Inclusion Criteria:

        Documented relapse or progressive multiple myeloma after last treatment. Subjects
        refractory to the most recent line of therapy are eligible, unless last treatment contained
        PI or lenalidomide and dexamethasone). Refractory is defined as disease that is
        nonresponsive or progresses within 60 days of last therapy.

        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 (unless at the time of enrollment that toxicity was neuropathy not exceeding
        grade 2 which has either resolved or if ongoing is less than or equal to grade 1), 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 a subject whose blood pressure exceeds ≥ 160 mmHg
        systolic or ≥ 100 mmHg diastolic when taken in accordance with the European Society of
        Hypertension/European Society of Cardiology 2018 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