DISEASE CHARACTERISTICS:

• Histologically or cytologically confirmed invasive breast carcinoma

  • Recurrent or metastatic disease
• Measurable disease, defined as ≥ 1 unidimensionally measurable lesion ≥ 20 mm by conventional techniques or ≥ 10 mm by spiral CT scan

• Patients who may still benefit from hormonal therapy are ineligible

  • Patients with hormone receptor-positive breast cancer should have received appropriate sequential hormonal therapy for metastatic disease until disease progression

• Patients with HER-2 positive disease who have not yet received trastuzumab (Herceptin^®) to maximal benefit are ineligible

  • Patients with disease progression during trastuzumab therapy are eligible
• No known brain metastases

PATIENT CHARACTERISTICS:

• ECOG performance status (PS) 0-1 or Karnofsky PS 60-100%
• Life expectancy > 12 weeks
• WBC ≥ 3,000/mm³
• Absolute neutrophil count ≥ 1,500/mm³
• Platelets ≥ 100,000/mm³
• Total bilirubin normal (exception made for patients with known Gilbert's disease)
• AST/ALT ≤ 2.5 times upper limit of normal (ULN)
• Creatinine normal OR creatinine clearance ≥ 60 mL/min
• No proteinuria > +1 on two consecutive dipsticks taken ≥ 1 week apart
• PT/INR/PTT ≤ 1.2 times ULN
• No allergic reactions attributed to compounds of similar chemical or biologic composition to pazopanib or other study agents
• No QTc prolongation (defined as a QTc interval ≥ 500 msecs) or other significant ECG abnormalities
• No condition (e.g., gastrointestinal tract disease resulting in an inability to take oral medication or a requirement for IV alimentation, or active peptic ulcer disease) that would impair ability to swallow and retain study drug

• No poorly controlled hypertension (systolic blood pressure [BP] ≥ 140 mm Hg or diastolic BP ≥ 90 mm Hg)

  • Initiation or adjustment of BP medication is allowed prior to study entry provided that the average of 3 BP readings prior to study entry is < 140/90 mm Hg
• No serious or non-healing wound, ulcer, or bone fracture
• No abdominal fistula, gastrointestinal perforation, or intra-abdominal abscess within the last 4 weeks
• No cerebrovascular accident within the last 6 months
• No myocardial infarction, cardiac arrhythmia, hospital admission for unstable angina within the last 12 weeks
• No venous thrombosis within the last 12 weeks

• No NYHA class III-IV heart failure

  • Patients with a history of class II heart failure may be considered eligible provided they are asymptomatic on treatment
• No concurrent uncontrolled illness including, but not limited to, ongoing or active infection or psychiatric illness/social situations that would preclude study compliance
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• Recovered from prior therapy
• At least 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin C), radiotherapy, or surgery
• At least 3 months since prior trastuzumab
• No cardiac angioplasty or stenting within the last 12 weeks
• No more than 1 prior chemotherapy regimen for recurrent disease
• No more than 2 prior palliative systemic chemotherapy regimens for de novo metastatic disease
• No prior surgical procedures affecting absorption
• No prior bevacizumab

• No CYP2C9 substrates during or for 1-2 weeks after completion of study treatment, including any of the following:

  • Therapeutic warfarin

    • Low molecular weight heparin or prophylactic low-dose warfarin are allowed
  • Oral hypoglycemics: glipizide, glyburide, or tolbutamide
  • Ergot derivatives: dihydroergotamine, ergonovine, ergotamine, or methylergonovine
  • Neuroleptics: pimozide
  • Erectile dysfunction agents: sildenafil, tadalafil, or vardenafil
  • Antiarrhythmics: bepridil, flecainide, lidocaine, mexilitine, amiodarone, or quinidine
  • Immune modulators: cyclosporine, tacrolimus, or sirolimus
  • Miscellaneous: theophylline, quetiapine, or risperidone
• No concurrent combination antiretroviral therapy for HIV-positive patients
• No other concurrent investigational agents
• No other concurrent anticancer therapy