Efficacy of Chemotherapy Plus Checkpoint Inhibition in Metastatic Breast Cancer Under Study
Posted: Monday, October 19, 2020
A previous phase I/II clinical trial reported antitumor activity and no new toxic effects with an eribulin/pembrolizumab combination in treating metastatic triple-negative breast cancer. A group of researchers conducted another trial, this time examining the efficacy of the drug combination on hormone receptor–positive, ERBB2-negative metastatic breast cancer, publishing their findings in JAMA Oncology. Ian E. Krop, MD, PhD, of Dana-Farber Cancer Institute, Boston, and colleagues found that in patients with hormone receptor–positive, ERBB2-negative metastatic breast cancer, the eribulin/pembrolizumab combination was not successful in improving progression-free survival, objective response rates, or overall survival, compared with eribulin alone.
“Prior studies have shown that only a small proportion of patients with hormone receptor–positive metastatic breast cancer…experience benefit from PD-L1 inhibitors given as monotherapy,” stated Dr. Krop and colleagues, further emphasizing the need for their work with combination drug treatments.
They conducted a multicenter phase II randomized clinical trial of 90 patients with hormone receptor–positive, ERBB2-negative metastatic breast cancer who had received 2 or more hormonal therapy lines and up to 2 lines of chemotherapy. Patients received either eribulin with pembrolizumab or eribulin monotherapy.
Overall, their findings revealed no differences between the median progression-free survival (4.1 vs. 4.2 months; hazard ratio = 0.80; P = .33) across the two groups. There was also no apparent statistical difference in the objective response rate (27% vs. 34%, P = .49) and no difference in overall survival across groups. PD-L1 assays were performed on archival tumor samples in 65 patients, and 24 (37%) had tumors positive for this ligand; however, this genomic alteration had no effect on progression-free survival.
Based on these findings, Dr. Krop and colleagues concluded: “Further efforts to explore the benefits of adding checkpoint inhibition to chemotherapy…are needed….”
Disclosure: For full disclosure of the study authors, visit jamanetwork.com.