bims-tremyl Biomed News
on Therapy resistance biology in myeloid leukemia
Issue of 2023–02–12
thirty-two papers selected by
Paolo Gallipoli, Barts Cancer Institute, Queen Mary University of London



  1. Blood. 2023 Feb 09. pii: blood.2022017808. [Epub ahead of print]
      The European LeukemiaNet (ELN) recently revised both the clinical (2022) and measurable residual disease (MRD) testing (2021) guidelines for acute myeloid leukemia (AML). Updated World Health Organization (WHO) and an International Consensus Classification (ICC) for myeloid neoplasms were also published in 2022. Together, these documents update the classification, risk stratification, prognostication, monitoring recommendations, and response assessment for patients with AML. Increased appreciation of the genetic drivers of AML over the past decade and our increasingly sophisticated understanding of AML biology have been translated into novel therapies and more complex clinical treatment guidelines. Somatic genetic abnormalities and germline predispositions now define and guide treatment and counseling for subtypes of this hematologic malignancy. In this paper, we discuss how we approach AML in daily clinical practice taking into consideration these recent updates in the context of new treatments and discoveries over the past decade.
    DOI:  https://doi.org/10.1182/blood.2022017808
  2. Blood Cancer Discov. 2023 Feb 10. pii: BCD-22-0086. [Epub ahead of print]
      Acute myeloid leukemia (AML) is fueled by leukemic stem cells (LSCs) whose determinants are challenging to discern from hematopoietic stem cells (HSCs) or uncover by approaches focused on general cell properties. We have identified a set of RNA binding proteins (RBPs) selectively enriched in human AML LSCs. Using an in vivo two-step CRISPR-Cas9 screen to assay stem cell functionality, we found 32 RBPs essential for LSCs in MLL-AF9;NrasG12D AML. Loss-of-function approaches targeting key hit RBP ELAVL1 compromised LSC-driven in vivo leukemic reconstitution and selectively depleted primitive malignant vs. healthy cells. Integrative multiomics revealed differentiation, splicing and mitochondrial metabolism as key features defining the leukemic ELAVL1-mRNA interactome with mitochondrial import protein, TOMM34 being a direct ELAVL1-stabilized target whose repression impairs AML propagation. Altogether, using a stem cell-adapted in vivo CRISPR screen, this work demonstrates pervasive reliance on RBPs as regulators of LSCs and highlights their potential as therapeutic targets in AML.
    DOI:  https://doi.org/10.1158/2643-3230.BCD-22-0086
  3. Br J Haematol. 2023 Feb 06.
      TET2 inactivating mutations serve as initiating genetic lesions in the transformation of haematopoietic stem and progenitor cells (HSPCs). In this study, we analysed known drugs in zebrafish embryos for their ability to selectively kill tet2-mutant HSPCs in vivo. We found that the exportin 1 (XPO1) inhibitors, selinexor and eltanexor, selectively kill tet2-mutant HSPCs. In serial replating colony assays, these small molecules were selectively active in killing murine Tet2-deficient Lineage-, Sca1+, Kit+ (LSK) cells, and also TET2-inactivated human acute myeloid leukaemia (AML) cells. Selective killing of TET2-mutant HSPCs and human AML cells by these inhibitors was due to increased levels of apoptosis, without evidence of DNA damage based on increased γH2AX expression. The finding that TET2 loss renders HSPCs and AML cells selectively susceptible to cell death induced by XPO1 inhibitors provides preclinical evidence of the selective activity of these drugs, justifying further clinical studies of these small molecules for the treatment of TET2-mutant haematopoietic malignancies, and to suppress clonal expansion in age-related TET2-mutant clonal haematopoiesis.
    Keywords:  HSPC; TET2; XPO1; clonal haematopoiesis; eltanexor; selinexor
    DOI:  https://doi.org/10.1111/bjh.18667
  4. Cell Rep. 2023 Feb 09. pii: S2211-1247(23)00110-9. [Epub ahead of print]42(2): 112099
      MLL-rearrangements (MLL-r) are recurrent genetic events in acute myeloid leukemia (AML) and frequently associate with poor prognosis. In infants, MLL-r can be sufficient to drive transformation. However, despite the prenatal origin of MLL-r in these patients, congenital leukemia is very rare with transformation usually occurring postnatally. The influence of prenatal signals on leukemogenesis, such as those mediated by the fetal-specific protein LIN28B, remains controversial. Here, using a dual-transgenic mouse model that co-expresses MLL-ENL and LIN28B, we investigate the impact of LIN28B on AML. LIN28B impedes the progression of MLL-r AML through compromised leukemia-initiating cell activity and suppression of MYB signaling. Mechanistically, LIN28B directly binds to MYBBP1A mRNA, resulting in elevated protein levels of this MYB co-repressor. Functionally, overexpression of MYBBP1A phenocopies the tumor-suppressor effects of LIN28B, while its perturbation omits it. Thereby, we propose that developmentally restricted expression of LIN28B provides a layer of protection against MYB-dependent AML.
    Keywords:  AML; CP: Cancer; LIN28B; MLL-rearrangements; MYB; MYBBP1A; hematopoiesis; leukemia-initiating cell; ontogeny; tumor suppression
    DOI:  https://doi.org/10.1016/j.celrep.2023.112099
  5. Leukemia. 2023 Feb 04.
      Mitochondrial metabolism recently emerged as a critical dependency in acute myeloid leukemia (AML). The shape of mitochondria is tightly regulated by dynamin GTPase proteins, which drive opposing fusion and fission forces to consistently adapt bioenergetics to the cellular context. Here, we showed that targeting mitochondrial fusion was a new vulnerability of AML cells, when assayed in patient-derived xenograft (PDX) models. Genetic depletion of mitofusin 2 (MFN2) or optic atrophy 1 (OPA1) or pharmacological inhibition of OPA1 (MYLS22) blocked mitochondrial fusion and had significant anti-leukemic activity, while having limited impact on normal hematopoietic cells ex vivo and in vivo. Mechanistically, inhibition of mitochondrial fusion disrupted mitochondrial respiration and reactive oxygen species production, leading to cell cycle arrest at the G0/G1 transition. These results nominate the inhibition of mitochondrial fusion as a promising therapeutic approach for AML.
    DOI:  https://doi.org/10.1038/s41375-023-01835-x
  6. Cancers (Basel). 2023 Jan 25. pii: 745. [Epub ahead of print]15(3):
      Although TP53 mutations in acute myeloid leukemia (AML) are associated with poor response to venetoclax, the underlying resistance mechanism remains unclear. Herein, we investigated the functional role of dynamin-related protein 1 (DRP1) in venetoclax sensitivity in AML cells with respect to TP53 mutation status. Effects of DRP1 inhibition on venetoclax-induced cell death were compared in TP53-mutated (THP-1 and Kasumi-1) and TP53 wild-type leukemia cell lines (MOLM-13 and MV4-11), as well as in primary AML cells obtained from patients. Venetoclax induced apoptosis in TP53 wild-type AML cells but had limited effects in TP53-mutated AML cells. DRP1 expression was downregulated in MOLM-13 cells after venetoclax treatment but was unaffected in THP-1 cells. Cotreatment of THP-1 cells with venetoclax and a TP53 activator NSC59984 downregulated DRP1 expression and increased apoptosis. Combination treatment with the DRP1 inhibitor Mdivi-1 and venetoclax significantly increased mitochondria-mediated apoptosis in TP53-mutated AML cells. The combination of Mdivi-1 and venetoclax resulted in noticeable downregulation of MCL-1 and BCL-xL, accompanied by the upregulation of NOXA, PUMA, BAK, and BAX. These findings suggest that DRP1 is functionally associated with venetoclax sensitivity in TP53-mutated AML cells. Targeting DRP1 may represent an effective therapeutic strategy for overcoming venetoclax resistance in TP53-mutated AML.
    Keywords:  DRP1 inhibition; TP53 mutation; acute myeloid leukemia; mitochondrial apoptosis; venetoclax resistance
    DOI:  https://doi.org/10.3390/cancers15030745
  7. Blood Adv. 2023 Feb 06. pii: bloodadvances.2022008405. [Epub ahead of print]
      The activation of β-catenin plays critical roles in normal stem cell function, and when aberrantly activated, maintenance and enhancement of cancer stemness in many solid cancers. The aberrant β-catenin activation is also observed in acute myeloid leukemia (AML), and crucially contributes to self-renewal and propagation of leukemic stem cells (LSCs) regardless of mutations in contrast to such solid tumors. In this study, we showed that the AML-specific autocrine loop constituted of T-cell immunoglobulin mucin-3 (TIM-3) and its ligand, galectin-9 (Gal-9), drives the canonical Wnt pathway to stimulate self-renewal and propagation of leukemic stem cells (LSCs), independent of Wnt ligands. Gal-9 ligation activates the cytoplasmic Src homology 2 (SH2) domain of TIM-3 to recruit hematopoietic cell kinase (HCK), an Src family kinase highly expressed in LSCs but not in HSCs, and HCK phosphorylates p120-catenin to promote formation of the LDL-receptor related protein 6 (LRP6) signalosome, hijacking the canonical Wnt pathway. This TIM-3/HCK/p120-catenin axis is principally employed in immature LSCs compared to TIM-3-expressed differentiated AML blasts and exhausted T-cells. These data suggest that human AML LSCs constitutively activates β-catenin through utilizing the autocrine TIM-3/HCK/p120-catenin signaling, and that molecules related to this signaling axis should be critical targets for selective eradication of LSCs without impairing normal HSCs.
    DOI:  https://doi.org/10.1182/bloodadvances.2022008405
  8. Leukemia. 2023 Feb 04.
      Murine models offer a valuable tool to recapitulate genetically defined subtypes of AML, and to assess the potential of compound mutations and clonal evolution during disease progression. This is of particular importance for difficult to treat leukemias such as FLT3 internal tandem duplication (ITD) positive AML. While conditional gene targeting by Cre recombinase is a powerful technology that has revolutionized biomedical research, consequences of Cre expression such as lack of fidelity, toxicity or off-target effects need to be taken into consideration. We report on a transgenic murine model of FLT3-ITD induced disease, where Cre recombinase expression alone, and in the absence of a conditional allele, gives rise to an aggressive leukemia phenotype. Here, expression of various Cre recombinases leads to polyclonal expansion of FLT3ITD/ITD progenitor cells, induction of a differentiation block and activation of Myc-dependent gene expression programs. Our report is intended to alert the scientific community of potential risks associated with using this specific mouse model and of unexpected effects of Cre expression when investigating cooperative oncogenic mutations in murine models of cancer.
    DOI:  https://doi.org/10.1038/s41375-023-01832-0
  9. Br J Haematol. 2023 Feb 06.
      Leukaemic stem cell (LSC) gene expression has recently been linked to prognosis in patients with acute myeloid leukaemia (17-gene LSC score, LSC-17) and myelodysplastic syndromes. Although chronic myelomonocytic leukaemia (CMML) is regarded as a stem cell disorder, the clinical and biological impact of LSCs on CMML patients remains elusive. Making use of multiple independent validation cohorts, we here describe a concise three-gene expression signature (LSC-3, derived from the LSC-17 score) as an independent and robust prognostic factor for leukaemia-free and overall survival in CMML. We propose that LSC-3 could be used to supplement existing risk stratification systems, to improve prognostic performance and guide management decisions.
    Keywords:  chronic myelomonocytic leukaemia; leukaemia stem cell; prognostic scoring system
    DOI:  https://doi.org/10.1111/bjh.18681
  10. Cell Signal. 2023 Feb 07. pii: S0898-6568(23)00037-2. [Epub ahead of print] 110623
      Acute myeloid leukemia (AML) is a heterogeneous disorder with high morbidity and mortality under the existing treatment strategy. Here, we found that lysosome-associated protein transmembrane 4 beta (LAPTM4B) was frequently upregulated in AML, and high LAPTM4B was associated with poor outcome. Moreover, LAPTM4B promoted leukemia progression in vitro and in vivo. Mechanically, LAPTM4B interacted with RPS9, and positively regulated RPS9 protein stability, which enhanced leukemia cell progression via activating STAT3. Our findings indicate for the first time that LAPTM4B contributes to leukemia progression in a RPS9/STAT3-dependent manner, suggesting that LAPTM4B may serve as a promising target for treatment of AML.
    Keywords:  Acute myeloid leukemia; LAPTM4B; Progression; RPS9; STAT3
    DOI:  https://doi.org/10.1016/j.cellsig.2023.110623
  11. JAMA Oncol. 2023 Feb 09.
       Importance: The ideal postremission strategy in intermediate-risk acute myeloid leukemia (AML) in first complete remission (CR) has been a matter of debate.
    Objective: To explore the optimal therapy for patients with intermediate-risk AML after first complete remission.
    Design, Settings, and Participants: This investigator-initiated, open-label, 2-armed, phase 3 randomized clinical trial assessed patients at 16 hospitals in Germany from February 2, 2011, until July 1, 2018. Key eligibility criteria included cytogenetically defined intermediate-risk AML according to Medical Research Council classification, first CR or CR with incomplete blood cell count recovery after conventional induction therapy, age of 18 to 60 years, and availability of a human leukocyte antigen (HLA)-matched sibling or unrelated donor. A detailed statistical analysis plan was written and finalized on July 7, 2020. Data were exported for analysis on April 13, 2021.
    Interventions: Patients were randomized 1:1 to receive allogeneic hematopoietic cell transplantation (HCT) or high-dose cytarabine for consolidation and salvage HCT only in case of relapse. Strata for randomization included age (18-40 vs 41-60 years), NPM1 and CEBPA variation status, and donor type (unrelated vs related).
    Main Outcomes and Measures: End points included overall-survival as the primary outcome and disease-free survival, cumulative incidence of relapse, treatment-related mortality, and quality of life measured according to the Medical Outcomes Study 36-Item Short-Form Health Survey as secondary outcomes.
    Results: A total of 143 patients (mean [SD] age, 48.2 [9.8] years; 81 [57%] male) with AML who fulfilled the eligibility criteria were randomized. In the intention-to-treat analysis, the probability of survival at 2 years was 74% (95% CI, 62%-83%) after primary allogeneic HCT and 84% (95% CI, 73%-92%) after consolidation chemotherapy (P = .22). Disease-free survival after HCT at 2 years was 69% (95% CI, 57%-80%) compared with 40% (95% CI, 28%-53%) after consolidation chemotherapy (P = .001). Allogeneic HCT during the first CR was associated with a cumulative incidence of relapse at 2 years of 20% (95% CI, 13%-31%) compared with 58% (95% CI, 47%-71%; P < .001). Nonrelapse mortality at 2 years after primary allogeneic HCT was 9% (95% CI, 5%-19%) and 2% (95% CI, 0%-11%) after consolidation chemotherapy (P = .005). Similar outcomes were observed when analyses were confined to the 96 patients at intermediate risk according to the European Leukemia Network classification. Most importantly, all 41 patients relapsing after consolidation chemotherapy (36 hematologic, 4 molecular, and 1 extramedullary) proceeded to allogeneic HCT. No significant differences in health-related quality of life measures were observed between groups.
    Conclusions and Relevance: Primary allogeneic HCT during first CR was not associated with superior overall survival compared with consolidation chemotherapy in patients 60 years or younger with intermediate-risk AML during the first CR and an available donor.
    Trial Registration: ClinicalTrials.gov Identifier: NCT01246752.
    DOI:  https://doi.org/10.1001/jamaoncol.2022.7605
  12. Cell Death Discov. 2023 Feb 04. 9(1): 44
      Acute myeloid leukemia (AML) patients with FLT3-ITD mutations are associated with poor prognosis. FLT3-ITD inhibitors are developed and result in transient disease remission, but generally resistance develops. We propose that resistance occurs due to apoptosis evasion. We compared the abilities of five clinically used FLT3-ITD inhibitors, namely, midostaurin, crenolanib, gilteritinib, quizartinib, and sorafenib, to induce apoptosis. These drugs inhibit FLT3-ITD and induce apoptosis. Apoptosis induction is associated with GSK3β activation, Mcl-1 downregulation, and Bim upregulation. Sorafenib-resistant MOLM-13/sor cells have the secondary D835Y mutation and increased Axl signaling pathway with cross-resistance to quizartinib. Gilteritinib and crenolanib inhibit both FLT3-ITD and Axl and induce apoptosis in MOLM-13/sor cells, in which they activate GSK3β and downregulate Mcl-1. Inactivation of GSK3β through phosphorylation and inhibitors blocks apoptosis and Mcl-1 reduction. The Axl/GSK3β/Mcl-1 axis works as a feedback mechanism to attenuate apoptosis of FLT3-ITD inhibition. Homoharringtonine decreases the protein levels of Mcl-1, FLT3-ITD, and Axl. Moreover, it synergistically induces apoptosis with gilteritinib in vitro and prolongs survival of MOLM-13/sor xenografts. The GSK3β/Mcl-1 axis works as the hub of FLT3-ITD inhibitors and plays a critical role in resistance against FLT3-ITD AML-targeted therapy.
    DOI:  https://doi.org/10.1038/s41420-023-01317-0
  13. Oncogene. 2023 Feb 04.
      Isocitrate dehydrogenase 2 (IDH2) mutations occur in more than 15% of cytogenetically normal acute myeloid leukemia (CN-AML) but comparative studies of their roles in leukemogenesis have been scarce. We generated zebrafish models of IDH2R172K and IDH2R140Q AML and reported their pathologic, functional and transcriptomic features and therapeutic responses to target therapies. Transgenic embryos co-expressing FLT3ITD and IDH2 mutations showed accentuation of myelopoiesis. As these embryos were raised to adulthood, full-blown leukemia ensued with multi-lineage dysplasia, increase in myeloblasts and marrow cellularity and splenomegaly. The leukemia cells were transplantable into primary and secondary recipients and resulted in more aggressive disease. Tg(Runx1:FLT3ITDIDH2R172K) but not Tg(Runx1:FLT3ITDIDH2R140Q) zebrafish showed an increase in T-cell development at embryonic and adult stages. Single-cell transcriptomic analysis revealed increased myeloid skewing, differentiation blockade and enrichment of leukemia-associated gene signatures in both zebrafish models. Tg(Runx1:FLT3ITDIDH2R172K) but not Tg(Runx1:FLT3ITDIDH2R140Q) zebrafish showed an increase in interferon signals at the adult stage. Leukemic phenotypes in both zebrafish could be ameliorated by quizartinib and enasidenib. In conclusion, the zebrafish models of IDH2 mutated AML recapitulated the morphologic, clinical, functional and transcriptomic characteristics of human diseases, and provided the prototype for developing zebrafish leukemia models of other genotypes that would become a platform for high throughput drug screening.
    DOI:  https://doi.org/10.1038/s41388-023-02611-y
  14. Hemasphere. 2023 Feb;7(2): e824
      RUNX1 familial platelet disorder (RUNX1-FPD) is a hematopoietic disorder caused by germline loss-of-function mutations in the RUNX1 gene and characterized by thrombocytopathy, thrombocytopenia, and an increased risk of developing hematologic malignancies, mostly of myeloid origin. Disease pathophysiology has remained incompletely understood, in part because of a shortage of in vivo models recapitulating the germline RUNX1 loss of function found in humans, precluding the study of potential contributions of non-hematopoietic cells to disease pathogenesis. Here, we studied mice harboring a germline hypomorphic mutation of one Runx1 allele with a loss-of-function mutation in the other Runx1 allele (Runx1 L148A/- mice), which display many hematologic characteristics found in human RUNX1-FPD patients. Runx1 L148A/- mice displayed robust and pronounced thrombocytopenia and myeloid-biased hematopoiesis, associated with an HSC intrinsic reconstitution defect in lymphopoiesis and expansion of myeloid progenitor cell pools. We demonstrate that specific deletion of Runx1 from bone marrow stromal cells in Prrx1-cre;Runx1 fl/fl mice did not recapitulate these abnormalities, indicating that the hematopoietic abnormalities are intrinsic to the hematopoietic lineage, and arguing against a driving role of the bone marrow microenvironment. In conclusion, we report a RUNX1-FPD mouse model faithfully recapitulating key characteristics of human disease. Findings do not support a driving role of ancillary, non-hematopoietic cells in the disruption of hematopoiesis under homeostatic conditions.
    DOI:  https://doi.org/10.1097/HS9.0000000000000824
  15. Br J Haematol. 2023 Feb 10.
      A significant proportion of events in paediatric acute myeloid leukaemia (AML) are caused by resistant disease (RD). We investigated clinical and biological characteristics in 66 patients with RD from 1013 children with AML registered and treated according to the NOPHO-AML 93, NOPHO-AML 2004, DB AML-01 and NOPHO-DBH AML 2012 protocols. Risk factors for RD were age10 years or older and a white-blood-cell count (WBC) of 100 × 109 /L or more at diagnosis. The five-year overall survival (OS) was 38% (95% confidence interval [CI]: 28%-52%). Of the 63 children that received salvage therapy with chemotherapy, 59% (N = 37) achieved complete remission (CR) with OS 57% (95% CI: 42%-75%) compared to 12% (95% CI: 4%-35%) for children that did not achieve CR. Giving more than two salvage chemotherapy courses did not increase CR rates. OS for all 43 patients receiving allogeneic haematopoietic stem cell transplantation (HSCT) was 49% (95% CI: 36%-66%). Those achieving CR and proceeding to HSCT had an OS of 56% (95% CI: 41%-77%, N = 30). This study showed that almost 40% of children with primary resistant AML can be cured with salvage therapy followed by HSCT. Children that did not achieve CR after two salvage courses with chemotherapy did not benefit from additional chemotherapy.
    Keywords:  acute myeloid leukaemia; paediatric; resistant disease; survival
    DOI:  https://doi.org/10.1111/bjh.18685
  16. Blood. 2023 Feb 06. pii: blood.2022017697. [Epub ahead of print]
      Polycythemia vera (PV) is a hematopoietic stem cell (HSC) neoplasm defined by activating somatic mutations in the JAK2 gene and characterized clinically by overproduction of red blood cells, platelets, and neutrophils; significant burden of disease-specific symptoms; high rates of vascular events; and evolution to a myelofibrosis phase or acute leukemia. The JAK2V617F variant allele frequency (VAF) is a key determinant of outcomes in PV, including thrombosis and myelofibrotic progression. Herein we critically review the dynamic role of JAK2V617F mutation burden in the pathogenesis and natural history of PV, suitability of JAK2V617F VAF as a diagnostic and prognostic biomarker, and utility of JAK2V617F VAF reduction in PV treatment.
    DOI:  https://doi.org/10.1182/blood.2022017697
  17. Leuk Lymphoma. 2023 Feb 06. 1-10
      The combination of venetoclax and hypomethylating agent (HMA/venetoclax) has emerged as a treatment option for patients with de novo acute myeloid leukemia (AML) who are unfit to receive intensive chemotherapy. In this single-center retrospective study, we evaluated clinical outcomes following treatment with HMA/venetoclax in 35 patients with advanced myeloproliferative neoplasms, myelodysplastic syndrome/myeloproliferative neoplasm overlap syndromes or AML with extramedullary disease. The composite complete remission (CR) rate (including confirmed/presumed complete cytogenetic response, acute leukemia response-complete, CR and CR with incomplete hematologic recovery) was 42.9% with median overall survival (OS) of 9.7 months. Complex karyotype was associated with inferior median OS (3.7 versus 12.2 months; p = 0.0002) and composite CR rate (22% versus 50.0%; p = 0.2444). Although SRSF2 mutations were associated with higher composite CR rate (80.0% versus 28.0%; p = 0.0082), this was not associated with longer median OS (10.9 versus 8.0 months; p = 0.2269). Future studies should include these patient subgroups.
    Keywords:  Myeloproliferative neoplasm; acute myeloid leukemia; azacitidine; decitabine; extramedullary disease; hypomethylating agents; myelodysplastic/myeloproliferative neoplasm; venetoclax
    DOI:  https://doi.org/10.1080/10428194.2023.2173523
  18. Cancer Discov. 2023 Feb 06. 13(2): 266-268
       SUMMARY: In this issue of Cancer Discovery, Thomas and colleagues leverage mass spectrometry metabolomics, stable isotope labeling, and functional studies to explore metabolic vulnerabilities in cancers harboring mutations in isocitrate dehydrogenase (IDH). The authors present compelling data to support the claim that dysregulated lipid synthesis underpins a synthetic lethal target in cancers with IDH1, but not IDH2, mutations. See related article by Thomas et al., p. 496 (9).
    DOI:  https://doi.org/10.1158/2159-8290.CD-22-1325
  19. Nature. 2023 Feb 08.
      Further advances in cell engineering are needed to increase the efficacy of chimeric antigen receptor (CAR) and other T cell-based therapies1-5. As T cell differentiation and functional states are associated with distinct epigenetic profiles6,7, we hypothesized that epigenetic programming may provide a means to improve CAR T cell performance. Targeting the gene that encodes the epigenetic regulator ten-eleven translocation 2 (TET2)8 presents an interesting opportunity as its loss may enhance T cell memory9,10, albeit not cause malignancy9,11,12. Here we show that disruption of TET2 enhances T cell-mediated tumour rejection in leukaemia and prostate cancer models. However, loss of TET2 also enables antigen-independent CAR T cell clonal expansions that may eventually result in prominent systemic tissue infiltration. These clonal proliferations require biallelic TET2 disruption and sustained expression of the AP-1 factor BATF3 to drive a MYC-dependent proliferative program. This proliferative state is associated with reduced effector function that differs from both canonical T cell memory13,14 and exhaustion15,16 states, and is prone to the acquisition of secondary somatic mutations, establishing TET2 as a guardian against BATF3-induced CAR T cell proliferation and ensuing genomic instability. Our findings illustrate the potential of epigenetic programming to enhance T cell immunity but highlight the risk of unleashing unchecked proliferative responses.
    DOI:  https://doi.org/10.1038/s41586-022-05692-z
  20. ACS Nano. 2023 Feb 08.
      Ferroptosis is an alternative strategy to overcome chemoresistance, but effective therapeutic approaches to induce ferroptosis for acute myeloid leukemia (AML) treatment are limited. Here, we developed glutathione (GSH)-responsive cysteine polymer-based ferroptosis-inducing nanomedicine (GCFN) as an efficient ferroptosis inducer and chemotherapeutic drug nanocarrier for AML treatment. GCFN depleted intracellular GSH and inhibited glutathione peroxidase 4, a GSH-dependent hydroperoxidase, to cause lipid peroxidation and ferroptosis in AML cells. Furthermore, GCFN-loaded paclitaxel (PTX@GCFN) targeted AML cells and spared normal hematopoietic cells to limit the myeloablation side effects caused by paclitaxel. PTX@GCFN treatment extended the survival of AML mice by specifically releasing paclitaxel and simultaneously inducing ferroptosis in AML cells with restricted myeloablation and tissue damage side effects. Overall, the dual-functional GCFN acts as an effective ferroptosis inducer and a chemotherapeutic drug carrier for AML treatment.
    Keywords:  chemotherapy; drug targeting; ferroptosis; leukemia; myeloablation
    DOI:  https://doi.org/10.1021/acsnano.2c06313
  21. Cancer Discov. 2023 Feb 08. pii: CD-22-0956. [Epub ahead of print]
      We present the first comprehensive investigation of clonal hematopoiesis (CH) in 2,860 long-term survivors of pediatric cancer with a median follow-up time of 23.5 years. Deep-sequencing over 39 CH-related genes reveals mutations in 15% of the survivors, significantly higher than the 8.5% in 324 community controls. CH in survivors is associated with exposures to alkylating agents, radiation, and bleomycin. Therapy-related CH shows significant enrichment in STAT3, characterized as a CH-gene specific to Hodgkin lymphoma survivors, and TP53. Single-cell profiling of peripheral blood samples revealed STAT3 mutations predominantly present in T-cells and contributed by SBS25, a mutational signature associated with procarbazine exposure. Serial-sample tracking reveals that larger clone size is a predictor for future expansion of age-related CH clones, while therapy-related CH remains stable decades post-treatment. These data depict the distinct dynamics of these CH subtypes and support the need for longitudinal monitoring to determine the potential contribution to late effects.
    DOI:  https://doi.org/10.1158/2159-8290.CD-22-0956
  22. Ann Hematol. 2023 Feb 11.
      Hyperleukocytosis is associated with a significant early mortality rate in patients with acute myeloid leukemia (AML). To date, no controlled trial has ever evaluated a strategy to reduce this risk, and the initial management of these patients remains heterogeneous worldwide. The aim of the present study was to evaluate the influence of a short course of intravenous dexamethasone on the early outcomes of patients with hyperleukocytic AML with white blood cell (WBC) count above 50 × 109/L. Clinical and biological data of all consecutive patients (1997-2017) eligible for intensive chemotherapy from a single center were retrospectively collected. A total of 251 patients with a median age of 51 years and a median WBC count of 120 × 109/L were included, 95 of whom received dexamethasone. Patients treated with dexamethasone had higher WBC count and a more severe disease compared with those who did not, and they presented more often with leukostasis and hypoxemia, resulting in a more frequent need for life-sustaining therapies (p < 0.001). To account for these imbalances, patients were compared after adjusting for a propensity score, which included all variables with a prognostic influence in the overall cohort. In the matched cohort, dexamethasone was associated with lower early death (OR = 0.34, p = 0.0026) and induction failure rate (OR = 0.44, p = 0.02) and better overall survival (HR = 0.60, p = 0.011), with no impact on relapse risk (cHR = 0.73, p = 0.39). The overall survival benefit was confirmed among all tested subgroups. This study suggests that dexamethasone administration is safe and associated with a lower risk of induction mortality in patients with hyperleukocytic AML and deserves prospective evaluation.
    Keywords:  Acute myeloid leukemia; Dexamethasone; Hydroxyurea; Hyperleukocytosis; Leukostasis
    DOI:  https://doi.org/10.1007/s00277-023-05119-3
  23. Lancet Haematol. 2023 Feb 07. pii: S2352-3026(22)00378-7. [Epub ahead of print]
       BACKGROUND: CYAD-01 is an autologous chimeric antigen receptor (CAR) T-cell product based on the natural killer (NK) group 2D (NKG2D) receptor, which binds eight ligands that are overexpressed in a wide range of haematological malignancies but are largely absent on non-neoplastic cells. Initial clinical evaluation of a single infusion of CYAD-01 at a low dose in patients with relapsed or refractory acute myeloid leukaemia, myelodysplastic syndromes, and multiple myeloma supported the feasibility of the approach and prompted further evaluation of CYAD-01. The aim of the present study was to determine the safety and recommended phase 2 dosing of CYAD-01 administered without preconditioning or bridging chemotherapy.
    METHODS: The multicentre THINK study was an open-label, dose-escalation, phase 1 study for patients with relapsed or refractory acute myeloid leukaemia, myelodysplastic syndromes, or multiple myeloma, after at least one previous line of therapy. Patients were recruited from five hospitals in the USA and Belgium. The dose-escalation segment evaluated three dose levels: 3 × 108 (dose level one), 1 × 109 (dose level two), and 3 × 109 (dose level three) cells per infusion with a 3 + 3 Fibonacci study design using a schedule of three infusions at 2-week intervals followed by potential consolidation treatment consisting of three additional infusions. The occurrence of dose-limiting toxicities post-CYAD-01 infusion was assessed as the primary endpoint in the total treated patient population. The trial was registered with ClinicalTrials.gov, NCT03018405, and EudraCT, 2016-003312-12, and has been completed.
    FINDINGS: Between Feb 6, 2017, and Oct 9, 2018, 25 patients were registered in the haematological dose-escalation segment. Seven patients had manufacturing failure for insufficient yield and two had screening failure. 16 patients were treated with CYAD-01 (three with multiple myeloma and three with acute myeloid leukaemia at dose level one; three with acute myeloid leukaemia at dose level two; and six with acute myeloid leukaemia and one with myelodysplastic syndromes at dose level three). Median follow-up was 118 days (IQR 46-180). Seven patients (44%) had grade 3 or 4 treatment-related adverse events. In total, five patients (31%) had grade 3 or 4 cytokine release syndrome across all dose levels. One dose-limiting toxicity of cytokine release syndrome was reported at dose level three. No treatment-related deaths occurred, and the maximum tolerated dose was not reached. Three (25%) of 12 evaluable patients with relapsed or refractory acute myeloid leukaemia or myelodysplastic syndromes had an objective response. Among responders, two patients with acute myeloid leukaemia proceeded to allogeneic haematopoietic stem-cell transplantation (HSCT) after CYAD-01 treatment, with durable ongoing remissions (5 and 61 months).
    INTERPRETATION: Treatment with a multiple CYAD-01 infusion schedule without preconditioning is well tolerated and shows anti-leukaemic activity, although without durability outside of patients bridged to allogeneic HSCT. These phase 1 data support the proof-of-concept of targeting NKG2D ligands by CAR T-cell therapy. Further clinical studies with NKG2D-based CAR T-cells are warranted, potentially via combinatorial antigen targeted approaches, to improve anti-tumour activity.
    FUNDING: Celyad Oncology.
    DOI:  https://doi.org/10.1016/S2352-3026(22)00378-7
  24. Blood. 2023 Feb 09. pii: blood.2022017976. [Epub ahead of print]
      JAK2-V617F mutation causes myeloproliferative neoplasms (MPN) that can manifest as polycythemia vera (PV), essential thrombocythemia (ET) or primary myelofibrosis (PMF). PV patients at diagnosis already exhibited iron deficiency, whereas ET patients had normal iron stores. We examined the influence of iron availability on MPN phenotype in mice expressing JAK2-V617F and in mice expressing JAK2 with a N542-E543del mutation in exon 12 (E12). At baseline on control diet, all JAK2-mutant mouse models with PV-like phenotype displayed iron deficiency, although E12 mice maintained more iron for augmented erythropoiesis than JAK2-V617F mutant mice. In contrast, JAK2-V617F mutant mice with an ET-like phenotype had normal iron stores comparable to wildtype (WT) mice. On low-iron diet, JAK2-mutant mice and WT controls increased platelet production at the expense of erythrocytes. Mice with PV phenotype responded to parenteral iron injections by decreasing platelet counts and further increasing hemoglobin and hematocrit, whereas no changes were observed in WT controls. Alterations of iron availability primarily affected the pre-megakaryocyte erythrocyte progenitors (pre-MegE), which constitute the iron-responsive stage of hematopoiesis in JAK2-mutant mice. The orally administered ferroportin inhibitor vamifeport and the minihepcidin PR73 normalized hematocrit and hemoglobin levels in JAK2-V617F and E12 mutant mouse models of PV, suggesting that ferroportin inhibitors and minihepcidins could be used in the treatment of PV patients.
    DOI:  https://doi.org/10.1182/blood.2022017976
  25. Nat Commun. 2023 Feb 09. 14(1): 724
      The PML::RARA fusion protein is the hallmark driver of Acute Promyelocytic Leukemia (APL) and disrupts retinoic acid signaling, leading to wide-scale gene expression changes and uncontrolled proliferation of myeloid precursor cells. While known to be recruited to binding sites across the genome, its impact on gene regulation and expression is under-explored. Using integrated multi-omics datasets, we characterize the influence of PML::RARA binding on gene expression and regulation in an inducible PML::RARA cell line model and APL patient ex vivo samples. We find that genes whose regulatory elements recruit PML::RARA are not uniformly transcriptionally repressed, as commonly suggested, but also may be upregulated or remain unchanged. We develop a computational machine learning implementation called Regulatory Element Behavior Extraction Learning to deconvolute the complex, local transcription factor binding site environment at PML::RARA bound positions to reveal distinct signatures that modulate how PML::RARA directs the transcriptional response.
    DOI:  https://doi.org/10.1038/s41467-023-36262-0
  26. Nat Cell Biol. 2023 Feb 06.
      SLC7A11-mediated cystine uptake suppresses ferroptosis yet promotes cell death under glucose starvation; the nature of the latter cell death remains unknown. Here we show that aberrant accumulation of intracellular disulfides in SLC7A11high cells under glucose starvation induces a previously uncharacterized form of cell death distinct from apoptosis and ferroptosis. We term this cell death disulfidptosis. Chemical proteomics and cell biological analyses showed that glucose starvation in SLC7A11high cells induces aberrant disulfide bonds in actin cytoskeleton proteins and F-actin collapse in a SLC7A11-dependent manner. CRISPR screens and functional studies revealed that inactivation of the WAVE regulatory complex (which promotes actin polymerization and lamellipodia formation) suppresses disulfidptosis, whereas constitutive activation of Rac promotes disulfidptosis. We further show that glucose transporter inhibitors induce disulfidptosis in SLC7A11high cancer cells and suppress SLC7A11high tumour growth. Our results reveal that the susceptibility of the actin cytoskeleton to disulfide stress mediates disulfidptosis and suggest a therapeutic strategy to target disulfidptosis in cancer treatment.
    DOI:  https://doi.org/10.1038/s41556-023-01091-2
  27. Br J Haematol. 2023 Feb 06.
    Consensus Meeting Attendees
      The implementation of whole genome sequencing and large somatic gene panels in haematological malignancies is identifying an increasing number of individuals with either potential or confirmed germline predisposition to haematological malignancy. There are currently no national or international best practice guidelines with respect to management of carriers of such variants or of their at-risk relatives. To address this gap, the UK Cancer Genetics Group (UKCGG), CanGene-CanVar and the NHS England Haematological Oncology Working Group held a workshop over two days on 28-29th April 2022, with the aim of establishing consensus guidelines on relevant clinical and laboratory pathways. The workshop focussed on the management of disease-causing germline variation in the following genes: DDX41, CEBPA, RUNX1, ANKRD26, ETV6, GATA2. Using a pre-workshop survey followed by structured discussion and in-meeting polling, we achieved consensus for UK best practice in several areas. In particular, high consensus was achieved on issues regarding standardised reporting, variant classification, multidisciplinary team working and patient support. The best practice recommendations from this meeting may be applicable to an expanding number of other genes in this setting.
    Keywords:  clinical pathways; germline predisposition; haematological malignancy; leukaemia; transplant; variant classification
    DOI:  https://doi.org/10.1111/bjh.18675
  28. Blood Adv. 2023 Feb 10. pii: bloodadvances.2022008510. [Epub ahead of print]
      Engraftment and differentiation of donor hematopoietic stem cells is decisive for the clinical success of allogeneic stem cell transplantation (alloSCT) and depends on the recipient's bone marrow (BM) niche. A damaged niche contributes to poor graft function post-alloSCT, but the underlying mechanisms and the role of BM multipotent mesenchymal stromal cells (MSC) are ill defined. Upon multivariate analysis in 732 individuals, we observed a reduced presence of proliferation-capable MSC in BM aspirates from patients (N=196) who had undergone alloSCT (OR 0.61, p=.028). This was confirmed by paired analysis in 30 patients showing a higher frequency of samples with a lack of MSC presence post-alloSCT compared to pre-alloSCT. This reduced MSC presence was associated with reduced survival of patients following alloSCT and specifically with impaired graft function. Post-alloSCT MSC showed diminished in vitro proliferation along with a transcriptional antiproliferative signature, upregulation of epithelial-mesenchymal transition and extracellular matrix pathways and altered impact on cytokine release upon contact with hematopoietic cells. In order to avoid in vitro culture bias, we isolated the CD146+/CD45-/HLA-DR- BM cell fraction, which comprised the entire MSC population. The post-alloSCT isolated native CD146+MSC showed a similar reduction in proliferation capacity and shared the same antiproliferative transcriptomic signature as for post-alloSCT CFU-F-derived MSC. Taken together, our data show that alloSCT confers damage to the proliferative capacity of native MSC, which is associated with reduced patient survival after alloSCT and impaired engraftment of allogeneic hematopoiesis. These data represent the basis to elucidate mechanisms of BM niche reconstitution post-alloSCT and its therapeutic manipulation.
    DOI:  https://doi.org/10.1182/bloodadvances.2022008510
  29. Blood Adv. 2023 Feb 10. pii: bloodadvances.2022008922. [Epub ahead of print]
      The recurrence of malignancy after hematopoietic cell transplantation (HCT) is the primary cause of transplant failure. The NKG2D axis is a powerful pathway for anti-tumor responses, but its role in the control of malignancy after HCT is not well-defined. We tested the hypothesis that gene variation of the NKG2D receptor and its ligands MICA and MICB affect relapse and survival in 1,629 patients who received a haploidentical HCT for the treatment of a malignant blood disorder. Patients and donors were characterized for MICA residue 129 and the exon 5 short tandem repeat (STR), and MICB residues 52, 57, 98, 189. Donors were additionally defined for NKG2D residue 72. Mortality was higher in patients with MICB-52Asn relative to 52Asp (HR 1.83 [95% CI 1.24-2.71; P = 0.002]) and lower with MICA STR-mismatching relative to STR-matching (HR 0.66 [95% CI 0.54-0.79; P = 0.00002]). Relapse was lower with NKG2D-72Thr donors relative to 72Ala (relapse HR 0.57 [95% CI 0.35-0.91; P = 0.02]). The protective effects of patient MICB-52Asp with donor MICA STR-mismatching and NKG2D-72Thr were enhanced when all three features were present. The NKG2D ligand/receptor pathway is a transplantation determinant. The immunobiology of relapse is defined by the concerted effects of MICA, MICB and NKG2D germline variation. Consideration of NKG2D ligand/receptor pairings may improve survival for future patients.
    DOI:  https://doi.org/10.1182/bloodadvances.2022008922
  30. BMC Infect Dis. 2023 Feb 06. 23(1): 78
       PURPOSE: Study objectives were to estimate the cumulative incidence of death due to different causes of death (CODs) and investigate the effect of invasive aspergillosis (IA) on each separate COD in a cohort of older patients with acute myeloid leukaemia (AML) or high-risk myelodysplastic syndrome (MDS) included in the Haemato-Oncology Foundation for Adults in the Netherlands (HOVON) 43 randomized controlled trial.
    METHODS: Pre-collected data from the trial was obtained from the HOVON data center and relevant clinical information was extracted. The cumulative incidence of death due to different CODs was estimated with a competing risk model and the association between each COD and prognostic factors, including IA, were investigated with a cause-specific hazard Cox regression model.
    RESULTS: In total 806 patients were included, mean age of 70 years and 55% were male. The cumulative incidences of death due to leukaemia or infection at 3, 6, 12 and 36 months were 0.06, 0.11, 0.23, 0.42 and 0.17, 0.19, 0.22, 0.25 respectively. Incidence of IA was 21% and diagnosis of IA up until the final chemotherapy cycle was associated with an increased risk of dying from leukaemia (cause-specific hazard ratio (CSHR): 1.75, 95% CI 1.34-2.28) and a trend was seen for infection (CSHR: 1.36, 95% CI 0.96-1.91).
    CONCLUSION: Leukaemia was the most likely cause of death over time, however in the first year after diagnosis of AML or high-risk MDS infection was the most likely cause of death. Patients with IA had a relatively increased risk of dying from leukaemia or infection.
    Keywords:  Acute myeloid leukaemia; Aged; Aspergillosis; Invasive fungal infection; Invasive pulmonary aspergillosis; Myelodysplastic syndromes
    DOI:  https://doi.org/10.1186/s12879-023-08013-5