A maintained absolute lymphocyte count predicts the overall survival benefit from eribulin therapy, including eribulin re-administration, in HER2-negative advanced breast cancer patients: a single-institutional experience

Purpose Eribulin methylate (eribulin) improved the overall survival (OS) of HER2-negative advanced breast cancer (HER2-ABC) patients; however, the mechanism underlying the OS improvement has not been clarified. Several reports suggest that eribulin promotes antitumor immunity via tumor micro-environment conditioning. Recently, a maintained baseline lymphocyte count was proposed as predictive marker for eribulin therapy in HER2-ABC patients; however, no associations with the OS have been noted. We retrospectively investigated the neutrophil-to-lymphocyte ratio and absolute lymphocyte count (ALC) in HER2-ABC patients receiving eribulin and assessed the utility of eribulin re-administration for further OS improvement. Methods HER2-ABC patients who received eribulin therapy at Shizuoka Cancer Center between November 2011 and December 2018 were retrospectively analyzed. Results A total of 144 HER2-ABC (108 estrogen receptor-positive [ER+], 36 ER-) patients were identified, and 32 patients (28 ER+ , 4 ER-) were re-administered with eribulin. In the ER+ subgroup, a multivariate analysis showed that an ALC >= 1000/mu L and re-administration were significantly associated with the OS (hazard ratio [HR] 0.503; P = 0.034 and HR 0.366; P < 0.0001, respectively), and an ALC >= 1000/mu L was also identified as the only predictive factor for re-administration (HR 0.329; P = 0.033). In contrast, a multivariate analysis in the ER- subgroup identified no predictive markers. Conclusion In HER2-ER + ABC patients, ALC was identified as a predictive marker for eribulin therapy, and the re-administration of eribulin is considered a valid therapeutic option for further improvement of the OS.