A Study to Learn About the Study Medicine Elranatamab Alone and With Daratumumab in People With Multiple Myeloma Who Have Received Other Treatments

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. * Urinary M-protein excretion ≥200 mg/24 hours. * 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. * ECOG performance status ≤2. * 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. * 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. * 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 preceding the first dose of study intervention used in this study.