Clinical outcomes of patients with HR-positive advanced breast cancer treated with eribulin: A retrospective multicenter study from China.

e13010 Background: Approximately 75% of patients with metastatic breast cancer are hormone receptor positive (HR+)/ human epidermal growth factor receptor 2 negative (HER2-) and are treated with endocrine therapy based on subtype. However, the high rate of resistance to endocrine therapy requires switching to new approaches, including chemotherapy. Eribulin is a novel synthetic analog of halichondrin B that acts as a non-taxane microtubule dynamics inhibitor and inhibits the G2-M growth phase. In this study, we retrospectively assessed the clinical outcomes of Chinese patients with HR+ advanced breast cancer (ABC) who received eribulin. Methods: The study included 62 patients with HR+/HER2– ABC in three Chinese institutions between August 2019 and August 2023. Socio-demographic, clinical, pathology, imaging, and therapy records were reviewed. Progression-free survival (PFS) and tumor response were evaluated. Results: A total of 62 patients were included. The median age was 50.0 years. Eribulin was used as a second, third, fourth and fifth or more therapy agent in 4 (6.5%), 23 (37.1%), 15 (24.2%) and 20 (32.3%) of ABC patients, respectively. 54.8% of the patients had previously used CDK4/6 inhibitors. Eribulin monotherapy and eribulin-based combination therapy were 59.7% and 40.3% of patients. The objective response rate (ORR) and disease control rate (DCR) were 21.0% (13/62) and 88.7% (55/62) overall. By number of lines of therapy, the less than or equal third line ORR was 33.3% and the greater than third line ORR was 11.4% ( p = 0.0577). The median progression-free survival (mPFS) of total population was 5.2 months (95% CI: 4.1–5.8). The mPFS was 6.1 and 4.1 months in the eribulin-based combination therapy group and eribulin monotherapy group ( p = 0.0219), respectively. By number of lines of therapy, the mPFS was 5.8 and 4.1 months in the less than or equal third line and greater than third line treatment ( p = 0.05), respectively. Whether CDK4/6i had been used in these ABC patients had no effect on PFS, which was 5.0 and 5.5 months, respectively. Conclusions: This retrospective study suggests that eribulin was effective in HR+ Chinese patients with ABC. The front-line and combined therapy of eribulin in HR+ ABC need further exploration.