Background:

Liver metastasis and multiple metastatic sites are associated with higher risk of progression or death among women with hormone receptor-positive, human epidermal growth factor receptor-2-negative (HR+/HER2-) metastatic breast cancer (mBC). Traditional treatments, like endocrine monotherapy (ET mono) or chemotherapy (CT), have limited effectiveness in these high-risk patients. Everolimus-based therapy (EVE) is a new treatment option with different mechanism of action. This study examined the real-world comparative effectiveness of EVE vs. ET mono or CT in patients with liver metastasis or multiple metastatic sites.

Methods:

A sample of postmenopausal women with HR+/HER2- mBC was obtained through a retrospective chart review of community-based oncology practices in the US. All patients initiated EVE, ET mono, or CT (defined as the index therapy) for mBC between July 2012 and April 2013 after the failure of a non-steroidal aromatase inhibitor. Patients with liver metastasis and those with multiple metastatic sites (i.e., ≥2 non-lymph-node metastases) at the index therapy initiation were analyzed separately. In each group, progression-free survival (PFS) and time on treatment (TOT) were compared between EVE vs. ET mono or CT, respectively, using Kaplan-Meier analyses with log-rank tests and Cox proportional hazards models adjusting for patient and disease characteristics, such as age, mBC type, performance status, tumor burden, and prior treatment. Patients without an event were censored at the last follow-up.

Results:

A total of 202 patients had liver metastasis, including 82 treated with EVE, 49 with ET mono, and 71 with CT. EVE patients had more severe mBC than ET mono patients and less severe mBC than CT patients, as indicated by proportion of patients receiving prior CT for mBC and tumor burden. Compared with ET mono, EVE was associated with significantly longer PFS (log-rank test p=0.049; hazard ratio (HR)=0.48, 95% confidence interval (CI): 0.27-0.87) and TOT (log-rank test p=0.054, HR=0.49, 95% CI: 0.28-0.86). Similarly, compared with CT, EVE was associated with significantly longer PFS (log-rank test p=0.024, HR=0.76, 95% CI: 0.44-1.32) and TOT (log-rank test p<0.001, HR=0.35, 95% CI: 0.22-0.55).

A total of 265 patients had multiple metastatic sites, including 100 treated with EVE, 79 with ET mono, and 86 with CT. Similarly, EVE patients had more severe mBC than ET mono patients and less severe mBC than CT patients, as indicated by tumor burden. Compared with ET mono, EVE was associated with significantly longer PFS (log-rank test p=0.043, HR=0.62, 95% CI: 0.41-0.95) and TOT (log-rank test p=0.054, HR=0.64, 95% CI: 0.42-0.97). Compared with CT, EVE was also associated with longer PFS (log-rank test p=0.004, HR=0.60, 95% CI: 0.39-0.92) and TOT (log-rank test p<0.001, HR=0.36, 95% CI: 0.24-0.53).

Conclusion:

In this retrospective chart review of HR+/HER2- mBC patients, EVE was associated with significantly longer PFS and TOT compared with ET mono or CT in high-risk patients with liver metastasis or multiple metastatic sites.

Citation Format: Li N, Hao Y, Lin PL, Koo V, Ohashi E, Wu EQ, Xie J. Real-world effectiveness of everolimus versus endocrine monotherapy or chemotherapy in HR+/HER2- metastatic breast cancer patients with liver metastasis or multiple metastatic sites. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-13-13.