Lapatinib Ditosylate and Capecitabine in Treating Patients With Stage IV Breast Cancer and Brain Metastases

DISEASE CHARACTERISTICS:

* Histologically confirmed invasive breast cancer

  * Stage IV disease
* At least 1 measurable CNS lesion ≥ 10 mm on T1-weighted gadolinium-enhanced MRI

  * No single brain metastasis that could be treated by surgery
* HER-2 positive primary tumor as defined as IHC3+ or IHC2+ and FISH-positive
* Hormone receptor status: not specified

PATIENT CHARACTERISTICS:

* Menopausal status not specified
* Eastern Cooperative Oncology Group (ECOG) performance status 0-2
* Life expectancy ≥ 3 months
* Absolute Neutrophil Count (ANC) ≥ 1,000/mm\^3
* Platelet count ≥ 100,000/mm\^3
* Hemoglobin ≥ 10g/dL
* Creatinine ≥ 1.5 times upper limit of normal (ULN)
* Albumin ≥ 2.5 g/dL
* Serum bilirubin ≤ 1.5 times ULN (unless due to Gilbert's syndrome)
* ASAT and ALAT ≤ 3 times ULN (≤ 5 times ULN with documented liver metastasis)
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception 2 weeks before, during, and for 28 days after completion of study treatment (female) or for 1 week after completion of treatment (male)
* Able to swallow and retain oral medication
* Affiliated to a Social Security System
* No known contraindication to MRI
* No prior or active malignancy, unless disease free for ≥ 10 years
* No other concurrent severe and/or uncontrolled medical disease which could compromise study participation, including any of the following:

  * Infection
  * Cardiac disease (e.g., uncontrolled hypertension, congestive cardiac failure, ventricular arrhythmias, active ischemic heart disease, myocardial infarction within the past year, Left Ventricular EJection Fraction (LVEF) \> grade 2)
  * Current active hepatic or biliary disease (except for Gilbert syndrome, asymptomatic gallstones, liver metastasis or stable chronic liver disease per investigator assessment)
  * Renal disease
  * Active gastrointestinal (GI) tract ulceration, malabsorption syndrome, active uncontrolled ulcerative colitis, or disease significantly affecting GI function
  * Severely impaired lung function (e.g., spirometry and diffusion capacity of lung for carbon monoxide (DLCO) ≤ 50% of normal, and O\_2 saturation ≤ 88% at rest on room air)
* No known dihydropyrimidine dehydrogenase deficiency
* No significantly altered mental status prohibiting the understanding of the study, or with psychological, familial, sociological, or geographical condition potentially hampering compliance with the study protocol and follow-up schedule
* Not deprived of liberty or placed under the authority of a tutor

PRIOR CONCURRENT THERAPY:

* At least 2 weeks since prior breast cancer treatment (e.g., trastuzumab, chemotherapy, immunotherapy or biological response modifiers, endocrine therapy, or radiotherapy)
* More than 30 days since prior investigational drugs
* More than 14 days since prior and no concurrent strong inhibitors or inducers of the cytochrome P450 isoenzyme 3A4 (CYP3A4) (i.e., clarithromycin, ketoconazole, itraconazole, voriconazole, ritonavir)
* No prior whole brain radiotherapy (WBRT) or brain stereotactic radiotherapy
* No prior treatment with capecitabine and/or lapatinib ditosylate
* No prior resection of the stomach or small bowel
* No concurrent systemic treatment or radiation therapy for breast cancer (except corticosteroid, bisphosphonates, or mannitol)