Background: Elranatamab is a humanized bispecific antibody targeting B cell maturation antigen (BCMA) on myeloma cells and CD3 on T cells. Elranatamab has shown promising efficacy and acceptable safety in pts with relapsed and/or refractory multiple myeloma (MM). The aim of the MagnetisMM-7 study is to evaluate elranatamab monotherapy vs lenalidomide monotherapy in pts with newly diagnosed MM (NDMM) after undergoing autologous stem cell transplant (ASCT). Methods: MagnetisMM-7 is an ongoing, open-label, 2-arm, multicenter, randomized phase 3 study estimated to enroll ~700 pts. ClinicalTrials.gov ID: NCT05317416. Pts are randomized to receive either subcutaneous elranatamab or oral lenalidomide once daily. After initial step-up dosing, two alternative dosing regimens of elranatamab are examined. The primary endpoint is progression-free survival (PFS) assessed by blinded independent review per International Myeloma Working Group (IMWG) criteria (up to ~5 y). Secondary endpoints include overall survival, minimal residual disease (MRD) negativity rate at 12 mo after randomization per IMWG criteria as assessed via next-generation sequencing (NGS), sustained MRD negativity rate at 24 mo after randomization as assessed via NGS, PFS by investigator, duration of MRD negativity, complete response (CR) rate, duration of CR, safety, quality of life, immunogenicity, and pharmacokinetics. Key inclusion criteria are: ≥18 y; a diagnosis of MM with measurable disease according to IMWG criteria; history of induction therapy for NDMM, followed by high dose therapy and ASCT with or without consolidation; partial response or better according to IMWG criteria; identification of the dominant malignant clone; and Eastern Cooperative Oncology Group performance status ≤1. Randomization must occur ≤120 d from ASCT; for pts who receive consolidation therapy after ASCT, randomization must occur ≤60 d of consolidation and ≤7 mo of ASCT. Key exclusion criteria are: plasma cell leukemia; amyloidosis; Waldenström's macroglobulinemia; POEMS syndrome; known active CNS involvement or clinical signs of myelomatous meningeal involvement; previous MM maintenance treatment; prior treatment with BCMA-targeted therapy; any other active malignancy ≤3 y of enrollment; active, uncontrolled bacterial, fungal, or viral infection; and previous administration of an investigational drug or vaccine ≤30 d or 5 half-lives preceding the first dose of study treatment. As of February 2023, the study is open and enrolling at 29 sites in 13 countries. Clinical trial information: NCT05317416.