3-AP and Gemcitabine in Treating Patients With Refractory Metastatic Breast Cancer

Inclusion Criteria: * Histologically or cytologically confirmed breast cancer * Refractory metastatic disease * Measurable disease * At least 1 unidimensionally measurable lesion ≥ 20 mm by conventional techniques OR ≥ 10 mm by spiral CT scan * Must have received 1, and only 1, prior chemotherapy regimen for metastatic disease * Patients overexpressing HER2/neu antigen must have received a prior trastuzumab (Herceptin®)-containing regimen * No known brain metastases * Hormone receptor status: * Not specified * Male or female * Performance status - ECOG 0-2 * At least 12 weeks * WBC ≥ 3,000/mm\^3 * Absolute neutrophil count ≥ 1,500/mm\^3 * Platelet count ≥ 100,000/mm\^3 * Bilirubin normal * AST and ALT ≤ 2.5 times upper limit of normal * Creatinine normal * Creatinine clearance ≥ 60 mL/min * No uncontrolled congestive heart failure * No unstable angina pectoris * No cardiac arrhythmia * No severe pulmonary disease requiring oxygen * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No glucose-6-phosphate dehydrogenase (G6PD) deficiency * No other uncontrolled illness * No active or ongoing infection * No history of allergic reaction attributed to compounds of similar chemical or biological composition to 3-AP (Triapine®) or other study agents * No psychiatric illness or social situation that would preclude study compliance * No other malignancy within the past 5 years * See Disease Characteristics * No concurrent immunotherapy * No concurrent routine colony-stimulating factors (e.g., filgrastim \[G-CSF\] or sargramostim \[GM-CSF\]) * See Disease Characteristics * More than 4 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin) * No prior gemcitabine for metastatic disease * No other concurrent chemotherapy * More than 4 weeks since prior hormonal therapy * More than 4 weeks since prior radiotherapy * No concurrent radiotherapy * Recovered from prior therapy * No concurrent antiretroviral therapy for HIV-positive patients * No other concurrent investigational therapy