886P - Efficacy of enzalutamide in hormone-sensitive metastatic prostate cancer: Clinical utility of 18F-choline PET and whole body MRI

Abstract

BackgroundAR-inhibition with Enzalutamide may be an attractive alternative for 1L treatment of men with hormone-sensitive prostate cancer compared to androgen deprivation therapy (ADT). There is an unmet need for robust, reproducible imaging technology allowing accurate quantification and qualification of bone plus soft tissue metastases and assessment of early tumour responses to novel agents. PET/CT or WB MRI imaging offer advantage over traditional bone and CT scans. MethodsSixty patients with metastatic hormone-sensitive PC were included in this prospective cohort study. Patients received Enzalutamide 160mg once daily until progression of disease. Imaging tests were performed at baseline and bone scintigraphy and CT repeated at 3 month intervals, 18F-choline PET/CT at 2 weeks, 2, 6, 9 and 12 months and WB-MRI at 6 and 12 months. Enumeration of circulating tumor cells and quality of life assessments were secondary outcomes. ResultsSixty patients with a median age of 72 yrs (range 57−85) and a median PSA of 62.8μg/L (range 3-622) were enrolled. This study is ongoing; all of the first 50 patients experienced a≥50% PSA decline and 49 a≥90% PSA decline. Choline-PET imaging and WB MRI were more frequently able to detect metastases and measure favorable responses than bone scan or CT thorax and abdomen. Investigator and central review of all imaging results are ongoing. Treatment was well tolerated. Conclusions18F-choline PET/CT and WB-MRI were superior in detection of bone and lymph node metastases and 18F-choline PET/CT was useful for early response detection already at 2 weeks. Based on results both 18F-choline-PET and WB MRI imaging have great clinical utility in aiding clinicians treating men with hormone-sensitive metastatic prostate cancer. Clinical trial identificationNCT02815033. Legal entity responsible for the studyEuropean Uro-Oncology Group (EUOG). FundingAstellas Pharma. DisclosureAll authors have declared no conflicts of interest.