Inclusion Criteria:

- Confirmed diagnosis of previously treated multiple myeloma with documented
progression by International Myeloma Working Group (IMWG) criteria after/during most
recent therapy.

- Eastern Cooperative Oncology Group (ECOG) performance status 0-1 (safety lead-in
cohort) or 0-2 (additional subjects)

- Measurable disease as defined by at least one of the following;

1. Serum IgG, IgA, IgM M-protein ≥ 0.5 g/dL, or serum IgD M-protein ≥ 0.05 g/dL; OR

2. Urine M protein ≥ 200 mg excreted in a 24-hour collection sample; OR

3. Involved serum free light chain level ≥ 10 mg/dL provided the free light chain
ratio is abnormal

Exclusion Criteria:

- Solitary bone or solitary extramedullary plasmacytoma as the only evidence of plasma
cell dyscrasia

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

- Active plasma cell leukemia (defined as either 20% of peripheral White Blood Cells
(WBC) comprised of plasma/CD138+ cells or an absolute plasma cell count of 2 x 109/L
to 2 x 100,000,0000/L)

- Subjects with non-secretory myeloma

- Active hepatitis A, B, or C

- Grade ≥2 neuropathy