Results of a recently reported prospective, randomized 2-year clinical trial support switching to a less frequent administration schedule when using zoledronic acid (Zometa) to prevent skeletal-related events in men with prostate cancer.
Published in JAMA (2017; 317:48-58), the study featured a noninferiority design and randomized 1,822 patients 1:1 to treatment with the bisphosphonate every 4 weeks or every 12 weeks. The population included 689 men with prostate cancer (37.8%) along with 855 patients with breast cancer (46.9%), and 278 patients with multiple myeloma (15.3%). A total of 795 patients completed the trial.
The primary outcome was the proportion of patients in each group having at least one skeletal-related event (clinical fracture, spinal cord compression, radiation to bone, surgery involving bone) within 2 years of randomization, and the trial met its criteria for noninferiority with 29.5% of patients in the every 4-week dosing group and 28.6% of patients treated every 12 weeks experiencing at least one skeletal-related event.
A secondary endpoint analysis found there were no significant differences between the two zoledronic acid dosing groups in the probability of experiencing at least one skeletal-related event among the subgroups of patients with breast cancer, prostate cancer, or multiple myeloma. In addition, there were no statistically significant differences between zoledronic acid treatment groups in any other prespecified secondary endpoints, which included pain assessed with the Brief Pain Inventory, ECOG performance status, and incidences of osteonecrosis of the jaw and kidney function. The less frequent dosing schedule was, however, associated with better treatment adherence.