primary as well as in metastatic prostate cancer. [3][4][5][6] This transmembrane protein has a large extracellular domain and a small intracellular domain and thus provides a promising theranostic target for prostate cancer imaging and therapy. 3 Extensive research is going on to develop PSMA ligands.…”