Brain Metastases from Breast Cancer and Response to Treatment with Eribulin: A Case Series

Brain metastases are common in patients with advanced breast cancer (BC), causing considerable morbidity and mortality. Eribulin is a microtubule dynamics inhibitor approved for treating certain patients with metastatic BC, previously treated with an anthracycline and a taxane. In the 301 phase 3 study in 1102 women with advanced BC, eribulin and capecitabine treatments did not differ for co-primary endpoints (overall survival [OS]: 15.9 vs 14.5 months, P = 0.056; progression-free survival [PFS]: 4.1 vs 4.2 months, P = 0.30). Here, we report outcomes for six patients (eribulin, n = 3; capecitabine, n = 3) who had received treatment for brain metastases from BC (BCBM) at baseline. All eribulin-treated patients experienced brain lesion shrinkage at some point during treatment, compared with one capecitabine-treated patient. Fewer patients in study 301 developed new BCBM with eribulin (13/544, 2.4%) compared with capecitabine (25/546, 4.6%). Eribulin does not cross the healthy blood–brain barrier (BBB), but could have the potential to do so after cranial radiation therapy. Capecitabine may cross the BBB and has demonstrated activity in BCBM. Data from these patients and previous cases suggest that further investigation of eribulin for BCBM may be warranted.