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Acute myeloid leukemia (AML) with retinoic acid receptor γ (RARG) rearrangement has clinical, morphologic, and immunophenotypic features similar to classic acute promyelocytic leukemia. However, AML with RARG rearrangement is insensitive to alltrans retinoic acid (ATRA) and arsenic trioxide (ATO) and carries a poor prognosis. We initiated a global cooperative study to define the clinicopathological features, genomic and transcriptomic landscape, and outcomes of AML with RARG rearrangements collected from 29 study groups/institutions worldwide. Thirty-four patients with AML with RARG rearrangements were identified. Bleeding or ecchymosis was present in 18 (54.5%) patients. Morphology diagnosed as M3 and M3v accounted for 73.5% and 26.5% of the cases, respectively. Immunophenotyping showed the following characteristics: positive for CD33, CD13, and MPO but negative for CD38, CD11b, CD34, and HLA-DR. Cytogenetics showed normal karyotype in 38% and t(11;12) in 26% of patients. The partner genes of RARG were diverse and included CPSF6, NUP98, HNRNPc, HNRNPm, PML, and NPM1. WT1- and NRAS/KRAS-mutations were common comutations. None of the 34 patients responded to ATRA and/or ATO. Death within 45 days from diagnosis occurred in 10 patients (∼29%). At the last follow-up, 23 patients had died, and the estimated 2-year cumulative incidence of relapse, event-free survival, and overall survival were 68.7%, 26.7%, and 33.5%, respectively. Unsupervised hierarchical clustering using RNA sequencing data from 201 patients with AML showed that 81.8% of the RARG fusion samples clustered together, suggesting a new molecular subtype. RARG rearrangement is a novel entity of AML that confers a poor prognosis. This study is registered with the Chinese Clinical Trial Registry (ChiCTR2200055810).

Acute myeloid leukemia (AML) featuring retinoic acid receptor-gamma (RARG) rearrangements exhibits morphological features resembling those of acute promyelocytic leukemia but is associated with drug resistance and poor clinical outcomes. However, the mechanisms underlying the role of RARG fusions in leukemogenesis remain elusive. Here, we show that RARG fusions disrupt myeloid differentiation and promote proliferation and self-renewal of hematopoietic stem and progenitor cells (HSPCs) by upregulating BCL2 and ATF3. RARG fusions overexpression leads to preleukemic phenotypes but fails to induce oncogenic transformation. However, the co-occurrence of RARG fusions and heterozygous Wt1 loss induce fully penetrant AML by activating MYC and HOXA9/MEIS1 targets. Leveraging Connectivity Map resources and high-throughput screening, we identify venetoclax, homoharringtonine, and daunorubicin as potential therapeutic options for RARG-AML. Overall, our findings provide pivotal insights into the molecular mechanisms governed by RARG fusions and enhanced by WT1 loss in AML development and propose a rational therapeutic strategy for RARG-AML. Acute Myeloid Leukaemia (AML) with Retinoic acid receptor-gamma (RARG) fusions have similarities to Acute Promyelocytic Leukemia (APL) but are not responsive to standard APL treatments. Here, the authors show the specific molecular mechanisms lead by RARG fusions in AML driving leukemogenesis and as potential therapeutic targets. [ABSTRACT FROM AUTHOR]

The prognostic significance of soluble immune checkpoint molecule TIM-3 and its ligands in the plasma has been illustrated in various solid tumors, but such study in newly diagnosed acute myeloid leukemia (AML) remains absent. Soluble TIM-3, Gal-9, and CEACAM1 levels in bone marrow plasma samples collected from 90 adult AML patients at diagnosis and 12 healthy donors were measured by enzyme-linked immunosorbent assays, and 16 AML patients were simultaneously tested cell membrane TIM-3 expression by multicolor flow cytometry. AML patients had significantly elevated soluble TIM-3 levels and similar soluble Gal-9 and CEACAM1 levels compared with healthy donors (P = 0.0003, 0.26, and 0.96, respectively). In the whole cohort, a high soluble TIM-3 level was the sole independent adverse prognostic factor for relapse-free survival (RFS) (P = 0.0060), and together with adverse European LeukemiaNet genetic risk they were independent poor prognostic factors for event-free survival (P = 0.0030 and 0.0040, respectively). A high soluble CEACAM1 level was significantly related to lower RFS (P = 0.028). In addition, a high soluble Gal-9 level had a significant association with lower RFS in patients receiving allogeneic hematopoietic stem cell transplantation at the first complete remission (P = 0.037). Furthermore, soluble TIM-3 level tended to have positive correlation with the percentage of nonblast myeloid TIM-3+ cells in nucleated cells in AML (r = 0.48, P = 0.073). Therefore, the high soluble TIM-3 level in the diagnostic BM plasma predicted poor outcome in adult AML patients, and a high sGal-9 level was associated with relapse after allogeneic hematopoietic stem cell transplantation. [ABSTRACT FROM AUTHOR]

Background: Compared to other immune checkpoint molecules, T cell immunoglobulin domain and mucin domain-3 (TIM-3) is highly expressed on natural killer (NK) cells, but its functional role and prognostic significance in acute myeloid leukemia (AML) remains unclear. This study aims to evaluate the role of TIM-3 expression on the cytotoxic and killing capacity of NK cells and its prognostic significance in AML. Methods: AML public single-cell RNA sequencing (scRNAseq) data were used to analyze the correlation of transcript levels between HAVCR2 (encoding TIM-3) and cytotoxic molecules in NK cells. NK cells from the bone marrows of seven newly diagnosed AML patients and five healthy donors (HDs) were stimulated in vitro and cell-killing activity was evaluated. A total of one hundred and five newly diagnosed adult AML patients and seven HDs were tested the expression of TIM-3 and cytotoxic molecules on the bone marrow NK cells by multi-parameter flow cytometry (MFC). Results: Both scRNAseq and MFC analysis demonstrated that TIM-3 expression on NK cells was positively related to the levels of perforin (PFP) and granzyme B (GZMB) (all p < 0.05) in AML. It was PFP and GZMB but not the TIM-3 level that was related to NK-cell-killing activity against K562 cells (p = 0.027, 0.042 and 0.55). A high frequency of TIM-3+ NK cells predicted poorer relapse-free survival (RFS) and event-free survival (EFS) (p = 0.013 and 0.0074), but was not an independent prognostic factor, whereas low GZMB levels in TIM-3+ NK cells independently predicted poorer RFS (p = 0.0032). Conclusions: TIM-3 expression on NK cells is positively related to PFP and GZMB levels but has no relation to cell-killing activity in AML, and low GZMB levels in TIM-3+ NK cells in the diagnostic bone marrows predicts poor outcomes. This study lays a theoretical foundation for the clinical application of immune checkpoint inhibitor treatment. [ABSTRACT FROM AUTHOR]

Summary: Wilms' tumour 1 (WT1) can function as an oncogene or a tumour suppressor. Our previous clinical cohort studies showed that low WT1 expression at diagnosis independently predicted poor outcomes in acute myeloid leukaemia (AML) with RUNX1::RUNX1T1, whereas it had an opposite role in AML with non‐favourable cytogenetic risk (RUNX1::RUNX1T1‐deficient). The molecular mechanism by which RUNX1::RUNX1T1 affects the prognostic significance of WT1 in AML remains unknown. In the present study, first we validated the prognostic significance of WT1 expression in AML. Then by using the established transfected cell lines and xenograft tumour model, we found that WT1 suppresses proliferation and enhances effect of cytarabine in RUNX1::RUNX1T1(+) AML but has opposite functions in AML cells without RUNX1::RUNX1T1. Furthermore, as a transcription factor, WT1 physically interacts with RUNX1::RUNX1T1 and acts as a co‐factor together with RUNX1::RUNX1T1 to activate the expression of its target gene DUSP6 to dampen extracellular signal‐regulated kinase (ERK) activity. When RUNX1::RUNX1T1‐deficient, WT1 can activate the mitogen‐activated extracellular signal‐regulated kinase/ERK axis but not through targeting DUSP6. These results provide a mechanism by which WT1 together with RUNX1::RUNX1T1 suppresses cell proliferation through WT1/DUSP6/ERK axis in AML. The current study provides an explanation for the controversial prognostic significance of WT1 expression in AML patients. [ABSTRACT FROM AUTHOR]

Background: The effect of the expression of the newly identified immune checkpoint, T cell immunoglobulin and immunoreceptor tyrosine-based inhibition motif domain (TIGIT) on NK cells in core binding factor-acute myeloid leukemia (CBF-AML) remains to be investigated. Methods: Fresh bone marrow samples from a total of 39 newly diagnosed CBF-AML patients and 25 healthy donors (HDs) were collected for testing the phenotype and function state of total NK, CD56bright, and CD56dim NK cell subsets after in vitro stimulation. Results: The frequencies of TIGIT+ cells in total NK, CD56bright, and CD56dim NK cell subsets had no significant difference between patients and HDs. TNF-α and INF-γ levels were uniformly lower in TIGIT+ cells than the corresponding TIGIT− cells in all HDs, whereas those for TIGIT+ to TIGIT− cells in patients were highly heterogenous; TIGIT expression was not related to PFP and GZMB expression in HDs, whereas it was related to higher intracellular PFP and GZMB levels in patients. Patients' TIGIT+ NK cells displayed lower K562 cell-killing activity than their TIGIT− NK cells. In addition, high frequencies of TIGIT+ cells in total NK and CD56dim NK cells were associated with poor RFS. Conclusions: TIGIT expression affected the diagnostic bone marrow-sited NK cell function and had prognostic significance in CBF-AML patients. [ABSTRACT FROM AUTHOR]

Introduction: Central nervous system leukemia (CNSL) remains a serious complication in patients with acute myeloid leukemia (AML) and an ambiguous prognostic factor for those receiving allo‐geneic hematopoiesis stem cell transplantation (allo‐HSCT). It is unknown whether using more sensitive tools, such as multiparameter flow cytometry (MFC), to detect blasts in the cerebrospinal fluid (CSF) would have an impact on outcome. Methods: We retrospectively analyzed the clinical outcomes of 1472 AML patients with or without cytology or MFC positivity in the CSF before transplantation. Abnormal CSF (CSF+) was detected via conventional cytology and MFC in 44 patients at any time after diagnosis. A control group of 175 CSF‐normal (CSF−) patients was generated via propensity score matching (PSM) analyses according to sex, age at transplant, and white blood cell count at diagnosis. Results: Compared to those in the CSF‐negative group, the conventional cytology positive and MFC+ groups had comparable 8‐year nonrelapse mortality (NRM) (4%, 4%, and 6%, p = 0.82), higher cumulative incidence of relapse (CIR) (14%, 31%, and 32%, p = 0.007), lower leukemia‐free survival (LFS) (79%, 63%, and 64%, p = 0.024), and overall survival (OS) (83%, 63%, and 68%, p = 0.021), with no significant differences between the conventional cytology positive and MFC+ groups. Furthermore, multivariate analysis confirmed that CSF involvement was an independent factor affecting OS and LFS. Conclusion: Our results indicate that pretransplant CSF abnormalities are adverse factors independently affecting OS and LFS after allotransplantation in AML patients. [ABSTRACT FROM AUTHOR]

Background: Currently, the goal of chronic myeloid leukemia (CML) treatment is normal survival and good quality of life without life-long treatment, namely, “treatment-free remission” (TFR). At present, approximately only 50% of patients with CML with a deep molecular response are able to discontinue tyrosine kinase inhibitor (TKI) without experiencing molecular relapse [MR; loss of major molecular response (MMR)]. In addition, prior interferon (IFN) treatment is associated with a higher rate of TFR. Methods: We aimed to evaluate the feasibility of TKI discontinuation in Chinese patients with CML and determine whether IFN could prevent MR when used after TKI discontinuation in patients with 0.0032% < BCR-ABL IS ⩽0.1%. Therefore, we retrospectively analyzed the data of patients with CML who discontinued TKI treatment at our center. Results: Forty-nine patients who discontinued TKI therapy after achieving MR 4.5 were included in this study, and the median follow-up time from TKI discontinuation was 27 (7, 75) months. Nineteen patients eventually lost MMR, and the TFR rate of the 49 patients was 67% (95% confidence interval 53.6%, 80.3%) at 12 months. The duration of MR 4.5 ⩾54 months and duration of imatinib ⩾85 months were significantly associated with a higher TFR rate. Of the 22 patients with 0.0032% < BCR-ABL IS ⩽0.1%, 12 received IFN-α treatment. The median IFN-α therapy duration was nine (2, 18) months, and three patients eventually lost MMR. Three patients discontinued IFN-α after 2, 2.5, and 10 months, and maintained MMR for 9, 8, and 11 months after IFN discontinuation, respectively. Of the 10 patients not receiving IFN-α treatment, eight eventually lost MMR. The MR-free survival rate was significantly different between the patients treated with and those treated without IFN-α over 24 months (70.7% versus 15.0%, p = 0.002). Conclusion: These results indicate that after TKI discontinuation, IFN-α can be administered to patients with 0.0032% < BCR-ABL IS ⩽0.1%, which may help prevent MR.

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]

In addition to RUNX1::RUNX1T1 transcript levels, measurable residual disease monitoring using KIT mutant (KITmut) DNA level is reportedly predictive of relapse in t (8; 21) acute myeloid leukemia (AML). However, the usefulness of KITmut transcript levels remains unknown. A total of 202 bone marrow samples collected at diagnosis and during treatment from 52 t (8; 21) AML patients with KITmut (D816V/H/Y or N822K) were tested for KITmut transcript levels using digital polymerase chain reaction. The individual optimal cutoff values of KITmut were identified by performing receiver operating characteristics curve analysis for relapse at each of the following time points: at diagnosis, after achieving complete remission (CR), and after Course 1 and 2 consolidations. The cutoff values were used to divide the patients into the KITmut‐high (KIT_H) group and the KITmut‐low (KIT_L) group. The KIT_H patients showed significantly lower relapse‐free survival (RFS) and overall survival (OS) rates than the KIT_L patients after Course 1 consolidation (p = 0.0040 and 0.021, respectively) and Course 2 consolidation (p = 0.018 and 0.011, respectively) but not at diagnosis and CR. The <3‐log reduction in the RUNX1::RUNX1T1 transcript levels after Course 2 consolidation was an independent adverse prognostic factor for RFS and OS. After Course 2 consolidation, the KIT_H patients with >3‐log reduction in the RUNX1::RUNX1T1 transcript levels (11/45; 24.4%) had similar RFS as that of patients with <3‐log reduction in the RUNX1::RUNX1T1 transcript levels. The combination of KITmut and RUNX1::RUNX1T1 transcript levels after Course 2 consolidation may improve risk stratification in t (8; 21) AML patient with KIT mutation. [ABSTRACT FROM AUTHOR]

Zinc finger protein 384 (ZNF384) rearrangement defined a novel subtype of B‐cell acute lymphoblastic leukemia (B‐ALL). The prognostic significance of ZNF384 fusion transcript levels represented measurable residual disease remains to be explored. ZNF384 fusions were screened out in 57 adult B‐ALL patients at diagnosis by real‐time quantitative polymerase chain reaction and their transcript levels were serially monitored during treatment. The reduction of ZNF384 fusion transcript levels at the time of achieving complete remission had no significant impact on survival, whereas its ≥2.5‐log reduction were significantly associated with higher relapse free survival (RFS) and overall survival (OS) rates after course 1 consolidation (p = 0.022 and = 0.0083) and course 2 consolidation (p = 0.0025 and = 0.0008). Compared with chemotherapy alone, allogeneic hematopoietic stem cell transplantation (allo‐HSCT) significantly improved RFS and OS of patients with <2.5‐log reduction after course 1 consolidation (p < 0.0001 and = 0.0002) and course 2 consolidation (p = 0.0003 and = 0.019), whereas exerted no significant effects in patients with ≥2.5‐log reduction (all p > 0.05). ZNF384 fusion transcript levels after course 1 and course 2 consolidation strongly predict relapse and survival and may guide whether receiving allo‐HSCT in adult B‐ALL. [ABSTRACT FROM AUTHOR]