SAN ANTONIO – Breast cancers that are positive for the estrogen receptor (ER) and human epidermal growth factor receptor–2 (HER2) are less likely than ER-negative/HER2-positive tumors to respond to dual anti-HER2 therapy, suggesting that the estrogen receptor may act as a pathway of resistance to anti-HER2 treatment.
The National Surgical Adjuvant Breast and Bowel Project (NSABP) B-52 trial was designed to test the hypothesis that concurrent inhibition of both ER and HER2 added to chemotherapy with a platinum compound and a taxane will overcome resistance to treatment and improve pathologic complete response (pCR) rates in patients with ER-positive/HER2-positive breast cancer.
In a video interview at the San Antonio Breast Cancer Symposium, Mothaffar F. Rimawi, MD, discusses the trial results, which failed to show a significant difference in pCR rates between women who received chemotherapy with estrogen deprivation or chemotherapy alone. However, the trial still provided important information about the interplay between hormonal and HER2 receptors, and may inform future clinical trials examining reduction in tumor burden as a prognostic measure, says Dr. Rimawi from the Breast Center at Baylor College of Medicine, Houston.