bims-tremyl Biomed News
on Therapy resistance biology in myeloid leukemia
Issue of 2024–04–07
twenty-six papers selected by
Paolo Gallipoli, Barts Cancer Institute, Queen Mary University of London



  1. Leuk Res. 2024 Mar 27. pii: S0145-2126(24)00063-8. [Epub ahead of print]140 107497
      Limited treatment options are available for patients with relapsed/refractory acute myeloid leukemia (R/R AML). We recently reported results from the phase 3 IDHENTIFY trial (NCT02577406) showing improved response rates and event-free survival with enasidenib monotherapy compared with conventional care regimens (CCR) in heavily pretreated, older patients with late-stage R/R AML bearing IDH2 mutations. Here we investigated the prognostic impact of mutational burden and different co-mutation patterns at study entry within the predominant IDH2 variant subclasses, IDH2-R140 and IDH2-R172. The prognostic relevance of these variants is well documented in newly diagnosed AML, but data are lacking in R/R AML. In this large R/R AML patient cohort, targeted next-generation sequencing at baseline (screening) revealed distinct co-mutation patterns and mutational burden between subgroups bearing different IDH2 variants: variant IDH2-R140 was associated with greater mutational burden and was enriched predominantly with poor-risk mutations, including FLT3, RUNX1, and NRAS, while variant IDH2-R172 was associated with lower mutational burden and was preferentially co-mutated with DNMT3A. In multivariable analyses, RAS and RTK pathway mutations were significantly associated with decreased overall survival, after adjusting for treatment arm, IDH2 variant, and mutational burden. Importantly, enasidenib-mediated survival benefit was more pronounced in patients with IDH2-R172 variants.
    Keywords:  Acute myeloid leukemia; Enasidenib; Gene mutation; IDH2-mutated; IDHENTIFY; Relapsed/refractory
    DOI:  https://doi.org/10.1016/j.leukres.2024.107497
  2. Leuk Res. 2024 Mar 16. pii: S0145-2126(24)00051-1. [Epub ahead of print]140 107485
      Over the years, the overall survival of older patients diagnosed with acute myeloid leukemia (AML) has not significantly increased. Although standard cytotoxic therapies that rapidly eliminate dividing myeloblasts are used to induce remission, relapse can occur due to surviving therapy-resistant leukemic stem cells (LSCs). Hence, anti-LSC strategies have become a key target to cure AML. We have recently shown that previously approved cardiac glycosides and glucocorticoids target LSC-enriched CD34+ cells in the primary human AML 8227 model with more efficacy than normal hematopoietic stem cells (HSCs). To translate these in vitro findings into humans, we developed a mathematical model of stem cell dynamics that describes the stochastic evolution of LSCs in AML post-standard-of-care. To this, we integrated population pharmacokinetic-pharmacodynamic (PKPD) models to investigate the clonal reduction potential of several promising candidate drugs in comparison to cytarabine, which is commonly used in high doses for consolidation therapy in AML patients. Our results suggest that cardiac glycosides (proscillaridin A, digoxin and ouabain) and glucocorticoids (budesonide and mometasone) reduce the expansion of LSCs through a decrease in their viability. While our model predicts that effective doses of cardiac glycosides are potentially too toxic to use in patients, simulations show the possibility of mometasone to prevent relapse through the glucocorticoid's ability to drastically reduce LSC population size. This work therefore highlights the prospect of these treatments for anti-LSC strategies and underlines the use of quantitative approaches to preclinical drug translation in AML.
    Keywords:  Acute myeloid leukemia; Hematopoiesis; Mathematical modeling; Preclinical investigation; Stochastic process
    DOI:  https://doi.org/10.1016/j.leukres.2024.107485
  3. Blood. 2024 Apr 05. pii: blood.2024024072. [Epub ahead of print]
      The overall prognosis of acute myeloid leukemia (AML) remains dismal, largely due to the inability of current therapies to kill leukemia stem cells (LSCs) with intrinsic resistance. Loss of the stress sensor GADD45A is implicated in poor clinical outcomes but its role in LSCs and AML pathogenesis is unknown. Here we define GADD45A as a key downstream target of LGR4 oncogenic signaling and discover a regulatory role for GADD45A loss in promoting leukemia-initiating activity and oxidative resistance in LGR4/HOXA9-dependent AML, a poor prognosis subset of leukemia. Knockout of GADD45A enhances AML progression in murine and patient-derived xenograft (PDX) mouse models. Deletion of GADD45A induces substantial mutations, increases LSC self-renewal and stemness in vivo and reduces levels of reactive oxygen species (ROS), accompanied by decreased response to ROS-associated genotoxic agents (e.g., ferroptosis inducer RSL3) and acquisition of an increasingly aggressive phenotype upon serial transplantation in mice. Our single-cell CITE-seq analysis on patient-derived LSCs in PDX mice and subsequent functional studies in murine LSCs and primary AML patient cells show that loss of GADD45A is associated with resistance to ferroptosis (an iron-dependent oxidative cell death caused by ROS accumulation) through aberrant activation of antioxidant pathways related to iron and ROS detoxification such as FTH1 and PRDX1, upregulation of which correlates with unfavorable outcomes in AML patients. These results reveal a therapy resistance mechanism contributing to poor prognosis and support a role for GADD45A loss as a critical step for leukemia-initiating activity and as a target to overcome resistance in aggressive leukemia.
    DOI:  https://doi.org/10.1182/blood.2024024072
  4. Br J Haematol. 2024 Apr 05.
      Allogeneic haematopoietic cell transplantation (allo-HCT) remains an option for tyrosine kinase inhibitor-resistant chronic myeloid leukaemia (CML) in first chronic phase (CP1) and high-risk patients with advanced disease phases. In this European Society for Blood and Marrow Transplantation (EBMT) registry-based study of 1686 CML patients undergoing first allo-HCT between 2012 and 2019, outcomes were evaluated according to donor type, particularly focusing on mismatched related donors (MMRDs). Median age at allo-HCT was 46 years (IQR 36-55). Disease status was CP1 in 43%, second CP (CP2) or later in 27%, accelerated phase in 12% and blast crisis in 18%. Donor type was matched related (MRD) in 39.2%, MMRD in 8.1%, matched unrelated (MUD) in 40.2%, and mismatched unrelated (MMUD) in 12.6%. In 4 years, overall survival (OS) for MRD, MMRD, MUD and MMUD was 61%, 56%, 63% and 59% (p = 0.21); relapse-free survival (RFS) was 48%, 42%, 52% and 46% (p = 0.03); cumulative incidence of relapse (CIR) was 33%, 37%, 27% and 30% (p = 0.07); non-relapse mortality (NRM) was 19%, 21%, 21% and 24% (p = 0.21); and graft-versus-host disease (GvHD)-free/relapse-free survival (GRFS) was 16%, 18%, 22% and 15% (p = 0.05) respectively. On multivariate analysis, MMRD use associated with longer engraftment times and higher risk of graft failure compared to MRD or MUD. There was no statistical evidence that MMRD use associated with different OS, RFS and incidence of GvHD compared to other donor types.
    Keywords:  TKI resistance; allogeneic haematopoietic cell transplant; chronic myeloid leukaemia; cyclophosphamide; haploidentical donor; mismatched related donor; post‐transplant
    DOI:  https://doi.org/10.1111/bjh.19448
  5. Bone Marrow Transplant. 2024 Mar 30.
      Older adults with acute myeloid leukemia (AML) refractory to initial or reinduction chemotherapy have a dismal prognosis if they do not undergo hematopoietic stem-cell transplantation (HCT). However, data assessing HCT outcomes from different donors are scarce. We evaluated results from a retrospective analysis on patients aged ≥70 years, with AML not in remission who received an allogeneic HCT from HLA-matched sibling donor (MSD), HLA-10/10 matched unrelated donor (MUD), or T-cell replete haploidentical (Haplo) donor, from 2010 to 2021, reported to the ALWP-EBMT database. A total of 360 patients (median age 72 years, range 70-79) were included in the analysis. Median follow-up for the entire population was 35.5 months. Donors were MSD (n = 58), 10/10 HLA-MUD (n = 228), and Haplo (n = 74). A total of 213 (59.2%) patients were primary induction failures, while 147 (40.8%) were in first or subsequent relapse. Graft source was peripheral blood in 92% of the patients. Patients transplanted from Haplo donors more frequently received marrow grafts (p < 0.01) and presented the combination female donor to male recipient (p < 0.01). The overall 2-year rates of overall survival (OS) and leukemia-free survival (LFS) were: 62.4% (95% CI 47.2-74.3) and 47.6% (95% CI 33.1-60.8) for MSD, 43% (95% CI 35.8-49.9), and 37.5% (95% CI 30.7-44.4) for MUD, and 25.9% (95% CI 15.8-37.2), and 26.5% (95% CI 16.3-37.8) for recipients of Haplo transplants. The 2-year cumulative incidence of relapse (RI) was slightly lower for Haplo recipients at 29.6% (95% CI 19-40.9), for MUD it was 30.2% (95% CI 23.9-36.7), and for MSD 34.9% (95% CI 22-48.2); counterbalanced by a higher incidence of non-relapse mortality (NRM) of 43.9% (95% CI 31.6-55.6) for Haplo recipients, 32.2% (95% CI 26-33.1) for MUD and 17.5% (95% CI 8.4-29.3) for MSD. Graft-versus-host disease (GVHD-free, relapse-free survival (GRFS) was 35.3% (95% CI 22.3-48.5) for MSD, 29.6% (95% CI 23.2-36.2) for MUD, and 19.2% (95% CI 10.7-29.6) for Haplo patients. In the multivariate model, compared to the referent group of MSD recipients, the risk of NRM was higher among patients transplanted from Haplo donors ([hazard ratio] HR 5.1, 95% CI 2.23-11.61, p < 0.001) and MUD (HR 3.21, 95% CI 1.48-0.6.94, p = 0.003). Furthermore, both Haplo and MUD were associated with inferior OS, (HR 3.6, 95% CI 1.98-0.6.56, p < 0.001, and HR 2.3, 95% CI 1.37-0.3.88, p = 0.002, respectively), and LFS (HR 2.24, 95% CI 1.31-0.3.84, p = 0.003, and HR 1.64, 95% CI 1.04-0.2.60, p = 0.034, respectively). Patients transplanted from Haplo donors were also associated with worse GFRS (HR 1.72, 95% CI 1.07-2.77, p:0.025) compared with MSD patients. Older adult AML patients with active disease transplanted from MSD experienced prolonged OS and LFS compared to 10/10 MUD and Haplo due to lower NRM. Prospective clinical trials are warranted.
    DOI:  https://doi.org/10.1038/s41409-024-02275-6
  6. Cancer Res. 2024 Apr 01. 84(7): 950-952
      Acute myeloid leukemia (AML) is one of the most prevalent blood cancers, characterized by a dismal survival rate. This poor outcome is largely attributed to AML cells that persist despite treatment and eventually result in relapse. Relapse-initiating cells exhibit diverse resistance mechanisms, encompassing genetic factors and, more recently discovered, nongenetic factors such as metabolic adaptations. Leukemic stem cells (LSC) rely on mitochondrial metabolism for their survival, whereas hematopoietic stem cells primarily depend on glycolysis. Furthermore, following treatments such as cytarabine, a standard in AML treatment for over four decades, drug-persisting leukemic cells exhibit an enhanced reliance on mitochondrial metabolism. In this issue of Cancer Research, two studies investigated dependencies of AML cells on two respiratory substrates, α-ketoglutarate and lactate-derived pyruvate, that support mitochondrial oxidative phosphorylation (OXPHOS) following treatment with the imipridone ONC-213 and the BET inhibitor INCB054329, respectively. Targeting lactate utilization by interfering with monocarboxylate transporter 1 (MCT1 or SLC16A1) or lactate dehydrogenase effectively sensitized cells to BET inhibition in vitro and in vivo. In addition, ONC-213 affected αKGDH, a pivotal NADH-producing enzyme of the TCA cycle, to induce a mitochondrial stress response through ATF4 activation that diminished the expression of the antiapoptotic protein MCL1, consequently promoting apoptosis of AML cells. In summary, targeting these mitochondrial dependencies might be a promising strategy to kill therapy-naïve and treatment-resistant OXPHOS-reliant LSCs and to delay or prevent relapse. See related articles by Monteith et al., p. 1101 and Su et al., p. 1084.
    DOI:  https://doi.org/10.1158/0008-5472.CAN-24-0019
  7. Leukemia. 2024 Mar 30.
      Infant and adult MLL1/KMT2A-rearranged (MLLr) leukemia represents a disease with a dismal prognosis. Here, we present a functional and proteomic characterization of in utero-initiated and adult-onset MLLr leukemia. We reveal that fetal MLL::ENL-expressing lymphomyeloid multipotent progenitors (LMPPs) are intrinsically programmed towards a lymphoid fate but give rise to myeloid leukemia in vivo, highlighting a complex interplay of intra- and extracellular factors in determining disease subtype. We characterize early proteomic events of MLL::ENL-mediated transformation in fetal and adult blood progenitors and reveal that whereas adult pre-leukemic cells are mainly characterized by retained myeloid features and downregulation of ribosomal and metabolic proteins, expression of MLL::ENL in fetal LMPPs leads to enrichment of translation-associated and histone deacetylases signaling proteins, and decreased expression of inflammation and myeloid differentiation proteins. Integrating the proteome of pre-leukemic cells with their secretome and the proteomic composition of the extracellular environment of normal progenitors highlights differential regulation of Igf2 bioavailability, as well as of VLA-4 dimer and its ligandome, upon initiation of fetal- and adult-origin leukemia, with implications for human MLLr leukemia cells' ability to communicate with their environment through granule proteins. Our study has uncovered opportunities for targeting ontogeny-specific proteomic vulnerabilities in in utero-initiated and adult-onset MLLr leukemia.
    DOI:  https://doi.org/10.1038/s41375-024-02235-5
  8. Haematologica. 2024 Apr 04.
      Azacitidine/venetoclax is an active regimen in patients with newly diagnosed AML. However, primary or secondary resistance to azacitidine/venetoclax is an area of unmet need and overexpression of MCL-1 is suggested to be a potential resistance mechanism. Pevonedistat inhibits MCL-1 through activation of NOXA, and pevonedistat/azacitidine has previously shown activity in AML. To assess the tolerability and efficacy of adding pevonedistat to azacitidine/venetoclax in relapsed/refractory AML, we conducted a phase I multicenter openlabel study in 16 adults with relapsed/refractory AML. Patients were treated with azacitidine, venetoclax along with pevonedistat intravenously on days 1, 3 and 5 of each 28-day cycle at 10, 15 or 20 mg/m2 in successive cohorts in the dose escalation phase. The impact of treatment on protein neddylation as well as expression of pro-apoptotic BCL2 family members was assessed. The recommended phase II dose of pevonedistat was 20 mg/m2. Grade 3 or higher adverse events included neutropenia (31%), thrombocytopenia (13%), febrile neutropenia (19%), anemia (19%), hypertension (19%) and sepsis (19%). The overall response rate was 46.7% for the whole cohort including complete remission (CR) in 5 of 7 (71.4%) patients who were naïve to the hypomethylating agent/venetoclax. No measurable residual disease (MRD) was detected in 80.0% of the patients who achieved CR. The median time to best response was 50 (range: 23 - 77) days. Four patients were bridged to allogeneic stem cell transplantation. The combination of azacitidine, venetoclax and pevonedistat is safe and shows encouraging preliminary activity in patients with relapsed/refractory AML. (NCT04172844).
    DOI:  https://doi.org/10.3324/haematol.2024.285014
  9. Genes Dev. 2024 Apr 02.
      Oncogenic activation of MYC in cancers predominantly involves increased transcription rather than coding region mutations. However, MYC-dependent lymphomas frequently acquire point mutations in the MYC phosphodegron, including at threonine 58 (T58), where phosphorylation permits binding via the FBW7 ubiquitin ligase triggering MYC degradation. To understand how T58 phosphorylation functions in normal cell physiology, we introduced an alanine mutation at T58 (T58A) into the endogenous c-Myc locus in the mouse germline. While MYC-T58A mice develop normally, lymphomas and myeloid leukemias emerge in ∼60% of adult homozygous T58A mice. We found that primitive hematopoietic progenitor cells from MYC-T58A mice exhibit aberrant self-renewal normally associated with hematopoietic stem cells (HSCs) and up-regulate a subset of MYC target genes important in maintaining stem/progenitor cell balance. In lymphocytes, genomic occupancy by MYC-T58A was increased at all promoters compared with WT MYC, while genes differentially expressed in a T58A-dependent manner were significantly more proximal to MYC-bound enhancers. MYC-T58A lymphocyte progenitors exhibited metabolic alterations and decreased activation of inflammatory and apoptotic pathways. Our data demonstrate that a single point mutation stabilizing MYC is sufficient to skew target gene expression, producing a profound gain of function in multipotential hematopoietic progenitors associated with self-renewal and initiation of lymphomas and leukemias.
    Keywords:  FBW7; MYC; hematopoiesis; leukemia; lymphoma; progenitor cells; protein stability; self-renewal
    DOI:  https://doi.org/10.1101/gad.351292.123
  10. Elife. 2024 Apr 02. pii: RP90532. [Epub ahead of print]12
      Currently, the identification of patient-specific therapies in cancer is mainly informed by personalized genomic analysis. In the setting of acute myeloid leukemia (AML), patient-drug treatment matching fails in a subset of patients harboring atypical internal tandem duplications (ITDs) in the tyrosine kinase domain of the FLT3 gene. To address this unmet medical need, here we develop a systems-based strategy that integrates multiparametric analysis of crucial signaling pathways, and patient-specific genomic and transcriptomic data with a prior knowledge signaling network using a Boolean-based formalism. By this approach, we derive personalized predictive models describing the signaling landscape of AML FLT3-ITD positive cell lines and patients. These models enable us to derive mechanistic insight into drug resistance mechanisms and suggest novel opportunities for combinatorial treatments. Interestingly, our analysis reveals that the JNK kinase pathway plays a crucial role in the tyrosine kinase inhibitor response of FLT3-ITD cells through cell cycle regulation. Finally, our work shows that patient-specific logic models have the potential to inform precision medicine approaches.
    Keywords:  Boolean model; acute myeloid leukemia; cancer biology; cancer therapy; computational biology; drug resistance; human; mouse; systems biology; tyrosine kinase
    DOI:  https://doi.org/10.7554/eLife.90532
  11. PLoS One. 2024 ;19(4): e0300623
      Regulation of protein synthesis is a key factor in hematopoietic stem cell maintenance and differentiation. Rio-kinase 2 (RIOK2) is a ribosome biogenesis factor that has recently been described an important regulator of human blood cell development. Additionally, we have previously identified RIOK2 as a regulator of protein synthesis and a potential target for the treatment of acute myeloid leukemia (AML). However, its functional relevance in several organ systems, including normal hematopoiesis, is not well understood. Here, we investigate the consequences of RIOK2 loss on normal hematopoiesis using two different conditional knockout mouse models. Using competitive and non-competitive bone marrow transplantations, we demonstrate that RIOK2 is essential for the differentiation of hematopoietic stem and progenitor cells (HSPCs) as well as for the maintenance of fully differentiated blood cells in vivo as well as in vitro. Loss of RIOK2 leads to rapid death in full-body knockout mice as well as mice with RIOK2 loss specific to the hematopoietic system. Taken together, our results indicate that regulation of protein synthesis and ribosome biogenesis by RIOK2 is essential for the function of the hematopoietic system.
    DOI:  https://doi.org/10.1371/journal.pone.0300623
  12. bioRxiv. 2024 Mar 16. pii: 2024.03.14.585083. [Epub ahead of print]
      The bone marrow is the organ responsible for blood production. Diverse non-hematopoietic cells contribute essentially to hematopoiesis. However, these cells and their spatial organization remain largely uncharacterized as they have been technically challenging to study in humans. Here, we used fresh femoral head samples and performed single-cell RNA sequencing (scRNA-Seq) to profile 29,325 enriched non-hematopoietic bone marrow cells and discover nine transcriptionally distinct subtypes. We next employed CO-detection by inDEXing (CODEX) multiplexed imaging of 18 individuals, including both healthy and acute myeloid leukemia (AML) samples, to spatially profile over one million single cells with a novel 53-antibody panel. We discovered a relatively hyperoxygenated arterio-endosteal niche for early myelopoiesis, and an adipocytic, but not endosteal or perivascular, niche for early hematopoietic stem and progenitor cells. We used our atlas to predict cell type labels in new bone marrow images and used these predictions to uncover mesenchymal stromal cell (MSC) expansion and leukemic blast/MSC-enriched spatial neighborhoods in AML patient samples. Our work represents the first comprehensive, spatially-resolved multiomic atlas of human bone marrow and will serve as a reference for future investigation of cellular interactions that drive hematopoiesis.
    DOI:  https://doi.org/10.1101/2024.03.14.585083
  13. Am J Hematol. 2024 Apr 02.
    CEREO Collaborators
      We investigated using a custom NGS panel of 149 genes the mutational landscape of 64 consecutive adult patients with tyrosine kinase fusion-negative hypereosinophilia (HE)/hypereosinophilic syndrome (HES) harboring features suggestive of myeloid neoplasm. At least one mutation was reported in 50/64 (78%) patients (compared to 8/44 (18%) patients with idiopathic HE/HES/HEUS used as controls; p < .001). Thirty-five patients (54%) had at least one mutation involving the JAK-STAT pathway, including STAT5B (n = 18, among which the hotspot N642H, n = 13), JAK1 (indels in exon 13, n = 5; V658F/L, n = 2), and JAK2 (V617F, n = 6; indels in exon 13, n = 2). Other previously undescribed somatic mutations were also found in JAK2, JAK1, STAT5B, and STAT5A, including three patients who shared the same STAT5A V707fs mutation and features consistent with primary polycythemia. Nearly all JAK-STAT mutations were preceded by (or associated with) myelodysplasia-related gene mutations, especially in RNA-splicing genes or chromatin modifiers. In multivariate analysis, neurologic involvement (hazard ratio [HR] 4.95 [1.87-13.13]; p = .001), anemia (HR 5.50 [2.24-13.49]; p < .001), and the presence of a high-risk mutation (as per the molecular international prognosis scoring system: HR 6.87 [2.39-19.72]; p < .001) were independently associated with impaired overall survival. While corticosteroids were ineffective in all treated JAK-STAT-mutated patients, ruxolitinib showed positive hematological responses including in STAT5A-mutated patients. These findings emphasize the usefulness of NGS for the workup of tyrosine kinase fusion-negative HE/HES patients and support the use of JAK inhibitors in this setting. Updated classifications could consider patients with JAK-STAT mutations and eosinophilia as a new "gene mutated-entity" that could be differentiated from CEL, NOS, and idiopathic HES.
    DOI:  https://doi.org/10.1002/ajh.27306
  14. Blood. 2024 Apr 05. pii: blood.2023023788. [Epub ahead of print]
      Hematopoietic stem cells (HSCs) are instrumental for organismal survival as they are responsible for lifelong production of mature blood lineages in homeostasis and response to external stress. To fulfill their function, HSCs rely on reciprocal interactions with specialized tissue microenvironments, termed HSC niches. From embryonic development to advanced aging, HSCs transition through several hematopoietic organs where they are supported by distinct extrinsic cues. Here, we describe recent discoveries on how HSC niches collectively adapt to ensure robust hematopoietic function during biological aging and following exposure to acute stress. We also discuss the latest strategies leveraging niche-derived signals to revert aging-associated phenotypes and enhance hematopoietic recovery post myeloablation.
    DOI:  https://doi.org/10.1182/blood.2023023788
  15. Blood Adv. 2024 Apr 02. pii: bloodadvances.2023012357. [Epub ahead of print]
      Clonal cytopenia of undetermined significance (CCUS) is defined by a myeloid driver mutation in the context of otherwise unexplained cytopenia. CCUS has an inherent risk of progressing to myeloid neoplasm. However, it is unknown how exposure to previous cytotoxic therapy may impact the risk of progression and survival. We stratified CCUS patients by prior exposure to DNA-damaging therapy. Of 151 patients, 46 (30%) had received cytotoxic therapy and were classified as therapy-related CCUS (t-CCUS), whereas 105 (70%) had de novo CCUS. A lower proportion of t-CCUS had hypercellular marrows (17.8% vs. 44.8%, P=0.002) but had higher median bone marrow blast percentages. After a median follow up of 2.2 years, t-CCUS had significantly shorter PFS (1.8 vs. 6.3 years, HR 2.1, P=0.007) and median OS (3.6 years vs. not reached, HR 2.3, P=0.007) compared to CCUS. Univariable and multivariable time-to-event analyses showed that exposure to cytotoxic therapy independently accounted for inferior PFS and OS. Despite the similarities in clinical presentation between CCUS and t-CCUS, we show that exposure to prior cytotoxic therapies was an independent risk-factor for inferior outcomes. This suggests that t-CCUS represents a unique clinical entity that needs more stringent monitoring or earlier intervention strategies.
    DOI:  https://doi.org/10.1182/bloodadvances.2023012357
  16. Leukemia. 2024 Apr 04.
      Myelodysplastic neoplasms (MDS) are characterized by clonal evolution starting from the compartment of hematopoietic stem and progenitors cells (HSPCs), leading in some cases to leukemic transformation. We hypothesized that deciphering the diversity of the HSPCs compartment may allow for the early detection of an emergent sub-clone that drives disease progression. Deep analysis of HSPCs repartition by multiparametric flow cytometry revealed a strong disorder of the hematopoietic branching system in most patients at diagnosis with different phenotypic signatures closely related to specific MDS features. In two independent cohorts of 131 and 584 MDS, the HSPCs heterogeneity quantified through entropy calculation was decreased in 47% and 46% of cases, reflecting a more advanced state of the disease with deeper cytopenias, higher IPSS-R risk and accumulation of somatic mutations. We demonstrated that patients with lower-risk MDS and low CD34 + CD38+HSPCs entropy had an adverse outcome and that this parameter is as an independent predictive biomarker for progression free survival, leukemia free survival and overall survival. Analysis of HSPCs repartition at diagnosis represents therefore a very powerful tool to identify lower-risk MDS patients with a worse outcome and valuable for clinical decision-making, which could be fully integrated in the MDS diagnostic workflow.
    DOI:  https://doi.org/10.1038/s41375-024-02234-6
  17. Res Sq. 2024 Mar 11. pii: rs.3.rs-4020184. [Epub ahead of print]
      There has been ongoing debate on the association between obesity and outcomes in acute myeloid leukemia (AML). Currently there are few studies that have stratified outcomes by class I obesity, class II obesity, and class III obesity; and a more nuanced understanding is becoming increasingly important with the rising prevalence of obesity. We examined the association between body mass index (BMI) and outcomes in previously untreated AML in younger patients (age ≤60) enrolled in SWOG S1203 (n=729). Class III obesity was associated with an increased rate of early death (p=0.004) and worse overall survival (OS) in multivariate analysis (hazard ratio (HR) 2.48, 95% confidence interval (CI) 1.62-3.80 versus normal weight). Class III obesity was also associated with worse OS after allogeneic hematopoietic cell transplant (HR 2.37, 95% CI 1.24-4.54 versus normal weight). These findings highlight the unique risk of class III obesity in AML, and the importance of further investigation to better characterize this patient population.
    DOI:  https://doi.org/10.21203/rs.3.rs-4020184/v1
  18. iScience. 2024 Apr 19. 27(4): 109443
      Spliceosome machinery mutations are common early mutations in myeloid malignancies; however, effective targeted therapies against them are still lacking. In the current study, we used an in vitro high-throughput drug screen among four different isogenic cell lines and identified RKI-1447, a Rho-associated protein kinase inhibitor, as selective cytotoxic effector of SRSF2 mutant cells. RKI-1447 targeted SRSF2 mutated primary human samples in xenografts models. RKI-1447 induced mitotic catastrophe and induced major reorganization of the microtubule system and severe nuclear deformation. Transmission electron microscopy and 3D light microscopy revealed that SRSF2 mutations induce deep nuclear indentation and segmentation that are apparently driven by microtubule-rich cytoplasmic intrusions, which are exacerbated by RKI-1447. The severe nuclear deformation in RKI-1447-treated SRSF2 mutant cells prevents cells from completing mitosis. These findings shed new light on the interplay between microtubules and the nucleus and offers new ways for targeting pre-leukemic SRSF2 mutant cells.
    Keywords:  Cancer; Cell biology; Molecular biology
    DOI:  https://doi.org/10.1016/j.isci.2024.109443
  19. Clin Transl Med. 2024 Apr;14(4): e1628
       BACKGROUND: Acute myeloid leukaemia (AML) is a haematological malignancy with unfavourable prognosis. Despite the effectiveness of chemotherapy and targeted therapy, relapse or drug resistance remains a major threat to AML patients. N6-methyladenosine (m6A) RNA methylation and super-enhancers (SEs) are extensively involved in the leukaemogenesis of AML. However, the potential relationship between m6A and SEs in AML has not been elaborated.
    METHODS: Chromatin immunoprecipitation (ChIP) sequencing data from Gene Expression Omnibus (GEO) cohort were analysed to search SE-related genes. The mechanisms of m6 A-binding proteins IGF2BP2 and IGF2BP3 on DDX21 were explored via methylated RNA immunoprecipitation (MeRIP) assays, RNA immunoprecipitation (RIP) assays and luciferase reporter assays. Then we elucidated the roles of DDX21 in AML through functional assays in vitro and in vivo. Finally, co-immunoprecipitation (Co-IP) assays, RNA sequencing and ChIP assays were performed to investigate the downstream mechanisms of DDX21.
    RESULTS: We identified two SE-associated transcripts IGF2BP2 and IGF2BP3 in AML. High enrichment of H3K27ac, H3K4me1 and BRD4 was observed in IGF2BP2 and IGF2BP3, whose expression were driven by SE machinery. Then IGF2BP2 and IGF2BP3 enhanced the stability of DDX21 mRNA in an m6A-dependent manner. DDX21 was highly expressed in AML patients, which indicated a poor survival. Functionally, knockdown of DDX21 inhibited cell proliferation, promoted cell apoptosis and led to cell cycle arrest. Mechanistically, DDX21 recruited transcription factor YBX1 to cooperatively trigger ULK1 expression. Moreover, silencing of ULK1 could reverse the promoting effects of DDX21 overexpression in AML cells.
    CONCLUSIONS: Dysregulation of SE-IGF2BP2/IGF2BP3-DDX21 axis facilitated the progression of AML. Our findings provide new insights into the link between SEs and m6A modification, elucidate the regulatory mechanisms of IGF2BP2 and IGF2BP3 on DDX21, and reveal the underlying roles of DDX21 in AML.
    Keywords:  DDX21; N6‐methyladenosine (m6A); acute myeloid leukaemia (AML); super‐enhancers (SEs)
    DOI:  https://doi.org/10.1002/ctm2.1628
  20. Mol Cancer Ther. 2024 Apr 02.
      CD33 (Siglec-3) is a cell surface receptor expressed in approximately 90% of AML blasts, making it an attractive target for therapy of acute myeloid leukemia (AML). While previous CD33-targeting antibody-drug conjugates (ADCs) like gemtuzumab ozogamicin (GO, Mylotarg) have shown efficacy in AML treatment, they have suffered from toxicity and narrow therapeutic window. This study aimed to develop a novel ADC with improved tolerability and a wider therapeutic window. GLK-33 consists of the anti-CD33 antibody lintuzumab and eight mavg-MMAU auristatin linker-payloads per antibody. The experimental methods included testing in cell cultures, patient-derived samples, mouse xenograft models, and rat toxicology studies. GLK-33 exhibited remarkable efficacy in reducing cell viability within CD33-positive leukemia cell lines and primary AML samples. Notably, GLK-33 demonstrated anti-tumor activity at single dose as low as 300 µg/kg in mice, while maintaining tolerability at single dose of 20 - 30 mg/kg in rats. In contrast to both GO and lintuzumab vedotin, GLK-33 exhibited a wide therapeutic window and activity against multidrug-resistant cells. The development of GLK-33 addresses the limitations of previous ADCs, offering a wider therapeutic window, improved tolerability, and activity against drug-resistant leukemia cells. These findings encourage further exploration of GLK-33 in AML through clinical trials.
    DOI:  https://doi.org/10.1158/1535-7163.MCT-23-0720
  21. Cancer Discov. 2024 Apr 04. 14(4): 605-609
      We explore the phenomenon of somatic mutations, including those in cancer driver genes, that are present in healthy, normal-appearing tissues and their potential implications for cancer development. We also examine the landscape of these somatic mutations, discuss the role of clonal cell competition and external factors like inflammation in enhancing the fitness of mutant clones, and conclude by considering how understanding these mutations will aid in prevention and/or interception of cancer.
    DOI:  https://doi.org/10.1158/2159-8290.CD-23-1508
  22. JCI Insight. 2024 Apr 02. pii: e174783. [Epub ahead of print]
      People with HIV (PWH) have a higher age-adjusted mortality due to chronic immune activation and age-related comorbidities. PWH also have higher rates of clonal hematopoiesis (CH) than age-matched non-HIV cohorts, however, risk factors influencing the development and expansion of CH in PWH remain incompletely explored. We investigated the relationship between CH, immune biomarkers, and HIV-associated risk factors (CD4, CD8 T-cells, nadir CD4 count, opportunistic infections [OIs], and immune reconstitution inflammatory syndrome [IRIS]) in a diverse cohort of 197-PWH with median age of 42-years, using a 56-gene panel. Seventy-nine percent had a CD4 nadir < 200, 58.9% had prior OIs, and 34.5% had a history of IRIS. The prevalence of CH was high (27.4%), even in younger individuals, and CD8 T-cells and nadir CD4 counts strongly associated with CH after controlling for age. A history of IRIS was associated with CH in a subgroup analysis of ≥ 35-years-old patients. Inflammatory biomarkers were higher in CH carriers compared to non-carriers supporting a dysregulated immune state. These findings suggest PWH with low nadir CD4 and/or inflammatory complications may be at high risk of CH regardless of age and represent a high-risk group that could benefit from risk reduction and potentially targeted immunomodulation.
    Keywords:  AIDS/HIV; Aging; Clonal selection; Macrophages; T cells
    DOI:  https://doi.org/10.1172/jci.insight.174783
  23. Exp Hematol. 2024 Mar 28. pii: S0301-472X(24)00072-9. [Epub ahead of print]133 104213
      
    DOI:  https://doi.org/10.1016/j.exphem.2024.104213
  24. Blood. 2024 Apr 04. 143(14): 1323-1324
      
    DOI:  https://doi.org/10.1182/blood.2023023757