Inclusion Criteria:

- 18 years of age or older

- ECOG (Eastern Cooperative Oncology Group) performance score of 1 or 0

- Diagnosis of multiple myeloma previously treated with more than 1 prior line of
therapy, induction therapy and following autologous stem cell transplant are
considered a single line of therapy (dose escalation only); or fewer than 4 separate
lines of therapy (safety expansion only) including a proteasome inhibitor and an IMiD
or immunomodulatory agent (e.g., thalidomide, lenalidomide), induction therapy and
following autologous stem cell transplant are considered a single line of therapy.

- Measurable disease at Screening: Serum monoclonal protein of at least 1.0 g/dL by
protein electrophoresis or at least 200 mg of monoclonal protein in the urine on
24-hr electrophoresis or serum immunoglobulin free light chain of at least 10 mg/dL
and abnormal serum immunoglobulin kappa to lambda free light chain ratio.

- If subject has a history of autologous stem cell transplant, must be more than 100
days post-transplant prior to first dose of study drug and have adequate peripheral
blood counts independent of any growth factor support, and have recovered from any
transplant related toxicity(s).

- Meet the following laboratory parameters, per the reference range: ANC of at least
1000/μL (Subjects with bone marrow that is heavily infiltrated with underlying
disease (80% or more) may use growth factor support to achieve ANC eligibility
criteria, discussion should occur between investigator and sponsor medical monitor
regarding any subject's use of growth factor to meet ANC criteria), AST and ALT not
higher than 3 x ULN, Calculated creatinine clearance of at least 30 mL/min using a
modified Cockcroft-Gault calculation (using Ideal Body Weight instead of Mass,
subjects with calculated creatinine clearance less than or equal to 50 mL/min should
have medical management discussed with sponsor medical monitor), platelet count of at
least 50,000 mm³ (independent of transfusion for 2 weeks), hemoglobin of at least 9.0
g/dL, total bilirubin not higher than 1.5 x ULN (subjects with Gilbert's Syndrome may
have bilirubin higher 1.5 x ULN with approval of sponsor medical monitor) and aPTT
and PT not higher than 1.2 x ULN.

Exclusion Criteria:

- Exhibits evidence of other clinically significant uncontrolled condition(s),
including, but not limited to: uncontrolled systemic infection (viral, bacterial, or
fungal), diagnosis of fever and neutropenia within 1 week prior to first dose of
study drug.

- Cardiovascular disability status of New York Heart Association Class greater than 2.
Class 2 is defined as cardiac disease in which patients are comfortable at rest but
ordinary physical activity results in fatigue, palpitations, dyspnea or anginal pain.

- Significant history of renal, neurologic, psychiatric, endocrinologic, metabolic,
immunologic, cardiovascular or hepatic disease, within the last 6 months that, in the
opinion of the investigator, would adversely affect his/her participation in the
study.

- History of other active malignancies other than multiple myeloma within the past 3
years prior to study entry, with the following exceptions: adequately treated in situ
carcinoma of the cervix uteri, basal cell carcinoma of the skin or localized squamous
cell carcinoma of the skin, previous malignancy confined and surgically resected (or
treated with other modalities) with curative intent.

- Tested positive for HIV.

- Seropositive for hepatitis A, hepatitis B surface antigen, or hepatitis C virus
antibody or RNA. Subjects with serologic evidence of prior vaccination to HBV may
participate after discussion between sponsor medical monitor and investigator.