Pertuzumab With High-Dose Trastuzumab in Human Epidermal Growth Factor Receptor 2 (HER2)-Positive Metastatic Breast Cancer (MBC) With Central Nervous System (CNS) Progression Post-Radiotherapy

Inclusion Criteria:

- Pathologically confirmed HER2-positive MBC

- Progression of or new brain metastases after completion of whole-brain radiotherapy or
stereotactic radiosurgery

- Completion of whole-brain radiotherapy or stereotactic radiosurgery more than 60 days
prior to enrollment

- Stable systemic disease

- Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1

- LVEF at least 50%

- Adequate hematologic, renal, and hepatic function

- Life expectancy more than 12 weeks

Exclusion Criteria:

- Progression of systemic disease at Screening

- Leptomeningeal disease

- History of intolerance or hypersensitivity to study drug

- Use of certain investigational therapies within 21 days prior to enrollment

- Current anthracycline use

- Unwillingness to discontinue ado-trastuzumab emtansine or lapatinib use

- Active infection

- Pregnant or lactating women

- Significant history or risk of cardiac disease

- Symptomatic intrinsic lung disease or lung involvement

- History of other malignancy within the last 5 years