A randomized phase II trial evaluating different schedules of zoledronic acid on bone mineral density in patients with prostate cancer beginning androgen deprivation therapy

Abstract

Objective: To assess the effects of timing and schedule of zoledronic acid (ZA) administration on bone mineral density (BMD) in patients beginning androgen deprivation therapy (ADT) for the treatment of recurrent prostate cancer.

Patients and methods: In this randomized, 3-arm trial, we evaluated changes in BMD after 3 different ZA administration schedules in men with recurrent prostate cancer who were beginning ADT. Forty-four patients were enrolled and randomized to receive a single dose of ZA given 1 week before beginning ADT (arm 1), a single dose of ZA given 6 months after beginning ADT (arm 2), or monthly administration of ZA starting 6 months after beginning ADT, for a total of 6 doses (arm 3).

Results: Patients who received ZA before ADT had a significant improvement in BMD at the total proximal femur and trochanter after 6 months compared with the other groups. In addition, only patients in the arm that received multiple doses improved lumbar spine BMD while on ADT, with these findings persisting to 24 months. However, this group also experienced more grade 1 adverse events.

Conclusions: Analysis of these data suggests that ZA administration before initiation of ADT was superior to treatment 6 months after starting ADT in maintaining BMD. In addition, monthly ZA administration can increase BMD above baseline but is associated with more adverse events. Further study is needed to examine whether the timing and frequency of ZA therapy in patients on ADT can reduce fracture risk.

Keywords: Androgen deprivation; Bone mineral density; Gamma delta T cells; Prostate cancer; Zoledronic acid.