Inclusion Criteria:

- Able to understand and voluntarily provide written informed consent before screening,
following an explanation of the nature and purpose of this study.

- Women, aged 18 years and older

- Histologically confirmed breast cancer, undergoing one of a variety of chemotherapy
regimens, or with other risk factors that could lead to a >20% risk of developing
severe neutropenia. Patients receiving chemotherapy regimens with high-risk for
severe neutropenia are eligible; eligibility of patients receiving intermediate-risk
chemotherapy regimens must be discussed with the Medical Monitor for the presence of
additional patient-specific risk factors.

- Must be receiving first-line adjuvant or neoadjuvant therapy for localized breast
cancer or first-line chemotherapy for metastatic breast cancer. It is recommended
that patients with human epidermal growth factor receptor 2 (HER2/neu)-positive
breast cancer should be receiving Herceptin® (trastuzumab), if approved and available
for this indication.

- Eastern Cooperative Oncology Group (ECOG) Performance Status of grade 0 to 2

- Adequate renal (serum creatinine and blood urea nitrogen [BUN] <3 times the upper
limit of normal [ULN]) and hepatic (serum bilirubin, aspartate aminotransferase
[AST], and alanine aminotransferase [ALT] <3 times ULN) function.

- Able to adhere to the study visit schedule and other protocol requirements.

- Women who are not pregnant and do not plan to become pregnant during the study.
Women of childbearing potential must have a negative serum pregnancy test result
within seven days before the first dose of study drug and must be using adequate non
hormonal barrier contraception before entering the study and throughout the study.
Non childbearing potential is defined as post-menopausal for at least one year,
surgically sterile, or having had a hysterectomy before study start.

Exclusion Criteria:

- Pregnant or lactating women.

- History or clinical evidence of a serious medical illness, including renal, hepatic,
respiratory, cardiovascular, endocrine, neurologic, psychiatric, or hematologic
disease, which in the opinion of the investigator will interfere with study
participation.

- Metastatic brain or meningeal tumors.

- Ascites or pleural effusions.

- Any active infection requiring systemic antimicrobial therapy.

- Known to be positive for human immunodeficiency virus (HIV, anti-HIV+), hepatitis B
antigen (HBAg[+]), or hepatitis C antibody (HCVAb[+]).

- Known or suspected hypersensitivity to the study drug or its components, such as
avian products, including influenza vaccine, or to E. coli-derived proteins.

- Currently receiving radiation therapy for treatment of a malignant condition, or have
completed radiation therapy within 14 days before study entry. Radiation therapy for
oncologic emergency is allowed.

- Participated in another therapeutic clinical study (i.e., not an epidemiological
study or genomic screening study) during the past 30 days, or are likely to
simultaneously participate in another therapeutic clinical study.

- History of, or known current problems with, substance abuse, or any medical,
psychological, and/or social condition that may interfere with the patient's
participation in the study, or with evaluation of the study results.

- Any condition that could jeopardize the patient's safety and compliance, as judged by
the investigator.