Two drugs before surgery help women with triple-negative breast cancer, research shows

"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," says William M. Sikov, MD, associate chief of clinical research with the Program in Women's Oncology at Women & Infants and associate professor of medicine at The Warren Alpert Medical School of Brown University.

Last year, Sikov and colleagues reported in a randomized, phase II clinical trial called CALGB/Alliance 40603 that adding either carboplatin or bevacizumab to standard preoperative chemotherapy increased pathologic complete response rates in 443 women with operable stage II or III triple-negative breast cancer. These latest results are based on analysis of tissue samples obtained before patients started treatment, correlated with findings at surgery after treatment. Pretreatment tumor samples from 360 of the patients showed that 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" Sikov says. "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."

Other studies using tissue and blood samples obtained from the patients treated on this study -- funded by the National Cancer Institute, Roche-Genentech, and the Breast Cancer Research Foundation -- are ongoing.