bims-tremyl Biomed News
on Therapy resistance biology in myeloid leukemia
Issue of 2024–11–03
thirty papers selected by
Paolo Gallipoli, Barts Cancer Institute, Queen Mary University of London



  1. Nature. 2024 Oct 30.
      Cancer driver mutations often show distinct temporal acquisition patterns, but the biological basis for this, if any, remains unknown. RAS mutations occur invariably late in the course of acute myeloid leukaemia, upon progression or relapsed/refractory disease1-6. Here, by using human leukaemogenesis models, we first show that RAS mutations are obligatory late events that need to succeed earlier cooperating mutations. We provide the mechanistic explanation for this in a requirement for mutant RAS to specifically transform committed progenitors of the myelomonocytic lineage (granulocyte-monocyte progenitors) harbouring previously acquired driver mutations, showing that advanced leukaemic clones can originate from a different cell type in the haematopoietic hierarchy than ancestral clones. Furthermore, we demonstrate that RAS-mutant leukaemia stem cells (LSCs) give rise to monocytic disease, as observed frequently in patients with poor responses to treatment with the BCL2 inhibitor venetoclax. We show that this is because RAS-mutant LSCs, in contrast to RAS-wild-type LSCs, have altered BCL2 family gene expression and are resistant to venetoclax, driving clinical resistance and relapse with monocytic features. Our findings demonstrate that a specific genetic driver shapes the non-genetic cellular hierarchy of acute myeloid leukaemia by imposing a specific LSC target cell restriction and critically affects therapeutic outcomes in patients.
    DOI:  https://doi.org/10.1038/s41586-024-08137-x
  2. Nature. 2024 Oct 30.
      Allogeneic haematopoietic cell transplantation (HCT) replaces the stem cells responsible for blood production with those from a donor1,2. Here, to quantify dynamics of long-term stem cell engraftment, we sequenced genomes from 2,824 single-cell-derived haematopoietic colonies of ten donor-recipient pairs taken 9-31 years after HLA-matched sibling HCT3. With younger donors (18-47 years at transplant), 5,000-30,000 stem cells had engrafted and were still contributing to haematopoiesis at the time of sampling; estimates were tenfold lower with older donors (50-66 years). Engrafted cells made multilineage contributions to myeloid, B lymphoid and T lymphoid populations, although individual clones often showed biases towards one or other mature cell type. Recipients had lower clonal diversity than matched donors, equivalent to around 10-15 years of additional ageing, arising from up to 25-fold greater expansion of stem cell clones. A transplant-related population bottleneck could not explain these differences; instead, phylogenetic trees evinced two distinct modes of HCT-specific selection. In pruning selection, cell divisions underpinning recipient-enriched clonal expansions had occurred in the donor, preceding transplant-their selective advantage derived from preferential mobilization, collection, survival ex vivo or initial homing. In growth selection, cell divisions underpinning clonal expansion occurred in the recipient's marrow after engraftment, most pronounced in clones with multiple driver mutations. Uprooting stem cells from their native environment and transplanting them to foreign soil exaggerates selective pressures, distorting and accelerating the loss of clonal diversity compared to the unperturbed haematopoiesis of donors.
    DOI:  https://doi.org/10.1038/s41586-024-08128-y
  3. Bone Marrow Transplant. 2024 Oct 25.
      Routine genetic profiling of acute myeloid leukemia (AML) at initial diagnosis has allowed subgroup specific prognostication, drug development, and clinical management strategies. The optimal approach for treatment response assessment for AML subgroups has not yet however been determined. A nationwide cohort of 257 adult patients in first remission (CR1) from AML associated with an IDH2 mutation (IDH2m) undergoing allogeneic transplant during the period 2013-2019 in the United States had rates of relapse and survival three years after transplantation of 24% and 71%, respectively. Pre-transplant clinical flow cytometry assessment was not useful in stratifying patients based on risk of post-transplant relapse or death. DNA-sequencing was performed on CR1 blood collected within 100 days before transplant. Persistent detection of IDH2m was common (51%) and associated with increased relapse and death compared to testing negative. Co-mutation at initial diagnosis with mutated NPM1 and/or FLT3-ITD was common in this cohort (41%) and use of these validated MRD markers provided superior stratification compared to IDH2m testing. Patients testing negative for IDH2m prior to transplant had low relapse-related death, regardless of conditioning intensity. Post-transplant relapse rates for those with persistently detectable IDH2m in pre-transplant remission were lower after the FDA approval of enasidenib in August 2017.
    DOI:  https://doi.org/10.1038/s41409-024-02449-2
  4. Expert Rev Hematol. 2024 Oct 30.
       INTRODUCTION: The development of oral therapies impacts management of acute myeloid leukemia and myelodysplastic syndromes, especially for targetable mutations including IDH1/2.
    AREAS COVERED: We discuss IDH1/2 activity and inhibitor therapy in various settings, including as monotherapy, combination therapy with hypomethylating agents, and other approaches.
    EXPERT OPINION: Olutasidenib, enasidenib, and ivosidenib are approved for relapsed AML. Ivosidenib is approved for relapsed MDS and alone or with azacitidine in newly diagnosed AML. However, unanswered questions exist. In newly diagnosed AML ivosidenib + azacitidine shows a survival benefit compared to azacitidine but it is unknown whether ivosidenib + azacitidine demonstrates improved survival compared to ivosidenib. Ivosidenib + azacitidine demonstrated a survival benefit not seen with enasidenib + azacitidine. It is unclear whether newly diagnosed AML should be treated with azacitidine + ivosidenib or azacitidine + venetoclax. Azacitidine + venetoclax shows excellent response rates in IDH mutated disease. Retrospective data shows low response rates of IDH inhibitor therapy post venetoclax whereas HMA + venetoclax retains activity post IDH inhibition. The role of IDH inhibition post-transplant is unclear. Single arm studies show post-transplant maintenance is safe, however, randomized trials are needed. Similarly, IDH inhibitors can be combined with chemotherapy however randomized studies are needed.
    Keywords:  IDH mutation; Leukemia; MDS; hematology; oral therapy
    DOI:  https://doi.org/10.1080/17474086.2024.2422554
  5. Leukemia. 2024 Oct 31.
      The association of graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL) effects after allogeneic stem-cell transplantation (SCT) is well-established but was not confirmed in the modern era and following post-transplant cyclophosphamide (PTCy). We assessed GVHD/ GVL association in AML patients following HLA-matched SCT with standard calcineurin-based (n = 12,653, 57% with additional in-vivo T-cell depletion) or PTCy-based (n = 508) GVHD prophylaxis. Following standard prophylaxis, acute GVHD grade II-IV and III-IV, chronic GVHD, and extensive chronic GVHD rates were 23.8%, 7.5%, 37.0%, and 16.3%, respectively. Acute GVHD grade II and III-IV were associated with lower relapse [hazard-ratio (HR) 0.85, P = 0.002; HR 0.76, P = 0.003, respectively)], higher non-relapse mortality (NRM) (HR 1.5, P < 0.001; HR 6.21, P < 0.001) and lower overall survival (OS) (HR 1.49, P < 0.001; HR 6.1, P < 0.001). Extensive chronic GVHD predicted lower relapse (HR 0.69, P < 0.001), higher NRM (HR 2.83, P < 0.001), and lower OS (HR 2.74, P < 0.001). Following PTCy, GVHD rates were 22.8%, 6.2%, 35.5%, and 17.7%, respectively. Acute GVHD was not associated with relapse (HR 1.37, P = 0.15) but predicted higher NRM (HR 3.34, P < 0.001) and lower OS (HR 1.92, P = 0.001). Chronic GVHD was not prognostic for these outcomes. In conclusion, GVHD and GVL are strongly associated with contemporary SCT. However, following PTCy, GVHD is not associated with reduced relapse.
    DOI:  https://doi.org/10.1038/s41375-024-02445-x
  6. Nat Commun. 2024 Oct 29. 15(1): 9341
      Chromosomal translocations involving the mixed-lineage leukemia (MLL) locus generate potent oncogenic fusion proteins (oncoproteins) that disrupt regulation of developmental gene expression. By profiling the oncoprotein-target sites of 36 broadly representative MLL-rearranged leukemia samples, including three samples that underwent a lymphoid-to-myeloid lineage-switching event in response to therapy, we find the genomic enrichment of the oncoprotein is highly variable between samples and subject to dynamic regulation. At high levels of expression, the oncoproteins preferentially activate either an acute lymphoblastic leukemia (ALL) program, enriched for pro-B-cell genes, or an acute myeloid leukemia (AML) program, enriched for hematopoietic-stem-cell genes. The fusion-partner-specific-binding patterns over these gene sets are highly correlated with the prevalence of each mutation in ALL versus AML. In lineage-switching samples the oncoprotein levels are reduced and the oncoproteins preferentially activate granulocyte-monocyte progenitor (GMP) genes. In a sample that lineage switched during treatment with the menin inhibitor revumenib, the oncoprotein and menin are reduced to undetectable levels, but ENL, a transcriptional cofactor of the oncoprotein, persists on numerous oncoprotein-target loci, including genes in the GMP-like lineage-switching program. We propose MLL oncoproteins promote lineage-switching events through dynamic chromatin binding at lineage-specific target genes, and may support resistance to menin inhibitors through similar changes in chromatin occupancy.
    DOI:  https://doi.org/10.1038/s41467-024-53399-8
  7. Semin Hematol. 2024 Sep 28. pii: S0037-1963(24)00110-0. [Epub ahead of print]
      In work spanning several decades, extensive studies have focused on the properties of malignant stem cells that drive the pathogenesis of acute myeloid leukemia (AML). However, relatively little attention has been devoted to several serious myeloid malignancies that occur prior to the onset of frank leukemia, including myelodysplastic syndrome (MDS). Like leukemia, MDS is hypothesized to arise from a pool of immature malignant stem and progenitor cells (MDS-SCs) that serve as a reservoir for disease evolution and progression1. While multiple studies have sought to identify and characterize the biology and vulnerabilities of MDS-SCs, yet translation of scientific concepts to therapeutically impactful regimens has been limited. Here, we evaluate the currently known properties of MDS-SCs as well as the post-transcriptional mechanisms that drive MDS pathogenesis at a stem and progenitor level. We highlight limits and gaps in our characterization and understanding of MDS-SCs and address the extent to which the properties of MDS-SC are (and can be) inferred from the characterization of LSCs.
    Keywords:  Leukemia stem cell; Myelodysplastic syndrome; Myelodysplastic syndrome stem cell
    DOI:  https://doi.org/10.1053/j.seminhematol.2024.09.007
  8. Clin Cancer Res. 2024 Oct 30.
      On December 1st, 2022, the FDA approved the new molecular entity olutasidenib (Rezlidhia: Rigel Pharmaceuticals), a small-molecule inhibitor of isocitrate dehydrogenase-1 (IDH1), for the treatment of adult patients with relapsed or refractory acute myeloid leukemia (R/R AML) with a susceptible IDH1 mutation as detected by an FDA-approved test. The efficacy of olutasidenib was established based on complete remission (CR) + CR with partial hematological recovery (CRh) rate, duration of CR + CRh, and conversion of transfusion dependence (TD) to transfusion independence (TI) in Study 2102-HEM-101. In the pivotal trial, 147 adult patients treated with 150mg twice daily (BID) of olutasidenib were evaluable for efficacy. With a median follow-up of 10.2 months, the CR/CRh rate was 35% (95% CI: 27-43%), with a median duration of response of 25.9 months (95% CI: 13.5 months, not reached [NR]). Of the 86 patients that were TD at baseline, 29 became TI (34%). The most common (≥20%) adverse reactions were nausea, fatigue, arthralgia, leukocytosis, dyspnea, pyrexia, rash, mucositis, diarrhea, and transaminitis. An assessment of long-term safety of olutasidenib is a condition of this approval.
    DOI:  https://doi.org/10.1158/1078-0432.CCR-24-2196
  9. Nat Commun. 2024 Oct 30. 15(1): 9402
    TumorProfiler Consortium
      Deep single-cell multi-omic profiling offers a promising approach to understand and overcome drug resistance in relapsed or refractory (rr) acute myeloid leukemia (AML). Here, we combine single-cell ex vivo drug profiling (pharmacoscopy) with single-cell and bulk DNA, RNA, and protein analyses, alongside clinical data from 21 rrAML patients. Unsupervised data integration reveals reduced ex vivo response to the Bcl-2 inhibitor venetoclax (VEN) in patients treated with both a hypomethylating agent (HMA) and VEN, compared to those pre-exposed to chemotherapy or HMA alone. Integrative analysis identifies both known and unreported mechanisms of innate and treatment-related VEN resistance and suggests alternative treatments, like targeting increased proliferation with the PLK inhibitor volasertib. Additionally, high CD36 expression in VEN-resistant blasts associates with sensitivity to CD36-targeted antibody treatment ex vivo. This study demonstrates how single-cell multi-omic profiling can uncover drug resistance mechanisms and treatment vulnerabilities, providing a valuable resource for future AML research.
    DOI:  https://doi.org/10.1038/s41467-024-53535-4
  10. Biomark Res. 2024 Oct 29. 12(1): 128
      Acute myeloid leukaemia (AML) is a highly heterogeneous malignancy, with a poor 5-year overall survival rate of approximately 30%. Consequently, the search for novel therapeutic strategies is ongoing, and the identification of new vulnerabilities could accelerate progress. Oxidative stress and metabolic rewiring are established hallmarks of cancer, and recent evidence suggests that NADPH oxidases may regulate metabolism, potentially linking these two processes. Increasing research highlights the importance of NOX2 in AML, particularly its role in metabolic regulation. In this study, we investigated the effects of simultaneously inhibiting NOX2 and glycolysis in AML cells. Dual inhibition of NOX2 and glycolysis-by targeting hexokinase or lactate dehydrogenase (LDH)-significantly reduced cell proliferation, markedly impaired clonogenic potential, and induced extensive cell death in a broad panel of AML cell lines. Importantly, these findings were further validated in primary bone marrow samples derived from AML patients, where combined inhibition triggered similar potent anti-leukemic effects. Furthermore, the combined inhibition of NOX2 and LDH enhanced the efficacy of cytarabine (AraC), suggesting this approach could boost the effectiveness of conventional therapies. In an in vivo AML model, targeting NOX2 and LDH in myeloid progenitor cells delayed the onset of leukaemia and extended survival. In conclusion, our findings propose a novel therapeutic strategy for AML through the dual targeting of NOX2 and glycolysis.
    Keywords:   CYBB ; Acute myeloid leukaemia; Glycolysis; Hexokinase; Lactate dehydrogenase (LDH); NADPH oxidase; NOX2
    DOI:  https://doi.org/10.1186/s40364-024-00674-x
  11. Am J Hematol. 2024 Oct 30.
      De novo normal karyotype AML 2017ELN and 2022ELN Genetic Risk Category Changes and Overall Survival in Induction Treated Patients.
    DOI:  https://doi.org/10.1002/ajh.27518
  12. Cell Rep. 2024 Oct 29. pii: S2211-1247(24)01252-X. [Epub ahead of print]43(11): 114901
      Control of stem cell-associated genes by Trithorax group (TrxG) and Polycomb group (PcG) proteins is frequently misregulated in cancer. In leukemia, oncogenic fusion proteins hijack the TrxG homolog KMT2A and disrupt PcG activity to maintain pro-leukemogenic gene expression, though the mechanisms by which oncofusion proteins antagonize PcG proteins remain unclear. Here, we define the relationship between NUP98 oncofusion proteins and the non-canonical polycomb repressive complex 1.1 (PRC1.1) in leukemia using Menin-KMT2A inhibitors and targeted degradation of NUP98 fusion proteins. Eviction of the NUP98 fusion-Menin-KMT2A complex from chromatin is not sufficient to silence pro-leukemogenic genes. In the absence of PRC1.1, key oncogenes remain transcriptionally active. Transition to a repressed chromatin state requires the accumulation of PRC1.1 and repressive histone modifications. We show that PRC1.1 loss leads to resistance to small-molecule Menin-KMT2A inhibitors in vivo. Therefore, a critical function of oncofusion proteins that hijack Menin-KMT2A activity is antagonizing repressive chromatin complexes.
    Keywords:  CP: Cancer; CP: Molecular biology; acute myeloid leukemia; chromatin complex; lysine methyltransferase 2A; menin; nascent transcriptomics; non-canonical polycomb repressive complex 1.1; nucleoporin 98-rearrangement; oncogenic fusion protein
    DOI:  https://doi.org/10.1016/j.celrep.2024.114901
  13. Sci Signal. 2024 Oct 29. 17(860): eadl5100
      Both cell-intrinsic and niche-derived, cell-extrinsic cues drive the specification of hematopoietic multipotent progenitors (MPPs) in the bone marrow, which comprise multipotent MPP1 cells and lineage-restricted MPP2, MPP3, and MPP4 subsets. Patients with WHIM syndrome, a rare congenital immunodeficiency caused by mutations that prevent desensitization of the chemokine receptor CXCR4, have an excess of myeloid cells in the bone marrow. Here, we investigated the effects of increased CXCR4 signaling on the localization and fate of MPPs. Knock-in mice bearing a WHIM syndrome-associated CXCR4 mutation (CXCR41013) phenocopied the myeloid skewing of bone marrow in patients. Whereas MPP4 cells in wild-type mice differentiated into lymphoid cells, MPP4s in CXCR41013 knock-in mice differentiated into myeloid cells. This myeloid rewiring of MPP4s in CXCR41013 knock-in mice was associated with enhanced signaling mediated by the kinase mTOR and increased oxidative phosphorylation (OXPHOS). MPP4s also localized further from arterioles in the bone marrow of knock-in mice compared with wild-type mice, suggesting that the loss of extrinsic cues from the perivascular niche may also contribute to their myeloid skewing. Chronic treatment with the CXCR4 antagonist AMD3100 or the mTOR inhibitor rapamycin restored the lymphoid potential of MPP4s in knock-in mice. Thus, CXCR4 desensitization drives the lymphoid potential of MPP4 cells by dampening the mTOR-dependent metabolic changes that promote myeloid differentiation.
    DOI:  https://doi.org/10.1126/scisignal.adl5100
  14. Curr Res Transl Med. 2024 Oct 25. pii: S2452-3186(24)00038-2. [Epub ahead of print]73(1): 103476
      Heterogeneous approaches exist in regard to the management of disease-related co-morbidities in potential allogeneic haematopoietic cell transplantation (allo-HCT) candidates with myelofibrosis (MF). The EBMT Chronic Malignancies Working Party launched an electronic survey to evaluate how MF-specific comorbidities are approached and whether they ultimately affect the decision to transplant. A total of 41/63 (65%) Centers, all of whom were experienced in the management of MF allo-HCT, responded. Responses were aggregated and reported in a comparative fashion. Screening for portal hypertension (PH) was routinely performed in 54% centers, never in 12% and guided by clinical manifestations in the remaining. Involvement of hepatologists/gastroenterologists was always/very often considered in patients with signs of PH prior to transplant. Centers reported that radiological evidence of PH did not routinely represent a formal contraindication for allo-HCT in most cases (78%). Of note, most centers (61%) did not perform routine screening for gastroesophageal varices; this was systematically considered or guided by clinical manifestations in only 7% and 32% centers, respectively. Presence of gastroesophageal varices was always (15%) or occasionally (19%) considered a formal contraindication to allo-HCT. A prior history of portal vein thrombosis never (78%) or occasionally (15%) represented a formal contraindication. Three Centers would not proceed to transplant in such cases. Less importance was assigned to non-portal splanchnic vein thrombosis (SVT), with all but one centre proceeding to transplant regardless of prior SVT. This survey highlights a considerable heterogeneity across responding centers in approaching MF-related comorbidities prior to transplant, suggesting that harmonisation guidelines are needed to address these issues in this patient population.
    Keywords:  Gastroesophageal varices; Hepatic dysfunction; Myelofibrosis; Portal hypertension; Portal thrombosis; Splanchnic vein thrombosis; Transplantation
    DOI:  https://doi.org/10.1016/j.retram.2024.103476
  15. Ann Hematol. 2024 Oct 29.
      Acute myeloid leukemia (AML) is the most prevalent hematologic malignancy in adults. In 2022, the European LeukemiaNet (ELN) has updated its prognostic system that incorporates cytogenetics and molecular genetics based on data from patients undergoing intensive chemotherapy (IC). Recently, a risk stratification framework has been established for hypomethylating agents (HMA)-based low-intensity treatment (LIT) to fill the gaps in stratification for this treatment modality, but this needs further refinement. Venetoclax (VEN), a BH3 mimetic, targets BCL-2 to modulate apoptosis and metabolism in AML cells. Its combination with HMA or low-dose cytarabine (LDAC) has been shown to enhance the response rates and prolong the survival outcomes of older or unfit patients with AML. In this review, we delved into the prognostic significance of FLT3-ITD and IDH mutations when used in combination with VEN and HMA, as well as in conjunction with their specific inhibitors. We also explored the role of VEN in NPM1-mutated AML and its efficacy in splicing factor mutations AML. Additionally, we examined the response rates and survival outcomes of CBF-AML when treated with a VEN-based regimen. Moving forward, it is imperative that risk stratification for LIT becomes more nuanced to better align with the requirements of personalized diagnosis and treatment strategies.
    Keywords:  Acute myeloid leukemia; Cytogenetics; Molecular genetics; Prognosis; Venetoclax
    DOI:  https://doi.org/10.1007/s00277-024-06050-x
  16. JCI Insight. 2024 Oct 29. pii: e173665. [Epub ahead of print]
      Despite the advances in the understanding and treatment of myeloproliferative neoplasm (MPN), the disease remains incurable with the risk of evolution to AML or myelofibrosis (MF). Unfortunately, the evolution of the disease to MF remains still poorly understood impeding preventive and therapeutic options. Recent studies in solid tumor microenvironment and organ fibrosis have shed instrumental insights on their respective pathogenesis and drug resistance, yet such precise data are lacking in MPN. In this study, through a patient-sample driven transcriptomic and epigenetic description of the MF microenvironment landscape and cell-based analyses, we identify HOXB7 overexpression and more precisely a novel TGFβ-Wnt-HOXB7 pathway as associated to a pro-fibrotic and pro-osteoblastic biased differentiation of mesenchymal stromal cells (MSCs). Using gene-based and chemical inhibition of this pathway we reverse the abnormal phenotype of MSCs from myelofibrosis patients, providing the MPN field with a potential novel target to prevent and manage evolution to MF.
    Keywords:  Bone marrow; Fibrosis; Hematology
    DOI:  https://doi.org/10.1172/jci.insight.173665
  17. Blood Adv. 2024 Oct 29. pii: bloodadvances.2024013361. [Epub ahead of print]
      Current efforts in translational studies in hematology often rely on immunodeficient mouse models for engrafting patient-derived hematopoietic stem and progenitor cells (HSPCs), yet these models often face challenges in effectively engrafting cells from patients with various diseases, such as myelodysplastic syndromes (MDS). In this study, we developed an induced pluripotent stem cell (iPSC)-derived human bone marrow organoid model that closely replicates the bone marrow microenvironment, facilitating the engraftment of MDS patient-derived HSPCs, thereby mirroring the patients' distinct disease characteristics. Specifically, through advanced microscopy, we verified the development of a complex three-dimensional network of endothelial, stromal, and hematopoietic cells within the organoids, resembling the autonomous human marrow microenvironment. Furthermore, we showed that HSPCs derived from the donor bone marrow of normal individuals or patients with MDS can migrate to and proliferate within the organoid's vascular niche while maintaining self-renewal and original genetic profiles. Within the organoids, the differentiation patterns from MDS HSPCs were significantly distinct compared to the multilineage hematopoiesis from normal HSPCs, which can be correlated with the clinical manifestations of the disease. These findings underscore the significance of the organoid model in studying human hematopoiesis and the pathophysiology of hematologic diseases, offering new avenues for personalized medicine and therapeutic interventions.
    DOI:  https://doi.org/10.1182/bloodadvances.2024013361
  18. Br J Haematol. 2024 Oct 29.
      Allogeneic haematopoietic stem cell transplantation (allo-HSCT) is an effective therapy for acute myeloid leukaemia (AML), predominantly due to its potent graft-versus-leukaemia (GVL) effect. However, leukaemia relapse remains a major obstacle to the success of allo-HSCT. In this study, we demonstrated that gallic acid (GA), a natural dietary compound, can enhance T-cell-mediated GVL effects both in vitro and in vivo. GA-treated T cells exhibited increased activation and elevated secretion of cytotoxic cytokines, leading to the apoptosis of AML cells in co-culture systems in vitro. In a non-irradiated leukaemia mouse model, we showed that GA treatment prolonged the survival of leukaemic mice and reduced leukaemia cell infiltration. Further analysis revealed that GA treatment increased T-cell activation and tumour necrosis factor-α secretion. Moreover, integrated transcriptomic and proteomic analyses indicated that GA augments T-cell-mediated GVL effects through the activation of the MAPK and NF-κB pathways. Blocking these pathways individually diminished the protective effect of GA in AML model mice. Importantly, GA administration did not accelerate graft-versus-host disease (GVHD) progression in a mouse model. In conclusion, our study revealed that GA can enhance the GVL effects of T cells without exacerbating GVHD, offering insights into its potential to improve outcomes for patients after HSCT.
    Keywords:  gallic acid; graft‐versus‐host disease; graft‐versus‐leukaemia; haematopoietic stem cell transplantation
    DOI:  https://doi.org/10.1111/bjh.19863
  19. Res Sq. 2024 Oct 15. pii: rs.3.rs-4954060. [Epub ahead of print]
      BTX-A51, a first-in-class oral small molecule inhibitor of casein kinase 1α (CK1α) and cyclin dependent kinase (CDK) 7 and 9, induces apoptosis of leukemic cells by activating p53 and inhibiting expression of Mcl1. Here, we report on the results of the phase 1 clinical trial of BTX-A51 in patients with relapsed or refractory AML and MDS. Thirty-one patients were enrolled into 8 dose-escalation cohorts at BTX-A51 doses ranging from 1mg to 42mg dosed three days/week for 21 or 28 days out a 28-day cycle. The recommended phase 2 dose was 21mg dosed three days/week for 4 weeks of a 28-day cycle. BTX-A51 increased expression of p53 and reduced expression of MCL1 and RNA polymerase II phosphorylation on pre- and post-treatment immunocytochemistry studies. Overall, 3 patients (10%) experienced complete remission with incomplete count recovery (CRi). All 3 responding patients had RUNX1 mutations and the CR/CRi rate for RUNX1 -mutated patients receiving BTX-A51 at efficacious doses (11mg or higher) was 30%. Ex-vivo studies confirmed higher efficacy of BTX-A51 on RUNX1 -mutated myeloblasts and demonstrate synergy with azacitidine and venetoclax. Although the overall efficacy was modest, this study lays the groundwork for future studies with improved patient selection and combination approaches.
    DOI:  https://doi.org/10.21203/rs.3.rs-4954060/v1
  20. Blood. 2024 Oct 30. pii: blood.2024025459. [Epub ahead of print]
      BCR::ABL1-negative myeloproliferative neoplasms (MPN) are clonal hematological malignancies resulting from the proliferation of myeloid cells harboring a JAK-STAT pathway activating driver mutation. MPN management recommendations are based on the evaluation of different risks to prevent disease evolution associated events while preserving patients' quality of life. Such risks can be common across all MPN or specific to each subtype (polycythemia vera (PV), essential thrombocythemia (ET), prefibrotic myelofibrosis (pre-MF), primary myelofibrosis (PMF)). MF-patients harbor the worse prognosis and hematopoietic stem cell transplantation (HSCT) is the only curative treatment, at the expense of a high morbi-mortality. Therefore, accurate scoring systems to estimate overall survival are crucial for MF patients' management and selection for HSCT. In PV and ET, vascular events prediction is prioritized given their higher incidence and related morbi-mortality. Finally, quality of life evaluation is important for all subtypes. To predict these risks and adapt MPN therapeutic strategies, clinical risk scores have been developed over the past decades, more recently including molecular risk factors for more accurate risk stratification. The large number of scoring systems available in combination with disease heterogeneity and the necessity to predict diverse outcomes, make it difficult for clinicians to choose the most appropriate score to evaluate their patients' risk in 2024. Here, we provide an overview of MPN disease evolution associated events incidence and conduct an exhaustive comparative review of the scoring systems currently available for each risk. Finally, we propose an algorithm for the use of these scores in clinical practice in each MPN subtype.
    DOI:  https://doi.org/10.1182/blood.2024025459
  21. bioRxiv. 2024 Oct 17. pii: 2024.10.14.617891. [Epub ahead of print]
      Deleterious germline DDX41 variants constitute the most common inherited predisposition disorder linked to myeloid neoplasms (MNs). The role of DDX41 in hematopoiesis and how its germline and somatic mutations contribute to MNs remain unclear. Here we show that DDX41 is essential for erythropoiesis but dispensable for the development of other hematopoietic lineages. Using stage-specific Cre models for erythropoiesis, we reveal that Ddx41 knockout in early erythropoiesis is embryonically lethal, while knockout in late-stage terminal erythropoiesis allows mice to survive with normal blood counts. DDX41 deficiency induces a significant upregulation of G-quadruplexes (G4), noncanonical DNA structures that tend to accumulate in the early stages of erythroid precursors. We show that DDX41 co-localizes with G4 on the erythroid genome. DDX41 directly binds to and dissolves G4, which is significantly compromised in MN-associated DDX41 mutants. Accumulation of G4 by DDX41 deficiency induces erythroid genome instability, defects in ribosomal biogenesis, and upregulation of p53. However, p53 deficiency does not rescue the embryonic death of Ddx41 hematopoietic-specific knockout mice. In parallel, genome instability also activates the cGas-Sting pathway, which is detrimental to survival since cGas-deficient and hematopoietic-specific Ddx41 knockout mice are viable without detectable hematologic phenotypes, although these mice continue to show erythroid ribosomal defects and upregulation of p53. These findings are further supported by data from a DDX41 mutated MN patient and human iPSC-derived bone marrow organoids. Our study establishes DDX41 as a G4 dissolver, essential for erythroid genome stability and suppressing the cGAS-STING pathway.
    DOI:  https://doi.org/10.1101/2024.10.14.617891
  22. Blood Cancer J. 2024 Oct 25. 14(1): 188
      This viewpoint summarizes findings from analyses of large personal patient databases of myeloproliferative neoplasms (MPNs) to assess the impact of thrombosis on mortality, disease progression, and second cancers (SC). Despite advances, the current incidence of arterial and venous thrombosis remains a challenge. These events appear to signal a more aggressive disease course, as evidenced by their association with myelofibrosis progression and mortality using multistate models and time-dependent multivariable analysis. Inflammatory biomarkers, such as the neutrophil-to-lymphocyte ratio (NLR), are associated with the aggressiveness of polycythemia vera (PV) and essential thrombocythemia (ET), linking thrombosis to SC risk. This suggests a common inflammatory pathway likely influencing cardiovascular disease and cancer incidence. Notably, this is observed more frequently in younger patients, likely due to prolonged exposure to MPN and environmental inflammatory triggers. These data underscore the need for new studies to validate these associations, delineate the sequence of events, and identify therapeutic targets to mitigate thrombotic events and potentially improve overall patient outcomes in MPN.
    DOI:  https://doi.org/10.1038/s41408-024-01169-6
  23. Mol Cancer. 2024 Oct 28. 23(1): 240
       BACKGROUND: In the ongoing battle against BCR-ABL+ leukemia, despite significant advances with tyrosine kinase inhibitors (TKIs), the persistent challenges of drug resistance and the enduring presence of leukemic stem cells (LSCs) remain formidable barriers to achieving a cure.
    METHODS: In this study, we demonstrated that Disulfiram (DSF) induces ferroptosis to synergize with TKIs in inhibiting BCR-ABL+ cells, particularly targeting resistant cells and LSCs, using cell models, mouse models, and primary cells from patients. We elucidated the mechanism by which DSF promotes GPX4 degradation to induce ferroptosis through immunofluorescence, co-immunoprecipitation (CO-IP), RNA sequencing, lipid peroxidation assays, and rescue experiments.
    RESULTS: Here, we present compelling evidence elucidating the sensitivity of DSF, an USA FDA-approved drug for alcohol dependence, towards BCR-ABL+ cells. Our findings underscore DSF's ability to selectively induce a potent cytotoxic effect on BCR-ABL+ cell lines and effectively inhibit primary BCR-ABL+ leukemia cells. Crucially, the combined treatment of DSF with TKIs selectively eradicates TKI-insensitive stem cells and resistant cells. Of particular note is DSF's capacity to disrupt GPX4 stability, elevate the labile iron pool, and intensify lipid peroxidation, ultimately leading to ferroptotic cell death. Our investigation shows that BCR-ABL expression induces alterations in cellular iron metabolism and increases GPX4 expression. Additionally, we demonstrate the indispensability of GPX4 for LSC development and the initiation/maintenance of BCR-ABL+ leukemia. Mechanical analysis further elucidates DSF's capacity to overcome resistance by reducing GPX4 levels through the disruption of its binding with HSPA8, thereby promoting STUB1-mediated GPX4 ubiquitination and subsequent proteasomal degradation. Furthermore, the combined treatment of DSF with TKIs effectively targets both BCR-ABL+ blast cells and drug-insensitive LSCs, conferring a significant survival advantage in mouse models.
    CONCLUSION: In summary, the dual inhibition of GPX4 and BCR-ABL presents a promising therapeutic strategy to synergistically target blast cells and drug-insensitive LSCs in patients, offering potential avenues for advancing leukemia treatment.
    Keywords:  BCR-ABL+ leukemia; Disulfiram; Ferroptosis; GPX4; Tyrosine kinase inhibitor
    DOI:  https://doi.org/10.1186/s12943-024-02162-0
  24. Leukemia. 2024 Oct 29.
      Targeted therapeutics for high-risk cancers remain an unmet medical need. Here we report the results of a large-scale screen of over 11,000 molecules for their ability to inhibit the survival and growth in vitro of human leukemic cells from multiple sources including patient samples, de novo generated human leukemia models, and established human leukemic cell lines. The responses of cells from de novo models were most similar to those of patient samples, both of which showed striking differences from the cell-line responses. Analysis of differences in subtype-specific therapeutic vulnerabilities made possible by the scale of this screen enabled the identification of new specific modulators of apoptosis, while also highlighting the complex polypharmacology of anti-leukemic small molecules such as shikonin. These findings introduce a new platform for uncovering new therapeutic options for high-risk human leukemia, in addition to reinforcing the importance of the test sample choice for effective drug discovery.
    DOI:  https://doi.org/10.1038/s41375-024-02400-w
  25. Br J Haematol. 2024 Oct 28.
      Hypereosinophilic syndromes (HES) comprise different clonal, reactive, or idiopathic disorders characterized by elevated eosinophil levels and subsequent organ damage. Kim et al. in a multicentre, single-arm, prospective phase II study, treated 32 patients with PDGFRA/B-negative HES with imatinib at the dose of 100-400 mg daily. Respective overall and complete haematological response rates were 46.9% and 18.8%, and the median time to response was 1.5 months. The molecular basis of responses was identified by using whole-exome and whole-transcriptome sequencing in 11 patients. STAT5B::RARA, PAK2::PIGX, and FIP1L1::CHIC2 fusions were identified in responders, whereas RNF130::BRAF and WNK1::KDM5A were identified in non-responders. Imatinib could be a therapeutic option for some, possibly clonal, PDGFRA/B-negative HES. Commentary on: Kim et al. Phase II trial of imatinib mesylate in patients with PDGFRA/B-negative hypereosinophilic syndrome. Br J Haematol 2024 (Online ahead of print). doi: 10.1111/bjh.19828.
    Keywords:   PDGFRA ; PDGFRB ; eosinophilia; hypereosinophilic syndrome; imatinib
    DOI:  https://doi.org/10.1111/bjh.19853
  26. Blood. 2024 Oct 30. pii: blood.2022017717. [Epub ahead of print]
      SAMD9 and SAMD9L (SAMD9/9L) are paralogous genes encoding antiviral proteins that negatively regulate cell proliferation. Heterozygous germline gain-of-function (GoF) SAMD9/9L variants cause multisystem syndromes with variable manifestations. The unifying features are cytopenia, immunodeficiency, infections, bone marrow failure (BMF), myelodysplasia (MDS) and monosomy 7. Non-hematopoietic presentations can affect almost every organ system. Growth impairment and adrenal insufficiency are typical in SAMD9, while progressive neurologic deficits characterize SAMD9L. Most patients (>90%) carry germline missense GoF variants. A subgroup of patients presenting with SAMD9L-associated inflammatory disease (SAAD) carry frameshift truncating variants that are also GoF. Somatic genetic rescue occurs in >2/3 of patients and involves monosomy 7, which may spontaneously disappear (transient monosomy 7) or progress to MDS/leukemia, and adaptive clones with somatic SAMD9/9L compensatory mutations or uniparental disomy 7q (UPD7q), both associated with remission. This manuscript examines the clinical and genetic spectrum, therapies and outcome based on 243 published patients compiled in our registry with additional genetic information on 62 unpublished cases. We consolidate the diverse clinical manifestations and diagnostic challenges of SAMD9/9L syndromes to enhance recognition and improve patient care. We highlight the knowledge gaps in pathomechanisms and emphasize the importance of genetic surveillance assessing disease remission versus disease progression. Insights are provided into variant curation and the necessity of testing for somatic SAMD9/9L mutations and UPD7q. Multidisciplinary care in specialized centers is critical to manage these complex disorders. Future natural history studies, especially in patients with monosomy 7, will help formulate evidence-based surveillance protocols and optimize transplant timing and outcomes.
    DOI:  https://doi.org/10.1182/blood.2022017717
  27. Blood. 2024 Nov 01. pii: blood.2024026311. [Epub ahead of print]
      Long-term outcomes with tyrosine kinase inhibitors (TKI) show that their impact on CML is sustained as shown by 13 studies with 5- to 14-year-follow-up and numerous shorter-term studies of newly diagnosed chronic-phase CML. Twenty-five years of imatinib (IM)-treatment confirm its beneficial effect on survival and possibly cure of CML. Large randomized academic treatment optimization studies have confirmed and extended the pivotal International Randomized Study on Interferon and STI571 (IRIS). The 3 academic trials in Germany, France and the UK did not show benefit of the IM-interferon (IFN) combination, despite the immunomodulatory properties of IFN. Second generation (2G)-TKI induce responses faster than IM and recognize IM-resistance-mutations, but do not prolong survival compared to IM. Serious drug related reactions (ADR) limit the general use of 2GTKI despite frequent, but mostly mild IM-ADR. Molecular monitoring of treatment efficacy has been established serving as an example for other neoplasms. Comorbidities, transcript type and the negative impact of high-risk additional chromosomal abnormalities (ACA) were addressed. A new prognostic score (EUTOS-long-term-survival or ELTS-score) accounts for the fact that the majority of CML-patients die of other causes. Non-CML determinants of survival have been identified. Large and long-term observational studies demonstrate that progress with CML-management has also reached routine care in most, but not all instances. Despite merits of 2GTKI IM remains the preferred treatment option for CML due to its efficacy and superior safety.
    DOI:  https://doi.org/10.1182/blood.2024026311