Open-Label, Phase 1 Study to Evaluate Duration of Severe Neutropenia After Same-Day Dosing of Eflapegrastim in Patients With Breast-Cancer

Inclusion Criteria:

• Willing and capable of giving written Informed Consent and able to adhere to studydrug dosing time and blood draw schedules

• New diagnosis of histologically confirmed early-stage breast cancer (ESBC), definedas operable Stage I to Stage IIIA breast cancer

• Candidate to receive adjuvant or neoadjuvant TC chemotherapy

• Age must be at least 18 years for the Early Phase, and between 18 to ≤55 years forthe Expansion Phase

• ANC ≥1.5×10^9/liter (L).

• Platelet count ≥100×10^9/liter (L).

• Hemoglobin >10 grams per deciliter (g/dL).

• Calculated creatinine clearance >50 milliliter per minute (mL/min).

• Total bilirubin ≤1.5 milligrams per deciliter (mg/dL).

• Aspartate aminotransferase (AST)/serum glutamic oxaloacetic transaminase (SGOT) andalanine aminotransferase (ALT)/serum glutamic pyruvic transaminase (SGPT) ≤2.5×upperlimit of normal (ULN).

• Alkaline phosphatase ≤2.0×ULN.

• Eastern Cooperative Oncology Group (ECOG) ≤2

• Willing to practice 2 forms of contraceptives (1 must be a barrier method), fromstudy entry through 30 days after last dose of study drug/ early discontinuation

• Negative urine pregnancy test within 30 days before randomization

Exclusion Criteria:

• Active concurrent malignancy (except non melanoma skin cancer or carcinoma in situof the cervix) or life-threatening disease

• Known sensitivity to Escherichia coli (E. coli) derived products

• Concurrent adjuvant cancer therapy other than the trial-specified therapies

• Locally recurrent/metastatic breast cancer

• Previous exposure to filgrastim, pegfilgrastim, or other G-CSF products in clinicaldevelopment within 3 months prior to the administration of study drug

• Receiving anti-infectives, has an underlying medical condition or other seriousillness that would impair the ability to receive protocol-specified treatment

• Used any investigational drugs, biologics, or devices within 30 days prior to studytreatment or plans to use any of these during the course of the study

• Prior bone marrow or stem cell transplant

• Prior radiation therapy within 30 days prior to enrollment

• Major surgery within 30 days prior to enrollment

• Pregnant or breastfeeding