The use of allogeneic hematopoietic stem cell transplantation (allo-HSCT) can improve survival in minimal residual disease (MRD)–negative remission patients with relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (B-ALL) after the start of monoclonal antibody treatment, according to the results of a landmark analysis presented at the virtual meeting of the European Society for Blood and Marrow Transplantation.
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A Wright's stained bone marrow aspirate smear of patient with precursor B-cell acute lymphoblastic leukemia.
Previous studies have indicated that allo-HSCT improves the results of treatment in r/r B-ALL patients, compared with chemotherapy alone. In addition, it has been found that the monoclonal antibodies (Mab), anti-CD19-blinatumomab and anti-CD22-inotuzumab ozogamicin, induced remission in a significant proportion of such patients.
To determine if the use of allo-HSCT improves the outcome of patients in MRD-negative remission with or without Mab treatment, researchers performed a landmark analysis of 110 patients who achieved MRD-negative status after Mab treatment. The analysis examined results at 2, 4, and 6 months subsequent to the initiation of Mab treatment, according to poster presentation by Inna V. Markova, MD, and colleagues at Pavlov University, Saint Petersburg, Russian Federation.
Study details
The researchers included 110 patients who achieved MRD-negative status outside of clinical trials at a single institution in the analysis. Forty of the patients (36%) were children and 70 (64%) were adults. The median age for all patients was 23 years and the median follow up was 24 months. Fifty-seven (52%) and 53 (48%) patients received Mab for hematological relapse and persistent measurable residual disease or for molecular relapse, respectively. Therapy with Mab alone without subsequent allo-HSCT was used in 36 (31%) patients (30 received blinatumomab and 6 received inotuzumab ozogamicin). A total of 74 (69%) patients received allo-HSCT from a matched related or unrelated donor (MD-HSCT, n = 38) or haploidentical donor (Haplo-HSCT, n = 36). All patients received posttransplantation cyclophosphamide (PTCY)–based graft-versus host disease (GVHD) prophylaxis. Landmark analysis was performed at 2, 4, and 6 months after Mab therapy initiation to determine the effect of allo-HSCT on the outcome and the optimal timing of HSCT. Overall survival and disease-free survival (DFS) were used as outcomes.
Promising results
No significant differences between the MD-HSCT, Mab alone, and Haplo-HSCT groups were observed in 2-month landmark analysis (P = .4 for OS and P =.65 for DFS). However, the 4-month landmark analysis demonstrated superior overall survival and DFS in patients after MD-HSCT, but not Haplo-HSCT, compared with Mab alone: 2-year OS was 75%, 50%, and 27,7% (P = .032) and DFS was 53.5%, 51.3%, and 16.6% (P = .02) for MD-HSCT, Mab alone and Haplo-HSCT groups, respectively. In addition, 6-month analysis showed that there was no benefit from subsequent transplantation, according to the authors, with regard to overall survival (P = .11).
“Our study demonstrated that at least MD-HSCT with PTCY platform improves survival in MRD-negative remission if performed during the first 4 months after Mab initiation. Haplo-HSCT or MD-HSCT beyond 4 months are not associated with improved outcomes in this groups of patients,” the researchers concluded.
The researchers reported they had no conflicts of interest to declare.