Washington: A drug approved in Europe to treat osteoporosis has now been shown to stop the growth of breast cancer cells, even in cancers that have become resistant to current targeted therapies.
The findings by Duke Cancer Institute indicate that the drug bazedoxifene packs a powerful one-two punch that not only prevents estrogen from fueling breast cancer cell growth, but also flags the estrogen receptor for destruction.
"We found bazedoxifene binds to the estrogen receptor and interferes with its activity, but the surprising thing we then found was that it also degrades the receptor; it gets rid of it," senior author Donald McDonnell, PhD, chair of Duke`s Department of Pharmacology and Cancer Biology, said.
In animal and cell culture studies, the drug inhibited growth both in estrogen-dependent breast cancer cells and in cells that had developed resistance to the anti-estrogen tamoxifen and/or to the aromatase inhibitors, two of the most widely used types of drugs to prevent and treat estrogen-dependent breast cancer.
Currently, if breast cancer cells develop resistance to these therapies, patients are usually treated with toxic chemotherapy agents that have significant side effects.
"Because the drug is removing the estrogen receptor as a target by degradation, it is less likely the cancer cell can develop a resistance mechanism because you are removing the target," lead author Suzanne Wardell, PhD, a research scientist working in McDonnell`s lab, said.