The Quantification of Minimal Residual Disease Pre‐ and Post‐Unmanipulated Haploidentical Allograft by Multiparameter Flow Cytometry in Pediatric Acute Lymphoblastic Leukemia

BackgroundThis study aimed to determine the impact of the pre‐ and post‐minimal residual disease (MRD) status as well as the peri‐transplant MRD kinetics on clinical outcomes in pediatric ALL patients who received haploidentical allografts.MethodsA retrospective study (n = 166) was performed. MRD was determined using multiparameter flow cytometry.ResultsPediatric ALL patients with pre‐MRDneg had a lower cumulative incidences of relapse (CIR) compared to those with pre‐MRDpos (19.7% vs. 41.2%, P = 0.009). Compared to post‐MRDneg group, patients with post‐MRDpos experienced higher CIR (81.0% vs. 15.9%, P < 0.001), inferior LFS (14.3% vs. 66.9%, P < 0.001) and OS (19.1% vs. 66.9%, P < 0.001). In regard to peri‐MRD kinetics, compared with the MRD‐decreasing group and MRDneg/MRDneg group, MRD‐increasing group had higher CIR, lower probabilities of LFS and OS (P < 0.001). Compared to pre‐MRDneg/post‐MRDneg group, a higher CIR was found in the pre‐MRDpos/post‐MRDpos group (66.7% vs. 12.5%, P < 0.001), pre‐MRDpos/post‐MRDneg group (32.0% vs. 12.5%, P = 0.016), and pre‐MRDneg/post‐MRDpos group (91.7% vs. 12.5%, P < 0.001). A lower incidence of LFS and OS were found in pre‐MRDpos/post‐MRDpos group and pre‐MRDneg/post‐MRDpos group than in pre‐MRDneg/post‐MRDneg group (P < 0.05). Multivariate analyses confirmed the association of pre‐MRD status, post‐MRD status, and peri‐MRD kinetics with outcomes (P < 0.05).ConclusionsThe results indicate that, in the pediatric ALL subgroup, not only pre‐MRD status or post‐MRD status but also peri‐SCT MRD dynamics, were associated with an increased CIR after haploidentical allografts. Patients are put into different risk group based on MRD kinetics versus single time MRD status. © 2019 International Clinical Cytometry Society