Trastuzumab and Pertuzumab in Treating Patients With Unresectable Locally Advanced or Metastatic Breast Cancer That Did Not Respond to Previous Trastuzumab

DISEASE CHARACTERISTICS: * Histologically confirmed invasive breast cancer of 1 of the following stages: * Metastatic disease (stage IV) * Inoperable locally advanced disease * Disease progression after prior neoadjuvant chemotherapy required * Disease progression on or after trastuzumab (Herceptin®) based-therapy * Received 1-3 prior trastuzumab-based regimens * HER2/neu-positive tumor, defined as 3+ by fluorescent in situ hybridization * Measurable disease, defined as at least 1 lesion that can be measured in at least one dimension * No clinical signs or symptoms of brain and/or leptomeningeal metastases confirmed by CT scan or MRI * Brain and/or leptomeningeal metastases allowed if patient has stable lesions after standard treatment (surgery or radiotherapy), is asymptomatic on neurological exam, and is not receiving corticosteroid therapy to control symptoms * Hormone receptor status: * Not specified PATIENT CHARACTERISTICS: * ECOG performance status 0-1 * Male or female * Menopausal status not specified * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * Absolute neutrophil count ≥ 1,500/mm\^3 * Platelet count ≥ 75,000/mm\^3 * Creatinine ≤ 1.5 times upper limit of normal (ULN) * Bilirubin ≤ 1.5 times ULN * Alkaline phosphatase \< 5 times ULN * AST and ALT ≤ 2.5 times ULN (5 times ULN if liver metastases are present) * LVEF above lower limit of normal by echocardiogram or MRI * No clinical signs or symptoms of heart failure * No uncontrolled hypertension (i.e., blood pressure ≥ 180/100 mm Hg) * No significant valvular disease (i.e., aortic or mitral regurgitation of 3 or 4+/4+ severity or stenosis of either valve) * No history of uncontrolled cardiac arrhythmia * No symptomatic or asymptomatic myocardial infarction * No angina pectoris requiring medication * No other documented significant cardiac event * No poorly controlled diabetes mellitus (i.e., fasting blood sugar ≥ 200 mg/dL) * No history of hypersensitivity reaction to trastuzumab * No AIDS * No nonmalignant condition requiring ≥ 20 mg of prednisone (or equivalent) * No other malignancy within the past 5 years except carcinoma in situ of the cervix or nonmelanoma skin cancer * No ongoing liver disease, including viral or other hepatitis, alcohol abuse, or cirrhosis * No other serious medical illness * No medical or psychiatric condition that would preclude study participation PRIOR CONCURRENT THERAPY: * See Disease Characteristics * Recovered from prior therapy * More than 3 weeks since prior investigational anticancer agents * More than 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin C), major surgery, or immunotherapy * More than 4 weeks since prior radiotherapy except short-course palliative radiotherapy for bone pain * More than 2 weeks since prior and no concurrent oral hormonal therapy * More than 4 weeks since prior fulvestrant * No prior doxorubicin hydrochloride or doxorubicin HCl liposome at a cumulative dose of \> 360 mg/m\^2 * No prior mitoxantrone hydrochloride at a cumulative dose of \> 120 mg/m\^2 * No prior epirubicin hydrochloride at a cumulative dose of \> 600 mg/m\^2 * No prior idarubicin at a cumulative dose of \> 90 mg/m\^2 * No concurrent radiation therapy, including for symptomatic bone metastases