Breast cancer cell growth thwarted by osteoporosis drug in preclinical studies

An osteoporosis drug approved in Europe could have another potential use--treating breast cancer, even cases in which the cancer has become resistant to current therapies.

Investigators at Duke Cancer Institute in Durham, NC, tested Pfizer's drug bazedoxifene and its effect on animals and cell culture studies, finding that the drug works in two ways--it both prevents estrogen from fueling breast cancer cell growth and destroys the estrogen receptor. In preclinical studies, the drug halted cell growth in estrogen-dependent breast cancer cells and in cells that had become resistant to the anti-estrogen therapy tamoxifen or to the aromatase inhibitor--two widely used drugs prescribed to treat estrogen-dependent breast cancer.

Researchers tested a variety of breast cancer cell types, including cells that are resistant to the common breast cancer drug lapatinib, which is used to treat patients whose tumors contain the mutant HER2 gene. The studies showed bazedoxifene effectively inhibited cancer cell growth.

The research, which was funded by a grant from Pfizer ($PFE), was presented June 15 at the annual Endocrine Society meeting in San Francisco.

In cases of drug-resistant breast cancer, patients must typically undergo chemotherapy, which has significant toxic side effects. In osteoporosis patients, the most commonly reported side effect is hot flashes. While more research needs to be done first, bazedoxifene could ultimately be a viable option to patients with drug-resistant advanced breast cancer since it has already been approved for a different use in Europe.

- here's the press release