Abstract P5-15-16: Utilization and outcomes of eribulin in triple negative metastatic breast cancer: Real-world findings

Abstract Background Triple-negative breast cancer (TNBC) accounts for 10-20% of all breast cancers (BCs) and a significant proportion of all BC deaths. Eribulin is approved for the treatment of metastatic BC (MBC) after treatment with two prior regimens. A pooled analysis of two phase III studies of eribulin in women with TNBC patients found a 26% reduction in the risk of death vs. controls. Treatment patterns of eribulin and clinical outcomes associated with early vs. late use among TNBC patients treated in community oncology practices have not been evaluated. Methods Physicians from the Cardinal Health Oncology Research Network completed an electronic case report form (CRF) on up to 7 TNBC patients treated with eribulin between 01/01/11 and 12/31/13. Adult female patients with pathologically confirmed metastatic disease and not participating in any interventional clinical trial were included. Providers indicated the usage of chemotherapy, either alone or in combination, by line of therapy (LOT) up to the LOT of eribulin initiation. Reported data points include: clinical parameters (eg, site of metastases, ECOG performance status, and comorbidities), treatment events (eg, LOT start/end date and rationale for discontinuation), and outcomes (eg, clinical response and date of death). Dosing, adverse events, use of supportive care medications, and hospitalization were also captured during eribulin treatment. Use of eribulin in LOT 1/LOT 2 was considered early; LOT 3+ was considered late. All comparisons are univariate. Results An interim analysis was performed on 123 TNBC patients (planned sample size of 250) collected from 26 providers. Patient mean age at eribulin treatment initiation was 55.0 years. Mean follow-up duration was 27 mo (SD = 11.9) from initiation of first line metastatic treatment until date of last visit, death, or loss to follow-up. Overall, 74.0% were deceased, 85.4% had received at least 3 LOTs in the metastatic setting, and 45.4% were stage IV at diagnosis. Most women were prescribed eribulin in a later LOT (61.8%), 3 (2.4%) patients received eribulin in LOT1 and 44 in LOT2 (36.7%). Among patients with known treatment start and end dates (87.0%), mean duration of treatment (DOT) was 6.2 mo (SD = 3.3), median 5.8 mo among early recipients and 5.5 mo (SD = 5.7), median 4.1 mo, among later recipients (p = 0.39). Early users were more likely (p = 0.05) to have a complete/partial response (71.1% vs. 47.7%) and less likely to have progressive disease (7.1% vs. 12.3%). In comparing eribulin users to all other therapies, eribulin users had a significantly longer DOT in LOT2 (5.9 vs. 4.7 mo, p = 0.01) and LOT3 (5.8 vs. 3.6 mo, p = 0.03). In LOT3, eribulin users were significantly more likely to have complete/partial response (54.2% vs. 18.8%) and less likely to have to have progressive disease (4.2% vs. 37.5%) compared to all other observed LOT3 therapies. Conclusions This interim analysis indicates longer DOT for patients treated with eribulin for TNBC in LOT2 and LOT3 and a more favorable response rate compared to all other agents used in each LOT, respectively, among patients treated in community oncology practices. Full results will be available at the conference. Citation Format: Kish JK, Mougalian SS, Copher R, McAllister L, Zhixiao W, Broscious M. Utilization and outcomes of eribulin in triple negative metastatic breast cancer: Real-world findings [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-15-16.