A Safety Study of SGN-CD352A for Patients With Relapsed/Refractory Multiple Myeloma

Inclusion Criteria: * Diagnosis of MM requiring systemic therapy (per the International Myeloma Working Group \[IMWG\] ). * Age 18 years or older. * An Eastern Cooperative Oncology Group (ECOG) Performance Status score of 0 or 1. * Life expectancy greater than 3 months. * Received at least 2 prior lines of therapy for MM including an immunomodulatory drug and a proteasome inhibitor. * Measurable disease, as defined by at least one of the following: Serum M protein 0.5 g/dL or higher, Urine M protein 200 mg/24 hr or higher, Serum free light chain (SFLC) 10 mg/dL or higher, and Abnormal SFLC ratio. * Adequate hematologic, renal, and hepatic function * A negative pregnancy test (for females of childbearing potential). * Patients must provide written informed consent. Exclusion Criteria: * Other invasive malignancy within the past 3 years. * Active cerebral/meningeal disease related to the underlying malignancy. * Active Grade 3 or higher infection. * Known to be positive for HIV or known to have active hepatitis B or C. * Previous allogeneic stem cell transplant. * Idiopathic interstitial pneumonia or impaired diffusion capacity of the lung for carbon monoxide (DLCO). * Cerebrovascular or cardiovascular event, or congestive heart failure within the last 6 months. * Females who are pregnant or breastfeeding.