Introduction:Adverse events (AE), such as cytokine release syndrome (CRS) and neurological toxicity (NT), have been associated with chimeric antigen receptor (CAR) T cell therapies. Idecabtagene vicleucel (ide-cel, bb2121), a B-cell maturation antigen-directed CAR T cell therapy, demonstrated deep and durable responses in triple-class exposed (TCE) patients (pts) with RRMM in the pivotal, single-arm, open-label phase 2 KarMMa (3 prior lines of therapy [LOTs]; NCT03361748) (Munshi NC, et al. NEJM2021;384:705-716) and superior progression-free survival with ide-cel vs standard regimens in the phase 3 KarMMa-3 trial (2-4 prior LOTS; NCT03651128) (Rodríguez-Otero P, et al. NEJM2023;388:1002-1014). Healthcare resource utilization (HCRU) and costs associated with CRS/NT management were estimated previously for pts receiving ide-cel in the KarMMa trial (McGarvey N, et al. Value Health 2023;26:S89) and suggested low rates of severe (grade ≥ 3) CRS/NT following ide-cel infusion and higher HCRU and costs with increasing AE severity. To further assess resource and economic burden associated with care of treatment-emergent AEs, this analysis evaluated HCRU and estimated cost of CRS/NT management among pts treated with ide-cel in earlier-line settings in the KarMMa-3 study.