Potential treatment for metaplastic breast cancer?

Metaplastic breast cancer is a rare type of breast cancer accounting for less than 1 percent of breast cancers. It’s invasive cancer, which means it has the potential to spread to surrounding breast tissue and to other parts of the body.

In this type of breast cancer, the cancer cells transform from one cancer cell type into another. Metaplastic breast cancers usually are divided into two main groups — purely epithelial and mixed epithelial.

In a study published in the Journal of the National Cancer Institute, a multi-institutional team led by Dr. Jenny C. Chang, Director of the Houston Methodist Cancer Center, identified a gene driving the formation of metaplastic breast cancer. The researchers now have advanced a potential treatment for metaplastic breast cancer — the most aggressive subtype of triple-negative breast cancer.

“The results showed elimination of the cancer in nearly all of the mice when combined with standard chemotherapy,” said Chang, also a professor of medicine at Weill Cornell Medicine. “Our goal is to turn metaplastic breast cancer from a debilitating disease into a chronic illness.”

Triple negative is the name given to breast cancer that is:

• oestrogen receptor negative (ER-);
• progesterone receptor negative (PR-);
• HER2 negative.

The symptoms of metaplastic breast cancer are similar to those of invasive ductal breast cancer. These can include a change in the size of the breast, a lump or thickening of the skin, breast pain, changes in the nipple and puckering or dimpling of the skin.

The research team found the same gene mutated in 39 of the 40 tumor samples from metaplastic breast patients. The mutation was in the gene RPL39, which like HER2 (a gene overexpressed in 1 out of 5 breast cancers), is considered an oncogene. This means that cells carrying the erroneous form of this gene divide uncontrollably and result in rapid tumor growth. Identifying RPL39 was the first step in determining how to treat this cancer.

RPL39 regulates the expression of an enzyme called inducible nitric oxide synthase (iNOS). The Houston Methodist researchers found that patients with high expression of RPL39 and iNOS had lower overall survival. Intuitively, the team investigated effects of an iNOS inhibitor in the treatment of metaplastic breast cancer and found the L-NMMA compound shrunk tumors in mice bearing human metaplastic breast tumors.

“We not only uncovered the biological pathway stimulating cancer growth, but we found a compound that blocked it, increasing the survival of mice carrying human metaplastic breast tumors,” Chang said.

Fonte: Cancer Tutor.