ERA-923 in Treating Postmenopausal Women With Metastatic Breast Cancer

DISEASE CHARACTERISTICS: Diagnosis of metastatic breast cancer Prior tamoxifen therapy failure within 1 year of study defined as follows: Prior tamoxifen therapy for metastatic disease with prior response and progression of disease while still on treatment or within 1 year of last treatment Prior adjuvant tamoxifen therapy for a minimum of 2 years with subsequent progression of disease while still on treatment or within 1 year of last treatment Postmenopausal Must be amenorrheic for at least 12 months Removal of both ovaries or chemotherapy induced menopause allowed At least 1 bideminsionally measurable lesion No disease restricted only to bone No symptomatic CNS metastases untreated by surgery or radiotherapy Hormone receptor status: Estrogen or progesterone receptor positive

PATIENT CHARACTERISTICS: Age: Not specified Menopausal status: Postmenopausal Performance status: ECOG 0-2 Life expectancy: At least 6 months Hematopoietic: Absolute neutrophil count at least 1,500/mm3 Platelet count at least 100,000/mm3 Hemoglobin greater than 9.0 g/dL Hepatic: Bilirubin no greater than 1.5 times upper limit of normal (ULN) AST no greater than 3 times ULN (no greater than 5 times ULN if liver metastases present) PT and PTT no greater than 1.25 times ULN Renal: Creatinine no greater than 1.5 times ULN Cardiovascular: No deep vein thrombosis, retinal vein thrombosis, or stroke within past year No unstable angina or myocardial infarction within past 6 months Pulmonary: No pulmonary embolism within past year Other: Not pregnant or nursing No other major illness or condition that would preclude study

PRIOR CONCURRENT THERAPY: Biologic therapy: No concurrent trastuzumab (Herceptin) Chemotherapy: No more than 2 prior chemotherapy regimens, including trastuzumab One regimen in adjuvant setting and one in metastatic setting OR Two regimens in metastatic setting No concurrent chemotherapy Endocrine therapy: See Disease Characteristics At least 6 months since prior raloxifene for osteoporosis No prior hormonal, antiestrogen, or aromatase inhibitors other than tamoxifen for breast cancer At least 4 weeks since prior tamoxifen No concurrent hormonal replacement therapy, other antiestrogens (including raloxifene), aromatase inhibitors, or systemic steroids (except physiologic replacement doses) Radiotherapy: See Disease Characteristics Surgery: See Disease Characteristics Other: At least 4 weeks since prior investigational drug No concurrent warfarin exept low dose warfarin for port maintenance No other concurrent investigational agent No concurrent immunosuppressive therapy