Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed breast cancer

- Metastatic (stage IV) disease

- Relapsed after 1 of the following prior therapy regimens*:

- Adjuvant therapy containing an anthracycline and a taxane

- Adjuvant anthracycline therapy followed by first-line metastatic treatment
containing a taxane NOTE: *No relapse within 12 months of initiation of prior
therapy

- Measurable disease by CT scan or MRI

- No ascites, pleural effusions, or osteoblastic bone metastases as the only site
of measurable disease

- Refractory to hormonal anticancer therapy completed more than 4 weeks before study
therapy

- HER2/neu positive allowed provided patient received prior trastuzumab (Herceptin®)

- MUGA or echocardiogram normal while on trastuzumab

- No known history of or current brain or leptomeningeal metastases

- Hormone receptor status:

- Not specified

PATIENT CHARACTERISTICS:

Age

- Over 18

Sex

- Female

Menopausal status

- Not specified

Performance status

- ECOG 0-2

Life expectancy

- At least 12 weeks

Hematopoietic

- WBC at least 3,000/mm^3

- Neutrophil count at least 1,500/mm^3

- Platelet count at least 100,000/mm^3

- Hemoglobin at least 10.0 g/dL

- No clinically significant abnormal hematological parameters

Hepatic

- Bilirubin no greater than 1.5 times upper limit of normal (ULN)

- Alkaline phosphatase no greater than 2.5 times ULN (5 times ULN in case of liver
metastases)

- AST or ALT no greater than 2.5 times ULN (5 times ULN in case of liver metastases)

Renal

- Creatinine no greater than 1.5 times ULN

Cardiovascular

- See Disease Characteristics

- No myocardial infarction within the past 3 months

- No unstable angina pectoris

- No New York Heart Association class III or IV heart disease

- No uncontrolled arrhythmia

- No cardiac insufficiency

- No uncontrolled hypertension

- LVEF at least 50% OR at least lower limit of normal

Other

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception 4 weeks before, during, and for at
least 4 weeks after study participation

- No preexisting neuropathy (motor or sensory) greater than grade 2

- No clinically significant abnormal biochemical parameters

- No clinically significant active infection

- No other prior malignancy except cured nonmelanoma skin cancer or curatively treated
carcinoma in situ of the cervix

- No other serious illness or medical condition

- No psychological illness or condition that would preclude study participation

- No other known condition that would preclude study participation

PRIOR CONCURRENT THERAPY:

Biologic therapy

- See Disease Characteristics

- More than 3 months since prior trastuzumab

- More than 2 weeks since prior growth factor therapy (i.e., filgrastim [G-CSF] or
sargramostim [GM-CSF])

- No concurrent systemic anticancer immune modulators

Chemotherapy

- See Disease Characteristics

Endocrine therapy

- See Disease Characteristics

- More than 4 weeks since prior hormonal therapy

- No concurrent anticancer hormonal therapy

- No concurrent chronic systemic steroids

- Concurrent topical or inhaled steroids for dermatological or allergy/asthma
conditions allowed provided therapy was initiated prior to study enrollment

- Concurrent hormone replacement therapy allowed provided therapy was initiated prior
to study enrollment

Radiotherapy

- More than 30 days since prior radiotherapy

- No concurrent radiotherapy directed at target lesions

Surgery

- At least 4 weeks since prior major surgery and recovered

Other

- More than 30 days since prior investigational new drug

- More than 2 weeks since prior blood transfusion

- No other concurrent systemic anticancer agents, including immunosuppressive agents

- No other concurrent investigational agents

- Concurrent bisphosphonates allowed provided therapy was initiated prior to study
enrollment