DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed invasive breast cancer

  • Stage IV disease

• HER2-overexpressing tumor

  • Must be 3+ positive by immunohistochemistry (IHC) OR positive by fluorescence in situ hybridization (FISH) assay

• At least 1 measurable lesion

  • At least 20 mm by conventional techniques OR at least 10 mm by spiral CT scan

• Prior therapy meets 1 of the following criteria:

  • Cohort 1:

    • No prior chemotherapy or trastuzumab (Herceptin®) for metastatic breast cancer
    • Prior hormonal therapy for metastatic disease or in the adjuvant setting is allowed
    • At least 6 months since prior chemotherapy in the adjuvant setting
    • Prior trastuzumab in the adjuvant setting is allowed if completed at least 12 months before study entry

  • Cohort 2:

    • Must have received 1 prior trastuzumab-containing regimen in the adjuvant or metastatic setting
    • Disease recurrence must have occurred within 12 months after completion of trastuzumab if given in the adjuvant setting
    • Up to 2 prior chemotherapy regimens for metastatic disease are allowed
    • Prior hormonal therapy for metastatic disease is allowed
    • Prior chemotherapy* and/or hormonal therapy for early stage disease is allowed NOTE: *Adjuvant chemotherapy completed less than 6 months before diagnosis of metastatic disease is considered as 1 of 2 possible regimens for metastatic disease

• History of brain metastasis allowed provided the following criteria are met:

  • More than 4 weeks since treatment completion
  • Currently asymptomatic
  • No concurrent steroids
• No leptomeningeal carcinomatosis

• Hormone receptor status:

  • Not specified

PATIENT CHARACTERISTICS:

Age

• 18 and over

Sex

• Female

Menopausal status

• Not specified

Performance status

• ECOG 0-2 OR
• Karnofsky 60-100%

Life expectancy

• More than 6 months

Hematopoietic

• Absolute neutrophil count ≥ 1,500/mm^3
• Platelet count ≥ 100,000/mm^3

Hepatic

• ALT ≤ 5 times upper limit of normal (ULN)
• Bilirubin ≤ 1.5 times ULN

Renal

• Not specified

Cardiovascular

• LVEF ≥ 50%
• No symptomatic congestive heart failure
• No unstable angina pectoris
• No cardiac arrhythmia

Immunologic

• Prior grade 1 or 2 hypersensitivity reaction to trastuzumab or taxane therapies allowed provided drug administration was possible
• No prior grade 3 or 4 allergic reaction to compounds of similar chemical or biological composition to study agents
• No prior severe Cremophor reactions
• No ongoing or active infection

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• No ≥ grade 2 neuropathy (neuromotor or neurosensory)
• No other concurrent uncontrolled illness
• No psychiatric illness or social situation that would preclude study compliance

PRIOR CONCURRENT THERAPY:

Biologic therapy

• See Disease Characteristics
• See Chemotherapy

Chemotherapy

• See Disease Characteristic
• More than 2 years since prior high-dose chemotherapy with bone marrow transplantation or peripheral blood stem cell support
• No prior epothilone therapy
• No other concurrent chemotherapy

Endocrine therapy

• See Disease Characteristics

• At least 2 weeks since prior hormonal therapy in the adjuvant or metastatic setting

  • Patients with overt disease progression on prior hormonal therapy are allowed (without waiting 2 weeks) provided they discontinue hormonal treatment before study participation
• No concurrent hormonal therapy

Radiotherapy

• At least 7 days since prior radiotherapy in the metastatic or early stage setting
• No concurrent radiotherapy

Other

• Concurrent bisphosphonate therapy (e.g., pamidronate) allowed
• No other concurrent anticancer agents or therapies
• No other concurrent investigational agents
• No concurrent antiretroviral therapy for HIV-positive patients