Cynthia X. Ma, MD, PhD, on Potential Immunotherapy Options for Patients With Metastatic Breast Cancer

CancerNetwork® spoke with Cynthia X. Ma, MD, PhD, during the American Association for Cancer Research Annual Meeting 2021 about data supporting the potential use of the exemestane/leuprolide acetate plus pembrolizumab combination.

CancerNetwork® sat down with Cynthia X. Ma, MD, PhD, of Washington University School of Medicine in St. Louis, to discuss what her thoughts were regarding some of the groundbreaking data to come out of the American Association for Cancer Research (AACR) Annual Meeting 2021.

She detailed findings from a phase 1b/2 study of exemestane (Aromasin)/leuprolide acetate (Lupron Depot) plus pembrolizumab (Keytruda) for use in patients with hormone receptor–positive, HER2-negative metastatic breast cancer. The combination demonstrated a promising safety profile as well as meaningful objective response and progression-free survival data.


There are so many excellent abstracts and research findings. They span so many different tumor types, but also basic science, biology of cancer, and new targets. I thought 1 study that I was really impressed with was a small study from Taiwan that was looking at exemestane in combination with Lupron [Depot plus] pembrolizumab in patients with metastatic hormone receptor–positive, HER2-negative premenopausal women with breast cancer. The study [investigators] only presented their first phase results in 14 patients, but they saw a fairly impressive response rate, around 38%. In the patient population were those who are resistant to endocrine therapy. In that setting, this is impressive, although it’s a small study and more are needed. I think immunotherapy perhaps does have a role for ER-positive breast cancer if we select the right patients. Hopefully, we will have more treatment options for these patients that have resistant cancers.


Chen I, Lin C, Chang D, et al. A pilot study of pembrolizumab and exemestane/leuprolide in premenopausal hormone receptor positive/HER2 negative locally advanced or metastatic breast cancer (PEER). Presented at: AACR Annual Meeting 2021. Virtual. Abstract CT028