Dr. Khong on Endocrine Therapy Combinations in ER+/HER2- Breast Cancer

Hung Khong, MD, a breast oncologist within the Chemical Biology and Molecular Medicine Program at Moffitt Cancer Center, discusses antiestrogen and immunotherapy combinations in ER-positive, HER2-negative breast cancer.

When immunotherapy is combined with a different drug in breast cancer, it is typically paired with chemotherapy, says Khong. The phase 2 I-SPY 2 study combined pembrolizumab (Keytruda) with paclitaxel, or other chemotherapies, followed by doxorubicin and cyclophosphamide, for patients with ER-positive disease in the neoadjuvant setting.

However, it is known that in this setting, endocrine therapy works just as well, if not better than, chemotherapy in this patient population. In the United States, there is a great deal of comfort with combining immunotherapy with chemotherapy in the neoadjuvant setting, says Khong, but many studies are demonstrating that endocrine therapy works just as well and with less toxicity. 

Different types of endocrine therapies are available, and the 2 major therapies are tamoxifen and the aromatase inhibitors. Tamoxifen has been shown to shift the T cells from a Th1 to Th2 phenotype and that will be impactful for a cancer treatment combinations, concludes Khong.