bims-tremyl Biomed News
on Therapy resistance biology in myeloid leukemia
Issue of 2021–08–22
25 papers selected by
Paolo Gallipoli, Barts Cancer Institute, Queen Mary University of London
  1. Genetic identification of patients with AML older than 60 years achieving long-term survival with intensive chemotherapy.
  2. Inferring the dynamic of mutated hematopoietic stem and progenitor cells induced by IFNα in myeloproliferative neoplasms.
  3. Acute Myeloid Leukemia Alters Group 1 Innate Lymphoid Cell Differentiation from a Common Precursor.
  4. RSPO2 inhibits BMP signaling to promote self-renewal in acute myeloid leukemia.
  5. Dual inhibition of FLT3 and AXL by gilteritinib overcomes hematopoietic niche-driven resistance mechanisms in FLT3-ITD acute myeloid leukemia.
  6. Targeting of IL-10R on acute myeloid leukemia blasts with chimeric antigen receptor-expressing T cells.
  7. Loss of erythroblasts in acute myeloid leukemia causes iron redistribution with clinical implications.
  8. EZH2/EHMT2 Histone Methyltransferases Inhibit the Transcription of DLX5 and Promote the Transformation of Myelodysplastic Syndrome to Acute Myeloid Leukemia.
  9. Assessing AML susceptibility in rearrangement-driven patients by DNA breakage at topoisomerase II and CTCF/cohesin binding sites.
  10. High Expression of RhoF Predicts Worse Overall Survival: A Potential Therapeutic Target for non-M3 Acute Myeloid Leukemia.
  11. CRISPR-Cas9 Technology as a Tool to Target Gene Drivers in Cancer: Proof of Concept and New Opportunities to Treat Chronic Myeloid Leukemia.
  12. Acquisition of IDH2 Mutations in Relapsed/Refractory AML Is Associated with Worse Patient Outcomes.
  13. Personalized Prediction Model to Risk Stratify Patients With Myelodysplastic Syndromes.
  14. Niche-directed therapy in acute myeloid leukemia: optimization of stem cell competition for niche occupancy.
  15. Ponatinib Dose-Ranging Study in Chronic-Phase Chronic Myeloid Leukemia: A Randomized, Open-Label Phase 2 Clinical Trial.
  16. A Phase 3, Open-Label, Randomized Study of Asciminib, a STAMP Inhibitor, vs Bosutinib in CML After ≥2 Prior TKIs.
  17. Midostaurin-induced Sweet syndrome in a patient with FLT3-ITD-positive AML.
  18. Is the Sokal or EUTOS long-term survival (ELTS) score a better predictor of responses and outcomes in persons with chronic myeloid leukemia receiving tyrosine-kinase inhibitors?
  19. NFĸB Targeting in Bone Marrow Mesenchymal Stem Cell-Mediated Support of Age-Linked Hematological Malignancies.
  20. Metabolic convergence on lipogenesis in RAS, BCR-ABL, and MYC-driven lymphoid malignancies.
  21. Prognostic significance of TIM-3 expression pattern at diagnosis in patients with t(8;21) acute myeloid leukemia.
  22. PRC2 Inhibitors Overcome Glucocorticoid Resistance Driven by NSD2 Mutation in Pediatric Acute Lymphoblastic Leukemia.
  23. Dietary fructose improves intestinal cell survival and nutrient absorption.
  24. TET2 as a tumor suppressor and therapeutic target in T-cell acute lymphoblastic leukemia.
  25. Chronic myeloid leukaemia presenting with monocytosis.
  1. Blood. 2021 Aug 19. 138(7): 507-519
    Genetic identification of patients with AML older than 60 years achieving long-term survival with intensive chemotherapy.
    Raphael Itzykson, Elise Fournier, Céline Berthon, Christoph Röllig, Thorsten Braun, Alice Marceau-Renaut, Cécile Pautas, Olivier Nibourel, Emilie Lemasle, Jean-Baptiste Micol, Lionel Adès, Delphine Lebon, Jean-Valère Malfuson, Lauris Gastaud, Laure Goursaud, Emmanuel Raffoux, Kevin-James Wattebled, Philippe Rousselot, Xavier Thomas, Sylvain Chantepie, Thomas Cluzeau, Hubert Serve, Nicolas Boissel, Christine Terré, Karine Celli-Lebras, Claude Preudhomme, Christian Thiede, Hervé Dombret, Claude Gardin, Nicolas Duployez.
      To design a simple and reproducible classifier predicting the overall survival (OS) of patients with acute myeloid leukemia (AML) ≥60 years of age treated with 7 + 3, we sequenced 37 genes in 471 patients from the ALFA1200 (Acute Leukemia French Association) study (median age, 68 years). Mutation patterns and OS differed between the 84 patients with poor-risk cytogenetics and the 387 patients with good (n = 13), intermediate (n = 339), or unmeasured (n = 35) cytogenetic risk. TP53 (hazards ratio [HR], 2.49; P = .0003) and KRAS (HR, 3.60; P = .001) mutations independently worsened the OS of patients with poor-risk cytogenetics. In those without poor-risk cytogenetics, NPM1 (HR, 0.57; P = .0004), FLT3 internal tandem duplications with low (HR, 1.85; P = .0005) or high (HR, 3.51; P < 10-4) allelic ratio, DNMT3A (HR, 1.86; P < 10-4), NRAS (HR, 1.54; P = .019), and ASXL1 (HR, 1.89; P = .0003) mutations independently predicted OS. Combining cytogenetic risk and mutations in these 7 genes, 39.1% of patients could be assigned to a "go-go" tier with a 2-year OS of 66.1%, 7.6% to the "no-go" group (2-year OS 2.8%), and 3.3% of to the "slow-go" group (2-year OS of 39.1%; P < 10-5). Across 3 independent validation cohorts, 31.2% to 37.7% and 11.2% to 13.5% of patients were assigned to the go-go and the no-go tiers, respectively, with significant differences in OS between tiers in all 3 trial cohorts (HDF [Hauts-de-France], n = 141, P = .003; and SAL [Study Alliance Leukemia], n = 46; AMLSG [AML Study Group], n = 223, both P < 10-5). The ALFA decision tool is a simple, robust, and discriminant prognostic model for AML patients ≥60 years of age treated with intensive chemotherapy. This model can instruct the design of trials comparing the 7 + 3 standard of care with less intensive regimens.
    DOI:  https://doi.org/10.1182/blood.2021011103
  2. Blood. 2021 Aug 18. pii: blood.2021010986. [Epub ahead of print]
    Inferring the dynamic of mutated hematopoietic stem and progenitor cells induced by IFNα in myeloproliferative neoplasms.
    Matthieu Mosca, Gurvan Hermange, Amandine Tisserand, Robert John Noble, Christophe Marzac, Caroline Marty, Cécile Le Sueur, Hugo Campario, Gaëlle Vertenoeil, Mira El-Khoury, Cyril Catelain, Philippe Rameau, Cyril Gella, Julien Lenglet, Nicole Casadevall, Remi Favier, Eric Solary, Bruno Cassinat, Jean-Jacques Kiladjian, Stefan N Constantinescu, Florence Pasquier, Michael E Hochberg, Hana Raslova, Jean-Luc J-L Villeval, François Girodon, William Vainchenker, Paul-Henry Cournède, Isabelle Plo.
      Classical BCR-ABL-negative myeloproliferative neoplasms (MPN) are clonal disorders of hematopoietic stem cells (HSC) caused mainly by recurrent mutations in genes encoding JAK2 (JAK2), calreticulin (CALR), or the thrombopoietin receptor (MPL). Interferon alpha (IFNα) has demonstrated some efficacy in inducing molecular remission in MPN. In order to determine factors that influence molecular response rate, we evaluated the long-term molecular efficacy of IFNα in MPN patients by monitoring the fate of cells carrying driver mutations in a prospective observational and longitudinal study of 48 patients over more than 5 years. We measured several times per year the clonal architecture of early and late hematopoietic progenitors (84,845 measurements) and the global variant allele frequency in mature cells (409 measurements). Using mathematical modeling and hierarchical Bayesian inference, we further inferred the dynamics of IFNα-targeted mutated HSC. Our data support the hypothesis that IFNα targets JAK2V617F HSC by inducing their exit from quiescence and differentiation into progenitors. Our observations indicate that treatment efficacy is higher in homozygous than heterozygous JAK2V617F HSC and increases with high IFNα dosage in heterozygous JAK2V617F HSC. Besides, we found that the molecular responses of CALRm HSC to IFNα were heterogeneous, varying between type 1 and type 2 CALRm, and high dosage of IFNα correlates with worse outcomes. Together, our work indicates that the long-term molecular efficacy of IFNα implies an HSC exhaustion mechanism and depends on both the driver mutation type and IFNα dosage.
    DOI:  https://doi.org/10.1182/blood.2021010986
  3. J Immunol. 2021 Aug 20. pii: ji2100023. [Epub ahead of print]
    Acute Myeloid Leukemia Alters Group 1 Innate Lymphoid Cell Differentiation from a Common Precursor.
    Matthew R Lordo, Kevin G Wu, Ekaterina Altynova, Nikolas Shilo, Parker Kronen, Ansel P Nalin, Christoph Weigel, Xiaoli Zhang, Jianhua Yu, Christopher C Oakes, Michael A Caligiuri, Aharon G Freud, Bethany L Mundy-Bosse.
      NK cells are known to be developmentally blocked and functionally inhibited in patients with acute myeloid leukemia (AML), resulting in poor clinical outcomes. In this study, we demonstrate that whereas NK cells are inhibited, closely related type 1 innate lymphoid cells (ILC1s) are enriched in the bone marrow of leukemic mice and in patients with AML. Because NK cells and ILC1s share a common precursor (ILCP), we asked if AML acts on the ILCP to alter developmental potential. A combination of ex vivo and in vivo studies revealed that AML skewing of the ILCP toward ILC1s and away from NK cells represented a major mechanism of ILC1 generation. This process was driven by AML-mediated activation of the aryl hydrocarbon receptor (AHR), a key transcription factor in ILCs, as inhibition of AHR led to decreased numbers of ILC1s and increased NK cells in the presence of AML. These results demonstrate a mechanism of ILC developmental skewing in AML and support further preclinical study of AHR inhibition in restoring normal NK cell development and function in the setting of AML.
    DOI:  https://doi.org/10.4049/jimmunol.2100023
  4. Cell Rep. 2021 Aug 17. pii: S2211-1247(21)00993-1. [Epub ahead of print]36(7): 109559
    RSPO2 inhibits BMP signaling to promote self-renewal in acute myeloid leukemia.
    Rui Sun, Lixiazi He, Hyeyoon Lee, Andrey Glinka, Carolin Andresen, Daniel Hübschmann, Irmela Jeremias, Karin Müller-Decker, Caroline Pabst, Christof Niehrs.
      Acute myeloid leukemia (AML) is a rapidly progressing cancer, for which chemotherapy remains standard treatment and additional therapeutic targets are requisite. Here, we show that AML cells secrete the stem cell growth factor R-spondin 2 (RSPO2) to promote their self-renewal and prevent cell differentiation. Although RSPO2 is a well-known WNT agonist, we reveal that it maintains AML self-renewal WNT independently, by inhibiting BMP receptor signaling. Autocrine RSPO2 signaling is also required to prevent differentiation and to promote self-renewal in normal hematopoietic stem cells as well as primary AML cells. Comprehensive datamining reveals that RSPO2 expression is elevated in patients with AML of poor prognosis. Consistently, inhibiting RSPO2 prolongs survival in AML mouse xenograft models. Our study indicates that in AML, RSPO2 acts as an autocrine BMP antagonist to promote cancer cell renewal and may serve as a marker for poor prognosis.
    Keywords:  BMP; HSPC; R-spondin; WNT; acute myeloid leukemia; drug resistance; leukemia stem cell; macrophages; monocytes; self-renewal
    DOI:  https://doi.org/10.1016/j.celrep.2021.109559
  5. Clin Cancer Res. 2021 Aug 16. pii: clincanres.3114.2020. [Epub ahead of print]
    Dual inhibition of FLT3 and AXL by gilteritinib overcomes hematopoietic niche-driven resistance mechanisms in FLT3-ITD acute myeloid leukemia.
    Pierre-Yves Dumas, Arnaud Villacreces, Amélie V Guitart, El Habhab Ali, Layal Massara, Olivier Mansier, Audrey Bidet, Delphine Martineau, Solène Fernandez, Thibaut Leguay, Arnaud Pigneux, Isabelle Vigon, Jean-Max Pasquet, Vanessa Desplat.
       PURPOSE: AXL has been shown to play a pivotal role in the selective response of FLT3-ITD AML cells to FLT3 tyrosine kinase inhibitors (TKI), particularly within the bone marrow microenvironment.
    EXPERIMENTAL DESIGN: Herein, we compared the effect of dual FLT3/AXL TKI Gilteritinib with Quizartinib through in vitro models mimicking hematopoietic niche conditions, ex vivo in primary AML blasts and in vivo with dosing regimens allowing plasma concentration close to those used in clinical trials.
    RESULTS: We observed that Gilteritinib maintained a stronger pro-apoptotic effect in hypoxia and coculture with bone marrow stromal cells compared with Quizartinib, linked to a dose-dependent inhibition of AXL phosphorylation. In vivo, use of the MV4-11 cell line with hematopoietic engraftment demonstrated that Gilteritinib was more effective than Quizartinib at targeting leukemic cells in bone marrow. Finally, FLT3-ITD AML patient-derived xenografts revealed that this effect was particularly reproducible in FLT3-ITD AML with high allelic ratio in primary and secondary xenograft. Moreover, Gilteritinib and Quizartinib displayed close toxicity profile on normal murine hematopoiesis, particularly at steady state.
    CONCLUSIONS: Overall, these findings suggest that Gilteritinib as a single agent, compared with Quizartinib, is more likely to reach leukemic cells in their protective microenvironment, particularly AML clones highly dependent on FLT3-ITD signaling.
    DOI:  https://doi.org/10.1158/1078-0432.CCR-20-3114
  6. Blood Cancer J. 2021 Aug 14. 11(8): 144
    Targeting of IL-10R on acute myeloid leukemia blasts with chimeric antigen receptor-expressing T cells.
    Nianci Chen, Yingxi Xu, Junli Mou, Qing Rao, Haiyan Xing, Zheng Tian, Kejing Tang, Min Wang, Jiangxiang Wang.
      Acute myeloid leukemia (AML) is a biologically and clinically heterogeneous disease with a dismal prognosis and limited treatment options. Chimeric antigen receptor (CAR) T cells have achieved unprecedented clinical responses in patients with B cell malignancies but a dismal consequences in AML. In our previous study, we found that interleukin-10 receptor (IL-10R) was overexpressed in most AML cells, and played an important role in promoting the stemness of leukemia cells. In this study, we developed a novel ligand-based CAR-T cell targeting IL-10R, which displayed striking cytotoxicity both in vitro and in vivo against AML cells. Except for monocytes, it had no significant adverse effects on the normal hematopoietic system, including CD34+ hematopoietic stem and progenitor cells (HSPCs). In addition, even though the incorporation of IL-10 in the CAR cassette led to phenotypes change, it had few adverse effects on the survival and biological activity of IL-10 CAR-T cells and did not cause excessive proliferation of leukemia cells. Therefore, we propose IL-10R is a novel promising therapeutic candidate for AML, and IL-10R targeted CAR-T therapy provides a new treatment strategy to improve the prognosis of AML.
    DOI:  https://doi.org/10.1038/s41408-021-00536-x
  7. Blood Adv. 2021 Aug 24. 5(16): 3102-3112
    Loss of erythroblasts in acute myeloid leukemia causes iron redistribution with clinical implications.
    Marta Lopes, Tiago L Duarte, Maria J Teles, Laura Mosteo, Sérgio Chacim, Eliana Aguiar, Joana Pereira-Reis, Mónica Oliveira, André M N Silva, Nuno Gonçalves, Gabriela Martins, Isabella Y Kong, Magnus Zethoven, Stephin Vervoort, Sandra Martins, Miguel Quintela, Edwin D Hawkins, Fernanda Trigo, João T Guimarães, José M Mariz, Graça Porto, Delfim Duarte.
      Acute myeloid leukemia (AML) is a heterogeneous disease with poor prognosis and limited treatment strategies. Determining the role of cell-extrinsic regulators of leukemic cells is vital to gain clinical insights into the biology of AML. Iron is a key extrinsic regulator of cancer, but its systemic regulation remains poorly explored in AML. To address this question, we studied iron metabolism in patients with AML at diagnosis and explored the mechanisms involved using the syngeneic MLL-AF9-induced AML mouse model. We found that AML is a disorder with a unique iron profile, not associated with inflammation or transfusion, characterized by high ferritin, low transferrin, high transferrin saturation (TSAT), and high hepcidin. The increased TSAT in particular, contrasts with observations in other cancer types and in anemia of inflammation. Using the MLL-AF9 mouse model of AML, we demonstrated that the AML-induced loss of erythroblasts is responsible for iron redistribution and increased TSAT. We also show that AML progression is delayed in mouse models of systemic iron overload and that elevated TSAT at diagnosis is independently associated with increased overall survival in AML. We suggest that TSAT may be a relevant prognostic marker in AML.
    DOI:  https://doi.org/10.1182/bloodadvances.2021004373
  8. Front Cell Dev Biol. 2021 ;9 619795
    EZH2/EHMT2 Histone Methyltransferases Inhibit the Transcription of DLX5 and Promote the Transformation of Myelodysplastic Syndrome to Acute Myeloid Leukemia.
    Zhuanzhen Zheng, Ling Li, Guoxia Li, Yaofang Zhang, Chunxia Dong, Fanggang Ren, Wenliang Chen, Yanping Ma.
      Myelodysplastic syndrome (MDS) is characterized by clonal hematopoiesis and impaired differentiation, and may develop to acute myeloid leukemia (AML). We explored the mechanism of histone methyltransferase EZH2/EHMT2 during the transformation of MDS into AML. Expression of EZH2/EHMT2 in patients and NHD13 mice was detected. EZH2 and EHMT2 were silenced or overexpressed in SKM-1 cells. The cell proliferation and cycle were evaluated. Levels of DLX5, H3K27me3, and H3K9me2 in SKM-1 cells were detected. Binding of DLX5 promoter region to H3K27me3 and H3K9me2 was examined. Levels of H3K27me3/H3K9me2 were decreased by EZH2/EHMT2 inhibitor (EPZ-6438/BIX-01294), and changes of DLX5 expression and cell proliferation were observed. EZH2 was poorly expressed in MDS patients but highly expressed in MDS-AML patients. EHMT2 was promoted in both MDS and MDS-AML patients. EZH2 expression was reduced and EHMT2 expression was promoted in NHD13 mice. NHD13 mice with overexpressing EZH2 or EHMT2 transformed into AML more quickly. Intervention of EZH2 or EHMT2 inhibited SKM-1 cell proliferation and promoted DLX5 expression. When silencing EZH1 and EZH2 in SKM-1 cells, the H3K27me3 level was decreased. EZH2 silencing repressed the proliferation of SKM-1 cells. Transcription level of DLX5 in SKM-1 cells was inhibited by H3K27me3 and H3K9me2. Enhanced DLX5 repressed SKM-1 cell proliferation. In conclusion, EZH2/EHMT2 catalyzed H3K27me3/H3K9me2 to inhibit the transcription of DLX5, thus promoting the transformation from MDS to AML.
    Keywords:  DLX5; EHMT2; EZH2; H3K27me3; H3K9me2; acute myeloid leukemia; myelodysplastic syndromes
    DOI:  https://doi.org/10.3389/fcell.2021.619795
  9. Genes Chromosomes Cancer. 2021 Aug 18.
    Assessing AML susceptibility in rearrangement-driven patients by DNA breakage at topoisomerase II and CTCF/cohesin binding sites.
    Naomi D Atkin, Heather M Raimer, Zhenjia Wang, Chongzhi Zang, Yuh-Hwa Wang.
      An initiating DNA double strand break (DSB) event precedes the formation of cancer-driven chromosomal abnormalities, such as gene rearrangements. Therefore, measuring DNA breaks at rearrangement-participating regions can provide a unique tool to identify and characterize susceptible individuals. Here, we developed a highly sensitive and low-input DNA break mapping method, the first of its kind for patient samples. We then measured genome-wide DNA breakage in normal cells of acute myeloid leukemia (AML) patients with KMT2A (previously MLL) rearrangements, compared to that of non-fusion AML individuals, as a means to evaluate individual susceptibility to gene rearrangements. DNA breakage at the KMT2A gene region was significantly greater in fusion-driven remission individuals, as compared to non-fusion individuals. Moreover, we identified select topoisomerase II (TOP2)-sensitive and CCCTC-binding factor (CTCF)/cohesin binding sites with preferential DNA breakage in fusion-driven patients. Importantly, measuring DSBs at these sites, in addition to the KMT2A gene region, provided greater predictive power when assessing individual break susceptibility. We also demonstrated that low-dose etoposide exposure further elevated DNA breakage at these regions in fusion-driven AML patients, but not in non-fusion patients, indicating that these sites are preferentially sensitive to TOP2 activity in fusion-driven AML patients. These results support that mapping of DSBs in patients enables discovery of novel break-prone regions and monitoring of individuals susceptible to chromosomal abnormalities, and thus cancer. This will build the foundation for early detection of cancer-susceptible individuals, as well as those preferentially susceptible to therapy-related malignancies caused by treatment with TOP2 poisons. This article is protected by copyright. All rights reserved.
    Keywords:  CTCF; DNA fragility; acute myeloid leukemia; cohesin; topoisomerase
    DOI:  https://doi.org/10.1002/gcc.22993
  10. J Cancer. 2021 ;12(18): 5530-5542
    High Expression of RhoF Predicts Worse Overall Survival: A Potential Therapeutic Target for non-M3 Acute Myeloid Leukemia.
    Yue Hou, Jie Zi, Zheng Ge.
      Rho GTPases are involved in multiple human malignancies and diverse biological functions. However, the patterns and prognostic significance of the expression of RhoD subfamily in acute myeloid leukemia (AML) remain unknown. Here, we detected the expressions of RhoD subfamily genes in AML on the basis of several published datasets and analyzed the survival of RhoD subfamily across the TCGA profiles and in a GEO series. We found that the expression of RhoF, but not RhoD, increased in AML patients in TCGA and GEO (all P<0.001); the survival analysis of two independent cohorts demonstrated that higher RhoF expression was significantly associated with poorer overall survival (OS) (P<0.001), whereas RhoD expression had no significant effect on OS in patients with AML (P>0.05); the subgroup analysis showed that high RhoF expression was correlated with poor 1-, 3-, and 5-year OS (P<0.05 for all); upregulated RhoF expression had a more significant prognostic value for OS in the younger patients (age<60), the intensive chemotherapy group, and wild-type groups (IDH1, NRAS, and TP53) (P<0.05 for all). Multivariate analysis indicated high RhoF expression as a strongly independent unfavorable prognostic factor for OS in patients without transplantation (P<0.05). Furthermore, a higher RhoF expression was closely associated with an older age, intermediate-/poor-risk cytogenetics and mutations in IDH1, NRAS, and TP53. RhoF expression was negatively correlated with BM blasts (P=0.020) and WBC (P=0.003). These findings suggest that high RhoF expression is associated with worsening OS in AML patients and is a potential therapeutic target for the treatment of AML.
    Keywords:  RhoF; acute myeloid leukemia; clinical feature; survival; therapeutic target
    DOI:  https://doi.org/10.7150/jca.52648
  11. CRISPR J. 2021 08;4(4): 519-535
    CRISPR-Cas9 Technology as a Tool to Target Gene Drivers in Cancer: Proof of Concept and New Opportunities to Treat Chronic Myeloid Leukemia.
    Elena Vuelta, José Luis Ordoñez, Verónica Alonso-Pérez, Lucía Méndez, Patricia Hernández-Carabias, Raquel Saldaña, Julián Sevilla, Elena Sebastián, Sandra Muntión, Fermín Sánchez-Guijo, Jesús María Hernández-Rivas, Ignacio García-Tuñón, Manuel Sánchez-Martín.
      Chronic myeloid leukemia (CML) is a hematopoietic malignancy produced by a unique oncogenic event involving the constitutively active tyrosine-kinase (TK) BCR/ABL1. TK inhibitors (TKI) changed its prognosis and natural history. Unfortunately, ABL1 remains unaffected by TKIs. Leukemic stem cells (LSCs) remain, and resistant mutations arise during treatment. To address this problem, we have designed a therapeutic CRISPR-Cas9 deletion system targeting BCR/ABL1. The system was efficiently electroporated to cell lines, LSCs from a CML murine model, and LSCs from CML patients at diagnosis, generating a specific ABL1 null mutation at high efficiency and allowing the edited leukemic cells to be detected and tracked. The CRISPR-Cas9 deletion system triggered cell proliferation arrest and apoptosis in murine and human CML cell lines. Patient and murine-derived xenografts with CRISPR-edited LSCs in NOD SCID gamma niches revealed that normal multipotency and repopulation ability of CRISPR edited LSCs were fully restored. Normal hematopoiesis was restored, avoiding myeloid bias. To the best of our knowledge, we show for the first time how a CRISPR-Cas9 deletion system efficiently interrupts BCR/ABL1 oncogene in primary LSCs to bestow a therapeutic benefit. This study is a proof of concept for genome editing in all those diseases, like CML, sustained by a single oncogenic event, opening up new therapeutic opportunities.
    DOI:  https://doi.org/10.1089/crispr.2021.0009
  12. Eur J Haematol. 2021 Aug 18.
    Acquisition of IDH2 Mutations in Relapsed/Refractory AML Is Associated with Worse Patient Outcomes.
    Amy Song, Omar Altabbakh, David A Sallman, Eric Padron, Chetasi Talati, Mohammad O Hussaini.
       OBJECTIVES: The presence of targeted therapy, Enasidenib, for IDH2-mutated AML underscores the importance of understanding the clonal dynamics of IDH2 mutations which has not been elucidated. In the largest study of IDH2 clonal dynamics, we detail the IDH2-evolutionary patterns and their clinical significance.
    METHODS: We analyzed ~6000 patients with NGS results to identify 120 AML patients with IDH2 mutations and longitudinal NGS testing. IDH2 mutation status was recorded at diagnosis, remission, relapse, and persistent disease.
    RESULTS: 105 were IDH2-positive at the initial diagnosis and 15 acquired the mutation later. Of those 15 patients, 7 patients gained the mutation during persistent disease, 6 during relapse, and 2 at remission. Twenty-one patients (18%) who were IDH2-positive in a prior test remained IDH2-positive in remission. Twenty-four patients with IDH2-positive AML were IDH2-positive at relapse. IDH2-positive at diagnosis had better survival than IDH2 mutation acquired later in disease (p=0.024). Patients who were IDH2-negative in remission had significantly improved survival (p=0.002). Also, loss of IDH2 mutation with persistent disease had better OS (p=0.035).
    CONCLUSIONS: 70% clear IDH2 in disease remission. 12% gain IDH2 mutation later, usually in the setting of refractory/relapsed AML. These patients fared worse. Longitudinal IDH2 testing may be helpful in prognostic stratification.
    Keywords:   IDH2 ; AML; Enasidenib; clonal evolution; mutation
    DOI:  https://doi.org/10.1111/ejh.13698
  13. J Clin Oncol. 2021 Aug 18. JCO2002810
    Personalized Prediction Model to Risk Stratify Patients With Myelodysplastic Syndromes.
    Aziz Nazha, Rami Komrokji, Manja Meggendorfer, Xuefei Jia, Nathan Radakovich, Jacob Shreve, C Beau Hilton, Yasunubo Nagata, Betty K Hamilton, Sudipto Mukherjee, Najla Al Ali, Wencke Walter, Stephan Hutter, Eric Padron, David Sallman, Teodora Kuzmanovic, Cassandra Kerr, Vera Adema, David P Steensma, Amy Dezern, Gail Roboz, Guillermo Garcia-Manero, Harry Erba, Claudia Haferlach, Jaroslaw P Maciejewski, Torsten Haferlach, Mikkael A Sekeres.
       PURPOSE: Patients with myelodysplastic syndromes (MDS) have a survival that can range from months to decades. Prognostic systems that incorporate advanced analytics of clinical, pathologic, and molecular data have the potential to more accurately and dynamically predict survival in patients receiving various therapies.
    METHODS: A total of 1,471 MDS patients with comprehensively annotated clinical and molecular data were included in a training cohort and analyzed using machine learning techniques. A random survival algorithm was used to build a prognostic model, which was then validated in external cohorts. The accuracy of the proposed model, compared with other established models, was assessed using a concordance (c)index.
    RESULTS: The median age for the training cohort was 71 years. Commonly mutated genes included SF3B1, TET2, and ASXL1. The algorithm identified chromosomal karyotype, platelet, hemoglobin levels, bone marrow blast percentage, age, other clinical variables, seven discrete gene mutations, and mutation number as having prognostic impact on overall and leukemia-free survivals. The model was validated in an independent external cohort of 465 patients, a cohort of patients with MDS treated in a prospective clinical trial, a cohort of patients with paired samples at different time points during the disease course, and a cohort of patients who underwent hematopoietic stem-cell transplantation.
    CONCLUSION: A personalized prediction model on the basis of clinical and genomic data outperformed established prognostic models in MDS. The new model was dynamic, predicting survival and leukemia transformation probabilities at different time points that are unique for a given patient, and can upstage and downstage patients into more appropriate risk categories.
    DOI:  https://doi.org/10.1200/JCO.20.02810
  14. Leuk Lymphoma. 2021 Aug 19. 1-9
    Niche-directed therapy in acute myeloid leukemia: optimization of stem cell competition for niche occupancy.
    Shyam A Patel, Disha Dalela, Amy C Fan, Maxwell R Lloyd, Tian Y Zhang.
      Acute myeloid leukemia (AML) is an aggressive malignancy of stem cell origin that contributes to significant morbidity and mortality. The long-term prognosis remains dismal given the high likelihood for primary refractory or relapsed disease. An essential component of relapse is resurgence from the bone marrow. To date, the murine hematopoietic stem cell (HSC) niche has been clearly defined, but the human HSC niche is less well understood. The design of niche-based targeted therapies for AML must account for which cellular subsets compete for stem cell occupancy within respective bone marrow microenvironments. In this review, we highlight the principles of stem cell niche biology and discuss translational insights into the AML microenvironment as of 2021. Optimization of competition for niche occupancy is important for the elimination of measurable residual disease (MRD). Some of these novel therapeutics are in the pharmacologic pipeline for AML and may be especially useful in the setting of MRD.
    Keywords:  Acute myeloid leukemia; bone marrow niche; hematopoietic stem cells; microenvironment; targeted therapy
    DOI:  https://doi.org/10.1080/10428194.2021.1966779
  15. Blood. 2021 Aug 18. pii: blood.2021012082. [Epub ahead of print]
    Ponatinib Dose-Ranging Study in Chronic-Phase Chronic Myeloid Leukemia: A Randomized, Open-Label Phase 2 Clinical Trial.
    Jorge Cortes, Jane F Apperley, Elza Lomaia, Beatriz Moiraghi, Maria Soledad Undurraga, Carolina Pavlovsky, Charles Chuah, Tomasz Sacha, Jeffrey H Lipton, Charles A Schiffer, James McCloskey, Andreas Hochhaus, Philippe Rousselot, Gianantonio Rosti, Hugues de Lavallade, Anna Turkina, Christine Rojas, Christopher Arthur, Lori J Maness, Moshe Talpaz, Michael J Mauro, Tracey Hall, Vickie Lu, Shouryadeep Srivastava, Michael W Deininger.
      In PACE, a phase 2 trial of ponatinib that included patients with chronic phase chronic myeloid leukemia (CP-CML) resistant to multiple prior tyrosine kinase inhibitors (TKIs), ponatinib showed deep and durable responses, but arterial occlusive events (AOEs) emerged as notable adverse events. Post hoc analyses indicated that AOEs are dose dependent. We assessed the benefit:risk ratio across 3 ponatinib starting doses in the first prospective study to evaluate a novel response-based dose-reduction strategy for a TKI in CP-CML. Adults with CP-CML resistant/intolerant to at least 2 prior BCR-ABL1 TKIs, or with a BCR-ABL1 T315I mutation, were randomized 1:1:1 to ponatinib 45mg (45mg cohort), 30mg (30mg cohort), or 15mg (15mg cohort) once daily. Patients who received 45 or 30mg daily reduced their dose to 15mg upon achievement of response (BCR-ABL1IS transcript levels ≤1%). The primary end point was response at 12 months. Between August 2015 and May 2019, 283 patients were randomized; 282 (94/group) received treatment (data cutoff, 5/31/20). The primary end point (98.3% confidence interval) was achieved in 44.1% (31.7-57.0) in the 45mg cohort, 29.0% (18.4-41.6) in the 30mg cohort, and 23.1% (13.4-35.3) in the 15mg cohort. Independently confirmed grade 3/4 treatment-emergent AOEs occurred in 5, 5, and 3 patients in the 45, 30, and 15mg cohorts, respectively. All cohorts showed benefit in this highly resistant CP-CML population. Optimal benefit:risk outcomes occurred with the 45mg starting dose reducing to 15mg upon achievement of response (ClinicalTrials.gov number, NCT02467270).
    DOI:  https://doi.org/10.1182/blood.2021012082
  16. Blood. 2021 Aug 18. pii: blood.2020009984. [Epub ahead of print]
    A Phase 3, Open-Label, Randomized Study of Asciminib, a STAMP Inhibitor, vs Bosutinib in CML After ≥2 Prior TKIs.
    Delphine Rea, Michael J Mauro, Carla Boquimpani, Yosuke Minami, Elza Lomaia, Sergey Voloshin, Anna Grigorievna Turkina, Dong-Wook Kim, Jane F Apperley, Andre Abdo, Laura M Fogliatto, Dennis Dong Hwan Kim, Philipp le Coutre, Susanne Saussele, Mario Annunziata, Timothy P Hughes, Naeem Chaudhri, Koji Sasaki, Lynette Chee, Valentin Garcia-Gutierrez, Jorge Cortes, Paola Aimone, Alex Allepuz, Sara Quenet, Véronique Bédoucha, Andreas Hochhaus.
      Patients with chronic myeloid leukemia in chronic phase (CML-CP) resistant or intolerant to ≥2 tyrosine kinase inhibitors (TKIs) are at high risk of experiencing poor outcomes due to disease biology and inadequate efficacy and/or safety of current therapies. Asciminib is a first-in-class STAMP (Specifically Targeting the ABL Myristoyl Pocket) inhibitor with the potential to overcome resistance or intolerance to approved TKIs. In this phase 3, open-label study, patients with CML-CP previously treated with ≥2 TKIs were randomized (2:1) to receive asciminib 40 mg twice daily vs bosutinib 500 mg once daily. Randomization was stratified by major cytogenetic response (MCyR) status at baseline. The primary objective was to compare the major molecular response (MMR) rate at week 24 for asciminib vs bosutinib. Two hundred and thirty-three patients were randomized to asciminib (n=157) or bosutinib (n=76). Median follow-up was 14.9 months. The MMR rate at week 24 was 25.5% with asciminib and 13.2% with bosutinib. The difference in MMR rate between treatment arms, after adjusting for MCyR at baseline, was 12.2% (95% CI, 2.19-22.30; 2-sided P=.029). Fewer grade ≥3 adverse events (50.6% vs 60.5%) and fewer adverse events leading to treatment discontinuation (5.8% vs 21.1%) occurred with asciminib than with bosutinib. The study showed a superior efficacy of asciminib compared with that of bosutinib, together with a favorable safety profile. These results support the use of asciminib as a new therapy in patients with CML-CP who are resistant or intolerant to ≥2 prior TKIs. The trial is registered at www.ClinicalTrials.gov as NCT03106779.
    DOI:  https://doi.org/10.1182/blood.2020009984
  17. BMJ Case Rep. 2021 Aug 20. pii: e243615. [Epub ahead of print]14(8):
    Midostaurin-induced Sweet syndrome in a patient with FLT3-ITD-positive AML.
    Samer Alkassis, Aliza Rizwan, Lina Daoud, Jie Chi.
      Sweet syndrome (SS), also referred as acute febrile neutrophilic dermatosis, is an inflammatory process characterised by the abrupt appearance of erythematous papules or nodules with predominant neutrophilic infiltration in the dermis. Fever and neutrophilia are common presenting features. However, extracellular manifestations, including ocular and musculoskeletal, may occur. SS is divided into three subtypes: classical (or idiopathic), malignancy associated and drug induced. Medication-induced subtype accounts for up to 26% of cases. In recent years, emerging evidence has showed that SS may also occur in neutropenic patients who underwent induction for acute myeloid leukemia (AML). The identification of FMS-like tyrosine kinase 3 (FLT3) gene mutation in approximately 30% of patients with AML has promoted the targeted therapy with FLT3-internal tandem duplication (ITD) inhibitors. Midostaurin, a recently Food and Drug Administration-approved medication for FLT3-ITD-positive AML, was reported once as cause for SS. We report a midostaurin-induced SS with neutropenia in a patient following induction chemotherapy of AML.
    Keywords:  dermatology; haematology (drugs and medicines); skin
    DOI:  https://doi.org/10.1136/bcr-2021-243615
  18. Leukemia. 2021 Aug 19.
    Is the Sokal or EUTOS long-term survival (ELTS) score a better predictor of responses and outcomes in persons with chronic myeloid leukemia receiving tyrosine-kinase inhibitors?
    Xiao-Shuai Zhang, Robert Peter Gale, Xiao-Jun Huang, Qian Jiang.
      Data from 1661 consecutive subjects with chronic-phase chronic myeloid leukemia (CML) receiving initial imatinib (n = 1379) or a 2nd-generation tyrosine-kinase inhibitor (2G-TKI; n = 282) were interrogated to determine whether the Sokal or European Treatment and Outcome Study for CML (EUTOS) long-term survival (ELTS) scores were more accurate responses and outcome predictors. Both scores predicted probabilities of achieving complete cytogenetic response (CCyR), major molecular response (MMR), failure- and progression-free survivals (FFS, PFS), and survival in all subjects and those receiving imatinib therapy. However, the ELTS score was a better predictor of MR4, MR4.5, and CML-related survival than the Sokal score. In subjects receiving 2G-TKI therapy, only the ELTS score accurately predicted probabilities of CCyR, MMR, MR4, FFS, and PFS. In the propensity score matching, subjects classified as intermediate risk by the ELTS score receiving a 2G-TKI had better responses (p < 0.001~0.061), FFS (p = 0.002), and PFS (p = 0.03) but not survival. Our data suggest better overall prediction accuracy for the ELTS score compared with the Sokal score in CML patients, especially those receiving 2G-TKIs. People identified as intermediate risk by the ELTS score may benefit more from initial 2G-TKI therapy in achieving surrogate endpoints but not survival, especially when a briefer interval to stopping TKI therapy is the therapy objective.
    DOI:  https://doi.org/10.1038/s41375-021-01387-y
  19. Stem Cell Rev Rep. 2021 Aug 19.
    NFĸB Targeting in Bone Marrow Mesenchymal Stem Cell-Mediated Support of Age-Linked Hematological Malignancies.
    Lauren S Sherman, Shyam A Patel, Marianne D Castillo, Rachel Unkovic, Marcelo Taborga, Marina Gergues, Shaun Patterson, Jean-Pierre Etchegaray, Mohammed Jaloudi, Anupama Hooda-Nehra, Joshua Kra, Darling P Rojas, Victor T Chang, Pranela Rameshwar.
      Mesenchymal stem cells (MSCs) can become dysfunctional in patients with hematological disorders. An unanswered question is whether age-linked disruption of the bone marrow (BM) microenvironment is secondary to hematological dysfunction or vice versa. We therefore studied MSC function in patients with different hematological disorders and found decreased MHC-II except from one sample with acute myeloid leukemia (AML). The patients' MSCs were able to exert veto properties except for AML MSCs. While the expression of MHC-II appeared to be irrelevant to the immune licensing of MSCs, AML MSCs lost their ability to differentiate upon contact and rather, continued to proliferate, forming foci-like structures. We performed a retrospective study that indicated a significant increase in MSCs, based on phenotype, for patients with BM fibrosis. This suggests a role for MSCs in patients transitioning to leukemia. NFĸB was important to MSC function and was shown to be a potential target to sensitize leukemic CD34+/CD38- cells to azacitidine. This correlated with their lack of allogeneic stimulation. This study identified NFĸB as a potential target for combination therapy to treat leukemia stem cells and showed that understanding MSC biology and immune response could be key in determining how the aging BM might support leukemia. More importantly, we show how MSCs might be involved in transitioning the high risk patient with hematological disorder to AML.
    Keywords:  Azacytidine; Bone marrow; Bortezomib; Leukemia; Mesenchymal stem cell; Myelodysplasia; Myeloproliferative disorder
    DOI:  https://doi.org/10.1007/s12015-021-10235-6
  20. Cancer Metab. 2021 Aug 16. 9(1): 31
    Metabolic convergence on lipogenesis in RAS, BCR-ABL, and MYC-driven lymphoid malignancies.
    Daniel F Liefwalker, Meital Ryan, Zhichao Wang, Khyatiben V Pathak, Seema Plaisier, Vidhi Shah, Bobby Babra, Gabrielle S Dewson, Ian K Lai, Adriane R Mosley, Patrick T Fueger, Stephanie C Casey, Lei Jiang, Patrick Pirrotte, Srividya Swaminathan, Rosalie C Sears.
       BACKGROUND: Metabolic reprogramming is a central feature in many cancer subtypes and a hallmark of cancer. Many therapeutic strategies attempt to exploit this feature, often having unintended side effects on normal metabolic programs and limited efficacy due to integrative nature of metabolic substrate sourcing. Although the initiating oncogenic lesion may vary, tumor cells in lymphoid malignancies often share similar environments and potentially similar metabolic profiles. We examined cells from mouse models of MYC-, RAS-, and BCR-ABL-driven lymphoid malignancies and find a convergence on de novo lipogenesis. We explore the potential role of MYC in mediating lipogenesis by 13C glucose tracing and untargeted metabolic profiling. Inhibition of lipogenesis leads to cell death both in vitro and in vivo and does not induce cell death of normal splenocytes.
    METHODS: We analyzed RNA-seq data sets for common metabolic convergence in lymphoma and leukemia. Using in vitro cell lines derived in from conditional MYC, RAS, and BCR-ABL transgenic murine models and oncogene-driven human cell lines, we determined gene regulation, metabolic profiles, and sensitivity to inhibition of lipogenesis in lymphoid malignancies. We utilize preclinical murine models and transgenic primary model of T-ALL to determine the effect of lipogenesis blockade across BCR-ABL-, RAS-, and c-MYC-driven lymphoid malignancies. Statistical significance was calculated using unpaired t-tests and one-way ANOVA.
    RESULTS: This study illustrates that de novo lipid biogenesis is a shared feature of several lymphoma subtypes. Using cell lines derived from conditional MYC, RAS, and BCR-ABL transgenic murine models, we demonstrate shared responses to inhibition of lipogenesis by the acetyl-coA carboxylase inhibitor 5-(tetradecloxy)-2-furic acid (TOFA), and other lipogenesis inhibitors. We performed metabolic tracing studies to confirm the influence of c-MYC and TOFA on lipogenesis. We identify specific cell death responses to TOFA in vitro and in vivo and demonstrate delayed engraftment and progression in vivo in transplanted lymphoma cell lines. We also observe delayed progression of T-ALL in a primary transgenic mouse model upon TOFA administration. In a panel of human cell lines, we demonstrate sensitivity to TOFA treatment as a metabolic liability due to the general convergence on de novo lipogenesis in lymphoid malignancies driven by MYC, RAS, or BCR-ABL. Importantly, cell death was not significantly observed in non-malignant cells in vivo.
    CONCLUSIONS: These studies suggest that de novo lipogenesis may be a common survival strategy for many lymphoid malignancies and may be a clinically exploitable metabolic liability.
    TRIAL REGISTRATION: This study does not include any clinical interventions on human subjects.
    Keywords:  ACACA; BCR-ABL; Cancer metabolism; De novo lipogenesis; FASN; Fatty acid synthesis; Lipogenesis; Lymphoma; Oncogene addiction; RAS; T-ALL; c-MYC
    DOI:  https://doi.org/10.1186/s40170-021-00263-8
  21. Leuk Lymphoma. 2021 Aug 18. 1-10
    Prognostic significance of TIM-3 expression pattern at diagnosis in patients with t(8;21) acute myeloid leukemia.
    Jun Wang, Lu Yang, Feng-Ting Dao, Ya-Zhe Wang, Yan Chang, Nan Xu, Wen-Min Chen, Qian Jiang, Hao Jiang, Yan-Rong Liu, Ya-Zhen Qin.
      Acute myeloid leukemia (AML) with t(8;21) is a heterogeneous disease and needs to be stratified. Both, cancer cells and immune cells participate in tumor initiation, growth and progression and might affect clinical outcomes. TIM-3 (T cell immunoglobulin and mucin domain-containing protein 3), an immune checkpoint molecule, is expressed not only on immune cells but also on leukemic stem cells (LSCs) in AML. This prompted us to investigate the prognostic significance of TIM-3 in t(8;21) AML. A total of 47 t(8;21) AML patients were tested for TIM-3 expression by multi-parameter flow cytometry at diagnosis. 35 of these, who received chemotherapy alone or along with allogeneic hematopoietic stem cell transplantation were followed up. The expression pattern of TIM-3 on T-cells and NK (natural killer) cells as a whole (T + NK) and LSCs were evaluated independently. High percentage of T + NK - TIM-3+ and CD34+CD38-TIM-3+ cells were significantly associated with a high 2-year cumulative incidence of relapse (CIR) (p = 0.028, 0.016). Further, concurrent high frequencies of T + NK-TIM-3+ and CD34+CD38-TIM-3+ cells at diagnosis were significantly associated with a high 2-year CIR (p < 0.0001) and this together with c-KIT D816 mutation were the independent adverse prognostic factors for relapse (hazard ratio (HR)=2.5, [95% confidence interval (CI), 1.1-6.0], p = 0.04; HR = 46.5, [95% CI, 2.7-811.5], p = 0.009). In conclusion, the expression pattern of TIM-3 on both T and NK cells and LSCs at diagnosis had prognostic significance in t (8;21) AML.
    Keywords:  T and NK cells; TIM-3; leukemic stem cells; t(8;21) acute myeloid leukemia
    DOI:  https://doi.org/10.1080/10428194.2021.1966785
  22. Cancer Discov. 2021 Aug 20. pii: candisc.1771.2020. [Epub ahead of print]
    PRC2 Inhibitors Overcome Glucocorticoid Resistance Driven by NSD2 Mutation in Pediatric Acute Lymphoblastic Leukemia.
    Jianping Li, Julia Hlavka-Zhang, Jonathan H Shrimp, Crissandra Piper, Daphne Dupere-Richer, Jacob S Roth, Duohui Jing, Heidi L Casellas Roman, Catalina Troche, Alok Swaroop, Marta Kulis, Jon A Oyer, Christine M Will, Min Shen, Alberto Riva, Richard L Bennett, Adolfo A Ferrando, Matthew D Hall, Richard B Lock, Jonathan D Licht.
      Mutations in epigenetic regulators are common in relapsed pediatric acute lymphoblastic leukemia (ALL). Here, we uncovered the mechanism underlying the relapse of ALL driven by an activating mutation of the NSD2 histone methyltransferase (p.E1099K). Using high-throughput drug screening, we found that NSD2 mutant cells were specifically resistant to glucocorticoids. Correction of this mutation restored glucocorticoid sensitivity. The transcriptional response to glucocorticoids was blocked in NSD2 mutant cells due to depressed glucocorticoid receptor (GR) levels and the failure of glucocorticoids to autoactivate GR expression. While H3K27me3 was globally decreased by NSD2 p.E1099K, H3K27me3 accumulated at the NR3C1/(GR) promoter. Pre-treatment of NSD2 p.E1099K cell lines and PDX samples with PRC2 inhibitors reversed glucocorticoid resistance in vitro and in vivo. PRC2 inhibitors restored NR3C1 autoactivation by glucocorticoids, increasing GR levels and allowing GR binding and activation of pro-apoptotic genes. These findings suggest a new therapeutic approach to relapsed ALL associated with NSD2 mutation.
    DOI:  https://doi.org/10.1158/2159-8290.CD-20-1771
  23. Nature. 2021 Aug 18.
    Dietary fructose improves intestinal cell survival and nutrient absorption.
    Samuel R Taylor, Shakti Ramsamooj, Roger J Liang, Alyna Katti, Rita Pozovskiy, Neil Vasan, Seo-Kyoung Hwang, Navid Nahiyaan, Nancy J Francoeur, Emma M Schatoff, Jared L Johnson, Manish A Shah, Andrew J Dannenberg, Robert P Sebra, Lukas E Dow, Lewis C Cantley, Kyu Y Rhee, Marcus D Goncalves.
      Fructose consumption is linked to the rising incidence of obesity and cancer, which are two of the leading causes of morbidity and mortality globally1,2. Dietary fructose metabolism begins at the epithelium of the small intestine, where fructose is transported by glucose transporter type 5 (GLUT5; encoded by SLC2A5) and phosphorylated by ketohexokinase to form fructose 1-phosphate, which accumulates to high levels in the cell3,4. Although this pathway has been implicated in obesity and tumour promotion, the exact mechanism that drives these pathologies in the intestine remains unclear. Here we show that dietary fructose improves the survival of intestinal cells and increases intestinal villus length in several mouse models. The increase in villus length expands the surface area of the gut and increases nutrient absorption and adiposity in mice that are fed a high-fat diet. In hypoxic intestinal cells, fructose 1-phosphate inhibits the M2 isoform of pyruvate kinase to promote cell survival5-7. Genetic ablation of ketohexokinase or stimulation of pyruvate kinase prevents villus elongation and abolishes the nutrient absorption and tumour growth that are induced by feeding mice with high-fructose corn syrup. The ability of fructose to promote cell survival through an allosteric metabolite thus provides additional insights into the excess adiposity generated by a Western diet, and a compelling explanation for the promotion of tumour growth by high-fructose corn syrup.
    DOI:  https://doi.org/10.1038/s41586-021-03827-2
  24. Proc Natl Acad Sci U S A. 2021 Aug 24. pii: e2110758118. [Epub ahead of print]118(34):
    TET2 as a tumor suppressor and therapeutic target in T-cell acute lymphoblastic leukemia.
    Maike Bensberg, Olof Rundquist, Aida Selimović, Cathrine Lagerwall, Mikael Benson, Mika Gustafsson, Hartmut Vogt, Antonio Lentini, Colm E Nestor.
      Pediatric T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy resulting from overproduction of immature T-cells in the thymus and is typified by widespread alterations in DNA methylation. As survival rates for relapsed T-ALL remain dismal (10 to 25%), development of targeted therapies to prevent relapse is key to improving prognosis. Whereas mutations in the DNA demethylating enzyme TET2 are frequent in adult T-cell malignancies, TET2 mutations in T-ALL are rare. Here, we analyzed RNA-sequencing data of 321 primary T-ALLs, 20 T-ALL cell lines, and 25 normal human tissues, revealing that TET2 is transcriptionally repressed or silenced in 71% and 17% of T-ALL, respectively. Furthermore, we show that TET2 silencing is often associated with hypermethylation of the TET2 promoter in primary T-ALL. Importantly, treatment with the DNA demethylating agent, 5-azacytidine (5-aza), was significantly more toxic to TET2-silenced T-ALL cells and resulted in stable re-expression of the TET2 gene. Additionally, 5-aza led to up-regulation of methylated genes and human endogenous retroviruses (HERVs), which was further enhanced by the addition of physiological levels of vitamin C, a potent enhancer of TET activity. Together, our results clearly identify 5-aza as a potential targeted therapy for TET2-silenced T-ALL.
    Keywords:  5-azacytidine; HERV; T-ALL; TET2; vitamin C
    DOI:  https://doi.org/10.1073/pnas.2110758118
  25. Br J Haematol. 2021 Aug 19.
    Chronic myeloid leukaemia presenting with monocytosis.
    Benjamin Podvin, Laure Goursaud, Pauline Roynard, Olivier Nibourel, Nicolas Duployez, Laurène Fenwarth.
      
    DOI:  https://doi.org/10.1111/bjh.17725
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