Inclusion Criteria:

- Histologically or cytologically confirmed breast cancer

- Metastatic disease

- Measurable disease

- At least 1 unidimensionally measurable lesion ≥ 20 mm by conventional techniques
OR ≥ 10 mm by spiral CT scan

- The following are not considered measurable disease:

- Bone disease only

- Pleural effusion

- Peritoneal effusion

- Must have received prior anthracycline (doxorubicin or epirubicin) and/or taxane
(paclitaxel or docetaxel) as adjuvant therapy or for advanced disease

- Therapy with high-dose regimens or bone marrow transplantation is considered 1
prior regimen

- No known brain metastases

- Hormone receptor status:

- Not specified

- Male or female

- Performance status - ECOG 0-1

- Performance status - Karnofsky 70-100%

- More than 12 weeks

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

- WBC ≥ 3,000/mm^3

- Platelet count ≥ 100,000/mm^3

- Bilirubin normal

- AST or ALT ≤ 2.5 times upper limit of normal

- Creatinine normal

- Creatinine clearance ≥ 60 mL/min

- QTc < 500 msec

- No New York Heart Association class III or IV congestive heart failure

- No myocardial infarction within the past year

- No uncontrolled dysrhythmia

- No poorly controlled angina

- No other significant cardiac disease

- No history of serious ventricular arrhythmia (ventricular tachycardia or ventricular
fibrillation ≥ 3 beats in a row)

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- No history of allergic reaction attributed to compounds of similar chemical or
biologic composition to FR901228

- No active or ongoing infection

- No psychiatric illness or social situation that would preclude study compliance

- No other uncontrolled illness

- No concurrent biologic agents

- No more than 1 prior chemotherapy regimen for metastatic disease

- More than 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin)
and recovered

- No prior FR901228 (depsipeptide)

- No other concurrent chemotherapy

- Prior hormonal therapy for metastatic disease or as adjuvant therapy allowed

- More than 4 weeks since prior radiotherapy and recovered

- No concurrent radiotherapy

- More than 2 weeks since prior minor surgery and recovered

- More than 4 weeks since prior major surgery and recovered

- Concurrent bisphosphonates allowed provided therapy was initiated ≥ 3 months ago

- No concurrent agents that cause QTc prolongation

- No concurrent combination antiretroviral therapy for HIV-positive patients

- No concurrent drugs known to have histone deacetylase activity (e.g., valproic acid)

- No other concurrent investigational agents

- No other concurrent anticancer therapy