Assessment of bone mineral density in men with de novo metastatic castration-sensitive prostate cancer treated with or without abiraterone acetate plus prednisone in the PEACE-1 phase 3 trial.

Aim: Addition of abiraterone acetate plus prednisone (AAP) to androgen deprivation therapy (ADT) with or without docetaxel (D) improved overall survival in patients with de novo metastatic castration sensitive prostate cancer in the PEACE-1 trial. The protocol was amended during the course of the study to assess whether addition of AAP increases bone loss.

Methods: Patients were randomized to receive either ADT + D with or without AAP. Bone mineral density (BMD) of the lumbar spine, femoral neck, and total hip were measured by dual X-ray absorptiometry at baseline, 6, 12, and 24 months (M). T-Scores and mean percent change in BMD values were assessed.

Results: With 97 patients treated with AAP and 98 without, the median age was 65 years and 69 patients were ECOG 0 in each arm. Median baseline body mass index was 25.6 and 26.5 kg/m in patients treated with or without AAP, respectively. Ten and 30 % presented with baseline osteoporosis and osteopenia, respectively. Mean T scores and mean percent changes in BMD measured on three anatomic sites decreased during the first year of treatment in both arms, without difference between arms. At M24, a numerical two-fold increase in patients with osteoporosis was observed in the AAP arm.

Conclusions: This is the first prospective assessment of BMD in a randomized trial with an experimental treatment using AAP. Bone loss occurred rapidly in both arms, and addition of AAP did not increase bone loss significantly although a numerically higher rate of osteoporosis was observed at 2 years.

Trial Registration: NCT01957436.