Inclusion Criteria:

- Documented progression from most recent line of therapy

- Measurable disease

- 1 to 3 prior lines of therapy

- Subjects may be proteasome inhibitor naive or have received prior proteasome
inhibitor therapy provided all the following criteria are met:

1. The subject did not discontinue any proteasome inhibitor due to intolerance
or grade ≥ 3 toxicity

2. The subject is not refractory to any proteasome inhibitor, defined as
progression during treatment or within 60 days after the last dose

3. The subject previously achieved a partial response (PR) or better to
previous proteasome inhibitor (PI)

Exclusion Criteria:

- Monoclonal gammopathy of undetermined significance (MGUS), smoldering myeloma, or
Waldenstrom's macroglobulinemia

- Active plasma cell leukemia

- Known Human immunodeficiency virus (HIV) infection or active hepatitis A, B, or C