Biological Therapy in Treating Women With Stage IV Breast Cancer

DISEASE CHARACTERISTICS: Phase I: * Histologically confirmed infiltrating ductal carcinoma of the breast * Metastatic disease * Clinically asymptomatic with non-life-threatening metastases allowed * Measurable or evaluable disease by radiograph, CT scan, MRI, nuclear medicine bone scan, or physical examination * No measurable disease allowed if tumor or metastasis has been removed or successfully treated prior to study * No rapidly progressive symptomatic disease affecting major organ systems (e.g., lungs and liver) * Stable or unstable disease for 3 months on hormonal therapy * Stable or unstable disease for at least 1 month after chemotherapy * No active brain metastases * Brain metastases previously treated with definitive radiotherapy and/or surgical resection allowed * Hormone receptor status: * Estrogen and progesterone receptor status known Phase II: * All Phase I criteria * HER2/neu overexpression (2+ or 3+) by immunohistochemistry * Prior trastuzumab (Herceptin) allowed if disease still overexpresses HER2/neu PATIENT CHARACTERISTICS: Age: * 18 and over Sex: * Female Menopausal status: * Not specified Performance status: * Karnofsky 70-100% OR * ECOG 0-2 Life expectancy: * At least 3 months Hematopoietic: * Granulocyte count at least 1,500/mm\^3 * Platelet count at least 50,000/mm\^3 * Hemoglobin at least 8 g/dL Hepatic: * Bilirubin less than 1.5 times normal * SGOT less than 1.5 times normal Renal: * Creatinine no greater than 1.8 mg/dL * Creatinine clearance at least 60 mL/min * BUN no greater than 1.5 times normal Cardiovascular: * No myocardial infarction within the past year * No prior myocardial infarction with coronary symptoms requiring medication and/or depressed left ventricular function (LVEF less than 50% by MUGA) * No angina or coronary symptoms requiring medication and/or with depressed left ventricular function (LVEF less than 50% by MUGA) * No congestive heart failure requiring medical management * LVEF at least 50% at rest by MUGA * No uncontrolled hypertension (i.e., systolic blood pressure \[BP\] ≥ 130 mm Hg or diastolic BP ≥ 80 mm Hg) Pulmonary: * FEV1, DLCO, and FVC at least 50% predicted Other: * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * HIV negative * No other serious medical or psychiatric illness that would preclude study participation * No other prior or concurrent malignancy within the past 5 years except curatively treated squamous cell carcinoma in situ of the cervix, basal cell skin cancer, or any other curatively treated disease in complete remission PRIOR CONCURRENT THERAPY: Biologic therapy: * See Disease Characteristics * Prior trastuzumab allowed for phase I Chemotherapy: * See Disease Characteristics * At least 4 weeks since prior chemotherapy Endocrine therapy: * See Disease Characteristics * Concurrent hormonal therapy for breast cancer must continue during study * No other concurrent hormonal therapy except steroids for adrenal failure, septic shock, or pulmonary toxicity or hormonal therapy for non-disease-related conditions (e.g., insulin for diabetes) Radiotherapy: * See Disease Characteristics Surgery: * See Disease Characteristics