A Study of Patients With HER2 Gene Amplified Metastatic Breast Cancer Treated With First Line Herceptin and a Taxane

Inclusion Criteria:

* Signed informed consent
* Available tissue for central laboratory evaluation of HER2 status
* Histologically confirmed, measurable or nonmeasurable but evaluable, HER2 positive metastatic breast cancer (HER2 positive is defined as 3+ staining by IHC or gene amplification by FISH, determined by the local or central laboratory)
* Life expectancy \>6 months
* Female, age \>=18 years
* ECOG performance status of 0, 1, or 2
* Adequate bone marrow function as indicated by the following: \*ANC \>1500/uL, \*Platelet count \>=100,000/uL
* Adequate renal function, as indicated by creatinine \<=1.5× upper limit of normal (ULN)
* Adequate liver function, as indicated by bilirubin \<=1.5× ULN and AST or ALT \<2× ULN unless related to primary disease
* Use of an adequate means of birth control (women of childbearing potential)

Exclusion Criteria:

* Initiation of Herceptin \>=4 weeks after beginning taxane chemotherapy
* Prior chemotherapy for metastatic disease
* Prior cumulative anthracycline dose of \>360 mg/m2
* History of significant cardiac disease or uncontrolled arrhythmias
* Ejection fraction of \<50% or below the lower limit of normal
* Active infection
* Symptomatic or untreated brain metastases
* Pregnancy or lactation
* Concomitant malignancies or previous malignancies within the last 5 years, with the exception of adequately treated basal or squamous cell carcinoma of the skin or carcinoma in situ of the cervix
* Symptomatic intrinsic lung disease or extensive tumor involvement of the lungs, resulting in dyspnea at rest
* Hypersensitivity to study medications
* Major organ failure or systemic disease precluding the safe administration of study medications