Impact of 18F-fluciclovine PET/CT on plans for androgen deprivation therapy in patients with biochemical recurrence of prostate cancer: data analysis from two prospective clinical trials.

INTRODUCTION: Despite early detection and primary therapy improvements, biochemical recurrence (BCR) of prostate cancer remains common. The advent of highly sensitive molecular imaging has facilitated identification of men with limited metastatic disease burden that might be more optimally treated with metastases-directed therapy than with androgen deprivation therapy (ADT). The LOCATE (NCT02680041) and FALCON (NCT02578940) trials assessed the impact of 18F-fluciclovine PET/CT on the management of patients with BCR after curative-intent primary therapy. We performed a secondary analysis of LOCATE and FALCON data to characterize sites of recurrence and management decisions for BCR patients who had an intended management plan including ADT prior to undergoing 18F-fluciclovine PET/CT. METHODS: Data from 317 LOCATE/FALCON patients who underwent 18F-fluciclovine PET/CT were analyzed and those with a prescan plan for ADT (± another treatment) were selected. 18F-Fluciclovine detection rates were determined at the patient level and for the prostate/prostate bed region, pelvic and extra-pelvic lymph nodes (LN), soft tissues, and bones. The patients' pre- and postscan treatment plans were compared and were stratified by imaging results. RESULTS: A total of 146 patients had a prescan plan for ADT (60 as monotherapy and 86 in combination with another modality). 18F-Fluciclovine detected lesions in 85 of 146 (58%) patients planned for ADT. Detection rates in the prostate/bed, pelvic LN, extra-pelvic LN, soft tissues and bone were 30%, 25%, 13%, 2.1%, and 13%, respectively. Twenty-five (17%) patients had positivity confined to the prostate/bed, 21 (14%) had 18F-fluciclovine-positive pelvic LN (±prostate/bed) but no other involvement and 39 (27%) had involvement outside the prostate/bed and pelvic LN. Postscan, 93 of 146 (64%) patients had a management change, 55 (59%) of which were to abort ADT. Only 25% of the patients originally planned for ADT monotherapy still had an unaltered plan for ADT monotherapy postscan. Patients with a postscan plan for ADT monotherapy had the most disseminated disease. Disease in the prostate/bed only was most common in those whose plan was altered to abort ADT. CONCLUSIONS: 18F-Fluciclovine-PET/CT influenced management plans for the majority of patients with a prescan plan for ADT. Plans were commonly amended to target salvage therapy for lesions identified with 18F-fluciclovine PET/CT, and consequently likely spared/delayed patients the morbidity associated with ADT.