The subanalysis of prospective randomized trials of E suggested E suppressed development of new lesion [NL] and it led to improvement of overall survival (Twelves, BCRT, 2015), however, behaviors of disease in real-world patients (pts) have not been well discussed.
Outcomes of HER2-MBC pts who received E at our institute from November 2011 to present were reviewed. Statistical analyses were performed using the chi-square test, the Kaplan-Meyer method.
We identified total 128 (90 ER+, 38 ER-) HER2-MBC who received E at least 2 cycles in our institute. Median age at the initiation of E were as follows; overall, 58 (range 30-77); ER+, 60 (30-77); ER- 55.5 (32-71). Median number of regimens prior to E were as follows; overall, 1 (range 0-8); ER+, 1 (0-6); ER-, 2 (0-8). While all pts had a history of anthracycline and/or taxane in ER- subset, Number of involved organ were 2 (1-5) in overall and both subsets and no significant difference was seen in the pattern of visceral involvement. Most of (122/128, 95.5%) the pts was discontinued E therapy, and median time-to-treatment failure (TTF) were as follows; overall, 125.0 days (95% confidence interval [CI] 43.0-328.0); ER+, 134.0 days (95%CI 62.0-314.0); ER-, 104.0 (95%CI 42.0-230.0). Reasons for the discontinuation of E were as follows; progression of known lesion(s), 77 (63.1%); development of NL, 27 (22.1%), decrease of performance status, 11 (9.0%); intolerable toxicity, 6 (4.9%); other, 1 (0.9%). In ER- subset, development of NL was more frequently seen compared to ER+ subset, however, it was not statistically significant. (7/20 vs 10/67, P = 0.12, chi-square). Multivariate cox regression analyses disclosed some risk factors for TTF as follows; liver metastasis, hazard ratio [HR] 0.39, P < 0.05; soft tissue metastasis, HR 0.53, P < 0.05; ≥3 involved organs, HR 2.99, P < 0.05; taxane for early breast cancer, HR 2.50, P < 0.05. When limited to ER+ pts who received E as 2nd-line therapy (N = 40), only one (2.5%) pt developed NL and there was a positive relationship between TTF and OS after E (Spearman's roh=0.64, p < 0.0001).
Our single institutional review with some limitations disclosed eribulin monotherapy revealed equivalent effect shown in prospective studies.
Junichiro Watanabe
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J. Watanabe: Advisory board member of Eisai Co., Ltd. Honoraria from Eisai Co., Ltd.