In a presentation at the ASCO Annual Meeting,  Dr. Andrew Himelstein, MD, FACP of the Helen F. Graham Cancer Center & Research Institute, presented the results of a trial evaluating Zoledronic Acid (Zometa) at a dosing schedule of every 12 weeks as opposed to the current standard of care of every 4 weeks. The trial included 1,822 patients (with three different diseases including Prostate Cancer, breast cancer and multiple myeloma) who were randomly assigned to receive zoledronic acid every 12 weeks or every 4 weeks for 2 years.

The primary endpoint was incidence of developing any skeletal-related event (SRE). One thousand seven hundred (1,766) patients were included in the primary endpoint cohort and 795 completed the 2 years of treatment.

They found that when Zoledronic acid was administered every 12 weeks instead of every 4 weeks it was non-inferior, or both dosing schedules were equal to each other as to the primary endpoint of developing any SRE.

There was no significant difference between the two arms with 29% of patients in both the 4-week arm and the 12-week arm experiencing at least one SRE.

When the researchers evaluated the subjects according to disease type (Prostate Cancer, breast cancer and multiple myeloma) there was no significant difference between the proportion of patients with at least one SRE according to treatment arm.

The researchers also found that there were not significant differences between the two arms for time to first SRE, skeletal morbidity rate), pain scores or Eastern Cooperative Oncology Group performance status.

They also determined that renal dysfunction and osteonecrosis of the jaw were uncommon toxicities and did not significantly differ between the two treatment schedule.

Since this was information was one of the posters that was discussed in live session one of the discussants, Jamie H. Von Roenn, MD, FASCO, of ASCO, said that this lack of difference was not surprising “because the bulk of toxicity from bisphosphonates is likely to occur after 2 years.” Dr. Von Roenn also said that the time is right to begin recommending the use of zoledronic acid every 12 weeks instead of every 4 weeks.

Some of her comments can be heard at the following link:

Joel T. Nowak, MA, MSW