Dose-Dense Mini-Hyper-CVD, Inotuzumab Ozogamicin and Blinatumomab Achieves Rapid MRD-Negativity in Philadelphia Chromosome-Negative B-cell Acute Lymphoblastic Leukemia

Background: The combination of low-intensity chemotherapy and inotuzumab ozogamicin (INO), with sequential blinatumomab, is highly effective in older adults with newly diagnosed B-cell acute lymphoblastic leukemia (ALL) and in relapsed or refractory B-cell ALL. Earlier, “dose-dense” administration of blinatumomab could lead to earlier and deeper measurable residual disease (MRD) responses and better outcomes. Patients and Methods: We performed a retrospective analysis of the safety and efficacy of a dose-dense regimen of mini-hyper-CVD (mini-hyperfractionated cyclophosphamide, vincristine, and dexamethasone alternating with mini-methotrexate and cytarabine), INO, and blinatumomab in patients with B-cell ALL. Results: Twenty-one patients were treated (frontline, n = 9; MRD consolidation, n = 4; relapsed/refractory, n = 8). In the frontline cohort, all patients achieved CR/CRi and MRD negativity by flow cytometry at the end of cycle 1. Across the frontline and MRD consolidation cohorts, 10/11 patients (91%) achieved next-generation sequencing MRD negativity at a sensitivity of 10⁻⁶, including 6/10 evaluable patients (60%) who achieved next-generation sequencing MRD negativity after cycle 1. The CR/CRi rate in the relapsed/refractory cohort was 63%, and all responders achieved MRD negativity by flow cytometry at the end of cycle 1. The 1-year overall survival rate for the combined cohort of the frontline and MRD-positive patients was 83%. No new safety signals were observed with the dose-dense mini-hyper-CVD, INO, and blinatumomab regimen. Conclusion: Dose-dense delivery of mini-hyper-CVD, INO, and blinatumomab was safe and resulted in rapid and deep MRD negativity in patients with B-cell ALL. This regimen is now being prospectively evaluated in both the frontline and relapsed/refractory settings.