Study to Assess Anti-CD38 Antibody Drug Conjugate in Relapsed or Refractory Multiple Myeloma

Inclusion Criteria: * Must have relapsed or refractory multiple myeloma (RRMM) after having received prior lines of anti-myeloma treatments, including being refractory to a proteasome inhibitor, immunomodulatory agent and an anti-CD38 monoclonal antibody * Measurable disease as defined by one of the following: abnormal serum or M-protein levels; abnormal serum free light chain (FLC) assay; ≥ 30% clonal plasma cells in the bone marrow aspirate or biopsy sample * Pulse oximetry ≥ 92% on room air * Eastern Cooperative Oncology Group (ECOG) performance of 0 - 2 * Be willing and able to comply with the study schedule and all study requirements * Willing to follow contraception guidelines Exclusion Criteria: * Prior systemic anti-tumor therapy or an investigational drug within 5 half-lives or 4 weeks of D1, whichever is shorter, preceding the first dose of study drug * Prior treatment with allogeneic hematopoietic stem cell transplantation within 6 months, has active graft versus host disease following transplant or currently receiving immunosuppressive therapy following transplant * Diagnosis of other malignancies if the malignancy required therapy in the last 3 years or is not in complete remission * Current history of CTCAE Grade 3 muscle paresis or ocular disorders that are Grade 3 or 2 * Has any clinically significant low baseline lab results for hemoglobin, platelet counts, and neutrophil counts at screening * Abnormal INR or aPTT, unless on a stable dose of an anticoagulant * Has ≥ Grade 3 neuropathy or Grade 2 neuropathy with associated pain * Has any clinically significant baseline lab results for creatinine clearance, serum aspartate aminotransferase, alanine aminotransferase, total bilirubin * New York Heart Association Class \> 2 * Left ventricular ejection fraction \< 40% * Prolonged QTcF interval on a 12-lead electrocardiogram * Has active COVID-19 infection, and not present with symptoms within 4 weeks of study drug * Has an active bacterial, viral, or fungal infection * Has known HIV or acquired immunodeficiency syndrome-related illness, acute or history of chronic hepatitis B or C * Is currently pregnant or breast feeding or planning on either during the study * Has any significant medical condition, abnormality, or psychiatric illness that would prevent study participation * Has any additional clinical history that would place the patient at an unacceptable risk if the patient participates in the study