RATIONALE: Drugs used in chemotherapy use different ways to stop tumor cells from dividing so they stop growing or die. Giving drugs in different forms may kill more tumor cells.

PURPOSE: Phase II trial to study the effectiveness of doxorubicin in treating women with advanced metastatic breast cancer.

OBJECTIVES: I. Determine the antitumor activity of doxorubicin-HPMA conjugate (PK1) in women with advanced breast cancer.

OUTLINE: This is an open label, multicenter study. Patients receive doxorubicin-HPMA conjugate (PK1) by intravenous infusion once every 3 weeks. Patients may receive a total of 6 courses of treatment in the absence of toxicity and progressive disease.

PROJECTED ACCRUAL: 14-25 patients will be accrued for this study.

DISEASE CHARACTERISTICS: Histologically or cytologically proven advanced metastatic carcinoma of the breast Bidimensionally measurable disease No brain or leptomeningeal disease

PATIENT CHARACTERISTICS: Age: Over 18 Performance status: WHO 0-2 Life expectancy: At least 3 months Hematopoietic: Hemoglobin at least 10 g/dL Neutrophil count at least 2,000/mm3 Platelet count at least 100,000/mm3 Hepatic: Bilirubin no greater than 11.7 mg/dL AST/ALT no greater than 2 times upper limit of normal (5 times upper limit of normal in presence of liver metastases) Renal: Creatinine no greater than 1.7 mg/dL Cardiovascular: No concurrent treatment for congestive cardiac failure Cardiac function within normal limits by MUGA or ECHO scan, if prior anthracycline therapy Other: Not pregnant or nursing Fertile patients must use effective contraception No concurrent nonmalignant systemic disease No active uncontrolled infection No prior history of malignant disease except: Squamous cell carcinoma of the skin Curatively treated carcinoma in situ of the cervix

PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent immunological therapy Chemotherapy: At least 1 prior chemotherapy regimen for advanced disease (including adjuvant therapy), but not more than 2 prior regimens At least 4 weeks since prior chemotherapy (6 weeks for nitrosourea or mitomycin) and recovered Cumulative dose of prior epirubicin no greater than 450 mg/m2 Cumulative dose of prior doxorubicin no greater than 240 mg/m2 No concurrent chemotherapy Endocrine therapy: No concurrent hormonal therapy Low dose steroid therapy allowed if dose established at least 4 weeks prior to study Radiotherapy: At least 4 weeks since prior radiotherapy and recovered Surgery: Not specified Other: No concurrent experimental therapy