Dr. O’Regan on the Utility of CDK4/6 Inhibitors in Breast Cancer

Ruth O’Regan, MD, professor, division head, Hematology and Oncology, Department of Medicine, University of Wisconsin School of Medicine and Public Health, associate director, Clinical Research, University of Wisconsin Carbone Cancer Center, discusses the utility of CDK4/6 inhibitors in breast cancer.

CDK4/6 inhibitors have demonstrated improved efficacy in metastatic hormone receptor–positive, HER2-negative breast cancer by way of progression-free survival, and, in some instances, overall survival compared with endocrine therapy alone. 

To date, there are limited data on ​the role of CDK4/6 inhibitors in HER2-positive and triple-negative breast cancer, ​O'Regan explains.

When palbociclib (Ibrance) was initially investigat​ed, the field evaluated various cell lines to deduce where the therapy was most effective​, says O'Regan. ​Moreover, estrogen receptor (ER)–positive luminal cell lines appeared to derive to most benefit. 

However, ​these data also indicated that HER2-positive cell lines, whether they were ER-positive or ER-negative, also benefited from palbociclib, O’Regan concludes.