Inclusion Criteria

• Eastern Cooperative Oncology Group (ECOG) performance score less than or equal to 2
• Documented relapsed or progressive multiple myeloma on or after any regimen or refractory to the most recent line of therapy
  • Relapsed myeloma is defined as previously treated myeloma that progresses and requires initiation of salvage therapy, but does not meet the criteria for refractory myeloma
  • Refractory myeloma is defined as disease that is non responsive (failure to achieve minimal response or development of progressive disease [PD]) while on primary or salvage therapy, or progresses within 60 days of last therapy
• Must have received prior treatment with at least one, but no more than three, prior lines of therapy for multiple myeloma
  • A line of therapy consists of greater than or equal to 1 complete cycle of a single agent, a regimen consisting of combination of several drugs, or a planned sequential therapy of various regimens
• Prior treatment with bortezomib or other proteasome inhibitor is allowed, provided ALL of the following criteria are met
  • Disease is not refractory to any proteasome inhibitor, defined as no disease progression (i.e., PD, per IMWG or European Society for Blood and Marrow Transplantation [EBMT] criteria) while receiving proteasome inhibitor therapy or within 60 days after the last dose,
  • Best response achieved with any proteasome inhibitor therapy (alone or in combination) was at least a PR
  • Proteasome inhibitor was not discontinued due to intolerance or greater than or equal to Grade 3 related toxicity
• Has measurable disease at screening, defined as at least one of the following
  • Serum M-protein greater than or equal to 0.5 g/dL
  • Urine M-protein greater than or equal to 200 mg in 24-hours
  • Serum immunoglobulin free light chain (FLC) greater than or equal to 10 mg/dL provided serum FLC ratio is abnormal

Exclusion Criteria

• Refractory to any proteasome inhibitor, defined as
  • Progression on or within 60 days of the last dose of a proteasome inhibitor-containing regimen
• Has had prior treatment with proteasome inhibitor within 60 days prior to first dose of study drug
• Has any of the following conditions
  • Non-secretory or oligo-secretory multiple myeloma
  • Active plasma cell leukemia i.e., either 20% of peripheral white blood cells or greater than 2.0 X 10^9/liter (L) circulating plasma cells by standard differential
  • Waldenstrom's macroglobulinemia
  • Amyloidosis
  • POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, and skin changes)
  • Known Human Immunodeficiency Viral (HIV) infection
  • Active hepatitis B or C infection based on blood screen tests
  • Significant cardiovascular disease including
    • Uncontrolled angina
    • Severe or uncontrolled arrhythmia
    • Recent myocardial infarction within 6 months of randomization
    • Congestive heart failure New York Heart Association (NYHA) Class greater than or equal to 3
  • Major surgery within 4 weeks prior to randomization
  • Acute infections requiring parenteral therapy (antibiotic, antifungal, or antiviral) within 14 days prior to randomization
  • Peripheral neuropathy greater than or equal to Grade 3 or greater than or equal to Grade 2 with pain within 2 weeks prior to randomization
  • Uncontrolled diabetes or uncontrolled hypertension within 14 days prior to randomization
  • Any other medical condition that, in the opinion of the Investigator, would adversely affect the participant's participation in the study
• Has a history of other active malignancies, including myelodysplastic syndrome (MDS), within the past 3 years prior to study entry, with the following exceptions
  • Adequately treated in situ carcinoma of the cervix uteri or the breast
  • Basal cell carcinoma of the skin or localized squamous cell carcinoma of the skin
  • Prostate cancer Gleason grade 6 or lower and with stable Prostate Specific Antigen (PSA) levels off treatment
  • Previous malignancy with no evidence of disease confined and surgically resected (or treated with other modalities) with curative intent and unlikely to impact survival during the duration of the study
• Had prior allogeneic stem cell transplant (SCT)
• Has evidence of ongoing graft-versus-host disease (GvHD)