The following article features coverage from the 2020 San Antonio Breast Cancer Symposium. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

The pathologic complete response (pCR) rate was low for patients with neoadjuvant endocrine therapy–resistant, estrogen receptor (ER)–positive, HER2-negative breast cancer, according to an analysis of the ALTERNATE trial ( Identifier: NCT01953588). The results of the analysis were presented at the 2020 Virtual San Antonio Breast Cancer Symposium (SABCS).

The ALTERNATE trial enrolled 1299 postmenopausal patients with ER-positive, HER2-negative breast cancer and randomly assigned patients to receive neoadjuvant treatment with anastrozole, fulvestrant, or anastrozole plus fulvestrant.

A total of 286 patients were found to have a Ki67 expression levels above 10%, and of those, 168 were switched to salvage neoadjuvant chemotherapy. This group of patients were the subject of the current analysis.

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Patients in this group tended to have high ER Allred scores, grade 2 or 3 disease, and high Ki67 expression levels.

The most common neoadjuvant chemotherapy regimens received were doxorubicin and cyclophosphamide followed by paclitaxel (36%), weekly paclitaxel (33%), and docetaxel and cyclophosphamide. (20%)

Among patients switched to neoadjuvant chemotherapy, 133 completed neoadjuvant chemotherapy and 154 underwent surgery. The pCR rate was 4.8% for the patients overall, and among patients who received weekly paclitaxel as their neoadjuvant chemotherapy, the pCR rate was 1.8%.

After neoadjuvant chemotherapy, most patients had residual cancer burden (RCB) class II (48.8%) or III (25.0%). Patients who received weekly paclitaxel also predominantly had RCB class II (37.5%) or III (33.9%).

“Salvage neoadjuvant chemotherapy induced a very low pCR rate of approximately 5% in patients with neoadjuvant endocrine therapy–resistant, ER-positive, HER2-negative breast cancer,” said study presenter Cynthia Ma, MD, PhD, Washington University School of Medicine, St. Louis, Missouri.

“Studies are ongoing to investigate the underlying biology of these high-risk breast cancers with the development of novel treatment approaches,” said Dr Ma.

Read more of Cancer Therapy Advisor‘s coverage of the 2020 SABCS meeting by visiting the conference page.


Ma CX, Suman V, Leitch AM, et al. Neoadjuvant chemotherapy (NCT) response in postmenopausal women with clinical stage II or III estrogen receptor positive (ER+) and HER2 negative (HER2-) breast cancer (BC) resistant to endocrine therapy (ET) in the ALTERNATE trial (Alliance A011106). Presented at: 2020 Virtual San Antonio Breast Cancer Symposium; December 8-11, 2020. Abstract GS4-05.