Blinatumomab or Inotuzumab Ozogamicin as Bridge to Allogeneic Stem Cell Transplantation for Relapsed or Refractory B-lineage Acute Lymphoblastic Leukemia: A Retrospective Single-Center Analysis.

Background: Blinatumomab and inotuzumab ozogamicin are now widely used to treat relapsed or refractory B-cell acute lymphoblastic leukemia (r/r B-ALL).
Patients and Methods: We have reported the clinical course of 34 adult patients with r/r B-ALL receiving blinatumomab or inotuzumab ozogamicin at our institution from 2009 to 2019.
Results: Blinatumomab-based salvage therapy was applied for overt r/r B-ALL (n = 13) or minimal residual disease (MRD) positivity (n = 5). Of the 13 patients with r/r B-ALL, 9 (69%; 95% confidence interval [CI], 39%-91%) achieved complete remission (CR), with 78% of CR patients (95% CI, 40%-97%) reaching MRD negativity. MRD negativity was also achieved in all 5 patients treated for MRD positivity. The 1-year overall survival of patients receiving blinatumomab for r/r B-ALL and MRD positivity was 54% (n = 13; 95% CI, 26%-81%) and 80% (n = 5; 95% CI, 44-100), respectively. In the inotuzumab ozogamicin group, all 16 patients were treated for overt r/r B-ALL. The rate of CR was 94% (95% CI, 70%-100%), with 67% (95% CI, 38%-88%) of CR patients reaching MRD negativity. The 1-year OS after the first application of inotuzumab ozogamicin was 46% (95% CI, 18%-74%). Of those patients receiving blinatumomab and inotuzumab ozogamicin as a bridge-to-transplant strategy, 79% and 80%, respectively, proceeded to allogeneic stem cell transplantation. The most frequent drug-specific adverse events were similar to those previously reported, including cytokine release syndrome, capillary leak syndrome, and neurotoxicity for blinatumomab and transplant-associated veno-occlusive disease of the liver for inotuzumab ozogamicin.
Conclusion: Together with previous observations from phase III clinical trials, these data suggest that blinatumomab and inotuzumab ozogamicin are highly effective salvage regimens in r/r B-ALL.
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