Dr. Tolaney on Abemaciclib Plus Pembrolizumab for HR+, HER2- Breast Cancer

Sara M. Tolaney, MD, MPH, instructor of medicine, Harvard Medical School, attending physician of medical oncology, Dana-Farber Cancer Institute, discusses the phase Ib results of abemaciclib (Verzenio) plus pembrolizumab (Keytruda) for hormone receptor (HR)-positive, HER2-negative metastatic breast cancer. She presented updated data of the MONARCH 1 trial at the 2018 ASCO Annual Meeting.

Tolaney says the rationale behind this study was that preclinical work done by investigators suggested that a CDK4/6 inhibitor could augment the immune response during treatment. Previous data of the MONARCH 1 trial tested abemaciclib alone for patients who were previously treated with chemotherapy. The second phase of the study used a similar patient population.

In patients who had previously received up to 2 lines of chemotherapy in the metastatic setting, abemaciclib plus pembrolizumab led to a nearly 30% overall response rate compared with less than 10% with abemaciclib monotherapy for the same time point.

Tolaney mentions the notion that HR-positive tumors are less immunogenic, so it is “exciting” for oncologists to see a signal for activity.