Genetic and clinical characteristics of acute B-cell lymphoblastic leukemia with MEF2D fusions and report of two novel MEF2D rearrangements.

The MEF2D rearrangement is a recurrent chromosomal abnormality detected in approximately 2.4-5.3% of patients with acute B-cell lymphoblastic leukemia (B-ALL). Currently, MEF2D-rearranged B-ALL is not classified as an independent subtype in the WHO classification. Consequently, the clinical significance of MEF2D rearrangement in B-ALL remains largely unexplored. In this study, we retrospectively screened 260 B-ALL patients with RNA sequencing data collected between November 2018 and December 2022. Among these, 10 patients were identified with MEF2D rearrangements (4 with MEF2D::HNRNPUL1, 3 with MEF2D::BCL9, 1 with MEF2D::ARID1B, 1 with MEF2D::DAZAP1 and 1 with MEF2D::HNRNPM). Notably, HNRNPM and ARID1B are reported as MEF2D fusion partners for the first time. The patient with the MEF2D::HNRNPM fusion was resistant to chemotherapy and chimeric antigen receptor T-cell therapy and relapsed early after allogenic stem cell transplantation. The patient with MEF2D::ARID1B experienced early extramedullary relapse after diagnosis. All 10 patients achieved complete remission after induction chemotherapy. However, 9/10 (90%) of whom experienced relapse. Three of the 9 patients relapsed with aberrant expression of myeloid antigens. The median overall survival of these patients was only 11 months. This small cohort showed a high incidence of early relapse and short survival in patients with MEF2D rearrangements.

Mutation spectrum of FLT3 and significance of non-canonical FLT3 mutations in haematological malignancy.

Fms-like tyrosine kinase 3 (FLT3) is frequently mutated in haematological malignancies. Although canonical FLT3 mutations including internal tandem duplications (ITDs) and tyrosine kinase domains (TKDs) have been extensively studied, little is known about the clinical significance of non-canonical FLT3 mutations. Here, we first profiled the spectrum of FLT3 mutations in 869 consecutively newly diagnosed acute myeloid leukaemia (AML), myelodysplastic syndrome and acute lymphoblastic leukaemia patients. Our results showed four types of non-canonical FLT3 mutations depending on the affected protein structure: namely non-canonical point mutations (NCPMs) (19.2%), deletion (0.7%), frameshift (0.8%) and ITD outside the juxtamembrane domain (JMD) and TKD1 regions (0.5%). Furthermore, we found that the survival of patients with high-frequency (>1%) FLT3-NCPM in AML was comparable to those with canonical TKD. In vitro studies using seven representative FLT3-deletion or frameshift mutant constructs showed that the deletion mutants of TKD1 and the FLT3-ITD mutant of TKD2 had significantly higher kinase activity than wild-type FLT3, whereas the deletion mutants of JMD had phosphorylation levels comparable with wild-type FLT3. All tested deletion mutations and ITD were sensitive to AC220 and sorafenib. Collectively, these data enrich our understanding of FLT3 non-canonical mutations in haematological malignancies. Our results may also facilitate prognostic stratification and targeted therapy of AML with FLT3 non-canonical mutations.

Rapid molecular response to dasatinib in Ph-like acute lymphoblastic leukemia patients with ABL1 rearrangements: case series and literature review.

Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk subtype with a poor prognosis under conventional chemotherapy. Ph-like ALL has a similar gene expression profile to Philadelphia chromosome-positive (Ph+) ALL, but is highly heterogeneous in terms of genomic alterations. Approximately 10-20% of patients with Ph-like ALL harbor ABL class (e.g. ABL1, ABL2, PDGFRB, and CSF1R) rearrangements. Additional genes that form fusion genes with ABL class genes are still being researched. These aberrations result from rearrangements including chromosome translocations or deletions and may be targets of tyrosine kinase inhibitors (TKIs). However, due to the heterogeneity and rarity of each fusion gene in clinical practice, there is limited data on the efficacy of tyrosine kinase inhibitors. Here, we report three cases of Ph-like B-ALL with ABL1 rearrangements treated with the dasatinib backbone for the CNTRL::ABL1, LSM14A::ABL1, and FOXP1::ABL1 fusion genes. All three patients achieved rapid and profound remission with no significant adverse events. Our findings suggest that dasatinib is a potent TKI for the treatment of ABL1-rearranged Ph-like ALL and can be used as a first-line treatment option for such patients.

Pattern and prognostic value of FLT3-ITD mutations in Chinese de novo adult acute myeloid leukemia.

FMS-like tyrosine kinase 3 (FLT3) is one of the most frequently mutated genes in hematological malignancies. FLT3 internal tandem duplication (FLT3-ITD) mutations located in juxtamembrane domain (JMD) and tyrosine kinase domain 1 (TKD1) regions account for two-thirds of all FLT3 mutations. The outcome of patients remains unsatisfactory, with low survival rates. It is not yet known whether the different mutations within the FLT3 gene are all associated with patient outcome. In addition, the cause of FLT3-ITD in-frame duplication events remains unknown. Although there are some published studies investigating the FLT3-ITD mutation and its clinical implications in Chinese acute myeloid leukemia (AML) patients, sample sizes tend to be small and detailed molecular profiles of FLT3 mutations are lacking in these studies. In our study, 227 FLT3-ITD sequences were analyzed from 227 Chinese de novo AML patients. ITD were next classified into 3 types based on molecular profiles of insertion DNA sequences: DNA complete duplication (type I), DNA partial duplication (type II) and complete random sequence (type III). From the 154 patients, we confirmed that high ITD allelic ratio (≥.5) and allogeneic stem cell transplant treatment under CR1 are independent prognostic factors. We also presented evidence that ITD integration sites in the hinge region or beta1-sheet region are an unfavorable prognostic factor in adult AML patients with FLT3-ITD mutations. These findings may help to decipher the mechanisms of FLT3-ITD in-frame duplication events and stratify patients when considering different therapeutic combinations.

RUNX1 together with DAT mutations predicted poor outcome in acute myeloid leukemia.

We retrospectively explored the prognostic impact of DAT mutations at diagnosis in 122 RUNX1mut AML patients. RUNX1 missense mutation was dominant in the RUNT domain, and frameshift mutation was dominant in the TAD domain. DAT mutations occurred in 38.5% of RUNX1mut AML. After propensity score matching, DATpos patients had worse two-year relapse-free survival (RFS) than DATneg patients (p = .041). Moreover, RUNX1high (VAF ≥ 37.6%) patients showed poorer two-year overall survival (OS) and RFS than RUNX1low (VAF < 37.6%) patients (OS, p = .033; RFS, p = .027), especially in the RUNX1highDATpos group. Additionally, multivariate analysis confirmed that DAT mutations at diagnosis were an independent adverse factor for RFS. There were no significant differences in two-year OS and RFS between DATpos and DATneg patients or between RUNX1high and RUNX1low patients who undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). Collectively, DAT mutations at diagnosis were adverse factors for RFS, and allo-HSCT could likely improve the poor outcomes of these patients.

Epigenetic therapy with chidamide alone or combined with 5­azacitidine exerts antitumour effects on acute myeloid leukaemia cells in vitro.

Chidamide, a selective histone deacetylase inhibitor, has antitumour effects. 5­azacitidine (5­AZA), a hypomethylating agent, is effective in treating acute myeloid leukaemia (AML) and myelodysplastic syndrome. However, to the best of our knowledge, the effect of chidamide and 5­AZA on AML cell lines has not been fully investigated. In the present study, the antileukaemia activity of chidamide, alone and in combination with 5­AZA, was assessed on different subtypes of AML cell lines (M1­M5) and primary samples from several patients with AML in vitro. The results indicated that the proliferation of leukaemia cells was significantly and dose­dependently inhibited by chidamide and 5­AZA alone or in combination. The combination also had marked synergistic effects to induce apoptosis of AML cells. The apoptosis of leukaemia cells was induced via downregulation of BCL­2 and myeloid­cell leukemia 1 (MCL­1) levels. Of note, chidamide also degraded the MCL­1 protein in venetoclax­resistant U937 cells, in which the MCL­1 protein is upregulated. In addition, chidamide was able to induce myeloid differentiation (with CD11b upregulation) of AML cell lines or monocytic/dendritic differentiation (with CD86 upregulation) of primary cultured cells from several patients with AML. Chidamide was also able to promote the differentiation of the venetoclax­resistant U937 cell line by upregulating CD11b expression. In conclusion, chidamide alone or combined with 5­AZA may be an effective therapy for AML.

[Observation of Nutritional Status Changes in Patients with Acute Leukemia During Chemotherapy].

OBJECTIVE: To assess changes of nutritional status by comprehensive nutrition assessment including nutritional risk screening, dietary assessment, blood biochemical index, and body composition in acute leukemia patients who had undergone chemotherapy. METHODS: A total of 169 patients with acute leukemia treated at The First Affiliated Hospital of Soochow University from June 2018 to August 2019 were recruited for this study. Before and after chemotherapy, the NRS-2002 and PG-SGA scales, dietary intake, blood biochemical index and body composition were evaluated to compare the changes of nutritional status. RESULTS: NRS-2002 score and PG-SGA score after chemotherapy were significantly increased than those before chemotherapy (P<0.001). Many patients had insufficient nutritional intake during chemotherapy, and the dietary intake score of patients with induction chemotherapy was significantly lower than that of patients with consolidation chemotherapy (P=0.043). The results of multivariate analysis showed that induction chemotherapy was the independent risk factor for the increase of PG-SGA scores and the decrease of dietary intake (all P<0.05). After chemotherapy, the white blood cell count, hemoglobin, and platelet count were significantly decreased (P<0.001), the prealbumin was significantly increased (P<0.001), and the blood glucose was increased (P=0.04), but albumin was not significantly changed. The weight, body mass index, fat-free mass, skeletal muscle mass and intracellular water were all significantly decreased (P<0.001), and visceral fat area was increased significantly after chemotherapy (P<0.05), especially in newly-diagnosed acute lymphoblastic leukemia patients after the induction of chemotherapy. CONCLUSION: The nutritional status of patients with acute leukemia has undergone significant changes after chemotherapy. A single indicator has limited significance for nutritional status assessment. Comprehensive assessment of nutritional status by multiple tools is worthy of clinical application.