Pre-transplant blinatumomab and/or inotuzumab ozogamicin therapy for relapsed/refractory acute lymphoblastic and B/myeloid mixed phenotype acute leukemia in adults

Real-world data on blinatumomab (BLI) and inotuzumab ozogamicin (INO) for relapsed or refractory B-acute lymphoblastic leukemia (RR-ALL) before hematopoietic stem cell transplantation (HCT) are limited. To compare the efficacy of salvage therapy with BLI and/or INO and conventional chemotherapy as a bridge to HCT, we retrospectively evaluated patients with RR-ALL who underwent first HCT at our institute between 2004 and 2023. Based on whether they had received salvage therapy with BLI and/or INO, 70 recipients were divided into a BLI/INO (n = 22) and a control group (n = 48). The complete remission (CR) rate before HCT was higher in the BLI/INO group than in the control group (77.3 % vs. 35.4 %, p = 0.002). Two years after the first HCT, the overall survival (OS) and disease-free survival (DFS) were significantly higher in the BLI/INO group than in the control group (OS, 63.0 % vs. 31.2 %, p = 0.022; DFS 49.6 % vs. 22.9 %, p = 0.049), with comparable cumulative incidence of relapse (CIR, 41.3 % vs. 47.9 %; p = 0.767) and lower tendency of non-relapse mortality (NRM, 9.1 % vs. 29.2 %; p = 0.057). Multivariate analysis revealed that non-CR status before HCT was the only factor associated with poor OS (hazard ratio [HR], 4.263; p < 0.001) and higher CIR (HR, 2.250; p = 0.048). In patients in CR at HCT, there was no difference in HCT outcomes at 2 years (OS, 82.4 % vs. 58.8 %; p = 0.324; DFS, 64.2 % vs. 47.1 %; p = 0.496; CIR, 24.1 % vs. 41.2 %; p = 0.375; NRM, 11.8 % vs. 11.8 %; p = 0.950). BLI and/or INO therapy for RR-ALL was associated with better survival after HCT, probably due to the higher CR rate.