Potential new treatment for breast cancer metastasis

Volume 6, Issue 2, 2017

Summary

CDK4/6 inhibitors may prevent the spread of triple-negative breast cancer, a new study shows.

Photograph of Zhenkun Lou, Ph.D.

Zhenkun Lou, Ph.D.

Photograph of Matthew P. Goetz, M.D.

Matthew P. Goetz, M.D.

Breast cancer metastasis might be preventable by using a class of drugs already approved by the U.S. Food and Drug Administration to treat estrogen positive breast cancer.

Mayo Clinic researchers have discovered that CDK4/6 inhibitors — which are approved to treat estrogen positive breast cancer — have the ability to target a protein called SNAIL involved in tumor metastasis. This means that the drugs might also be able to prevent the spread of triple-negative breast cancer.

"Metastasis is a hallmark of cancer and a leading cause of cancer death," said Zhenkun Lou, Ph.D., senior author of a paper on the cancer study and a Mayo Clinic oncology researcher in Rochester, Minnesota. "Despite great progress in cancer therapy, the prevention of cancer metastasis is still an unfulfilled challenge." The cancer metastasis paper was published online in the Jan. 9, 2017, issue of the journal Nature Communications.

In the tumor metastasis study, Dr. Lou and his colleagues focused on triple-negative breast cancer. Triple-negative breast cancer is difficult to treat because it doesn't exhibit receptors for estrogen, progesterone or the HER-2/neu gene, which are targets for many existing treatments for breast cancer.

"Prior published data suggested that CDK4/6 inhibitors were not effective in reducing the growth rates of estrogen receptor negative breast cancer," Dr. Lou said. "Our data confirmed that while the rate of growth of triple-negative breast cancer was not affected by CDK 4/6 inhibitors, this class of drugs was able to significantly inhibit the spread of triple-negative breast cancer to distant organs when tested in multiple different triple-negative breast cancer models, including patient-derived xenografts."

A patient-derived xenograft is tumor tissue that has been implanted into an animal model, in this case an immunodeficient mouse. The mouse becomes an avatar to help identify which drug or drug combinations are most likely to be effective for an individual patient with cancer.

More research is necessary to corroborate Dr. Lou's findings. If his findings are confirmed, it would be an important discovery that could expand the use of CDK4/6 inhibitors to prevent the metastasis of many other cancers that exhibit a high level of the SNAIL protein.

"These findings may provide a new treatment for the prevention of cancer metastasis," said Mayo Clinic oncologist Matthew P. Goetz, M.D., co-author of the tumor metastasis paper and co-leader of the Women's Cancer Program in the Mayo Clinic Cancer Center. "Mayo Clinic is now developing new studies that will focus on the role of CDK4/6 inhibitors and their potential to inhibit cancer metastasis in women with triple-negative breast cancer who are at highest risk for cancer metastasis."