Recipient-derived vs. donor-derived CAR-T-cell therapy in relapsed B-cell acute lymphoblastic leukemia patients after transplantation: A multi-center retropective study.

[BACKGROUND] Chimeric antigen receptor T (CAR-T) cells have been demonstrated to be an effective treatment for relapsed B-cell acute lymphoblastic leukemia (B-ALL) following allogeneic hematopoietic stem cell transplantation (allo-HSCT). T cells for CAR-T therapy can be derived from the peripheral blood (recipient) of the patient or donor. Despite having identical genomes, the different maturation environments of these T cells can lead to functional differences. This study aimed to compare the clinical outcomes of CAR-T cells derived from these two sources.

[METHODS] This multicenter, retrospective cohort study collected clinical data from 36 patients who experienced B-ALL relapse after allo-HSCT and received CD19 CAR-T cell therapy between January 2016 and October 2023 across seven centers. The primary endpoint was complete remission (CR)/CR with an incomplete hematologic recovery (CRi) rate at 28 days post-CAR-T cell infusion. Secondary endpoints included the 2-year overall survival (OS) rate, 2-year event-free survival (EFS) rate, incidence of graft-versus-host disease (GVHD), cytokine release syndrome (CRS), and CAR-T cell-related encephalopathy syndrome (CRES).

[RESULTS] A retrospective analysis was performed on 36 patients: 12 in the recipient group and 24 in the donor group. The recipient and donor groups showed no statistically significant differences in CR/CRi rates (83.3% vs. 100.0%, P = 0.105), 2-year EFS rates (50.8% vs. 51.6%, P = 0.617), or 2-year OS rates (49.5% vs. 63.6%, P = 0.215). In addition, the incidences of GVHD, CRS, and CRES did not significantly differ between the two groups. Further analysis within the donor group revealed 12 matched sibling donors (MSDs) and 12 haploidentical donors (HIDs). The 2-year EFS rate was statistically significantly greater in the HID group than in the MSD group (75.0% vs. 30.7%, P = 0.043), whereas no significant differences were observed in the CR/CRi rates, 2-year OS, or the incidence of GVHD, CRS, and CRES between these subgroups.

[CONCLUSIONS] Both recipient-derived and donor-derived CD19 CAR-T cell therapies are effective treatment options for B-ALL relapsed post-allo-HSCT patients. HID-derived CAR-T cells offer a longer EFS and may be considered the optimal choice.