The purpose of this study is to evaluate the pharmacokinetic (PK) profile of a fixed dose of SPI-2012 in patients with early-stage breast cancer receiving docetaxel and cyclophosphamide (TC) chemotherapy, as measured by the serum concentration of SPI-2012 on specific days following drug administration.

This is a Phase 1, single-arm multicenter study to evaluate the PK and safety of SPI-2012 (a long acting myeloid growth factor) in breast cancer patients treated with TC chemotherapy.

Approximately 25 patients will be enrolled.

Each cycle will be 21 days and patients will receive 4 cycles of treatment with 2 additional cycles based on the investigator's discretion. On Day 1 of each cycle, patients will receive TC chemotherapy and on Day 2 of each cycle, patients will receive SPI-2012.

Pharmacokinetics will be evaluated only in Cycles 1 and 3.

Inclusion Criteria:

• Newly diagnosed, histologically confirmed early-stage breast cancer, defined as operable Stage I to Stage IIIA breast cancer.
• Candidate to receive adjuvant or neoadjuvant TC chemotherapy.
• ANC ≥1.5x10^9/L
• Platelet count ≥100x10^9/L
• Hemoglobin >9 g/dL
• Calculated creatinine clearance >50 mL/min
• Total bilirubin ≤1.5 mg/dL
• AST and ALT ≤2.5xULN
• Alkaline phosphatase ≤2.0xULN
• ECOG ≤2

Exclusion Criteria:

• Active concurrent malignancy (except non melanoma skin cancer or carcinoma in situ of cervix) or life-threatening disease. If history of prior malignancies or contralateral breast cancer, must be disease free for at least 5 years.
• Known sensitivity to E. coli derived products or known sensitivity to any of the products to be administered during dosing.
• Concurrent adjuvant cancer therapy.
• Locally recurrent/metastatic breast cancer.
• Previous exposure to filgrastim, pegfilgrastim, or other G-CSF products in clinical development within 12 months prior to the administration of study drug.
• Active infection, receiving antibiotics or any serious underlying medical condition which would impair the ability of the patient to receive protocol-specified treatment.
• Prior bone marrow or hematopoietic stem cell transplant
• Used any investigational drugs, biologics, or devices within 30 days prior to study treatment or plans to use any of these during the course of the study.
• Prior radiation therapy within 30 days prior to enrollment.
• Major surgery within 30 days prior to enrollment.