Abstract P1-12-02: Results of a phase 2, multicenter, single-arm study of eribulin mesylate as first-line therapy for locally recurrent or metastatic HER2-negative breast cancer

Abstract

Abstract Background: Eribulin mesylate is a novel nontaxane microtubule dynamics inhibitor that is approved in patients (pts) with metastatic breast cancer (MBC) who have previously received at least two chemotherapeutic regimens for MBC. We are reporting a preliminary planned analysis (first 6 cycles of treatment) of a phase 2 study that evaluates efficacy and safety of eribulin as first-line therapy for HER2-negative MBC. Methods: Pts with measureable HER2-negative locally recurrent or MBC with at least 12 months since prior neoadjuvant or adjuvant chemotherapy received eribulin mesylate at 1.4 mg/m2 IV on days 1 and 8 of each 3-week cycle. Endpoints include objective response rate (ORR) (primary), safety, progression free survival (PFS), time to response (TTR), and duration of response (DOR). Tumor assessments were evaluated every 6 weeks for the first 6 cycles and every 6–12 weeks thereafter per RECIST 1.1. Results: 54 of 56 enrolled pts had at least 1 post-baseline assessment. The median number of cycles delivered was 7 (range 1,21). Pt characteristics: median age, 56 yrs (range 31–85); ECOG of 0, 32 (57%); 29% had de novo stage IV; 38/56 (68%) had prior neo/adjuvant (45% had anthracycline and 45% taxane, the majority of which were given together). Seventy percent have visceral disease (45% liver, 38% lung); 41 (73%) have estrogen receptor-positive (ER) disease and 12 (21%) have triple negative (TN) (ER−/PR−/HER2−) disease. Objective response data are found in Table 1. The most common treatment-related AEs are reported in Table 2. Treatment-related serious AEs occurred in 5 (9%) pts, neutropenia (4%), and febrile neutropenia (5%). Five pts stopped study therapy due to adverse events. Fourteen pts remain on study treatment. Conclusions: The preliminary results of this first-line study suggest that eribulin has antitumor activity in ER+/HER2− and TN MBC with an acceptable safety profile. Further exploration of this treatment as part of neo/adjuvant therapy is warranted. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-12-02.