Common osteoporosis drugs may prevent breast, lung, colon cancers

Dr Zaidi

Bisphosphonates, the most commonly used drugs for osteoporosis may be able to reduce the growth of certain cancers by inhibiting the activity of a cancer-producing family of receptor called the human epidermal growth factor receptor (HER), according to 2 studies published online this week in the Proceedings of the National Academy of Sciences(PNAS).

These include HER-driven breast, lung and colon cancers.

Bisphosphonates had been associated by past studies with slowed tumor growth in some patients but not others, and the mechanism behind these patterns was unknown. The connection between bisphosphonates and HER receptors was detected first in a genetic database analysis and confirmed in studies of human cancer cells and in mice.    

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Researcher Mone Zaidi, MD, of the Icahn School of Medicine at Mount Sinai, and colleagues conducted proof-of-concept studies that involved studying the action of the drugs on the HER receptors, as well as on cancer cells driven by the HER receptor family. In separate experiments, the cancer cells were implanted into mice that were given the drug. Tumor volume was dramatically reduced in the mice given bisphosphonates compared with placebo.

“Essentially the drugs interact directly with the receptors to inhibit the passage of cancer signals,” according Dr Zaidi. “These drugs are FDA approved for use in osteoporosis and cancer-related bone disease. Their safety is also well established over 2 decades of use. If proven to be efficacious in reducing the growth of certain cancers in people, which our proof-of-concept studies suggest, significant clinical implications in the prevention and therapy of these cancers will ensue.”

The study was conducted because “there is rich evidence in the clinical literature that bisphosphonates have beneficial effects on certain cancers in people, but not on others,” according to Dr Zaidi.

“The idea thus emerged that this selective action was due to a molecule that was present on some cells, and not on others,” he added. “Genomic connectivity mapping led us to the human epidermal growth factor receptor.”

Consumers of bisphosphonates could expect beneficial effects of using these drugs on the development of certain HER-driven cancers, although this effect has not yet been proven in humans, Dr Zaidi said.