MagnetisMM-32: A Study to Learn About the Study Medicine Called Elranatamab in People With Multiple Myeloma (MM) That Has Come Back After Taking Other Treatments (Including Prior Treatment With an Anti-CD38 Antibody and Lenalidomide)

Inclusion Criteria:

• Prior diagnosis of multiple myeloma as defined by International Myeloma WorkingGroup (IMWG) criteria and previously received 1 to 4 prior lines of therapyincluding prior anti-cluster of differentiation 38 (CD38) antibody and priorlenalidomide.

• Documented evidence of progressive disease or failure to achieve a response to lastline of therapy per IMWG criteria.

• Measurable disease defined as at least 1 of the following: (a) Serum M-protein ≥0.5g/dL; (b) Urinary M-protein excretion ≥200 mg/24 hours; (c) Serum involvedimmunoglobulin FLC ≥10 mg/dL AND abnormal serum immunoglobulin kappa to lambda FLCratio (<0.26 or >1.65).

• Have clinical laboratory values within the specified range.

• ECOG (Eastern Cooperative Oncology Group) performance status ≤2.

• Not pregnant or breastfeeding and willing to use contraception.

Exclusion Criteria:

• Smoldering multiple myeloma.

• Plasma cell leukemia.

• Amyloidosis.

• Polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy and skinabnormalities (POEMS) syndrome.

• Known central nervous system (CNS) involvement or clinical signs of myelomatousmeningeal involvement.

• Stem cell transplant within 12 weeks prior to enrolment, or active graft versus hostdisease.

• Any active, uncontrolled bacterial, fungal, or viral infection.

• Any other active malignancy within 3 years prior to enrolment (exceptions include,adequately treated basal cell or squamous cell skin cancer, carcinoma in situ)

• Previous treatment with a B cell maturation antigen (BCMA)-directed therapy orCD3-redirecting therapy.

• Unable to receive investigator's choice therapy.

• Live attenuated vaccine within 4 weeks of the first dose of study intervention.

• Administration with an investigational product (e.g. drug or vaccine) within 30 dayspreceding the first dose of study intervention used in this study.