Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed adenocarcinoma of the breast

- Evaluable metastatic disease (no need for measurable disease)

- Must have had anthracycline therapy in the adjuvant setting or failed anthracycline
treatment in the metastatic setting

- Total cumulative dose of lifetime exposure of doxorubicin not greater than 360
mg/m^2 or epirubicin not greater than 640 mg/m^2

- Must have failed previous taxane (paclitaxel or docetaxel) therapy, defined as:

- Taxane use in the adjuvant setting with metastatic relapse within 12 months of
therapy

- Progression on taxane therapy in the metastatic setting

- Discontinuation of taxane therapy in the metastatic setting secondary to lack of
resolution of ≥ grade 2 toxicity

- No symptomatic brain metastases

- Patients with a history of brain metastases are eligible provided they are
clinically stable and not taking steroids or therapeutic anticonvulsants that
are CYP3A4 modifiers

- Patients with asymptomatic brain metastasis are eligible provided they are not
on prophylactic anticonvulsants that are CYP3A4 modifiers

- Hormone receptor status not specified

PATIENT CHARACTERISTICS:

Inclusion criteria

- Menopausal status not specified

- ECOG performance status 0-1

- Absolute neutrophil count ≥ 1,500/mm^3

- Platelet count ≥ 100,000/mm^3

- Bilirubin ≤ 1.5 times upper limit of normal (ULN)

- SGOT and SGPT ≤ 2.5 times ULN

- Albumin > 30 g/L

- Creatinine ≤ 1.5 upper limit of normal

- INR normal provided the patient is not on warfarin therapy

- Not pregnant or nursing

- Negative pregnancy test for premenopausal patients

- Fertile patients must use effective barrier method contraception during and for 3
months after completion of study treatment

- Patients must be disease-free of prior invasive cancers for > 5 years with the
exception of basal cell or squamous cell cancer of the skin or cervical carcinoma in
situ

Exclusion criteria

- Serious or non-healing active wound, ulcer, or bone fracture

- Known human immunodeficiency virus positivity

- Uncontrolled intercurrent illness including, but not limited to, any of the following

- Ongoing or active infection requiring parenteral antibiotics

- Impairment of lung function (COPD, lung conditions requiring oxygen therapy)

- Symptomatic congestive heart failure (New York Heart Association class III or IV
heart disease)

- Unstable angina pectoris or myocardial infarction within the past 6 months

- Uncontrolled hypertension (i.e., systolic blood pressure > 180 mm Hg or
diastolic blood pressure > 100 mm Hg, found on two consecutive measurements
separated by a 1-week period despite adequate medical support)

- Clinically significant cardiac arrhythmia (multifocal premature ventricular
contractions, bigeminy, trigeminy, ventricular tachycardia that is symptomatic
or requires treatment)

- Uncontrolled diabetes

- Psychiatric illness/social situations that would compromise patient safety or
limit compliance with study requirements including maintenance of a
compliance/pill diary

PRIOR CONCURRENT THERAPY:

Inclusion criteria

- See Disease Characteristics

- Prior trastuzumab (Herceptin®) in the first-line treatment of metastatic breast
cancer is required for patients who have HER2/neu overexpressing tumors

- More than 6 months since prior cardiac angioplasty or stenting

- Use of endocrine therapy (i.e., aromatase inhibitors, fulvestrant, tamoxifen or
ovarian ablation) in the first-line treatment of metastatic breast cancer is required
for patients who have estrogen receptor and or progesterone receptor expressing
tumors

- Concurrent endocrine therapy is not allowed

- Patients may receive concurrent radiotherapy to painful bone metastases or areas of
impending bone fracture as long as radiotherapy is initiated prior to study entry

- Patients who have received prior radiotherapy must have recovered from toxicity
induced by this treatment

- More than 3 weeks since prior chemotherapy, biological or hormonal therapy while on
protocol therapy.

- No other concurrent antineoplastic or antitumor agents, including chemotherapy,
radiotherapy, immunotherapy, or hormonal anticancer therapy

Exclusion criteria

- More than 3 prior chemotherapy treatments in the metastatic setting

- This restriction does not include endocrine therapies or single agent biologic
therapies (i.e., trastuzumab [Herceptin®])

- Use of steroids or immunosuppressants

- Use of CYP3A4 modifiers

- Concurrent therapy with trastuzumab (Herceptin®)

- Use of growth support factors (e.g., filgrastim [G-CSF], sargramostim [GM-CSF],
recombinant erythropoietin) during the phase I portion of the study

- Other concurrent investigational agents