Exemestane With or Without ATN-224 in Treating Postmenopausal Women With Recurrent or Advanced Breast Cancer

DISEASE CHARACTERISTICS:

* Histologically confirmed breast cancer

  * Recurrent disease after 2-3 years of adjuvant treatment with an anti-estrogen (documented by imaging techniques)
  * Advanced disease that has recurred during or after anti-estrogen therapy
* Measurable or evaluable disease by conventional techniques, with ≥ 1 lesion that can be followed for response

  * Bone metastases only are eligible provided they have ≥ 1 lytic lesion (not previously irradiated or planned for irradiation) that can be followed by X-ray or CT scanning
  * Cutaneous skin metastases only are eligible provided the skin lesions are \> 10 mm and can be followed by good quality photography with a ruler included in the photograph
* No clinically apparent brain metastases
* Hormone receptor status must meet 1 of the following criteria:

  * Estrogen receptor-positivity

    * Score ≥ 3 on a scale (range of 0 to 8), or equivalent score from other grading methods, representing the intensity and percentage of positive-staining tumor cells by immunohistochemistry
    * Greater than or equal to 5 fmol/mg protein by ligand binding assay or ELISA
  * Progesterone receptor-positivity

    * Score ≥ 3 on a scale (range of 0 to 8) or equivalent score from other grading methods, representing the intensity and percentage of positive-staining tumor cells by immunohistochemistry
* No HER-2 overexpression, defined as gene amplification by fluorescence in situ hybridization \[FISH\] OR 3+ overexpression by IHC)

PATIENT CHARACTERISTICS:

* Postmenopausal as defined by any of the following:

  * Surgical or radiation-induced
  * No menstrual periods for 12 consecutive months with no other biological or physiological cause in women with an intact uterus
  * Age ≥ 55 years
* WHO performance status 0-2
* Life expectancy ≥ 6 months
* Hemoglobin ≥ 9.0 g/dL
* ANC ≥ 1.5 x 10\^9/L
* Platelet count ≥100 x 10\^9/L
* Serum bilirubin ≤ 1.5 times upper limit of normal (ULN)
* ALT and/or AST ≤ 2.5 times ULN (5 times ULN if due to tumor)
* Creatinine clearance ≥ 50 mL/min
* No history of malabsorption syndromes or other gastrointestinal disorders that may affect SOD1 inhibitor ATN-224 absorption, including any of the following:

  * Bowel obstruction
  * Celiac disease
  * Sprue
  * Cystic fibrosis
* No history of allergic reactions attributed to compounds of similar chemical or biologic composition to SOD1 inhibitor ATN-224, omeprazole (or other proton pump inhibitor), or exemestane
* No non-malignant systemic disease including active uncontrolled infection
* No serologic positivity for hepatitis B, hepatitis C, or HIV
* No concurrent congestive heart failure
* No history of NYHA class III-IV cardiac disease
* No other concurrent malignancy, except adequately treated cone-biopsied carcinoma in situ of the uterine cervix, basal cell or squamous cell carcinoma of the skin

  * Cancer survivors who have undergone potentially curative therapy for a prior malignancy, have no evidence of that disease for 5 years, and are deemed at low risk for recurrence are eligible
* No other condition which, in the investigator's opinion, would not make the patient a good candidate for this study

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* Recovered from all prior therapy (alopecia allowed)
* At least 1 year since prior bilateral oophorectomy
* Prior adjuvant or neoadjuvant treatment with tamoxifen allowed
* Prior adjuvant therapy with a non-steroidal aromatase inhibitor allowed
* More than 4 weeks since prior immunotherapy or chemotherapy (6 weeks for nitrosoureas and mitomycin-C)
* More than 4 weeks since prior major thoracic and/or abdominal surgery
* More than 3 weeks since prior endocrine therapy
* More than 4 weeks since prior and no concurrent radiotherapy (except to control pain or prevent fracture)
* No prior exemestane
* Concurrent iron-containing vitamins or supplements are allowed
* No concurrent luteinizing hormone-releasing hormone analog
* No concurrent oral bisphosphonates (IV bisphosphonates allowed)
* No concurrent chronic steroid therapy for concurrent illness or cancer (short-term steroid use for concurrent illness allowed \[e.g., for acute asthma\])
* No concurrent copper- or zinc-containing vitamins or supplements
* No concurrent participation in another interventional clinical study (participation in an observational study allowed)
* No other concurrent copper-binding drug (e.g., penicillamine or trientine)
* No other concurrent anticancer therapy or investigational agent