Real World Outcomes for Young Adult Patients Receiving CD19 CAR T-cell Therapy

• Real-world efficacy among young adults receiving CD19 CAR T therapy was comparable irrespective of CAR T construct.

• CRS and ICANS were observed more frequently in young adult recipients of brexu-cel vs tisa-cel

Tisagenlecleucel (tisa-cel) and brexucabtagene autoleucel (brexu-cel) are approved CD19 CAR T products for young adults (YAs) with relapsed/refractory B-ALL. A distinct analysis of YAs receiving commercial CD19 CAR T has not been reported. Utilizing retrospective data from the Pediatric Real-World CAR T Consortium and the Real-World Outcomes of CAR T in Adult ALL collaboration, we describe efficacy and safety of tisa-cel and brexu-cel in 70 young adults (18-26 years; tisa-cel: 50, brexu-cel: 20). Cytokine release syndrome (CRS) and immune-effector cell associated neurotoxicity syndrome (ICANS) were observed more frequently for brexu-cel vs tisa-cel (CRS= 85% vs 56%, p=0.01; ICANS= 40% vs 18%, p=0.05). CR rates were similar between products at 80% for brexu-cel and 88% for tisa-cel (p=0.39). Relapse free survival (RFS) at 12 months was 46% for brexu-cel (95% CI 31-81%) and 36% for tisa-cel (95% CI 26-52%, p=0.79). Durability of remission over 12 months was 61% for brexu-cel (95% CI 41-93%) vs 41% for tisa-cel (95% CI 27-61%, p=0.12). 12-month overall survival (OS) for brexu-cel was 84% (95% CI 81-100) vs 68% for tisa-cel (95% CI 56-85, HR 1.9, p=0.35). In multivariate analysis, low disease burden was associated with improved OS (HR 0.23, 95% CI 0.06-0.86, p=0.03), while inotuzumab pre-CAR T was associated with inferior outcomes (OS HR 6.32, 95% CI 1.48-27, p=0.01; RFS HR 3.65, 95% CI 1.41-9.46, p=0.008). This study demonstrates comparable real-world efficacy among young adults receiving CD19 CAR T therapy irrespective of CAR T construct, however, rates of toxicity appear higher with brexu-cel.