The impact of estrogen on the micro-environment could be a factor, agreed Dr. Rowan T. Chlebowski at the press briefing. "If you have an estrogen-rich environment, in many cases that estrogen is driving tumor growth. "When you get rid of the estrogen and the estrogen is not running the cell, then the things that bisphosphonates change in the microenvironment – the other pathways that it blocks – can have an effect," said Dr. Chlebowski, a medical oncologist at the Los Angeles Biomedical Research Institute at Harbor-University of California.
Dr. Rowan T. Chlebowski
In terms of safety, "zoledronic acid is a pretty well tolerated drug and it’s difficult to see any major differences between the control group and test group in terms of serious adverse events – certainly in terms of chemotherapy toxicities," Dr. Coleman said.
Notably there were 17 confirmed cases of osteonecrosis of the jaw in the zoledronic acid arm (1.16%) and another 9 possible cases. There were no cases among control patients.
Zometa is approved for the reduction or delay of bone complications (skeletal-related events, or SREs) across a broad range of metastatic cancers (breast, hormone-refractory prostate, lung, and other solid tumors) involving bone and multiple myeloma, as well as for the treatment of hypercalcemia of malignancy (HCM).