Inclusion Criteria:

Documented relapse or progressive multiple myeloma on or after any treatment (subjects refractory to the most recent line of therapy are eligible, unless last treatment contained PI or lenalidomide and dexamethasone).

Subjects must have at least PR to at least 1 line of prior therapy.

Subjects must have received at least 1 but not more than 3 prior lines of therapy for multiple myeloma (induction therapy followed by stem cell transplant and consolidation maintenance therapy will be considered as 1 line of therapy).

Prior therapy with a PI or the combination of lenalidomide and dexamethasone are allowed, if, the patient had at least a PR to the most recent therapy with a PI or lenalidomide and dexamethasone, neither PI or lenalidomide and dexamethasone in combination were ceased due to toxicity, the patient has not received a PI and has not received lenalidomide and dexamethasone in combination in the 6 months prior to first study treatment. (Patients are permitted to have received single agent lenalidomide as maintenance therapy during the 6 months prior to first treatment)

Previous treatment with a lenalidomide and dexamethasone containing regimen is allowed, as long as the subject did not progress during the first 3 months after initiating lenalidomide and dexamethasone containing therapy.

Measurable disease with at least 1 of the following assessed within 21 days prior to randomization:

• Inmunoglobulin G (IgG) multiple myeloma: serum monoclonal protein (M-protein) level ≥ 1.0 g/dL
• Inmunoglobulin A (IgA), Inmunoglobulin D (IgD), Inmunoglobulin E (IgE) multiple myeloma: serum M-protein level ≥ 0.5 g/dL
• Urine M-protein ≥ 200 mg per 24 hours
• In subjects without measurable serum or urine M-protein, serum-free light chain (SFLC) ≥ 100 mg/L (involved light chain) and an abnormal serum kappa lambda ratio

Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0 ≤ 2

Other inclusion criteria may apply

Exclusion Criteria:

Waldenström macroglobulinemia.

Multiple myeloma of Inmunoglobulin M (IgM) subtype.

Plasma cell leukemia (> 2.0 × 10^9 /L circulating plasma cells by standard differential).

Uncontrolled hypertension, defined as an average systolic blood pressure ≥ 160 mmHg or diastolic ≥ 100 mmHg despite optimal treatment (blood pressure to be measured following European Society of Hypertension/European Society of Cardiology 2013 guidelines).

Active congestive heart failure (New York Heart Association Class III to IV), symptomatic ischemia, uncontrolled arrhythmias, screening ECG with corrected QT interval (QTc) of > 470 msec, pericardial disease, or myocardial infarction within 4 months prior to randomization.

Calculated or measured creatinine clearance < 1.0 mL/s (calculation must be based on the Cockcroft and Gault formula) within 21 days prior to randomization.

Other exclusion criteria may apply