A Phase 2, Multicenter, Single-Arm Study of Single-Agent Eribulin Mesylate as First-Line Therapy for Locally Recurrent or Metastatic Human Epidermal Growth Factor Receptor Two (HER2) Negative Breast Cancer

Inclusion Criteria

Key Inclusion Criteria

Females age 18 years or older at the time of informed consent

Have histologically or cytologically proven adenocarcinoma of the breast

Subjects with locally recurrent or metastatic disease with at least one measurable lesion
according to Response Evaluation Criteria in Solid Tumors

(RECIST) criteria v 1.1

Human epidermal growth factor receptor (HER2)-negative disease as determined by
fluorescence in situ hybridization (FISH) or 0 or 1+ by immunohistochemical (IHC)
staining.

Life expectancy of >24 weeks

Eastern Cooperative Oncology Group (ECOG) Performance Score (PS) of 0, 1 or 2

At least 12 months since prior neoadjuvant or adjuvant chemotherapy

At least 2 weeks since prior radiotherapy or endocrine therapy, with complete recovery
from the effects of these interventions

Adequate renal function

Adequate bone marrow function

Adequate liver function

Key Exclusion Criteria

Subjects who meet any of the following criteria will be excluded from participation in
this study:

Prior chemotherapy, biologic therapy, or investigational therapy for locally recurrent or
metastatic breast cancer

Subjects who have had a prior malignancy other than carcinoma in situ of the cervix or
nonmelanoma skin cancer

Prior exposure of >360 mg/m2 doxorubicin or liposomal doxorubicin, >120 mg/m2
mitoxantrone, >90 mg/m2 idarubicin, or >720 mg/m2 epirubicin

Inflammatory breast cancer

Clinically significant cardiovascular impairment

Subjects with known CNS disease are not eligible, except for those with treated brain
metastasis.

Pulmonary lymphangitic involvement that results in pulmonary dysfunction requiring the use
of oxygen

Currently pregnant or breast-feeding.

Subjects with pre-existing Grade 3 or 4 neuropathy. Any peripheral neuropathy must recover
to Grade 2 before enrollment.