Efficacy and safety comparison of CAR-T and blinatumomab immunotherapy as bridge-to-transplant strategies in relapsed/refractory B cell acute lymphoblastic leukemia.

Background: Despite recent advances, B cell acute lymphoblastic leukemia (B-ALL) remains a therapeutic challenge. Hematopoietic stem cell transplantation (HSCT) provides a potential cure but is hindered by various limitations. Emerging immunotherapies, including chimeric antigen receptor T cell (CAR-T) therapy and blinatumomab, have shown potential as bridging strategies to HSCT in relapsed/refractory (R/R) patients.

Methods: This retrospective study was conducted at Tongji Hospital from March 2017 to March 2023 and involved 36 R/R B-ALL patients who underwent HSCT. Prior to transplantation, 27 patients received CD19/CD22 CAR-T therapy, while 9 received blinatumomab. The outcomes assessed included overall survival (OS), progression-free survival (PFS), graft-versus-host disease-free and relapse-free survival (GRFS), and non-relapse mortality (NRM), with comparisons between treatment groups. Hematopoietic reconstitution and transplant-related complications were also evaluated.

Results: The median follow-up time was 28.07 months (range: 2.29-92.21 months). The 2-year OS, PFS, GRFS, and NRM rates of the entire cohort were 76.54%, 54.97%, 40.12%, and 9.93%, respectively. In the CAR-T and blinatumomab treatment groups before transplantation, the 2-year OS rates were 73.89% and 88.89% (P = 0.862), the PFS rates were 59.03% and 44.44% (P = 0.501), the GRFS rates were 47.86% and 13.89% (P = 0.083), and the NRM rates were 8.52% and 11.11% (P = 0.713), respectively. The safety profiles were similar, with no significant differences observed in hematopoietic reconstitution, infection, incidence of grade II-IV acute graft-versus-host disease (GVHD), or chronic GVHD incidence between the CAR-T and blinatumomab groups.

Conclusion: CAR-T and blinatumomab therapies demonstrate comparable safety and efficacy as bridging treatments to HSCT in patients with R/R B-ALL. Further studies are needed to optimize these treatment strategies.