A Study of the Safety and Pharmacology of SGN-40 Administered in Combination With Bortezomib in Patients With Relapsed or Refractory Multiple Myeloma

Inclusion Criteria: * Age ≥ 18 years * Documented pathologic diagnosis of multiple myeloma that has relapsed or failed to respond after treatment with at least one prior systemic therapy (other than corticosteroid monotherapy) * Measurable disease * At least one prior systemic therapy other than single-agent corticosteroids * European Union patients must have had prior bone marrow transplant (autologous) or be ineligible for transplant * If previously received bortezomib, demonstration of clinical response of any duration or stable disease with progression-free interval of ≥ 6 months from the start of that therapy * If previously received bortezomib, must have recovered from bortezomib-related toxicities and must have a peripheral neuropathy score of Grade ≤ 1, according to the NCI CTCAE v3.0 * If applicable, completion of autologous transplant ≥ 12 weeks prior to Day 1 * Discontinuation of previous anticancer or investigational therapy for ≥ 21 days prior to treatment, or ≥ 90 days prior to treatment for previous monoclonal antibody administration Exclusion Criteria: * Prior allogeneic bone marrow transplant * Other invasive malignancies within 3 years prior to Day 1 except for adequately treated basal cell or squamous cell skin cancer; carcinoma in situ of the cervix, breast, or prostate; or other cancer of which the patient has been disease-free for ≥ 3 years * Prior anaphylactic reaction to human immunoglobulin administration * Symptomatic hyperviscosity syndrome * Active infection requiring parenteral antibiotics within 14 days of Day 1 * Major surgical procedure or significant traumatic injury within 28 days prior to Day 1, or anticipation of need for major surgical procedure during the course of the study * Clinically significant cardiac dysfunction or other significant organ dysfunction