Longer Dosing Interval of Zoledronic Acid Found Acceptable for Bone Metastasis

Inês Martins, PhD avatar

by Inês Martins, PhD |

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Zoledronic acid and bone metastasis

Patients with bone metastasis due to multiple myeloma, breast or prostate cancer, who received zoledronic acid every 12 weeks for two years, did not have increased risk of skeletal-related events compared to patients who received the drug every four weeks, researchers have found.

The study, “Effect of Longer-Interval vs Standard Dosing of Zoledronic Acid on Skeletal Events in Patients With Bone Metastases,” published in JAMA, suggests that using the treatment every 12 weeks might be an acceptable option for these patients.

Zoledronic acid, a third-generation bisphosphonate (available under brand name Zometa in the U.S.), is given to patients with bone metastasis to reduce skeletal-related events — such as bone fractures, spinal cord compression, radiation to bone, or bone surgery — and pain. It slows the breakdown of bones, increases bone density, and decreases the amount of calcium being released by the bones into the blood.

The optimal dosing interval for the drug has not been established. It usually is given to patients every four weeks, but researchers at the Helen F. Graham Cancer Center & Research Institute sought to assess whether the drug could be administered at longer intervals.

Andrew L. Himelstein, MD, and his colleagues conducted a randomized, multicenter, open-label Phase 3 clinical trial (NCT00869206) at 269 academic and community sites in the United States. The study enrolled 1,822 patients with metastatic breast cancer (855), prostate cancer (689), or multiple myeloma (278) who were randomized to receive zoledronic acid intravenously every four weeks or every 12 weeks for two years.

The primary endpoint, or goal, was to find out how many patients experienced at least one skeletal-related event within two years of the study’s start.

At two years, 795 patients had completed the study. The number of skeletal-related events was not significantly different between the four-week and 12-week groups. In the former group, 260 patients (29.5%) experienced at least one skeletal-related event, while 253 (28.6%) did in the 12-week group.

“Among patients with bone metastases due to breast cancer, prostate cancer, or multiple myeloma, the use of zoledronic acid every 12 weeks compared with the standard dosing interval of every 4 weeks did not result in an increased risk of skeletal events over 2 years. This longer interval may be an acceptable treatment option,” the researchers wrote.