MTD was determined by testing increasing doses up to 20 mg/kg once daily dose escalation cohorts 1 to 3 with 3 patients each. MTD reflects highest dose of drug that did not cause an unacceptable side effect (dose limiting toxicity \[DLT\]) in more than 30% of patients; e.g., hematologic toxicities like Common Toxicity Criteria for Adverse Events (CTCAE) Grade 4 neutropenia in specific conditions, platelets \< 10,000 cells/mm\^3 that do not recover to 25,000 cells/mm\^3; and specific non-hematologic/biochemical toxicities CTCAE Grade 3 or 4 (except fatigue and Grade 3 infections); CTCAE version 3.0 were used.

ORR: Percentage of participants with confirmed complete response (CR; negative immunofixation on the serum and urine, disappearance of any soft tissue plasmacytomas, and ≤5% plasma cells in bone marrow), partial response (PR; ≥50% reduction of serum M-protein and reduction in 24-hour urinary M-protein by ≥90% or to ≤200 mg per 24 hour; if serum and urine M-protein are unmeasurable, a ≥50% decrease in the difference between involved and uninvolved free light chain (FLC\] levels is required in place of the M-protein criteria; if serum and urine M-protein are unmeasurable, and serum FLC is also unmeasurable, a ≥50% reduction in plasma cells is required in place of M-protein, provided baseline bone marrow plasma cell percentage was ≥30%; and, if present at baseline, a ≥50% reduction in the size of soft tissue plasmacytomas), very good PR (VGPR; normal FLC ratio and absence of clonal cells in bone marrow by immunohistochemistry or immunofluorescence), or stringent CR (sCR; CR plus VGPR).