Inclusion Criteria

DISEASE CHARACTERISTICS: Histologically confirmed metastatic adenocarcinoma of the breast
Must have failed at least one but no more than two prior therapies for metastatic breast
cancer, including endocrine and chemotherapy Relapsing while receiving or within 6 months
of completing adjuvant chemotherapy Disease progression during or subsequent to the most
recent therapy Measurable and evaluable disease Bone is an evaluable site only No CNS
metastases Hormone receptor status: Estrogen receptor negative, positive, or unknown

PATIENT CHARACTERISTICS: Age: 18 and over Sex: Female Menopausal status: Any status
Performance status: ECOG 0-2 Life expectancy: Not specified Hematopoietic: Absolute
neutrophil count greater than 1,500/mm3 Platelet count greater than 100,000/mm3 Hepatic:
Bilirubin no greater than 1.5 mg/dL AST/ALT less than 3 times upper limit of normal PTT
within normal limits Renal: Creatinine no greater than 1.5 mg/dL Cardiovascular: No active
congestive heart failure No poorly controlled hypertension At least 3 months since prior
myocardial infarction Other: No history of other malignant neoplasms, except curatively
treated basal cell or squamous cell carcinoma of the skin or carcinoma in situ of the
cervix Not pregnant or nursing Negative pregnancy test, documented sterilization, or
postmenopausal status Fertile patients must use effective contraception No uncontrolled
nonmalignant systemic diseases (including active peptic ulcer and poorly controlled
diabetes mellitus) No underlying disease state associated with active bleeding No
unexplained abnormality of prothrombin time (e.g., warfarin therapy)

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease
Characteristics At least 28 days since prior chemotherapy Endocrine therapy: See Disease
Characteristics At least 28 days since prior hormonal therapy Radiotherapy: Not specified
Surgery: At least 2 weeks since major surgery Other: At least 28 days since prior use of
other investigational drugs No therapeutic anticoagulation with heparin