CAR-T versus allogeneic transplantation as consolidation for B-cell acute lymphoblastic leukemia in remission: a propensity-score matched study

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Background: Despite being a standard consolidation treatment, allogeneic hematopoietic stem cell transplantation (allo-HSCT) for B-cell acute lymphoblastic leukemia (B-ALL) in remission is still hampered by relapse and complications. While CAR-T therapy is revolutionizing later-line treatment, its role as a consolidation strategy in remission, particularly for patients ineligible for transplantation, remains unexplored. This study compared the efficacy of CAR-T therapy with that of allo-HSCT as consolidation for B-ALL patients in complete remission (CR). Methods: A retrospective, propensity-score matched study was performed from September 1, 2012 to December 31, 2024, including 75 B-ALL patients treated with CAR-T or allo-HSCT as consolidation therapy. Firth penalized likelihood Cox models and restricted mean survival time (RMST) models were built for time-to-event outcomes. Results: The 2-year progression-free survival (PFS) and 2-year overall survival (OS) rates showed no significant differences between the CAR-T and HSCT cohorts (CR1: 2-year PFS rate: 65.8% vs. 88.9%, P = 0.146, 2-year OS rate: 83.6% vs. 91.3%, P = 0.512; CR2: 2-year PFS rate: 42.2% vs. 64.3%, P = 0.360). The RMSTs of PFS and OS also have no significant differences (CR1: RMST of PFS difference = -7.738, P = 0.496, RMST of OS difference = -2.257, P = 0.788; CR2: RMST of PFS difference = -6.176, P = 0.700, RMST of OS difference = -8.391, P = 0.477) truncated at the minimum of the largest follow-up times in each cohort (CR1, 74.6 months; CR2, 75.0 months). In multivariate analysis, patients treated with allo-HSCT had better PFS in CR1 group (HR = 4.579, 95%CI, 1.020-20.563, P = 0.038). High risk stratification was an independent factor associated with worse OS for B-ALL patients in CR (CR1: HR = 8.010; 95%CI, 1.744-36.781, P = 0.048; CR2 HR = 5.110, 95%CI, 1.167-22.378, P = 0.004). Conclusion: The results indicated that CAR-T consolidation regimen showed comparable survival to that of allo-HSCT in matched B-ALL patients, which might support its potential as a consolidation alternative for B-ALL patients ineligible for allo-HSCT.