Edith A. Perez, MD, the deputy director at large for the Mayo Clinic Cancer Center, discusses the potential for immune checkpoint inhibition as treatment for patients with advanced breast cancer.
There has been a great deal of interest in CTLA-4, PD-1, and PD-L1 inhibitors as treatments across a variety of malignancies, Perez explains. These strategies were explored first in tumors that had demonstrated susceptibility to immunotherapies, such as melanoma, and are now being investigated in breast cancer.
Two presentations at the 2014 San Antonio Breast Cancer Symposium showed that immune checkpoint inhibition is effective in patients with breast cancer, notes Perez. These early studies demonstrated that further investigation is warranted for this treatment strategy in breast cancer.
At the meeting, results were presented from a phase Ib study that demonstrated clinical efficacy with the PD-1 inhibitor pembrolizumab in patients with triple-negative breast cancer (TNBC). In this study, in heavily pretreated patients, the objective response rate (ORR) was 18.5%. Additionally, a second small trial showed clinical efficacy for the PD-L1 inhibitor MPDL3280A in pretreated patients with TNBC.
Future research will focus on the discovery of a biomarker of response for the immune checkpoint inhibitors in breast cancer, Perez notes. Additionally, optimal combination strategies need to be uncovered, in order to further enhance the efficacy of these novel immunotherapies.
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