Inclusion Criteria:

- Patients must have histologically or cytologically confirmed invasive breast cancer,
with stage IV disease

- Tumors must be HER2 overexpressing; acceptable methods of measurement of HER2
expression include immunohistochemistry IHC) and fluorescence in situ hybridization
(FISH); tumors tested by IHC must be 3+ positive for HER2 overexpression; tumors
tested by FISH must be positive by the specific FISH assay for genetic amplification
of HER2; tumors that are 3+ by IHC, but negative by FISH assay are ineligible;
consideration should be given to performing a repeat biopsy, with reanalysis for HER2
overexpression, in patients who have received prior trastuzumab, as little data exist
on the persistence of HER2 overexpression after prior treatment with trastuzumab;
biopsy in this circumstance, however, is not required

- Patients must have measurable disease, defined as at least one lesion that can be
accurately measured in at least one dimension (longest diameter to be recorded) as >=
20 mm with conventional techniques or as >= 10 mm with spiral CT scan; the protocol
will employ the RECIST criteria

- Prior Therapy - Two cohorts of patients will be treated on this treatment regimen;
the two cohorts are determined by prior therapy and are as follows:

- Treatment Cohort 1:

- Chemotherapy: metastatic breast cancer: Patients in treatment Cohort 1 may
NOT have received prior chemotherapy or prior trastuzumab therapy for
metastatic breast cancer; patients may have received prior hormonal therapy
for metastatic breast cancer

- Chemotherapy: early stage breast cancer: Patients in treatment Cohort 1 may
have received prior chemotherapy and/or hormonal therapy for early stage
breast cancer; patients must be at least 6 months from prior chemotherapy
received in the adjuvant setting

- Trastuzumab: Patients in treatment Cohort 1 may have received trastuzumab
in the adjuvant setting, provided that trastuzumab therapy ended at least
12 months prior to study participation; patients may not have previously
received trastuzumab in the metastatic setting

- Radiation therapy: Patients in treatment Cohort 1 may have received prior
radiation therapy in either the metastatic or early stage settings;
radiation therapy must be completed at least 7 days prior to study
participation

- Hormonal therapy: Patients in treatment Cohort 1 may have received hormonal
therapy (therapies) in the adjuvant or metastatic setting; patients must
discontinue hormonal therapy 2 weeks prior to study participation; patients
with overt disease progression on prior hormonal therapy are eligible
without waiting two weeks after discontinuing hormonal therapy, but must
discontinue hormonal treatments prior to study participation

- Treatment Cohort 2:

- Chemotherapy: metastatic breast cancer: Patients in treatment Cohort 2 may
have received up to two prior chemotherapy regimens for metastatic breast
cancer; prior trastuzumab or other biologic or immunologic therapies are
not considered to be chemotherapeutic regimens unless they were
administered in conjunction with a chemotherapeutic agent; patients may
have received prior hormonal therapy for metastatic breast cancer

- Chemotherapy: early stage breast cancer: Patients in treatment Cohort 2 may
have received prior chemotherapy and/or hormonal therapy for early stage
breast cancer; if adjuvant chemotherapy was completed less than 6 months
prior to the diagnosis of metastatic disease, the adjuvant regimen will be
considered one of the two possible metastatic regimens

- Trastuzumab: Patients in treatment Cohort 2 must have received one prior
trastuzumab-containing regimen either in the metastatic setting or in the
adjuvant setting; if the trastuzumab was administered in the adjuvant
setting, disease recurrence must have occurred within 12 months of
completion of adjuvant therapy

- Radiation therapy: Patients in treatment Cohort 2 may have received prior
radiation therapy in either the metastatic or early stage settings;
radiation therapy must be completed at least 7 days prior to study
participation

- Hormonal therapy: Patients in treatment Cohort 2 may have received hormonal
therapy (therapies) in the adjuvant or metastatic setting; patients must
discontinue hormonal therapy 2 weeks prior to study participation; patients
with overt disease progression on prior hormonal therapy are eligible
without waiting two weeks after discontinuing hormonal therapy, but must
discontinue hormonal treatments prior to study participation

- Life expectancy of greater than 6 months

- ECOG performance status =< 2 (Karnofsky >= 60%)

- Patients must have adequate organ and marrow function as defined below; laboratory
tests should be completed within 14 days prior to registration; left ventricular
ejection fraction (LVEF) may be determined by either echocardiography or nuclear
scintigraphy (i.e. MUGA scan or RVG), and should be obtained within 28 days prior to
registration

- Absolute neutrophil count >= 1,500/mm^3

- Platelets >= 100,000/mm^3

- Total bilirubin =< 1.5 X institutional upper limit of normal

- ALT(SGPT) =< 5 X institutional upper limit of normal

- LVEF >= 50%

- Concurrent Therapy: patients may not receive concurrent hormonal therapy,
chemotherapy, or radiation treatments while on study; patients requiring radiation
therapy during protocol-based treatment will be taken off study; if patients develop
intraparenchymal brain metastases while on treatment, but do not have evidence of
other systemic progression, they will be allowed to resume treatment with the
combination once their radiation has been completed; they will be allowed to continue
trastuzumab therapy during radiation, at the treating physician's discretion;
nevertheless, the date of discovery of the CNS disease will still be considered the
date of disease progression; patients may receive concurrent bisphosphonate therapy
(e.g. pamidronate) while on study; patients may not receive other experimental
treatments while on study

- The effects of BMS-247550 on the developing human fetus at the recommended
therapeutic dose are unknown; for this reason, women of child-bearing potential and
men must agree to use adequate contraception (hormonal or barrier method of birth
control; abstinence) prior to study entry and for the duration of study
participation; should a woman become pregnant or suspect she is pregnant while
participating in this study, she should inform her treating physician immediately

- Ability to understand and the willingness to sign a written informed consent document

- Patient Registration and Data Submission: Patients will be registered by contacting
and faxing the completed eligibility checklist and all pages of the consent form to
the Quality Assurance Office of Clinical Trials (QACT) at the Dana-Farber Cancer
Institute; please fax to 617-632-2295 or telephone at 617-632-3761; a research nurse,
Kathryn Clarke, will be available at 617-632-3478 to answer any protocol-related
questions; you many also contact the study coordinator, Keri Hannagan, at
617-632-5584

- Regular data submissions should be made to Dana-Farber Cancer Institute's QACT;
please fax all data in a timely manner to the number above

Exclusion Criteria:

- Patients may not be receiving any other investigational antitumor agents

- Patients with leptomeningeal carcinomatosis are excluded from this clinical trial
because of their poor prognosis and because they often develop progressive neurologic
dysfunction that would confound the evaluation of neurologic and other adverse
events; patients with a history of brain metastases are eligible, providing that they
have completed treatment for their brain metastases at least 1 week prior to
enrollment, are asymptomatic from their brain metastases and are not taking steroids;
screening for CNS disease is not required if patients do not have symptoms that might
be related to CNS metastases; patients with such symptoms should be evaluated for the
possibility of CNS disease prior to study participation

- Patients with a history of grade 3 or 4 allergic reactions attributed to compounds of
similar chemical or biologic composition to the agents used in the study are
ineligible; patients with a history of severe Cremophor reactions should be excluded;
patients who experienced grade 1 or 2 hypersensitivity reactions to prior trastuzumab
or taxane therapies are eligible IF these reactions did not prevent previous
administration of such agents; patients who were deemed inappropriate candidates for
trastuzumab or taxane-based treatments based on their hypersensitivity reactions are
not eligible

- Received prior epothilone therapy

- Grade 2 or greater neuropathy (neuromotor or neurosensory)

- Received prior high dose chemotherapy with bone marrow transplant or peripheral blood
stem cell support within 2 years of study entry

- Uncontrolled intercurrent illness including, but not limited to, ongoing or active
infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac
arrhythmia, or psychiatric illness/social situations that would limit compliance with
study requirements

- Pregnant women are excluded from this study because BMS-247550 and trastuzumab are
agents which may have the potential for teratogenic or abortifacient effects; because
there is an unknown but potential risk for adverse events in nursing infants
secondary to treatment of the mother with these drugs, breastfeeding should be
discontinued if the mother is treated on study

- Because patients with immune deficiency are at increased risk of lethal infections
when treated with marrow-suppressive therapy, HIV-positive patients receiving
anti-retroviral therapy are excluded from the study because of possible
pharmacokinetic interactions with agents administered during the study