bims-tremyl Biomed News
on Therapy resistance biology in myeloid leukemia
Issue of 2022‒01‒30
nineteen papers selected by
Paolo Gallipoli
Barts Cancer Institute, Queen Mary University of London

  1. Cancer J. 2022 Jan-Feb 01;28(1):28(1): 21-28
      ABSTRACT: Identification of recurrent mutations in isocitrate dehydrogenase genes (IDH1 and IDH2) in patients with acute myeloid leukemia (AML) coupled with an understanding of the pathologic role these mutant IDH isoforms impart in leukemogenesis resulted in the development of IDH1 and IDH2 inhibitors comprising a novel, molecularly defined class of targeted therapies for the treatment of AML. This review herein describes the unique cellular pathophysiology and vulnerabilities in IDH-mutated AML; the clinical development, efficacy, and known resistance mechanisms to first-generation IDH inhibitors; summarizes the literature surrounding combination therapies incorporating targeted or cytotoxic therapies with IDH inhibitors in patients with IDH-mutated AML; and identifies future challenges and areas of active ongoing investigation within this molecular subgroup.
  2. Blood Cancer J. 2022 Jan 25. 12(1): 10
      Preclinically, enasidenib and azacitidine (ENA + AZA) synergistically enhance cell differentiation, and venetoclax (VEN), a small molecule Bcl2 inhibitor (i) is particularly effective in IDH2 mutated acute myeloid leukemia (IDH2mutAML). This open label phase II trial enrolled patients (pts) with documented IDH2mutAML. All patients received AZA 75 mg/m2/d x 7 d/cycle and ENA 100 mg QD continuously. Concomitant Bcl2i and FLT3i were allowed (NCT03683433).Twenty-six pts received ENA + AZA (median 68 years, range, 24-88); 7 newly diagnosed (ND) and 19 relapsed/refractory (R/R). In R/R AML patients, three had received prior ENA and none had received prior VEN. The composite complete remission rate (CRc) [complete remission (CR) or complete remission with incomplete hematologic recovery (CRi)] was 100% in ND AML, and 58% in R/R AML. Median OS was not reached in ND AML with median follow-up of 13.1 months (mo); Pts treated in first relapse had improved OS than those with ≥2 relapse (median OS not reached vs 5.2 mo; HR 0.24, 95% CI 0.07-0.79, p = 0.04). Two patients received ENA + AZA with a concomitant FLT3i, one responding ND AML patient and one nonresponding R/R AML patient. Seven R/R AML pts received ENA + AZA + VEN triplet, and with median follow up of 11.2 mo, median OS was not reached and 6-mo OS was 70%. The most frequent treatment-emergent adverse events include febrile neutropenia (23%). Adverse events of special interest included all-grade IDH differentiation syndrome (8%) and indirect hyperbilirubinemia (35%). ENA + AZA was a well-tolerated, and effective therapy for elderly pts with IDH2mut ND AML as well as pts with R/R AML. The addition of VEN to ENA + AZA appears to improve outcomes in R/R IDH2mutAML.Clinical trial registration information:
  3. Blood Adv. 2022 Jan 25. pii: bloodadvances.2021006307. [Epub ahead of print]
      Using ex vivo drug screening of primary patient specimens, we identified the combination of the p38 MAPK inhibitor doramapimod (DORA) with the BCL2 inhibitor venetoclax (VEN) as demonstrating broad, enhanced efficacy compared to each single agent across 335 AML patient samples while sparing primary stromal cells. Single-agent DORA and VEN sensitivity associated with distinct, non-overlapping tumor cell differentiation states. In particular, increased monocytes, M4/M5 FAB classification, and CD14+ immunophenotype tracked with sensitivity to DORA and resistance to VEN, but were mitigated with the combination. Increased expression of MAPK14 and BCL2, the respective primary targets of DORA and VEN, were observed in monocytic and undifferentiated leukemias, respectively. Enrichment for DORA and VEN sensitivities were observed in AML with monocyte-like and progenitor-like transcriptomic signatures, respectively, and these associations diminished with the combination. The mechanism underlying the combination's enhanced efficacy may result from inhibition of p38 MAPK-mediated phosphorylation of BCL2, which in turn enhances sensitivity to venetoclax. These findings suggest exploiting complementary drug sensitivity profiles with respect to leukemic differentiation state, such as dual targeting of p38 MAPK and BCL2, offers opportunity for broad, enhanced efficacy across the clinically challenging heterogeneous landscape of AML.
  4. Blood. 2022 Jan 26. pii: blood.2021011583. [Epub ahead of print]
      The phase 3 ADMIRAL trial demonstrated superior overall survival (OS) in relapsed/refractory FLT3-mutation-positive acute myeloid leukemia patients randomized 2:1 to the oral FLT3 inhibitor, gilteritinib, versus those randomized to salvage chemotherapy (SC). Here we provide a follow-up of the ADMIRAL trial 2 years after the primary analysis to clarify the long-term treatment effects and safety of gilteritinib. At the time of this analysis, the median survival follow-up was 37.1 months, with deaths in 203/247 and 97/124 patients in the gilteritinib and SC arms, respectively; 16 gilteritinib-arm patients remained on treatment. The median OS for gilteritinib and SC arms was 9.3 and 5.6 months, respectively (HR=0.665; 95% CI: 0.518, 0.853; two-sided P=0.0013); 2-year estimated survival rates were 20.6% (95% CI: 15.8, 26.0) and 14.2% (95% CI: 8.3, 21.6), respectively. The gilteritinib-arm 2-year cumulative incidence of relapse after composite complete remission was 75.7%, with few relapses occurring after 18 months. Overall, 49/247 patients in the gilteritinib arm and 14/124 patients in the SC arm were alive for ≥2 years. Twenty-six gilteritinib-arm patients remained alive for ≥2 years without relapse; 18 of these patients underwent transplantation (HSCT) and 16 restarted gilteritinib as post-HSCT maintenance therapy. Most common adverse events (AEs) of interest during Years 1 and 2 of gilteritinib therapy were increased liver transaminases; AE incidence decreased in Year 2. Thus, continued and post-HSCT gilteritinib maintenance treatment sustained remission with a stable safety profile. These findings confirm that prolonged gilteritinib therapy is safe and is associated with superior survival versus SC. NCT02997202.
  5. Cancer J. 2022 Jan-Feb 01;28(1):28(1): 2-13
      ABSTRACT: Venetoclax has transformed the therapeutic landscape of acute myeloid leukemia (AML). Hypomethylating agents with venetoclax (HMA-VEN) have significantly improved outcomes and have become the standard therapy for older/unfit patients with newly diagnosed AML and are comparable to intensive chemotherapy in salvage setting. Venetoclax with intensive chemotherapy have shown high response rates in both frontline and salvage setting in younger patients, and triplet combinations with HMA-VEN and FLT3 inhibitors have shown encouraging results in FLT3mut AML. While patients with NPM1mut, IDH1/2mut experience favorable outcomes, those with TP53mut and secondary AML may experience minimal benefit from the addition of venetoclax. Despite improved outcomes, severe cytopenias and infectious complications are common with venetoclax-based regimens. Early response evaluation, dose reductions, venetoclax interruptions, use of growth factors, and prophylactic antimicrobials may minimize such myelosuppression and risk of infections. Outcomes after failure of frontline HMA-VEN are dismal, and novel approaches are needed to abrogate primary and acquired resistance.
  6. Blood Adv. 2022 Jan 24. pii: bloodadvances.2021006239. [Epub ahead of print]
      A subset of myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) show complex karyotype (CK), and these cases include a relatively high proportion of cases of therapy-related myeloid neoplasms and TP53 mutations. We aimed to evaluate the clinicopathologic features of outcome of 299 AML and MDS patients with CK. Mutations were present in 287 patients (96%) and the most common mutation detected was in TP53 gene (83%). A higher frequency of TP53 mutations was present in therapy-related cases (p=0.008) with a trend for worse overall survival (OS) in therapy-related patients as compared with de novo (p=0.08) and within the therapy-related group, the presence of TP53 mutation strongly predicted for worse outcome (p=0.0017). However, there was no difference in survival between CK patients based on categorization of AML versus MDS, (p=0.96) or presence of absence of circulating blasts ≥1% (p=0.52). TP53 mutated patients presented with older age (p=0.06) and lower hemoglobin (p=0.004) and marrow blast (p=0.02) compared to those with CK lacking TP53 mutation. Multivariable analysis identified presence of multi-hit TP53 mutation as strongest predictor of worse outcome, while neither a diagnosis of AML versus MDS nor therapy-relatedness independently influenced OS. Our findings suggest that among patients with MDS and AML, the presence of TP53 mutation (in particular multi-hit TP53 mutation) in the context of CK identifies a homogeneously aggressive disease, irrespective of the blast count at presentation or therapy-relatedness. The current classification of these cases into different disease categories artificially separates a single biologic disease entity.
  7. Bio Protoc. 2021 Dec 20. 11(24): e4262
      Acute myeloid leukaemia (AML) is a highly heterogenous blood cancer, in which the expansion of aberrant myeloid blood cells interferes with the generation and function of normal blood cells. Although key driver mutations and their associated inhibitors have been identified in the last decade, they have not been fully translated into better survival rates for AML patients, which remain dismal. In addition to DNA mutation, studies in mouse models strongly suggest that the cell of origin, where the driver mutation (such as MLL fusions) occurs, emerges as an additional factor that determines the treatment outcome in AML. To investigate its functional relevance in human disease, we have recently reported that AML driven by MLL fusions can transform immunophenotypically and functionally distinctive human hematopoietic stem cells (HSCs) or myeloid progenitors resulting in immunophenotypically indistinguishable human AML. Intriguingly, these cells display differential treatment sensitivities to current treatments, attesting the cell of origin as an important determinant governing treatment outcome for AML. To further facilitate this line of investigation, here we describe a comprehensive disease modelling protocol using human primary haematopoietic cells, which covers all the key steps, from the isolation of immunophenotypically defined human primary haematopoietic stem and progenitor populations, to oncogene transfer via viral transduction, the in vitro liquid culture assay, and finally the xenotransplantation into immunocompromised mice.
    Keywords:  AML; CD34; HSPC; Human disease modelling; MLL fusion
  8. Ann Hematol. 2022 Jan 26.
      TP53 aberrations are found in approximately 10% of patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) and are considered early driver events affecting leukemia stem cells. In this study, we compared features of a total of 84 patients with these disorders seen at a tertiary cancer center. Clinical and cytogenetic characteristics as well as immunophenotypes of immature blast cells were similar between AML and MDS patients. Median overall survival (OS) was 226 days (95% confidence interval [CI], 131-300) for the entire cohort with an estimated 3-year OS rate of 11% (95% CI, 6-22). OS showed a significant difference between MDS (median, 345 days; 95% CI, 235-590) and AML patients (median, 91 days; 95% CI, 64-226) which is likely due to a different co-mutational pattern as revealed by next-generation sequencing. Transformation of TP53 aberrant MDS occurred in 60.5% of cases and substantially reduced their survival probability. Cox regression analysis revealed treatment class and TP53 variant allele frequency as prognostically relevant parameters but not the TP53-specific prognostic scores EAp53 and RFS. These data emphasize similarities between TP53 aberrant AML and MDS and support previous notions that they should be classified and treated as a distinct disorder.
    Keywords:  Acute myeloid leukemia; EAp53 and RFS score; Myelodysplastic syndromes; Stem cell disorder; TP53
  9. Blood Adv. 2022 Jan 26. pii: bloodadvances.2021006166. [Epub ahead of print]
      Bleeding in patients with acute myeloid leukemia (AML) receiving intensive induction chemotherapy is multifactorial and contributes to early death. We sought to define incidence and risk factors of grade 4 bleeding to support strategies for risk mitigation. Bleeding events were retrospectively assessed between day-14 and day+60 of induction treatment according to the WHO bleeding assessment scale, which includes grade 4 bleeding as fatal, life-threatening, retinal with visual impairment, or involving the central nervous system. Predictors were considered pretreatment or prior to grade 4 bleeding. Using multivariable competing-risk regression analysis with grade 4 bleeding as the primary outcome, we identified risk factors in the development cohort (n=341), which were tested in an independent cohort (n=143). Grade 4 bleeding occurred in 5.9% and 9.8% of patients in the development and validation cohort, respectively. Risk factors that were independently associated with grade 4 bleeding included baseline platelet count <40 x109/L compared with >40 x109/L, and baseline PT-INR >1.5 or >1.3-1.5 compared with <1.3. These variables were allocated points, which allowed for stratification of patients with low- and high-risk for grade 4 bleeding. Cumulative incidence of grade 4 bleeding at day+60 was significantly higher among patients with high- versus low-risk (development: 31+7% vs. 2+1%, P<0.001, validation: 25+9% vs. 7+2%, P=0.008). In both cohorts, high bleeding risk was associated with disseminated intravascular coagulation (DIC) and proliferative disease. We developed and validated a simple risk model for grade 4 bleeding, which enables development of rational risk mitigation strategies to improve early mortality of intensive induction treatment.
  10. Cancer Lett. 2022 Jan 22. pii: S0304-3835(22)00040-4. [Epub ahead of print]
      C/EBPβ has recently emerged as a pro-leukemogenic transcription factor that cooperates with oncoprotein MYB to maintain proliferation and differentiation block of AML cells, making C/EBPβ an interesting drug target for AML. Here we have studied the inhibitory potential and biological effects of a synthetic analog of the natural product helenalin, a known inhibitor of C/EBPβ. The synthetic compound inhibits C/EBPβ by covalent binding to cysteine residues in the transactivation domain, thereby causing up-regulation of differentiation-associated genes, cell death and reduced self-renewal potential of AML cells. Suppression of these effects by ectopic expression of C/EBPβ or MYB and gene expression profiling validate C/EBPβ as a relevant target of the helenalin-mimic and highlight its role as a pro-leukemogenic factor. Overall, our work demonstrates that the synthetic helenalin mimic acts as a covalent inhibitor of C/EBPβ and identifies the cysteine residues in the transactivation domain of C/EBPβ as ligandable sites. The helenalin mimic can be considered a potential "lead molecule" but needs further development towards more effective C/EBPβ inhibitors before being used as a therapeutic agent.
    Keywords:  AML; Apoptosis; C/EBPβ; Covalent inhibitor; Cysteine alkylation; Helenalin mimic; MYB; p300
  11. Cancer J. 2022 Jan-Feb 01;28(1):28(1): 14-20
      ABSTRACT: Therapeutic outcomes for acute myeloid leukemia patients with Fms-like tyrosine kinase 3 (FLT3) mutations have improved substantially since the discovery of small molecule tyrosine kinase inhibitors. Today, use of FLT3 inhibitors is standard in frontline intensive chemotherapy as well as patients with relapsed or refractory acute myeloid leukemia and FLT3 mutations and increasingly used as for prolonged remission maintenance posttransplant and/or postconsolidation. Yet, FLT3 inhibitors alone are not curative, and best outcomes are seen when the drugs are used as part of combination regimens. Optimizing therapy for patients with FLT3 mutations remains a work in progress. Overall, modern therapeutic approaches generate cure rates for this group at levels that argue against considering these mutations adverse risk. Still, such survivals require intensive therapy and often transplant. Therefore, efforts are underway to determine if lower toxicity regimens can attain comparable outcomes, at least for patients responding optimally. This review will review the various FLT3 inhibitors that are approved or in development, highlight the areas where they have been shown to add value, and identify areas where their use remains controversial.
  12. Sci Transl Med. 2022 Jan 26. 14(629): eabh2548
      Leukemia stem cells (LSCs) propagate leukemia and are responsible for the high frequency of relapse of treated patients. The ability to target LSCs remains elusive, indicating a need to understand the underlying mechanism of LSC formation. Here, we report that miR-31-5p is reduced or undetectable in human LSCs compared to hematopoietic stem progenitor cells (HSPCs). Inhibition of miR-31-5p in HSPCs promotes the expression of its target gene FIH, encoding FIH [factor inhibiting hypoxia-inducing factor 1α (HIF-1α)], to suppress HIF-1α signaling. Increased FIH resulted in a switch from glycolysis to oxidative phosphorylation (OXPHOS) as the predominant mode of energy metabolism and increased the abundance of the oncometabolite fumarate. Increased fumarate promoted the conversion of HSPCs to LSCs and initiated myeloid leukemia-like disease in NOD-Prkdcscid IL2rgtm1/Bcgen (B-NDG) mice. We further demonstrated that miR-31-5p inhibited long- and short-term hematopoietic stem cells with a high frequency of LSCs. In combination with the chemotherapeutic agent Ara-C (cytosine arabinoside), restoration of miR-31-5p using G7 poly (amidoamine) nanosized dendriplex encapsulating miR-31-5p eliminated LSCs and inhibited acute myeloid leukemia (AML) progression in patient-derived xenograft mouse models. These results demonstrated a mechanism of HSC malignant transformation through altered energy metabolism and provided a potential therapeutic strategy to treat patients with AML.
  13. J Clin Invest. 2022 Jan 27. pii: e149856. [Epub ahead of print]
      Eltrombopag, an FDA-approved non-peptidyl thrombopoietin receptor agonist is clinically used for the treatment of aplastic anemia, a disease characterized by hematopoietic stem cell failure and pancytopenia, to improve platelet counts and stem cell function. Eltrombopag treatment results in durable tri-lineage hematopoietic expansion in patients. Some of the eltrombopag hematopoietic activity has been attributed to its off-target effects including its iron chelation properties. However, eltrombopag mechanism of action is still poorly understood with respect to its full spectrum of clinical effects. Here, we report that eltrombopag bound to the TET2 catalytic domain and inhibited its dioxygenase activity, which was independent of its iron chelating activity. The DNA demethylating enzyme TET2, essential for hematopoietic stem cell differentiation and lineage commitment, is frequently mutated in myeloid malignancies. Eltrombopag treatment expanded TET proficient normal hematopoietic stem and progenitor cells, in part, due to its ability to mimic loss of TET2 with simultaneous thrombopoietin receptor activation. On the contrary, TET inhibition in TET2 mutant malignant myeloid cells prevented neoplastic clonal evolution, in vitro and in vivo. This new mechanism of action may offer a restorative therapeutic index and provide a scientific rationale to treat selected patients with TET2-mutant or TET deficiency associated myeloid malignancies.
    Keywords:  Clonal selection; Drug therapy; Hematology; Hematopoietic stem cells
  14. Nat Med. 2022 Jan;28(1): 71-80
      Patients with Wiskott-Aldrich syndrome (WAS) lacking a human leukocyte antigen-matched donor may benefit from gene therapy through the provision of gene-corrected, autologous hematopoietic stem/progenitor cells. Here, we present comprehensive, long-term follow-up results (median follow-up, 7.6 years) (phase I/II trial no. NCT02333760 ) for eight patients with WAS having undergone phase I/II lentiviral vector-based gene therapy trials (nos. NCT01347346 and NCT01347242 ), with a focus on thrombocytopenia and autoimmunity. Primary outcomes of the long-term study were to establish clinical and biological safety, efficacy and tolerability by evaluating the incidence and type of serious adverse events and clinical status and biological parameters including lentiviral genomic integration sites in different cell subpopulations from 3 years to 15 years after gene therapy. Secondary outcomes included monitoring the need for additional treatment and T cell repertoire diversity. An interim analysis shows that the study meets the primary outcome criteria tested given that the gene-corrected cells engrafted stably, and no serious treatment-associated adverse events occurred. Overall, severe infections and eczema resolved. Autoimmune disorders and bleeding episodes were significantly less frequent, despite only partial correction of the platelet compartment. The results suggest that lentiviral gene therapy provides sustained clinical benefits for patients with WAS.
  15. Bone Marrow Transplant. 2022 Jan 25.
      Whether to choose Haploidentical (Haplo) or one-antigen mismatched unrelated donor (1Ag-MMUD) hematopoietic cell transplantation (HCT) with post-transplant cyclophosphamide (PTCy) remains an unanswered question. We compared PTCy- Haplo-HCT to PTCy-1Ag-MMUD-HCT for acute myeloid leukemia (AML) in complete remission (three groups: 1Ag-MMUD using peripheral blood (1Ag-MMUD-PB; n = 155); Haplo using bone marrow (Haplo-BM; n = 647) or peripheral blood (Haplo-PB; n = 949)). Haplo-BM and Haplo-PB had a higher non-relapse mortality (NRM) compared to 1Ag-MMUD-PB (HR 2.28, 95% CI 1.23-4.24, p < 0.01; HR 2.65, 95% CI 1.46-4.81, p < 0.01, respectively). Haplo groups experienced a lower leukemia-free survival (LFS) compared to 1Ag-MMUD-PB (Haplo-BM: HR 1.51, 95% CI 1.06-2.14, p = 0.02; Haplo-PB: 1.47, 95% CI 1.05-2.05, p = 0.02); overall survival (OS) was also lower in Haplo-HCT (Haplo-BM: HR 1.50, 95% CI 1.02-2.21, p = 0.04; Haplo-PB: HR 1.51, 95% CI 1.05-2.19, p = 0.03). No differences were observed for graft-versus-host/relapse-free survival (GRFS) and relapse incidence (RI). Haplo-BM was associated with a lower risk of grade III-IV acute graft-versus-host disease (GVHD) (HR 0.44, 95% CI 0.24-0.81; p < 0.01), while no statistical differences were observed between groups for grade II-IV aGVHD and for cGVHD. Use of PTCy in 1Ag-MMUD-HCT is a valid alternative to consider when using alternative donors. Larger analysis of 1Ag-MMUD versus Haplo-HCT are warranted.
  16. Cell Rep. 2022 Jan 25. pii: S2211-1247(21)01765-4. [Epub ahead of print]38(4): 110253
      Acute myeloid leukemia (AML) is a genetically heterogeneous and frequently fatal malignancy. The ten-eleven translocation (TET)-mediated DNA demethylation is known to be critically associated with AML pathogenesis. Through chemical compound screening, we find that the opioid receptor agonist, loperamide hydrochloride (OPA1), significantly suppresses AML cell viability. The potential therapeutic effects of opioid receptor agonists, especially OPA1, are verified in AML cells in vitro and mouse and human AML models in vivo. OPA1-induced activation of OPRM1 signaling enhances the transcription of TET2 and thus activates both catalytic-dependent and -independent functions of TET2. Notably, AMLs with TET2 mutations or chemotherapy resistance are sensitive to OPA1 as well. Our results reveal the OPRM1-TET2 regulatory axis in AML and suggest that opioid agonists, particularly OPA1, a US Food and Drug Administration (FDA)-approved antidiarrheal drug, have therapeutic potential in AML, especially in TET2-mutated and chemotherapy-resistant AMLs, which have a poor prognosis.
    Keywords:  5hmC; AML; TET; acute myeloid leukemia; loperamide; opioid signaling; targeted therapy
  17. Blood. 2022 Jan 24. pii: blood.2021013450. [Epub ahead of print]
      Rare hematopoietic stem and progenitor cell (HSPC) pools outside the bone marrow (BM) contribute to blood production in stress and disease but remain ill-defined. Although non-mobilized peripheral blood (PB) is routinely sampled for clinical management, the diagnosis and monitoring potential of PB HSPCs remains untapped, as no healthy PB HSPC baseline has been reported. Here we comprehensively delineate human extramedullary HSPC compartments comparing spleen, PB and mobilized PB (mPB) to BM using single-cell RNA-seq and/or functional assays. We uncover HSPC features shared by extramedullary tissues and others unique to PB. First, in contrast to actively dividing BM HSPCs, we find no evidence of substantial ongoing hematopoiesis in extramedullary tissues at steady state, but report increased splenic HSPC proliferative output during stress erythropoiesis. Second, extramedullary stem cells/multipotent progenitors (HSC/MPPs) from spleen, PB and mPB share a common transcriptional signature and increased abundance of lineage-primed subsets compared to BM. Third, healthy PB HSPCs display a unique bias towards erythroid-megakaryocytic differentiation. At HSC/MPP level, this is functionally imparted by a subset of phenotypic CD71+ HSC/MPPs, exclusively producing erythrocytes and megakaryocytes, highly abundant in PB but rare in other adult tissues. Finally, the unique erythroid-megakaryocytic-skewing of PB is perturbed with age, in essential thrombocythemia and in beta-thalassemia. Collectively, we identify extramedullary lineage-primed HSPC reservoirs that are non-proliferative in situ and report involvement of splenic HSPCs during demand-adapted hematopoiesis. Our data also establish aberrant composition and function of circulating HSPCs as potential clinical indicators of BM dysfunction.
  18. Sci Rep. 2022 Jan 24. 12(1): 1243
      RUNX proteins belong to a family of transcription factors essential for cellular proliferation, differentiation, and apoptosis with emerging data implicating RUNX3 in haematopoiesis and haematological malignancies. Here we show that RUNX3 plays an important regulatory role in normal human erythropoiesis. The impact of altering RUNX3 expression on erythropoiesis was determined by transducing human CD34+ cells with RUNX3 overexpression or shRNA knockdown vectors. Analysis of RUNX3 mRNA expression showed that RUNX3 levels decreased during erythropoiesis. Functionally, RUNX3 overexpression had a modest impact on early erythroid growth and development. However, in late-stage erythroid development, RUNX3 promoted growth and inhibited terminal differentiation with RUNX3 overexpressing cells exhibiting lower expression of glycophorin A, greater cell size and less differentiated morphology. These results suggest that suppression of RUNX3 is required for normal erythropoiesis. Overexpression of RUNX3 increased colony formation in liquid culture whilst, corresponding RUNX3 knockdown suppressed colony formation but otherwise had little impact. This study demonstrates that the downregulation of RUNX3 observed in normal human erythropoiesis is important in promoting the terminal stages of erythroid development and may further our understanding of the role of this transcription factor in haematological malignancies.
  19. Blood Rev. 2022 Jan 21. pii: S0268-960X(22)00002-9. [Epub ahead of print] 100928
      FMS-like tyrosine kinase 3 (FLT3) is one of the most closely studied genes in blood diseases. Numerous methods have been adopted for analyses, mainly in acute myeloid leukemia (AML) diagnostic work-up. According to international recommendations, the current gold standard approach allows FLT3 canonical mutations to be investigated, providing the main information for risk assessment and treatment choice. However, the technological improvements of the last decade have permitted "black side" gene exploration, revealing numerous hidden aspects of its role in leukemogenesis. The advent of the next-generation sequencing era emphasizes lights and shadows of FLT3 conventional mutational analysis, highlighting the need for a more comprehensive study of the gene. However, more extensive analysis is opening new, unexplored questions whose impact on clinical outcomes is still unknown. The present work is focused on the main topics regarding FLT3 mutational analysis in AML, debating the strengths and weaknesses of the current gold standard approach. The rights and wrongs of NGS introduction in clinical practice will be discussed, showing that a more extensive knowledge of FLT3 mutational status could lead to reconsidering its role in AML management.
    Keywords:  Acute myeloid leukemia; FLT3 mutational analysis; Fragment analysis; Next-generation sequencing