Mortality and readmission rates post CAR-T cell therapy in relapsed/refractory multiple myeloma: Real-world, multicentre, retrospective cohort study using TriNetX database.

e19564 Background: Immunotherapy, particularly CAR T-cell therapy, emerges as a promising frontier in the ongoing pursuit of effective multiple myeloma treatment. The pivotal KarMMa trial and CARTITUDE 4 trial demonstrated promising progression-free survival, but data on the readmission rates are lacking. We aimed to study the real-world data on the 30-day and 90-day readmission rates post-B-cell maturation antigen (BCMA) CART cell therapy in relapsed refractory multiple myeloma (RRMM) patients. Methods: We conducted a retrospective study that included adult patients with RRMM who received CART cell therapy using the TriNetX database network, a federated EMR network of more than 117 million de-identified patients. Patients were diagnosed with RRMM on or before the index event of CAR T-cell initiation therapy (either Ciltacabatagene Autoleucel OR Idecabatagene Ciloleucel). The outcomes of interest were:1) Index admission: Complications and mortality rates and 2) 30-day and 90-day readmission and mortality rates. Results: A total of 781 RRMM patients received CAR-T cell therapy. The mean age of the study population is 66 years (±9), 51.6% were males and 65.3% were white population. At a median follow-up of 11.5 months, the mortality rates were 14.2%. 49.2% had CRS with 3.84% having ≥ Grade 3 CRS, and 52.7% needed Tocilizumab. The 30-day readmission rates were 77.7% (n=607) and 30-day mortality rates were 1.9% (n=12). The 90-day readmission rates were 78.8% (n=616) and the 90-day mortality rates were 3.4% (n=28) (Table 1). Conclusions: RRMM post-CART cell therapy is associated with high 30-day and 90-day readmission rates. However, these readmissions are associated with less than 5% of the mortality. Further, evaluation of the causes of readmission and implementing strategies to mitigate them would be the group's next step. Demographic, clinical, and outcome parameters. Baseline characteristic feature RRMM Post BCMA CART therapy (n=781) Mean age in years (SD) 66 (9) Gender * MalesFemales 51.68%40.22% Race * WhitesBlacks or African Americans 65.37%13.07% ComorbiditiesHypertensionType 2 DMObesityHyperlipidemiaHeart failureHypothyroidism 69%28%29%43%22%20% Median follow-up (months)(IQR) 11.5 (14.9) Mortality rates 111 (14.2%) CRS rates 385 (49.2%) CRS Grade ≥ 3 30 (3.84%) ICANS rates 155 (19.8%) ICANS Grade ≥ 3 41 (5.24%) Used Tocilizumab 412 (52.7%) 30-Day readmissions 607 (77.7%) 30-day mortality 12 (1.97%) 90-day readmissions 616 (78.8%) 90-day mortality 28 (3.48%) *Indicates unknown categories are present. DM: Diabetes mellitus; CRS: Cytokine release syndrome; ICANS: Immune effector cell associated neurotoxicity syndrome; SD: Standard deviation; IQR: Interquartile range; RRMM: Relapsed/refractory multiple myeloma; BCMA: B-cell maturation antigen; CART: Chimeric antigen receptor T-cell therapy.