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Introduction: Immune microenvironment plays an important role in the occurrence and development of acute myeloid leukemia (AML). Studies assessing the prognostic significance of bone marrow (BM) lymphocyte subsets' frequencies at diagnosis in patients with AML were limited. Methods: Fresh BM samples collected from 97 adult AML patients at diagnosis were tested for lymphocyte, T, CD4+T, CD8+T, γδT, NK, and B cell frequencies using multi‐parameter flow cytometry. Results: Low frequencies of lymphocytes, T, CD4+T, and CD8+T cells were associated with significantly lower rates of one‐course complete remission (CR) (all p < 0.05). Moreover, the frequency of CD4+T cells independently predicted one‐course CR achievement (p = 0.021). Low frequencies of T and CD8+T cells were significantly associated with lower relapse‐free survival (RFS) rates (p = 0.032; 0.034), respectively, and a low frequency of CD8+T cells was associated with a significantly lower overall survival (OS) rate (p = 0.028). Combination of frequency of CD8+T cells and ELN risk stratification showed that patients with ELN‐intermediate/adverse risk + high CD8+T cell frequency had a similar RFS rate to those with ELN‐favorable risk + high CD8+T cell frequency and those with ELN‐favorable risk + low CD8+T cell frequency (p = 0.88; 0.76), respectively. The RFS rate of patients with ELN intermediate/adverse risk + low CD8+T cell frequency was significantly lower than that of all aforementioned patients (p = 0.021; 0.0007; 0.028), respectively. Conclusion: The frequencies of BM lymphocyte subsets at diagnosis predicted clinical outcomes and could help improve risk stratification in AML. [ABSTRACT FROM AUTHOR]

Many studies have confirmed that overexpressed WT1 exists in leukemic cells, especially in AML. However, the immunophenotypic features of this sort of leukemic cells remain to be unclarified. We retrospectively analyzed the immunophenotype of 283 newly diagnosed AML patients with intermediated and poor cytogenetic risk to evaluate the correlation between phenotype and WT1 overexpression. EVI1 transcripts, KMT2A-PTD, FLT3-ITD, and NPM1 mutations were simultaneously assessed. Our results revealed that overexpressed WT1 was significantly associated with the expression of CD117, CD13, and CD123. Besides, leukemic cells with WT1 overexpression also lacked lymphoid and myeloid differentiation-related markers. FAB subtype M2 patients had higher WT1 levels, compared with other FAB subtype. Multivariate analysis was proved that NPM1 mutation, M2 subtype, and the expression of CD123 were independently associated with WT1 overexpression. These indicated that AML with overexpressed WT1 was proliferated and blocked in the early stage of AML development. It presumably provided some clues to detect overexpressed WT1 cells via multiparameter flow cytometry. CD123-targeted drugs might become one of the alternative treatments for patients with WT1 overexpression. [ABSTRACT FROM AUTHOR]

Highlights • A seven-color panel including CD34 and TdT was built to detect MRD in T-ALL. • The panel could be applied to >97% T-ALL patients independent of initial phenotype. • Only one MRD false-negative result occurred because of antigen shifts. • MRD positive detected by the panel at post-HSCT could effectively predict relapse. Abstract A seven-color panel was used to detect minimal residual disease (MRD) in T cell acute lymphoblastic leukemia (T-ALL) via flow cytometry (FCM). Its availability and clinical significance were studied in T-ALL patients with newly diagnosed (n = 64), relapsed (n = 48) and morphologically complete remission (n = 103). The following four features were used to identify immature cCD3+ T cells: CD34+, TdT+, but mCD3-/dim+, and CD45dim+. Among these features, either TdT or CD34 expression was the most useful and were found in 93.8% of patients at diagnosis and 86.7% of patients who relapsed. Although some of the immature markers had disappeared in 23 of 59 cases after therapy, only one case presented with a false negative MRD. Of the 74 consecutive patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT), MRD-positive patients showed a higher relapse rate, a higher cumulative incidence of relapse at 4 years and a shorter median relapse-free survival than MRD-negative patients at post-HSCT(72.7% vs 17.3%, P = 0.000; 100% vs 19.9%, P < 0.0001; and 16 months vs undefined, P < 0.0001). We demonstrated that this panel could be applied to>97% of T-ALL patients to detect MRD and predict relapse after allo-HSCT even in the absence of the initial immunophenotype. [ABSTRACT FROM AUTHOR]