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.

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.

[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.

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.

Combination of Venetoclax and Midostaurin Efficiently Suppressed Relapsed t(8;21)Acute Myeloid Leukemia With Mutant KIT After Failure of Venetoclax Plus Azacitidine Treatment.

Acute myeloid leukemia (AML) with t(8;21) is categorized as favorable-risk AML, but KIT mutations show a significantly poor prognostic impact in such patients. Persistent vulnerability to relapse is a major challenge in the treatment of this subtype of patients. Venetoclax is a BCL-2 selective inhibitor. The venetoclax+HMA strategy is also a notable salvage regimen that achieves good clinical outcomes in the treatment of relapsed or refractory (R/R) AML. However, in our clinical practice, we found that disease progressed rapidly even after venetoclax+azacitidine (AZA) therapy in two relapsed t(8;21) AML patients with KIT mutations. We report for the first time the therapeutic potential of venetoclax+midostaurin as a new combination therapy for relapsed t(8;21) AMLs with KIT mutations showing resistance to venetoclax+AZA therapy. Our ex vivo study also showed that midostaurin alone could inhibit proliferation and induce apoptosis of Kasumi-1 cells (e.g. Midostaurin induced G2 phase cell arrest, down-regulated p-KIT and BCL-2, while Bax protein levels were up-regulated) and observed a synergistic anti effect when the two drugs were combined. Our study shows that the venetoclax+midostaurin regimen may be a promising treatment option for R/R t(8;21) AML with KIT mutations.

A Combined Histone Deacetylases Targeting Strategy to Overcome Venetoclax Plus Azacitidine Regimen Resistance in Acute Myeloid Leukaemia: Three Case Reports.

The management of patients with relapsed or refractory (R/R) acute myeloid leukaemia (AML) remains a challenge with few reliably effective treatments. Chidamide, a new selective HDAC inhibitor, has demonstrated some effectiveness in AML patients. Herein, we reported three patients with R/R AML who were unresponsive to venetoclax plus azacitidine (VA) but were successfully treated with VA when chidamide was added to the regimen. MCL1 is one of the anti-apoptotic proteins. Chidamide targets the MCL1 protein, which may permit venetoclax resistance when upregulated. We determined MCL1 protein expression in different AML cell lines, and chidamide could downregulate MCL1 expression in venetoclax resistance AML cells. In general, our experience showed that the chidamide/VA combination could improve the condition of R/R AML patients who are resistant to VA. Formally evaluating this regimen in R/R AML patients may be meaningful.

[Effect of FLT3-ITD Length on 32D Cell Proliferation, Apoptosis and Sensitivity to FLT3 Inhibitor].

OBJECTIVE: To study the effects of FLT3-ITD length on 32D cell proliferation, apoptosis and sensitivity to FLT3 inhibitor, so as to provide references for stepwise therapy of FLT3-ITD mutated acute myeloid leukemia patients. METHODS: Three different FLT3-ITD mutants with same or adjacent insert sites were selected and constructed in an eukaryotic expression vector. FLT3-ITD mutants stably expressed 32D cell strains were selected with the help of lentivirus system and IL3 free cell culture medium. The proliferation and apoptosis of 32D cell strains after AC220 treatment were detected. RESULTS: FLT3-ITD mutants (ITD1, ITD2 and ITD3) stably expressed 32D cell strains were constructed successfully. In the absence of IL3 factor, the proliferation number of ITD1, ITD2 and ITD3 cell strains were mounted up to 2.3 folds, 3.7 folds, and 4.3 folds after 48 hours, respectively. Under the exposure of FLT3 inhibitor AC220, the IC50 values was 0.183, 0.446 and 0.836 nmol/L, and apoptosis rates was 88.6%, 34.2% and 16.1%, respectively. CONCLUSION: FLT3-ITD mutant expressed cell strains with longer ITD show higher capacity of proliferation and higher tolerance to AC220 treatment.

[Analysis of Factors Influencing Overall Survival of MDS Patients Transplanted with HSCs].

OBJECTIVE: To analyze the effect of clinical features, routine laboratory examination and related gene mutation on the OS of patients with myelodysplastic syndrome (MDS) after hematopoietic stem cell transplantation (HSCT). METHODS: 121 patients diagnosed as MDS and underwent hematopoietic stem cell transplantation in the First Affiliated Hospital of Soochow University from October 2013 to August 2018 were selected. Basic information of the patients was collected, and blood cells, bone marrow blasts at initial diagnosis, chromosomal karyotypes and gene mutations of the patients were detected.The effect of different factors on overall survival (OS) was analyzed by statistical method. RESULTS: Kaplan-Meier univariate analysis shows that OS was significanly different among different age groups. The 3-year OS rate of patients aged 0-29 years was (83.3±7.7) %, the 3-year OS rate in patients aged 30-49 years was (58.1±7.7 %), and the 3-year OS rate of patients aged 50-69 years was (31.0±22.6) %, which was statistically different (P＜0.05) between different groups. There were also significant differences in OS among patients with different transplantation types. 3-year OS rate: HLA-matched sibling HSCT＞unrelated HLA-matched HSCT＞haploidentical HSCT＞micro HSCT. The OS rate of patients with bone marrow blasts≥10% seems lower than blasts＜10%, but there was no statistical difference.The 3-year OS rate of patients with chromosomal karyotype complex abnormality was (47.7±11.5) %, and that of patients without complex abnormality was (80±4.2) % which was statistical difference (P＜0.05). Patients with DNMT3A, NRAS, TP53 and GATA2 mutations had shorter OS time compared with patients without mutation of these genes, which shows statistically significant (P＜0.05). COX multivariate analysis showed that age, chromosome karyotype, DNMT3A, TET2, GATA2 and NRAS were the independent factors influencing OS of patients after HSCT, with statistically significant difference. CONCLUSION: age of patients, donor selection of HSCT, chromosome karyotype, DNMT3A, NRAS, TP53, GATA2 and TET2 gene mutations are all independent factors affecting the OS of patients after HSCT. Therefore, the assessment of the OS of MDS patients with transplantation requires comprehensive consideration.

The Clinical and Molecular Characteristics of FLT3 Mutations in Chinese De Novo Adolescent and Adult Acute Lymphoblastic Leukemia Patients.

BACKGROUND: Activating mutations in FMS-like tyrosine kinase 3 (FLT3) are frequent in acute myeloid leukemia (AML) and have important prognostic and therapeutic implications. FLT3 aberrations have been detected in a smaller fraction of acute lymphoblastic leukemia (ALL), and their prognostic value is not well established. We therefore assessed the FLT3 mutation in Chinese adolescent and adult ALL patients. PATIENTS AND METHODS: We have examined a cohort of 117 Chinese de novo adolescent and adult ALL patients enrolled between June 2016 and June 2017 from the First Affiliated Hospital of Soochow University. Prognostic factors for the ALL patient population were estimated by the Cox regression method. FLT3 mutation was detected by PCR, and its clinical effect was assessed by Kaplan-Meier curves. Differences in FLT3 mutation rate between subgroups were tested by chi-square test. RESULTS: FLT3 mutations accounted for 6.8% (8/117) in our cohort, including 3 internal tandem duplications (2.6%) and 5 tyrosine kinase domains (4.3%, 3 D835Y mutations, 1 M664I mutation, and 1 I867S mutation), which had no clinical significance on either overall survival (OS) or event-free survival. Alterations in FLT3 occurred more often in early thymic precursor (ETP)-ALL compared to non-ETP T-cell acute lymphoblastic leukemia (P = .028). However, the age at onset (P = .004), initial platelet counts (P = .018), and transplantation status (P = .007) were independent prognostic factors of OS for ALL in multivariate analysis. CONCLUSION: The FLT3 mutation was not common in Chinese ALL patients. Age at onset, platelet counts, and transplantation status rather than the presence of the FLT3 mutation were independent prognostic variables for ALL on OS in our cohort. Despite our small sample size, ETP-ALL may indicate a comparable higher FLT3-mutant rate. Because ETP-ALL has been identified as high-risk subgroup, these data warrant clinical studies with the implementation of FLT3 inhibitors in addition to early allogeneic hematopoietic stem-cell transplantation for FLT3-mutant ETP-ALL.

[Mutation Spectrum of FANCJ Gene in Adult Acute Myeloid Leukemia].

OBJECTIVE: To detect and analyze the mutation status of FANCJ gene in adult AML patients, so as to provide the basis for studying the mechanism of FANCJ driven AML and guiding the preventim and treatment of deseese. METHODS: The cDNAs were extracted and transeripted from bone marrow cells and normal skin cells in 222 newly diagnosed AML patients. The primers were designed for FANCJ gene coding region, the mutations of FANCJ gene coding region in AML patients as well as the mutations of FANCJ gene in mucous membrane epethelia in patients were detected by PCR and sanger seguencing; the evolutionary conservation of FANCJ mutation in different organisms was analyzed by NCBI Blast online bioinformaties software. RESULTS: The sequencing analysis showed that the mutations of FANCJ gene happened in 11 sites of FANCJ gene coding region, which were as followed: exon5:c.G430A:p.A144T, exon6:c.A587G:pN196S, exon9:c.C1255T:p.R419W, exon10:c.G1442A:p.G481D, exon11:c.C1609G:p.L537V, exon16:c.C2360T:p.P787L, exon17:c.C2440T:p.R814C, exon19:c.C2608T:pH870Y, exon19:c.A2686G:p.I896V, exon19:c.C2830G:p.Q944E, exon20:c.G3412A:p.D1138N. Among them, the repeatability existed in mutations of A144T, N196S, R814C, I896V and Q944E. Beside, the mutation sites of A144, R419, G381, L537, P787, H870, Q944 and D1138 were highly conserved in different organisms. CONCLUSION: Among 222 adult AML patients, the mutations of FANCJ gene have been found in 26 patients, moreover, the mutation sites are relatively conserved in different organisms, and possess important fanction. The results of this study provide the basis for exploring the mexhanism of FANCJ gene driven AML and for guiding the prevantion and treatment of AML.

The Role of FLT3-ITD Mutation on de Novo MDS in Chinese Population.

BACKGROUND: FLT3 mutations have been well-studied in acute myeloid leukemia (AML), and the detection of the FLT3 gene has become a clinical routine. However, it has not been fully analyzed in other hematologic malignancies, such as myelodysplastic syndromes (MDS). MATERIALS AND METHODS: Between 2010 and 2016, 304 adult patients with de novo MDS had the FLT3 sequence tested on their bone marrow sample. With 279 patients who had follow-up information, we also analyzed the impact of clinical and laboratory characteristics as well as FLT3 mutation status and treatment on prognosis. RESULTS: We found that the transformation rate was 3 (42.9%) of 7 patients in the FLT3-ITD-positive group, compared with 31 (10.4%) of 297 among FLT3-ITD-negative patients (P = .033). The median progression-free survival of the FLT3-ITD mutated and wild-type groups were 43 days and 363.5 days, respectively (P < .0001). The median overall survival (OS) of the 2 groups were 218 days and 410.5 days, respectively (P < .0001). We also found that 5 factors had independent prognostic impact on OS: white blood cell counts, bone marrow blast percentage, cytogenetics, transplantation status, and FLT3-ITD mutation. Furthermore, compared with the transformation group, the non-progression group was younger (P = .034), with a lower platelet count (P = .022), a lower bone marrow blast percentage (P = .001), a lower FLT3-ITD incidence (P = .007), and a longer OS (P < .0001). CONCLUSIONS: When observed at the MDS stage, patients harboring FLT3-ITD mutations had higher AML transformation rate, quicker disease progression, and shorter survival than wild-type patients. Nevertheless, once the disease progressed to leukemia, the impact of FLT3-ITD mutations on prognosis was slight. In addition, the prognosis of secondary AML was very poor whether there was an FLT3-ITD mutation or not.

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.

[Expression and purification of FLT3 and FLT3-ITD mutated proteins in HEK293T cells].

Objective To construct the eukaryotic expression vectors of human fms related tyrosine kinase 3 (FLT3) gene and FLT3-internal tandem duplication (FLT3-ITD) mutants and purify the native proteins through immunoprecipitation from HEK293T cell lysates. Methods The cDNA fragments of FLT3wt and FLT3-ITD were amplified from bone marrow cells of healthy individuals and FLT3-ITD-mutated acute myeloid leukemia (AML) patients with specific primers, and the PCR products were cloned in CD530A-T2A-GFP expression vectors. FLT3wt and FLT3-ITD plasmids were transfected in HEK293T cells by Polyjet reagent, and the recombinant proteins were purified by immunoprecipitation and competing elution methods. Results FLT3wt and FLT3-ITD-mutated DNA sequences were successfully cloned in CD530A-T2A-GFP expression vectors. FLT3wt and FLT3-ITD mutated proteins were successfully expressed and purified in HEK293T cells as verified by Western blotting and sliver staining. Conclusion FLT3wt and FLT3-ITD expression vectors were successfully constructed, and purified proteins were successfully obtained from HEK293T cells.