Inclusion Criteria:  Prior diagnosis of multiple myeloma as defined by IMWG criteria (Rajkumar et al, 2014).  Measurable disease based on IMWG criteria as defined by at least 1 of the following:  Serum M-protein ≥0.5 g/dL by SPEP. Urinary M-protein excretion ≥200 mg/24 hours by UPEP. Serum immunoglobulin FLC ≥10 mg/dL (≥100 mg/L) AND abnormal serum immunoglobulin kappa to lambda FLC ratio (<0.26 or >1.65). Prior anti-multiple myeloma therapy including treatment with lenalidomide and a proteasome inhibitor. ECOG performance status ≤1. Resolved acute effects of any prior therapy to baseline severity or CTCAE Grade ≤1. Not pregnant and willing to use contraception.  Exclusion Criteria:  Smoldering multiple myeloma. Plasma cell leukemia. Systemic amyloid light chain amyloidosis. POEMS Syndrome. Stem cell transplant within 12 weeks prior to enrolment, or active graft versus host disease. Active HBV, HCV, SARS-CoV2, HIV, or any active, uncontrolled bacterial, fungal, or viral infection. Any other active malignancy within 3 years prior to enrolment, except for adequately treated basal cell or squamous cell skin cancer, or carcinoma in situ. Previous treatment with a BCMA-directed therapy. Anti-CD38-directed therapy within 6 months preceding the first dose of treatment in this study. Live attenuated vaccine within 4 weeks of the first dose of study intervention. Administration with an investigational product (e.g. drug or vaccine) concurrent with study intervention or within 30 days or 5 half-lives preceding the first dose of study intervention used in this study (whichever is longer).