An Efficacy and Safety Study of Daratumumab in Patients With Multiple Myeloma Who Have Received at Least 3 Prior Lines of Therapy (Including a Proteasome Inhibitor [PI] and Immunomodulatory Drug [IMiD]) or Are Double Refractory to a PI and an IMiD

Daratumumab 16 mg/kg administered at weekly intervals (QW) for 8 weeks, then every 2 weeks (Q2W) for an additional 16 weeks, then every 4 weeks (Q4W) thereafter by intravenous infusion

Daratumumab 8 mg/kg every 4 weeks (Q4W) continuously by intravenous infusion

Administered in prophylactic doses intravenously (or equivalent in accordance with local standards) prior to and after study drug administration. Intravenous administration is preferred, but oral steroids may be substituted

650 to 1000 mg administered in prophylactic doses by mouth prior to study drug administration.

25 to 50 mg administered in prophylactic doses by mouth (or equivalent in accordance with local standards) prior to and after study drug administration.

Based on the Part 1 response rate, Group A or B treatment will be selected as the treatment regimen for participants enrolled in Part 2.