A Phase 1/2, Open-label, Multicenter Study of mRNA-2808 in Participants With Relapsed or Refractory Multiple Myeloma

Key Inclusion Criteria: * RRMM with prior exposure to a proteasome inhibitor, an immunomodulatory drug (IMiD), and an anti-cluster of differentiation (CD38) monoclonal antibody. * Measurable disease defined as at least 1 of the following: * Serum M-protein ≥0.5 grams/deciliter * Urine M-protein ≥200 milligrams (mg)/24-hour * Involved free light chain (FLC) ≥100 mg/liter and an abnormal FLC ratio * Plasmacytoma with a single diameter ≥2 centimeters * Bone marrow plasma cells \>30% Key Exclusion Criteria: * Known central nervous system (CNS) myeloma or clinical signs and symptoms o…