Real World Outcomes for AYA Patients with Relapsed/Refractory B-Cell ALL Receiving CD19-Directed CAR T-Cell Therapy

Introduction Tisagenlecleucel (tisa-cel) and brexucabtagene autoleucel (brexu-cel) are approved CD19 CAR T products for adolescents and young adults (AYAs) with r/r B-ALL. These products have not previously been compared, yet overlap in age range presents a choice in therapy for AYAs. We describe real world efficacy and safety in AYAs with r/r B-ALL receiving tisa-cel or brexu-cel. Objectives/Method Retrospective data were collected from 25 institutions participating in the Pediatric Real World CAR-T Consortium and the Real World Outcomes of CAR-T in ALL collaboration. Frequency and Kaplan-Meier survival analyses were conducted. Results Sixty-nine infused patients aged 18-26 years were analyzed (Tisa-cel: 50, brexu-cel: 19). Baseline characteristics did not differ across cohorts (Table 1). CR/CRi rate was 90% for tisa-cel and 84% for brexu-cel recipients (P=0.5). With median follow-up of 10.5mo (range 1.1-27.2) for tisa-cel and 9.7mo (range 1.7-15.1) for brexu-cel, 12mo tisa-cel OS was 68% vs 89% for brexu-cel (P=0.31, Fig 1.). Median survival was 23.5mo for tisa-cel and was not reached for brexu-cel. Ten patients (3 tisa-cel, 7 brexu-cel) received alloHCT in remission after CAR-T. Censored for post-CAR-T alloHCT, 12mo EFS was 40% vs 67% in patients receiving tisa-cel or brexu-cel, respectively (P = 0.61, fig 2A). Among those achieving CR/CRi, median duration of remission was 12mo for tisa-cel and not reached for brexu-cel (P<0.05, Fig 3). CRS was more frequent in brexu-cel recipients, with 84% (11% gr3) experiencing CRS vs 52% (18% gr3/4) of tisa-cel recipients (P=0.01). ICANS was also increased with brexu-cel, with 47% (42% gr3/4) of patients experiencing ICANS vs 18% (4% gr3) of tisa-cel recipients (P=0.02). There was no treatment-related mortality in either cohort. Conclusions We report encouraging efficacy for tisa-cel and brexu-cel in treating AYA r/r B-ALL. No significant differences in 12mo OS or PFS were noted between products, though limited by small sample size. Results suggest more durable remission with brexu-cel, yet increased toxicity. Studies with larger patient populations are warranted to better characterize outcomes and clarify the role of post-CAR T alloHCT in this population.