The significance of peri-transplantation minimal residual disease assessed by multiparameter flow cytometry on outcomes for adult AML patients receiving haploidentical allografts

A retrospective study (n = 460) was performed to assess the relationship between minimal residual disease (MRD) and transplant outcomes in a haplo-stem cell transplantation (SCT) setting. Patients from the pre-MRDneg group and the pre-MRDpos group had comparable outcomes. Compared to post-MRDneg patients, post-MRDpos patients had a higher incidence of relapse (100.0% vs. 8.3%, p < 0.001), lower incidences of overall survival (OS) (16.9% vs. 78.2%, p < 0.001) and leukemia-free survival (LFS) (0% vs. 76.5%, p < 0.001), and comparable probability of NRM (13.4% vs. 16.9%, p = 0.560). In a second set of analyses, all adult AML patients undergoing haplo-SCT were classified into the MRDneg/MRDneg group, the MRD decreasing group, and the MRD increasing group according to MRD dynamics by flow cytometry peri-SCT. Compared to the other two groups, patients from the MRD increasing group had higher cumulative incidences of relapse (MRD increasing, 100.0%; MRDneg/MRDneg, 9.6%; MRD decreasing, 19.2%; p < 0.001) and worse probabilities of OS (MRD increasing, 28.5%; MRDneg/MRDneg, 76.3%; MRD decreasing, 76.0%; p < 0.001) and LFS (MRD increasing, 0.0%; MRDneg/MRDneg, 73.9%; MRD decreasing, 74.0%; p < 0.001). The results indicated that haploidentical allografts might have a beneficial anti-leukemia effect in eradicating pretransplantation MRD, and MRD assessment peri-SCT is useful for risk stratification from a practical perspective.