A Study of the Safety and Efficacy of CNTO 328 and Bortezomib to Bortezomib Alone in Patients With Relapsed or Refractory Multiple Myeloma

Siltuximab 6 mg/kg will be administered as intravenous infusion once every 2 weeks during cycle 1 in Part 1. Siltuximab 6 mg/kg will be administered as intravenous infusion once every 2 weeks during 42-day Treatment Phase and 35-day Maintenance Phase in Part 2.

Bortezomib 1.3 mg/m\^2 will be administered as intravenous bolus once every 2 weeks during cycle 1 in Part 1. Bortezomib 1.3 mg/m\^2 will be administered as intravenous bolus on Days 1, 4, 8, 11, followed by a 10-day rest period; and on Days 22, 25, 29, and 32 followed by a 10-day rest period during 42-day treatment phase in Part 2. Bortezomib 1.3 mg/m2 will be administered as intravenous bolus on Days 1, 8, 15, 22 followed by a 13-day rest period (cycle Days 23 to 35) during 35-day Maintenance Phase in Part 2.

Matching placebo will be administered as intravenous infusion once every 2 weeks during 42-day treatment phase and 35-day maintenance phase in Part 2.

Dexamethasone tablet will be administered in this study at the first occurrence of documented disease progression or if bortezomib was discontinued due to intolerable toxicity. Dexamethasone 40 mg/day will be administered on days 1-4, 9-12, and 17-20 for four 28-day cycles then 40 mg/day for Days 1-4 for all subsequent cycles in treatment phase and maintenance phase of Part 2.