Safety and Efficacy of Standard of Care Ciltacabtagene Autoleucel for Relapsed/Refractory Multiple Myeloma

• SOC cilta-cel in RRMM results in deep and durable response despite over half the patients not meeting CARTITUDE-1 eligibility criteria.

• Close surveillance for late complications like SPMs and efforts to mitigate delayed neurotoxicity and non relapse mortality are crucial.

Ciltacabtagene autoleucel (cilta-cel) CAR-T therapy was approved in 2022 for patients with relapsed/refractory multiple myeloma (RRMM). We report outcomes with cilta-cel in the standard-of-care setting. Patients with RRMM who underwent leukapheresis for cilta-cel manufacturing between 3/1/2022-12/31/2022 at 16 US academic medical centers were included. RESULTS: 255 patients underwent leukapheresis and 236 (92.5%) received cilta-cel. Of leukapheresed patients, 56% would not have met CARTITUDE-1 trial eligibility criteria. Manufacturing failure rates at first attempt and overall were 6% and 1%, respectively. Median prior lines of therapy were 6. In treated patients (N=236), cytokine release syndrome was seen in 75% (>= grade 3: 5%), immune effector cell-associated neurotoxicity syndrome in 14% (>= grade 3: 4%), and delayed neurotoxicity in 10%. Best overall and >= CR rates were as follows: infused patients (N=236): 89% and 70%; patients receiving conforming CAR-T product (N=191) 94% and 74%; conforming CAR-T product with fludarabine/cyclophosphamide lymphodepletion (N=152): 95% and 76%, respectively. Non-relapse mortality was 10%, most commonly from infection. After median follow-up of 13 months from CAR-T, median progression-free survival (PFS) was not reached, with 12- month estimate being 68% (95% CI: 62-74%). High ferritin levels, high-risk cytogenetics, and extramedullary disease were independently associated with inferior PFS, with a signal for prior BCMA-TT (p=0.08). Second primary malignancies (SPMs) excluding non-melanoma skin cancers were seen in 5.5% and myeloid malignancies/acute leukemia in 1.7%. We observed a favorable efficacy profile of standard of care cilta-cel in RRMM despite more than half the patients not meeting CARTITUDE-1 eligibility criteria.