Triple-negative breast cancer does not respond to hormonal therapies, limiting treatment options for the disease.
Study co-author Sam Thiagalingam, associate professor of genetics & genomics, medicine and pathology & laboratory medicine at Boston University School of Medicine (BUSM), MA, and colleagues publish their findings in the journal Breast Cancer Research.
Triple-negative breast cancer, also referred to as basal-like breast cancer (BLBC), is estimated to account for 10-20% of breast cancers in the US, and it is most common among African-American women and those under the age of 40.
In triple-negative breast cancer, the cancer cells lack three types of receptors - estrogen receptors, progesterone receptors and human epidermal growth factor receptor 2 (HER2) - meaning the growth of cancer is not fueled by estrogen, progesterone or too many HER2 receptors.
As such, triple-negative breast cancer does not respond to hormonal therapies - such as tamoxifen or aromatase inhibitors - or treatments that target HER2 receptors, including trastuzumab. A combination of surgery, chemotherapy and radiotherapy is the most common treatment strategy for the condition.
Because there are limited treatment options for triple-negative breast cancer, survival rates for the disease are lower compared with other types. "Therefore, the discovery of alternative targets to restrain its metastatic potential is urgently needed," note Thiagalingam and colleagues.
Reducing IL13RA2 expression slowed tumor growth and spread
For their study, the researchers assessed the markers on the surface of breast cancer cell lines, comparing them with the gene expression profiles of breast tumors identified from international public databases.
The team discovered high levels of a molecule called IL13R alpha2 (IL13RA2) on the surface of metastatic or advanced triple-negative breast cancer cells.
From analyzing data of patients with triple-negative breast cancer, they found they were able to predict disease progression based on whether they had high levels of IL13RA2 in their cancer cells.
In addition, they found patients with a subtype of triple-negative breast cancer characterized by rapid spread to the lungs had high levels of IL13RA2 in their cancer cells.
Using mouse models of triple-negative breast cancer, the team reduced expression of IL13RA2 in cancer cells. They found that lowering IL13RA2 was associated with much slower tumor growth, and the cancer cells were much less likely to spread to the lungs.
Based on their findings, Thiagalingam and colleagues believe IL13RA2 plays a role in the growth and spread of triple-negative breast cancer, suggesting the molecule may be an important drug target for the disease. Thiagalingam adds:
"This discovery offers a glimmer of hope for patients stricken with BLBC. Personalized cancer therapies could be developed by targeting breast cancer cells that express copious levels of IL13RA2."
What is more, the researchers say their findings could lead to treatment strategies for other forms of cancer involving high IL13RA2 expression, such as ovarian, brain, colon and pancreatic cancers.
"Studies directed at this biomarker will be of high significance to improve the quality of life of all cancer patients harboring this alteration," adds Thiagalingam.
Last month, Medical News Today reported on a study suggesting aromatase inhibitors may be more effective than tamoxifen for reducing death rates among women with estrogen receptor-positive breast cancer.