Recent research presented at the 2014 San Antonio Breast Cancer Symposium, showed that the addition of either carboplatin (chemotherapy drug) or bevacizumab (monoclonal anti-VEGF antibody) to standard chemotherapy treatment before surgery was able to help women suffering from basal-like subtype of triple-negative breast cancer.
“We found that adding either carboplatin or bevacizumab to standard preoperative chemotherapy increased pathologic complete response rates for women with basal-like cancers — that is, it increased the proportion of women who had no residual cancer detected at surgery. At the same time, we found that while carboplatin had a similar effect in the smaller group of triple-negative patients with nonbasal-like cancers, adding bevacizumab actually decreased response rates for women with nonbasal-like cancers,” William M. Sikov, MD, associate professor of medicine at The Warren Alpert Medical School of Brown University, explained in a press release.
Bevacizumab is a biological antibody, delivered intravenously, that specifically binds to the vascular endothelial growth factor (VEGF) protein. VEGF is a key player in the tumor lifecycle, allowing it to grow and develop through the formation of new blood vessels, that are manipulated by the cancer itself to maintain its own supply of oxygen and nutrients. By binding to VEGF, bevacizumab can block the tumor blood supply, affecting its ability to metastasize.
The research team had already conducted a randomized, phase II clinical trial (CALGB/Alliance 40603) where they demonstrated the addition of carboplatin or bevacizumab to preoperative chemotherapy could improve the response rates in 443 women with operable stage II or III triple-negative breast cancer.
These new results originated from the analysis of tissue samples taken before the same patients had began treatment, and showed that among the pretreatment tumor samples from 360 of the patients, 314 were basal-like and 46 nonbasal-like.
“We have also looked at expression of variety of gene signatures in the pretreatment tissue samples to determine if they benefit from the addition of bevacizumab or carboplatin,” Dr. Sikov added. “We found that gene signatures characteristic of high proliferation rates and low estrogen-receptor signaling, which are both considered characteristics of more aggressive disease, are associated with higher rates of response rates overall and increased benefit from adding bevacizumab.”