Phase II trial of 6 months ADT/abiraterone acetate plus prednisone (AAP) and definitive radiotherapy (AbiRT) for men with intermediate to high risk localized prostate cancer.

11Background: Combined external beam radiotherapy (RT) and androgen deprivation therapy (ADT) improves survival over RT alone for high risk prostate cancer (PC). Long-term ADT use, currently recommended for high risk PC, also increases toxicity. Recent data suggests synergistic efficacy with the addition of abiraterone acetate plus prednisone (AAP) to RT/ADT. Potent androgen blockade may provide biochemical control with short-term ADT course in men with aggressive but localized PC. Methods: This was a two center prospective phase 2 single arm clinical trial within the Department of Defense PCCTC (NCT01717053). Eligibility included 2+ intermediate or 1 high NCCN risk factors and no metastatic disease. Men received 6 months of ADT concurrently with 1000mg AA/5mg P daily and 78 Gy RT to prostate/SV. Primary endpoint was PSA < 0.1 ng/ml at 1 year. Secondary objectives included BPFS, PSA nadir, testosterone recovery, toxicity, and patient-reported QOL. Results: We enrolled 37 men (82% white, 18% black) with in...