Existing drug could prevent spread of triple-negative breast cancer

New research has revealed that breast cancer metastasis may be prevented by a class of drugs that have already been approved in the US.

Metastasis is the process by which cancer spreads. Researchers at the US’ Mayo Clinic have identified that enzyme pathway CDK4/6 regulates a cancer metastasis protein, known as Snail. They found that drugs that inhibit CDK 4/6 could also prevent the spread of triple-negative breast cancer.

Currently, CDK4/6 inhibitors are approved for treating estrogen-positive breast cancer, but not triple-negative breast cancer.

Study senior author Dr Zhenkun Lou, of the Mayo Clinic, explained: “Metastasis is a hallmark of cancer and a leading cause of cancer death. Despite great progress in cancer therapy, the prevention of cancer metastasis is still an unfulfilled challenge.”

During this study, the researchers focused on triple-negative breast cancer. This is a very difficult to treat cancer because it does not exhibit receptors for estrogen, progesterone or the HER-2/neu gene, which are targets for many current breast cancer treatments.

Dr Lou said: “Prior published data suggested that CDK 4/6 inhibitors were not effective in reducing the growth rates of estrogen receptor-negative breast cancer.

“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.”

Patient-derived xenographts involve the implantation of tumour tissue into an immunodeficient mouse which becomes an avatar to help identify which drug or drug combinations are most likely to be effective for an individual cancer patient.