18F-fluorocholine positron emission tomography/computed tomography for early outcome prediction in metastatic castration-resistant prostate cancer patients treated with enzalutamide: A proof-of-principle study.

e16040 Background: We investigated the role of 18F-fluorocholine positron emission tomography/computed tomography (FCH-PET/CT) in the early treatment evaluation and outcome prediction in patients with metastatic castration-resistant prostate cancer (CRPC) treated with enzalutamide. Methods: Patients received enzalutamide daily after at least one chemotherapeutic regimen with docetaxel. Patients were evaluated monthly for serological prostate specific antigen (PSA) response and safety. FCH-PET/CT was done at baseline and was repeated after approximately 3 to 6 weeks. Univariate and multivariate Cox regression models addressed potential predictors of progression-free survival (PFS) and overall survival (OS). Results: Thirty-six patients, median age 72 years (range, 48-90 years) were treated with enzalutamide, whose 21 received one or more lines of therapy after docetaxel. Fourteen of 36 (36%) received previously abiraterone. A decline in PSA level of 50% or more was seen in 13 of 36 (36%) patients. Thirty-f...