Capecitabine in Treating Patients With Metastatic Breast Cancer

RATIONALE: Drugs used in chemotherapy, such as capecitabine, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing.

PURPOSE: This phase II trial is studying how well capecitabine works in treating patients with metastatic breast cancer.

OBJECTIVES:

Primary

* Determine the response rate in patients with metastatic breast cancer treated with a fixed-dose of capecitabine.

Secondary

* Determine the clinical benefit, time to treatment failure (TTF), safety, and toxicity profile of this regimen in these patients.
* Determine the pharmacokinetics (PK) and pharmacogenetics in these patients.
* Correlate pharmacodynamic effects of this drug with toxicity and response in these patients.
* Determine compliance and adherence to this regimen and correlate with PK parameters in these patients.

OUTLINE: This is an open-label study.

Patients receive a fixed-dose of oral capecitabine twice daily on days 1-14. Courses repeat every 21 days in the absence of disease progression or unacceptable toxicity.

After completion of study treatment, patients are followed periodically.

PROJECTED ACCRUAL: A total of 45 patients will be accrued for this study.

Eligibility Criteria:
DISEASE CHARACTERISTICS:

* Histologically or cytologically confirmed diagnosis of adenocarcinoma of the breast

  * Evidence of metastatic involvement (stage IV disease)
* Patients must have measurable disease

  * At least one measurable lesion as defined by the Response Evaluation Criteria in Solid Tumors (RECIST)
* Treated brain metastases (surgery or radiation therapy) allowed if clinically stable
* Patients with leptomeningeal disease are ineligible
* Hormone receptor status:

  * Not specified

PATIENT CHARACTERISTICS:

* Eastern Cooperative Oncology Group (ECOG) performance status 0-2
* Male or female
* Menopausal status not specified
* Absolute neutrophil count (ANC) ≥ 1,500/mm\^3
* Platelet count ≥ 100,000/mm\^3
* Creatinine clearance \> 50 mL/min
* Fertile patients must use effective contraception
* No history of another severe and/or life-threatening medical disease
* No other active primary malignancy
* Not pregnant or nursing
* Negative pregnancy test
* Patients with asymptomatic HIV infection are eligible
* Liver dysfunction score ≤ 9
* No pre-existing liver disease (i.e., cirrhosis or active viral hepatitis)
* No active gastrointestinal malabsorption illness
* No clinically significant cardiac disease, including the following:

  * Congestive heart failure, symptomatic coronary artery disease, and cardiac arrhythmias not well controlled with medication, or myocardial infarction within the past six months
* No prior unanticipated severe reaction to fluoropyrimidine therapy, known hypersensitivity to fluorouracil, or known dihydropyrimidine dehydrogenase deficiency
* No history of uncontrolled seizures or central nervous system disorders
* No significant history of noncompliance to medical regimens
* No clinically significant psychiatric disability that would preclude study compliance

PRIOR CONCURRENT THERAPY:

* No previous capecitabine
* Up to 3 prior cytotoxic regimens allowed for metastatic disease

  * Prior noncytotoxic therapy allowed (e.g., hormonal treatment or trastuzumab)
* No other concurrent therapies intended to treat the primary condition including chemotherapy, biologic agents, or immunotherapy
* No concurrent anti-estrogen therapy, radiation therapy, or investigational systemic therapy
* No other concurrent investigational drugs
* No concurrent use of the following drugs: warfarin for full anticoagulation, cimetidine, or azidothymidine (AZT)

  * Mini-dose warfarin for prophylaxis of central venous catheter thrombosis allowed
* At least 4 weeks since prior sorivudine or brivudine
* Concurrent use of bisphosphonates allowed if initiated before beginning study therapy
* Concurrent use of megestrol acetate suspension as an appetite stimulant allowed