The GLP-1 receptor is expressed in vivo by human metastatic prostate cancer.

The glucagon-like peptide-1 (GLP-1) receptor agonist, liraglutide, reduces human prostate cancer incidence, and similar GLP-1 receptor agonists reduce in vitro proliferation and in vivo growth of prostate cancer cell lines. Primary human prostate cancer expresses the GLP-1 receptor (GLP-1R) in vitro. Cancer evolves with stage, and whether advanced-stage human prostate cancer expresses GLP-1R is unknown. We hypothesised and aimed to prove that human metastatic castrate-resistant prostate cancer (mCRPC) expresses the GLP-1R in vivo. We hypothesised that mCRPC would thus be detectable by positron emission tomography/computed tomography (PET/CT) using a radiotracer bound to a GLP-1R ligand, as in exendin PET/CT.

Men with mCRPC, with more than one prostate-specific membrane antigen (PSMA)-avid lesion on PET/CT scanning (pathognomic in that setting for prostate cancer lesions), were approached to undergo PET/CT with gallium68-Dota-exendin-4. We documented PET/CT PSMA-avid lesions, which were also PET/CT exendin avid, as evidence of in vivo GLP-1R expression.

Out of the 24 men referred, three did not meet the inclusion criteria. Seventeen declined, largely because the study offered them no therapeutic benefit. Among the four men imaged, three had no exendin-avid lesions, while one had six osseous PSMA-avid lesions, three of which were also exendin avid.

We demonstrated in vivo GLP-1R expression by human mCPRC, detecting PET/CT lesions avid for both PSMA and exendin, in one of four participants. GLP-1R expression may thus occur even in advanced-stage prostate cancer. Our data contribute to growing evidence supporting the testing of GLP-1 receptor agonists for therapeutic benefit in prostate cancer.

Endocrine oncology (Bristol, England). 2024 Jan 22*** epublish ***

Mark S Stein, Victor Kalff, Scott G Williams, Declan G Murphy, Peter G Colman, Michael S Hofman

Knox Private Hospital, Wantirna, Victoria, Australia., Molecular Imaging and Therapeutic Nuclear Medicine, Cancer Imaging, Prostate Cancer Theranostics and Imaging Centre of Excellence (ProsTIC), Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia., Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia., Sir Peter MacCallum Department of Oncology, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia., Department of Diabetes and Endocrinology, The Royal Melbourne Hospital and University of Melbourne Department of Medicine, Parkville, Victoria, Australia.