Osteoporosis drug bazedoxifene stops growth of breast cancer cells, even in resistant tumors

Bazedoxifene, a drug approved in some countries 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, according to a Duke Cancer Institute study reported by EurekAlert.

The study was funded by a research grant from US drugs behemoth Pfizer (NYSE: PFE), maker of bazedoxifene, which is approved in the European Union and already marketed under the trade name Conbriza in some countries, and is also cleared in Japan, though still awaiting approval in the USA.

The findings, which were presented at the annual Endocrine Society meeting in San Francisco, indicate that 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," said senior author Donald McDonnell, chairman of Duke's Department of Pharmacology and Cancer Biology.