bortezomib:1.3 mg/m2 IVP over 3-5 sec. days 1, 4, 8, 11 of 21 day cycle doxorubicin: 20 mg/m2 IV over 3-5 min. days 1,8 (one hour after bortezomib) of 21 day cycle

Determine the clinical efficacy of bortezomib and doxorubicin in patients with metastatic breast cancer. Overall response rate is defined as both complete and partial response per RECIST, where complete response is the disappearance of all target lesions. Any pathological lymph nodes (whether target or non-target) must have reduction in short axis to <10mm. Partial response is defined as at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters.

Progressive disease is defined as at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5mm.

Number of days to progression, where progression is defined as the number of days from the day of first study drug administration to the day the patient experiences an event of disease progression, or the appearance of one or more new lesions and/or unequivocal progression of existing non-target lesions. If a patient has not experienced an event of disease progression, then the patient's data will be censored at the date of the last available evaluation. Progression-free survival will be summarized by medium time to progression.

Subjects received therapy on days 1, 4, 8, and 11 of a 21-day cycle. 1.3 mg/m2 of Bortezomib was administered intravenously over 3-5 seconds on days 1, 4, 8, and 11, no less than 72 hours apart. 20 mg/m2 of Doxorubicin was administered intravenously over 3-5 minutes on days 1 and 8, one hour after Bortezomib administrations.

Determine the clinical efficacy of bortezomib and doxorubicin in patients with metastatic breast cancer. Overall response rate is defined as both complete and partial response per RECIST, where complete response is the disappearance of all target lesions. Any pathological lymph nodes (whether target or non-target) must have reduction in short axis to <10mm. Partial response is defined as at least a 30% decrease in the sum of diameters of target lesions, taking as reference the baseline sum diameters.

Progressive disease is defined as at least a 20% increase in the sum of diameters of target lesions, taking as reference the smallest sum on study. In addition to the relative increase of 20%, the sum must also demonstrate an absolute increase of at least 5mm.

Protocol accrued only 4 of 54 subjects, and was ultimately terminated. No data analysis was done.

Subjects received therapy on days 1, 4, 8, and 11 of a 21-day cycle. 1.3 mg/m2 of Bortezomib was administered intravenously over 3-5 seconds on days 1, 4, 8, and 11, no less than 72 hours apart. 20 mg/m2 of Doxorubicin was administered intravenously over 3-5 minutes on days 1 and 8, one hour after Bortezomib administrations.