Does Eribulin Mesylate Plus Pembrolizumab Improve Outcomes in Metastatic Breast Cancer?
Posted: Monday, July 29, 2019
Concomitant eribulin mesylate plus pembrolizumab did not improve progression-free survival compared with eribulin mesylate alone in patients with hormone receptor–positive/HER2-negative metastatic breast cancer, according to a randomized phase II study. However, Sara M. Tolaney, MD, of the Dana-Farber Cancer Institute, and colleagues noted that a PD-L1–positive subgroup “had very limited power” to assess the benefit of pembrolizumab. These study findings were presented at the 2019 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract 1004).
The study included 88 patients with hormone receptor–positive/HER2-negative metastatic breast cancer who had received no more than two lines of both hormonal therapies and chemotherapy. Participants were randomly assigned to receive either eribulin mesylate intravenously on days 1 and 8 plus pembrolizumab on day 1 of a 21-day cycle (arm A) or eribulin mesylate treatment alone (arm B). Patients in arm B were allowed to cross over to arm A for pembrolizumab monotherapy if disease progression occurred.
At a median follow-up of 63 months, arms A and B did not differ in terms of median progression-free survival (4.1 vs. 4.2 months, respectively, P = .38) or overall response rate (25% vs. 34%, P = .49). Of the 14 patients who crossed over to arm A, 1 achieved a partial response.
All patients experienced adverse events, including two deaths in arm A, with 54.6% of patients having grade 3 or 4 toxicity. Overall, 24 of the 65 patients who underwent a PD-L1 assay had PD-L1–positive tumors, although PD-L1 status, tumor-infiltrating lymphocytes, neutrophil-lymphocyte ratio, tumor mutation burden, and genomic alterations were all found to have no impact on progression-free survival.
Disclosure: The study authors’ disclosure information may be found at coi.asco.org.