A Study of Pertuzumab in Participants With Metastatic Breast Cancer

Open-Label, Phase II, Multicenter, Randomized Study of Efficacy and Safety for Two Different Doses of a Recombinant Humanized Antibody to HER2 (rhuMAb 2C4) Administered Every 3 Weeks to Patients With Metastatic Breast Cancer With Low Expression of HER2

This study will evaluate the efficacy and safety of pertuzumab (rhuMAb 2C4) in participants with metastatic breast cancer which has progressed during or after standard chemotherapy and which is not amenable to curative therapy. Those who are maintaining a response to therapy or who have stable disease at the end of the formal study period will continue treatment until disease progression or unacceptable toxicity. Approximately 120 participants will be enrolled.

Inclusion Criteria:

• Females at least 18 years of age
• Histologically-confirmed metastatic breast cancer with low HER2 expression and at least one measurable lesion according to Response Evaluation Criteria in Solid Tumors (RECIST)
• Karnofsky performance status at least 80%
• Disease progression on/after up to 2 different chemotherapy regimens, including an anthracycline-containing therapy
• Left ventricular ejection fraction (LVEF) at least 50%
• Adequate liver function

Exclusion Criteria:

• Pleural effusions, ascites, or bone lesions as the only manifestation(s) of cancer
• Pulmonary or central nervous system (CNS) metastases
• Chemotherapy, radiotherapy, or immunotherapy within 4 weeks; or hormone therapy within 2 weeks of Day 1
• Previous treatment with any drug that targets the HER2 receptor family
• Previous treatment with corticosteroids as cancer therapy
• History of significant cardiac disease
• Major surgery or trauma within 4 weeks of Day 1
• Pregnant or lactating women