A Study of Elranatamab Outpatient Administration in Patients With Relapsed/Refractory Multiple Myeloma

This is a Phase II, open-label, nonrandomized, single-arm study of elranatamab that will be administered in the outpatient setting in 2 sequential cohorts of participants with relapsed or refractory multiple myeloma (RRMM). The primary objective of this study is to evaluate the overall incidence of cytokine release syndrome (CRS) during Cycle 1 of elranatamab treatment following a single prophylactic dose of tocilizumab.

Inclusion Criteria: 1. Written informed consent, according to institutional guidelines, signed and dated by the participant or by a legal guardian prior to the performance of any study-specific procedures, sampling, or analyses 2. At least 18 years-of-age at the time of signature of the ICF 3. Has documented diagnosis of MM according to IMWG diagnostic criteria 4. Measurable disease at screening, as assessed by local laboratory, defined by any of the following: 1. Serum M-protein level ≥0.5 g/dL 2. Urine M-protein level ≥200 mg/24 hours 3. Light chain MM without measurable M-protein in the serum or the urine: serum free light chain (sFLC) ≥10 mg/dL and abnormal serum immunoglobulin kappa lambda FLC ratio 4. For participants without measurable disease in the serum, urine, or involved FLC, presence of plasmacytomas (≥2 cm x 1 cm) 5. Relapsed and/or refractory MM received ≥1 prior line of therapy and must have been exposed to both lenalidomide and an anti-CD38 monoclonal antibody (in the same or separate prior lines) 6. ECOG Performance Status score of 0 or 1 7. Human immunodeficiency virus (HIV)-positive participants are eligible if they meet all of the following: 1. No detectable viral load (i.e., \300 cells/mm3 at screening 3. No acquired immunodeficiency syndrome (AIDS)-defining opportunistic infections within 6 months of screening 4. Receiving highly active antiretroviral therapy (HAART). Any changes in HAART due to resistance/progression should occur at least 3 months prior to enrollment. A change in HAART due to toxicity is allowed up to 4 weeks prior to enrollment. HAART that could interfere with study treatment is excluded (consult the Medical Monitor for a review of medications prior to enrollment, if needed). 8. Adequate organ function, defined as follows: 1. Hemoglobin (Hgb) ≥8 g/dL (≥5 mmol/L; without prior red blood cell \[RBC\] transfusion within 7 days before laboratory testing; recombinant human erythropoietin use is permitted) 2. Platelets \>50 x109/L 3. Absolute neutrophil count (ANC) ≥10.x109/L (prior growth factor support is permitted but must be without support for 7 days for G-CSF or GM-CSF and for 14 days for pegylated G-CSF) 4. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤2.5xupper limit of normal (ULN) 5. Estimated glomerular filtration rate (eGFR) ≥30 mL/min based on Modified Diet in Renal Disease (MDRD) 4-variable formula calculation or creatinine clearance measured by 24-hour urine collection 6. Total bilirubin \