The purpose of this study is to monitor the long-term safety of participants who received idecabtagene vicleucel treatment as part of the KarMMa-9 (CA089-1043) Phase 3 clinical trial.

Inclusion Criteria:

• Adult participants ≥19 years of age
• Korean participants with newly diagnosed multiple myeloma who had a suboptimal response after autologous stem cell transplantation (ASCT) and who were treated with idecabtagene vicleucel (assigned to Arm A) in the KarMMa-9 trial (CA089-1043)
• Participants must understand and voluntarily sign and informed consent form (ICF) for the Korea long-term follow-up surveillance study prior to any surveillance-related procedures being conducted

Exclusion Criteria:

• Participants who participate in KarMMa-9 trial (CA089-1043) but disagree with long-term follow-up surveillance in Korea
• Participants who are not possible to treat with Ide-cel within 9 days post-completion of lymphodepleting chemotherapy (LDC), if delays occur. However, depending on the participants recovery status, whether idecabtagene vicleucel is administered or not, should be discussed with a medical monitor

Adult participants with newly diagnosed multiple myeloma (NDMM) who had a suboptimal response after autologous stem cell transplantation (ASCT) and who were treated with idecabtagene vicleucel in the KarMMa-9 (CA089-1043) Phase 3 clinical trial.