Abstract P5-20-04: Eribulin mesylate + trastuzumab as first-line therapy for locally recurrent or metastatic HER2-positive breast cancer: results from a phase 2, multicenter, single-arm study

Abstract

Abstract Background: Eribulin mesylate, a novel non-taxane microtubule dynamics inhibitor, has been approved for patients with metastatic breast cancer (MBC) who have previously received at least two chemotherapeutic regimens for MBC. This study evaluates efficacy and safety of eribulin + trastuzumab (TRAZ) as first-line therapy for human epidermal growth factor receptor 2 positive (HER2+) locally recurrent or MBC. Methods: Patients received eribulin mesylate at 1.4 mg/m2 IV on days 1, 8 and TRAZ initial dose of 8 mg/kg IV on day 1 every 21 days, followed by 6 mg/kg on day 1 of each subsequent cycle. For study inclusion, patients could have been previously treated with TRAZ, but at least 12 months should have passed since any prior neoadjuvant or adjuvant chemotherapy was used. Endpoints include objective response rate (ORR) (primary), safety, progression free survival (PFS), time to response (TTR), and duration of response (DOR). Tumor assessments are evaluated every 6 weeks for the first 6 cycles and every 6–12 weeks thereafter per RECIST 1.1. Results: Updated results presented here as of June 1, 2012; 37 of 52 planned patients have been treated. Patient characteristics are as follows: median age: 58 years (range, 31–81), 70% have luminal subtype, 95% are stage IV disease, and 73% have visceral disease, 46% had prior neo/adjuvant, 22% had prior anthracycline and 32% had prior taxane, 35% had original diagnosis of MBC. Patients received median of 7 (1,20) cycles for eribulin and 9 (1,23) cycles for TRAZ. The most common treatment related AEs are reported in Table 1. Treatment-related serious AEs were reported for 4 (11%) patients; neutropenia 3 (8%) and febrile neutropenia 2 (6%) patients each. Eight patients have discontinued treatment due to disease progression (PD). Best patient responses are found in Table 2. Conclusions: Based on the updated preliminary results of this Phase II study, the combination of eribulin + trastuzumab as first-line therapy for HER2+ locally recurrent or MBC appears to demonstrate an acceptable safety profile with considerable tumor responses, including in patients with ER/PR+ disease. Accrual is ongoing and study completion is anticipated prior to SABCS 2012. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-20-04.