Patient and Survivor Care Abstracts

April 2014, Vol 5, No 3 - AVBCC 2014 4th Annual Conference Abstracts


The Impact of Anthracycline on Progression-Free Survival and Time-to-Treatment Failure in Patients with Metastatic Breast Cancer Receiving Eribulin Mesylate in a Community Oncology Setting
Faria C1, Knoth R1, Jackson J2, Lunacsek O2, Hennenfent K2
1Eisai, 2Xcenda LLC

Objectives: In a phase 3 study of metastatic breast cancer (MBC), eribulin demonstrated a significant overall survival improvement for heavily pretreated patients, including both prior anthracycline and taxane therapy. Eribulin is FDA-approved for these patients. This study’s purpose was to evaluate progression-free survival (PFS) and time-to-treatment failure (TTF) in anthracycline-experienced patients (AE) compared with anthracycline-naïve patients (AN) with MBC receiving eribulin therapy in a real-world practice setting.

Methods: Patients with MBC initiating eribulin (November 2010-January 2013) were identified in an electronic medical record database of 21 US community oncology practices. PFS and TTF were compared between the AE and AN cohorts using the Kaplan-Meier method and Cox proportional hazards models adjusted for age, region, presence of multiple metastatic sites, and number of metastatic therapy lines.

Results: Study criteria were met by 178 AE and 76 AN patients. Age was lower for the AE cohort (median AE=59 yrs vs AN=65 yrs, P=0.0006), while the proportions of patients with multiple metastatic sites (78% for both cohorts, P=ns),
triple-negative MBC (AE=22% vs AN=21%, P=ns) and HER2-positive MBC (AE=17% vs AN=13%, P=ns) were similar. Number of metastatic lines of therapy prior to eribulin (median AE=5 vs AN=4, P=ns) were also similar. Of the AE patients, 57% received anthracycline in the adjuvant setting, 37% in the metastatic setting, and 6% in both settings. Median PFS (AE=3.3 mo vs AN=4 mo; P=0.5419) and median TTF (AE=2.8 mo vs AN=2.3 mo; P=0.6511) were not statistically different between cohorts, although PFS numerically favored AN, and TTF favored AE. Adjusted analyses did not show significant inter-cohort differences in the risk of progression (hazard ratio (HR)=1.073; 95% CI 0.753-1.53; P=0.6947; reference=AN) or risk of treatment failure (HR=0.953; 95% CI 0.717-1.267; P=0.7385; reference=AN).

Conclusion: In this retrospective study evaluating the impact of prior anthracyclines on treatment outcomes, MBC patients with and without prior exposure to anthracyclines achieved similar treatment benefit from eribulin.


Impact of Duration of Prior Taxanes on Progression-Free Survival and Time-to-Treatment Failure in Patients with Metastatic Breast Cancer Receiving Eribulin Mesylate in a Community Oncology Setting
Faria C1, Knoth R1, Jackson J2, Lunacsek O2, Hennenfent K2
1Eisai, 2Xcenda LLC

Objectives: Patients with metastatic breast cancer (MBC) commonly develop chemotherapy-resistant disease, leaving few effective treatment options. In a phase 3 trial, eribulin demonstrated a significant improvement in overall survival for heavily pretreated patients who received prior anthracyclines and taxanes. Moreover, in preclinical studies, eribulin retained activity against taxane-resistant cell lines. This study’s purpose was to evaluate the impact of the duration of prior taxane therapy on progression-free survival (PFS) and time-to-treatment failure (TTF) in patients with MBC treated with eribulin in a real-world practice setting.

Methods: Patients with MBC initiating eribulin (November 2010-January 2013) were identified in an electronic medical record database of 21 US community oncology practices. Two cohorts were created: patients who received ?6 months of taxane therapy (TGE6) in the metastatic setting prior to eribulin, and patients who received <6 months of prior taxane therapy (TLT6). PFS and TTF during eribulin therapy were compared between the TGE6 and TLT6 cohorts. Treatment failure was defined as discontinuation of eribulin therapy for any reason, including progression, toxicity, or other/unknown reason. PFS and TTF were analyzed using the Kaplan-Meier method and Cox proportional hazards models adjusted for age, region, presence of multiple metastatic sites, and number of metastatic therapy lines.

Results: Study criteria were met by 54 TGE6 and 136 TLT6 patients. Age (median TGE6=62 yrs vs TLT6=61 yrs, P=ns), proportions of patients with multiple metastatic sites (TGE6=80% vs TLT6=77%, P=ns), triple-negative MBC (TGE6=15% vs TLT6=24%, P=ns) and HER2-positive MBC (TGE6=9% vs TLT6=15%, P=ns) were similar between cohorts. Number of metastatic lines of therapy prior to eribulin (median TGE6=6 vs TLT6=4, P=0.0067) was higher for the TGE6 cohort. Median PFS (TGE6=3.2 mo vs TLT6=3.4 mo; P=0.4909) and median TTF (TGE6=3.2 mo vs TLT6=2.7 mo; P=0.0518) were not statistically different between cohorts, although PFS numerically favored TLT6, and TTF favored TGE6. Adjusted analyses did not show significant inter-cohort differences in the risk of progression (hazard ratio (HR)= 0.824; 95% CI 0.56-1.214; P=0.3287; reference=TLT6) or risk of treatment failure (HR=0.732; 95% CI 0.525-1.02; P=0.0651; reference=TLT6).

Conclusion: In this retrospective study, patients receiving prior taxane therapy for less than 6 months achieved similar treatment benefit from eribulin compared with those patients who were treated with taxanes 6 months or longer in the metastatic setting.