Inclusion Criteria:

- Patients must have histologically or cytologically confirmed stage IV adenocarcinoma
of the breast; tumor blocks and/or slides from original diagnosis or metastatic
work-up must be available for correlative studies

- 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

- Prior adjuvant therapy, and up to 2 lines of prior chemotherapy (including
trastuzumab containing regimens in Her-2 positive patients) for metastatic disease
are allowed; prior radiation therapy is allowed, prior hormonal therapy is allowed

- Life expectancy of greater than 6 months

- Performance status: ECOG 0- 2

- Absolute neutrophil count >= 1,000/μl

- Platelets >= 100,000/μl

- Serum creatinine =< 1.6 mg/dl or calculated measured clearance >= 60 cc/min

- Total bilirubin =< 2 mg/dL

- AST and ALT =< 3 times institutional upper normal level

- Eligibility of patients receiving any medications or substances known to affect or
with the potential to affect the activity or pharmacokinetics of SAHA will be
determined following review by the Principal Investigator

- 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

- Patients should not have taken valproic acid for at least two weeks prior to study
entry

Exclusion Criteria:

- Patients who have had chemotherapy or radiotherapy within 4 weeks (6 weeks for
nitrosoureas or mitomycin C) prior to entering the study or those who have not
recovered from adverse events due to agents administered more than 4 weeks earlier

- Patients may not be receiving any other investigational agents

- Patients with known brain metastases are excluded from this clinical trial unless the
metastases are controlled after therapy and have not been treated with steroids
within the past two months

- History of allergic reactions attributed to compounds of similar chemical or biologic
composition to SAHA; these compounds include sodium butyrate, trichostatin A (TSA),
trapoxin (TPX), MS-27-275 and depsipeptide

- 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 SAHA is a HDAC inhibitor agent
with an unknown potential for teratogenesis; because there is an unknown but
potential risk for adverse events in nursing infants secondary to treatment of the
mother with SAHA, breastfeeding should be discontinued if the mother is treated with
SAHA

- HIV-positive patients receiving combination antiretroviral therapy are ineligible
because of the potential for pharmacokinetic interactions with SAHA