The GLP-1 receptor is expressed <i>in vivo</i> by human metastatic prostate cancer.

OBJECTIVES: The glucagon-like peptide-1 (GLP-1) receptor agonist, liraglutide, reduces human prostate cancer incidence, and similar GLP-1 receptor agonists reduce proliferation and growth of prostate cancer cell lines. Primary human prostate cancer expresses the GLP-1 receptor (GLP-1R) . 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 . 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. MATERIALS AND METHODS: 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 gallium-Dota-exendin-4. We documented PET/CT PSMA-avid lesions, which were also PET/CT exendin avid, as evidence of GLP-1R expression. RESULTS: 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. CONCLUSIONS: We demonstrated 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.