Non Interventional Study to Investigate the Safety and Effectiveness in Patients With Relapsed and Refractory Multiple Myeloma Treated With Elranatamab Under the Actual Use.

The objective of this study is to assess the safety and efficacy in patients with relapsed and refractory multiple myeloma (RRMM) treated with elranatamab under the actual use.

• Primary objective: Confirm whether the onset status (the number of patients, incidence, grade, seriousness, timing of onset, duration, treatment and outcome) of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) is comparable to that in the clinical studies and whether adverse reactions were appropriately treated.

• Secondary objective: Confirm the onset status of any adverse reaction (including unknown adverse reaction) to long-term treatment with elranatamab and the overall response (ORR) as efficacy assessment and evaluate them in terms of benefit-risk.

Conditions for approval; Because of the extremely limited number of patients treated in Japanese clinical studies, a drug use investigation in all patients should be conducted to understand the background information of patients on elranatamab, early collect data on the safety and efficacy of elranatamab, and take measures necessary for the proper use of elranatamab until the data of a certain number of patients are accumulated.