• Time to progression (TTP) [ Time Frame: For up to 2 years ] [ Designated as safety issue: No ]
  

• Overall survival [ Time Frame: Up to 2 years ] [ Designated as safety issue: No ]
  
• Response rate [ Time Frame: Up to 2 years ] [ Designated as safety issue: No ]
  
• Adverse Events as a measure of safety [ Time Frame: Up to 30 days after the last dose of study drug ] [ Designated as safety issue: No ]
  
• Laboratory test results as a measure of safety [ Time Frame: Up to 30 days after the last dose of study drug ] [ Designated as safety issue: No ]
  

This is a randomized (study drug assigned by chance), parallel-group, open-label (all involved people know the identity of the intervention), multicenter study in 18 countries. A total of 646 patients with multiple myeloma whose disease has progressed after an initial response to at least 1 line of prior therapy or was refractory to initial treatment will be enrolled. The primary endpoint is time to progression (the interval between the date of randomization and the date of disease progression); secondary endpoints are overall survival (the interval between the date of randomization and the patient's death from any cause), response rate (the proportion of patients in the evaluable population who achieved a complete or partial response), and safety. Other study endpoints include patient reported outcomes and exploratory pharmacogenics (to identify genetic markers of response). Patients are assessed for efficacy and safety every 3 weeks until disease progression is documented or for up to 42 weeks from the start of the first dose of study drug. Patients, who do not progress after the 42-week period, are assessed every 6 weeks until disease progression is documented. Efficacy evaluations includes: serum protein electrophoresis, 24-hour urine collection for protein electrophoresis, skeletal survey (plain films), bone marrow biopsy and aspirate, clinical or radiologic assessment of plasmacytomas, and serum calcium. Responses and progressions are assessed objectively by a computer algorithm based on the EBMT criteria. Safety evaluations include adverse event reports, changes in clinical laboratory findings, and tests for cardiac function (multiple gated acquisition scan/echocardiogram and electrocardiogram). Group A: VELCADE monotherapy: VELCADE 1.3 mg/m2 to be administered by i.v. bolus on Days 1, 4, 8, and 11 of each 21-day cycle. Group B: DOXIL/VELCADE combination: treated with VELCADE at the same dose and schedule as specified in Group A. DOXIL/CAELYX 30 mg/m2 by intravenous infusion given on Day 4 of every 21-day cycle following the administration of VELCADE.