At least 18 years of age with measurable progressive multiple myeloma responsive to at least one prior regimen by the International Myeloma Working Group Uniform Response Criteria and the European Blood and Marrow Transplantation Group Criteria
Received at least two prior regimens for relapsed disease, including bortezomib, thalidomide, or lenalidomide, an alkylating agent, or an anthracycline, alone or in combination
Eastern Cooperative Oncology Group score 0–2
Baseline platelet count of at least 50,000/mm3
Serum hemoglobin of at least 8 g/dL
Absolute neutrophil count of at least 1,000/mm3
Aspartate aminotransferase or alanine aminotransferase less than three times the upper limit of normal
Total bilirubin less than twice the upper limit of normal
Creatinine clearance more than 30 mL/min