bims-tremyl 2021-03-28 papers

on Therapy resistance biology in myeloid leukemia

Issue of 2021–03–28
twenty-six papers selected by
Paolo Gallipoli, Barts Cancer Institute, Queen Mary University of London

Mitochondrial metabolism supports resistance to IDH mutant inhibitors in acute myeloid leukemia.
Outcomes of patients with IDH1-mutant relapsed or refractory acute myeloid leukemia receiving ivosidenib who proceeded to hematopoietic stem cell transplant.
Cytoplasmic DNA accumulation preferentially triggers cell death of myeloid leukemia cells by interacting with intracellular DNA sensing pathway.
The JmjC-domain protein NO66/RIOX-1 affects the balance between proliferation and maturation in acute myeloid leukemia.
Which novel agents will have a clinically meaningful impact in AML at diagnosis?
Measurable residual disease as a biomarker in acute myeloid leukemia: theoretical and practical considerations.
A prognostic score including mutation profile and clinical features for patients with CMML undergoing stem cell transplantation.
Mechanisms for resistance in AML insights into molecular pathways mediating resistance to venetoclax.
Gene Expression Analysis of Pediatric Acute Myeloid Leukemia Identified a Hyperactive ASXL1/BAP1 Axis Linked with Poor Prognosis and over Expressed Epigenetic Modifiers.
WGS Outshines Cytogenetics in Myeloid Cancers.
Effect of post-treatment MRD status on subsequent outcomes according to chemotherapy intensity in acute myeloid leukemia (AML).
Prognostic impact of the adverse molecular-genetic profile on long-term outcomes following allogeneic hematopoietic stem cell transplantation in acute myeloid leukemia.
Malic enzyme 2 connects the Krebs cycle intermediate fumarate to mitochondrial biogenesis.
YBX1 is required for maintaining myeloid leukemia cell survival by regulating BCL2 stability in an m6A-dependent manner.
What are the molecular mechanisms driving the switch from MPNs to leukemia?
Modeling acute erythroid leukemia via CRISPR.
Nuclear DEK preserves hematopoietic stem cells potential via NCoR1/HDAC3-Akt1/2-mTOR axis.
EVI1 dysregulation: impact on biology and therapy of myeloid malignancies.
Azacitidine maintenance after allogeneic hematopoietic cell transplantation for MDS and AML.
Mutant ASXL1 induces age-related expansion of phenotypic hematopoietic stem cells through activation of Akt/mTOR pathway.
The origins and genetic interactions of KRAS mutations are allele- and tissue-specific.
Phase III, Randomized, Placebo-Controlled Trial of CC-486 (Oral Azacitidine) in Patients With Lower-Risk Myelodysplastic Syndromes.
HLA class I allele-lacking leukocytes predict rare clonal evolution to MDS/AML in patients with acquired aplastic anemia.
A drug targeting 5-lipoxygenase enhances the activity of a JAK2 inhibitor in CD34+ bone marrow cells from patients with JAK2V617F-positive polycythemia vera in vitro.
High Expression of CLEC11A Predicts Favorable Prognosis in Acute Myeloid Leukemia.
Distinct bone marrow immunophenotypic features define the splicing factor 3B subunit 1 (SF3B1)-mutant myelodysplastic syndromes subtype.

J Exp Med. 2021 May 03. pii: e20200924. [Epub ahead of print]218(5):

Mitochondrial metabolism supports resistance to IDH mutant inhibitors in acute myeloid leukemia.

Lucille Stuani, Marie Sabatier, Estelle Saland, Guillaume Cognet, Nathalie Poupin, Claudie Bosc, Florence A Castelli, Lara Gales, Evgenia Turtoi, Camille Montersino, Thomas Farge, Emeline Boet, Nicolas Broin, Clément Larrue, Natalia Baran, Madi Y Cissé, Marc Conti, Sylvain Loric, Tony Kaoma, Alexis Hucteau, Aliki Zavoriti, Ambrine Sahal, Pierre-Luc Mouchel, Mathilde Gotanègre, Cédric Cassan, Laurent Fernando, Feng Wang, Mohsen Hosseini, Emeline Chu-Van, Laurent Le Cam, Martin Carroll, Mary A Selak, Norbert Vey, Rémy Castellano, François Fenaille, Andrei Turtoi, Guillaume Cazals, Pierre Bories, Yves Gibon, Brandon Nicolay, Sébastien Ronseaux, Joseph R Marszalek, Koichi Takahashi, Courtney D DiNardo, Marina Konopleva, Véra Pancaldi, Yves Collette, Floriant Bellvert, Fabien Jourdan, Laetitia K Linares, Christian Récher, Jean-Charles Portais, Jean-Emmanuel Sarry.

Mutations in IDH induce epigenetic and transcriptional reprogramming, differentiation bias, and susceptibility to mitochondrial inhibitors in cancer cells. Here, we first show that cell lines, PDXs, and patients with acute myeloid leukemia (AML) harboring an IDH mutation displayed an enhanced mitochondrial oxidative metabolism. Along with an increase in TCA cycle intermediates, this AML-specific metabolic behavior mechanistically occurred through the increase in electron transport chain complex I activity, mitochondrial respiration, and methylation-driven CEBPα-induced fatty acid β-oxidation of IDH1 mutant cells. While IDH1 mutant inhibitor reduced 2-HG oncometabolite and CEBPα methylation, it failed to reverse FAO and OxPHOS. These mitochondrial activities were maintained through the inhibition of Akt and enhanced activation of peroxisome proliferator-activated receptor-γ coactivator-1 PGC1α upon IDH1 mutant inhibitor. Accordingly, OxPHOS inhibitors improved anti-AML efficacy of IDH mutant inhibitors in vivo. This work provides a scientific rationale for combinatory mitochondrial-targeted therapies to treat IDH mutant AML patients, especially those unresponsive to or relapsing from IDH mutant inhibitors.

DOI: https://doi.org/10.1084/jem.20200924
Leukemia. 2021 Mar 26.

Outcomes of patients with IDH1-mutant relapsed or refractory acute myeloid leukemia receiving ivosidenib who proceeded to hematopoietic stem cell transplant.

Courtney D DiNardo, Eytan M Stein, Arnaud Pigneux, Jessica K Altman, Robert Collins, Harry P Erba, Justin M Watts, Geoffrey L Uy, Thomas Winkler, Hongfang Wang, Sung Choe, Hua Liu, Bin Wu, Stephanie M Kapsalis, Gail J Roboz, Stéphane de Botton.

DOI: https://doi.org/10.1038/s41375-021-01229-x
Cell Death Dis. 2021 Mar 26. 12(4): 322

Cytoplasmic DNA accumulation preferentially triggers cell death of myeloid leukemia cells by interacting with intracellular DNA sensing pathway.

Tomohisa Baba, Takeshi Yoshida, Yamato Tanabe, Tatsunori Nishimura, Soji Morishita, Noriko Gotoh, Atsushi Hirao, Rikinari Hanayama, Naofumi Mukaida.

Accumulating evidence indicates the presence of cytoplasmic DNAs in various types of malignant cells, and its involvement in anti-cancer drug- or radiotherapy-mediated DNA damage response and replication stress. However, the pathophysiological roles of cytoplasmic DNAs in leukemias remain largely unknown. We observed that during hematopoietic stem cell transplantation (HSCT) in mouse myeloid leukemia models, double-stranded (ds)DNAs were constitutively secreted in the form of extracellular vesicles (EVs) from myeloid leukemia cells and were transferred to the donor cells to dampen their hematopoietic capabilities. Subsequent analysis of cytoplasmic DNA dynamics in leukemia cells revealed that autophagy regulated cytoplasmic dsDNA accumulation and subsequent redistribution into EVs. Moreover, accumulated cytoplasmic dsDNAs activated STING pathway, thereby reducing leukemia cell viability through reactive oxygen species (ROS) generation. Pharmaceutical inhibition of autophagosome formation induced cytoplasmic DNA accumulation, eventually triggering cytoplasmic DNA sensing pathways to exert cytotoxicity, preferentially in leukemia cells. Thus, manipulation of cytoplasmic dsDNA dynamics can be a novel and potent therapeutic strategy for myeloid leukemias.

DOI: https://doi.org/10.1038/s41419-021-03587-x
Exp Cell Res. 2021 Mar 18. pii: S0014-4827(21)00098-7. [Epub ahead of print] 112566

The JmjC-domain protein NO66/RIOX-1 affects the balance between proliferation and maturation in acute myeloid leukemia.

Weijia Yu, Christoph Lutz, Alwin Krämer, Marion S Schmidt-Zachmann.

  As epigenetic regulators are frequently dysregulated in acute myeloid leukemia (AML) we determined expression levels of the JmjC-protein NO66 in AML cell lines and sub fractions of healthy human hematopoietic cells. NO66 is absent in the AML cell lines KG1/KG1a which consist of cells with the immature CD34+/CD38- phenotype and is regarded as a "stem cell-like" model system. Similarly, NO66 is not detectable in CD34+/CD38- cells purified from healthy donors but is clearly expressed in the more committed CD34+/CD38+ cell population. Loss of NO66 expression in KG1/KG1a cells is due to hyper-methylation of its promoter and is released by DNA-methyltransferase inhibitors. In KG1a cells stably expressing exogenous wild type (KG1a66wt) or enzymatically inactive mutant (KG1a66mut) NO66, respectively, the wild type protein inhibited proliferation and rDNA transcription. Gene expression profiling revealed that the expression of NO66 induces a transcriptional program enriched for genes with roles in proliferation and maturation (e.g.EPDR1, FCER1A, CD247, MYCN, SNORD13). Genes important for the maintenance of stem cell properties are downregulated (e.g. SIRPA, Lin28B, JAML). Our results indicate that NO66 induces lineage commitment towards myeloid progenitor cell fate and suggest that NO66 contributes to loss of stem cell properties.

Keywords:  Hematopoietic stem cells; JmjC-proteins; NO66; acute myeloid leukemia; epigenetic modifiers; nucleolus; ribosome biogenesis

DOI:  https://doi.org/10.1016/j.yexcr.2021.112566
Best Pract Res Clin Haematol. 2021 Mar;pii: S1521-6926(21)00022-0. [Epub ahead of print]34(1): 101257

Which novel agents will have a clinically meaningful impact in AML at diagnosis?

Alexander E Perl.

  New drug approvals now afford AML physicians a wider choice of initial treatment options than ever before. Although chemotherapy for AML is by no means ready to be replaced entirely by novel agents, the role of traditional cytotoxics in AML therapy is rapidly changing. In particular, biologically targeted agents such as the BCL2 inhibitor venetoclax and inhibitors of FLT3 and IDH mutations stand out as drugs likely to take AML therapy in important new directions. Maximum response and survival benefits likely require combinations of novel agents and chemotherapy or multiple novel agents together. The recently-published phase 3 VIALE-A study demonstrates a very successful example of a new combination approach, which led to venetoclax plus azacitidine establishing itself as the new standard of care for patients unfit for intensive chemotherapy. One could reasonably expect other subsets of AML to benefit from this regimen or other applications of venetoclax combinations. Building on this experience, venetoclax-based regimens also have the potential to replace standard intensive cytarabine/anthracycline "7&3" induction approach for some if not many patients who are fit for induction. This review will describe novel agents with the greatest potential for impactful frontline applications that will change the AML treatment paradigm.

Keywords:  Acute myeloid leukemia; BLC2 inhibition; FLT3 inhibition; IDH inhibition; Novel therapeutics

DOI:  https://doi.org/10.1016/j.beha.2021.101257
Leukemia. 2021 Mar 23.

Measurable residual disease as a biomarker in acute myeloid leukemia: theoretical and practical considerations.

Roland B Walter, Yishai Ofran, Agnieszka Wierzbowska, Farhad Ravandi, Christopher S Hourigan, Lok Lam Ngai, Adriano Venditti, Francesco Buccisano, Gert J Ossenkoppele, Gail J Roboz.

Several methodologies that rely on the detection of immunophenotypic or molecular abnormalities of the neoplastic cells are now available to quantify measurable ("minimal") residual disease (MRD) in acute myeloid leukemia (AML). Although the perfect MRD test does not (yet) exist, the strong association between MRD and adverse patient outcomes has provided the impetus to use measures of MRD as biomarker in the routine care of AML patients and during clinical trials. MRD test results may inform the selection of postremission therapy in some patients but evidence supporting the use of MRD as predictive biomarker is still limited. Several retrospective studies have shown that conversion from undetectable to detectable MRD or increasing MRD over time is associated with overt disease recurrence, and MRD testing may therefore be valuable as a monitoring biomarker for early detection of relapse. Interpreting serial MRD data is complex, with open questions regarding the optimal timing and frequency of testing, as well as the identification of test-specific thresholds to define relapse. Importantly, it is unknown whether intervening at the time of MRD detection, rather than at overt disease recurrence, improves outcomes. Finally, using MRD as a surrogate efficacy-response biomarker to accelerate drug development/approval has already been accepted by regulatory authorities in other diseases and is of great interest as a potential strategy in AML. While the prognostic value of MRD in AML is well established, data from prospective clinical trials confirming that treatment effects on MRD directly relate to clinical outcomes are needed to further establish the role of MRD as a surrogate endpoint in AML.

DOI: https://doi.org/10.1038/s41375-021-01230-4
Blood Adv. 2021 Mar 23. 5(6): 1760-1769

A prognostic score including mutation profile and clinical features for patients with CMML undergoing stem cell transplantation.

Nico Gagelmann, Anita Badbaran, Dietrich W Beelen, Rachel B Salit, Friedrich Stölzel, Christina Rautenberg, Heiko Becker, Aleksandar Radujkovic, Victoria Panagiota, Rashit Bogdanov, Maximilian Christopeit, Yong Park, Olivier Nibourel, Thomas Luft, Michael Koldehoff, Maarten Corsten, Michael Heuser, Jürgen Finke, Guido Kobbe, Uwe Platzbecker, Marie Robin, Bart L Scott, Nicolaus Kröger.

The inclusion of mutation status improved risk stratification for newly diagnosed patients with chronic myelomonocytic leukemia (CMML). Stem cell transplantation is a potentially curative treatment option, and patient selection is critical because of relevant transplant-related morbidity and mortality. We aimed to evaluate the impact of mutation status together with clinical presentations on posttransplant outcome. Our study included 240 patients with a median follow-up of 5.5 years. A significant association with worse survival was identified for the presence of mutations in ASXL1 and/or NRAS. In multivariable analysis, ASXL1- and/or NRAS-mutated genotype (hazard ratio [HR], 1.63), marrow blasts >2% (HR, 1.70), and increasing comorbidity index (continuous HR, 1.16) were independently associated with worse survival. A prognostic score (CMML transplant score) was developed, and the following points were assigned: 4 points for an ASXL1- and/or NRAS-mutated genotype or blasts >2% and 1 point each for an increase of 1 in the comorbidity index. The CMML transplant score (range, 0-20) was predictive of survival and nonrelapse mortality (P < .001 for both). Up to 5 risk groups were identified, showing 5-year survival of 81% for a score of 0 to 1, 49% for a score of 2 to 4, 43% for a score of 5 to 7, 31% for a score of 8 to 10, and 19% for a score >10. The score retained performance after validation (concordance index, 0.68) and good accuracy after calibration. Predictions were superior compared with existing scores designed for the nontransplant setting, which resulted in significant risk reclassification. This CMML transplant score, which incorporated mutation and clinical information, was prognostic in patients specifically undergoing transplantation and may facilitate personalized counseling.

DOI: https://doi.org/10.1182/bloodadvances.2020003600
Best Pract Res Clin Haematol. 2021 Mar;pii: S1521-6926(21)00016-5. [Epub ahead of print]34(1): 101251

Mechanisms for resistance in AML insights into molecular pathways mediating resistance to venetoclax.

Marina Y Konopleva.

  Resistance to therapy continues to pose hurdles in the therapeutic management of acute myeloid leukemia (AML). Although the approval and development of therapies such as venetoclax, was expected to overcome this issue, resistance remains a common occurrence in AML treatment. This review has summarized evidence that will provide insights into acquired mutations that influence response to venetoclax therapy and the utility of novel combination approaches in improving outcomes.

Keywords:  AML; Acute myeloid leukemia; Complete response (CR); Venetoclax

DOI:  https://doi.org/10.1016/j.beha.2021.101251
Pediatr Hematol Oncol. 2021 Mar 25. 1-11

Gene Expression Analysis of Pediatric Acute Myeloid Leukemia Identified a Hyperactive ASXL1/BAP1 Axis Linked with Poor Prognosis and over Expressed Epigenetic Modifiers.

Ghaleb Elyamany, Ariz Akhter, Hamza Kamran, Hassan Rizwan, Meer-Taher Shabani-Rad, Nawaf Alkhayat, Omar Al Sharif, Yasser Elborai, Mohammad Al Shahrani, Adnan Mansoor.

  Genetic aberrations in the epigenome are rare in pediatric AML, hence expression data in epigenetic regulation and its downstream effect is lacking in childhood AML. Our pilot study screened epigenetic modifiers and its related oncogenic signal transduction pathways concerning clinical outcomes in a small cohort of pediatric AML in KSA. RNA from diagnostic BM biopsies (n = 35) was subjected to expression analysis employing the nCounter Pan-Cancer pathway panel. The patients were dichotomized into low ASXL1 (17/35; 49%) and high ASXL1 (18/35; 51%) groups based on ROC curve analysis. Age, gender, hematological data or molecular risk factors (FLT3 mutation/molecular fusion) exposed no significant differences across these two distinct ASXL1 expression groups (P > 0.05). High ASXL1 expression showed linkage with high expression of other epigenetic modifiers (TET2/EZH2/IDH1&2). Our data showed that high ASXL1 mRNA is interrelated with increased BRCA1 associated protein-1 (BAP1) and its target gene E2F Transcription Factor 1 (E2F1) expression. High ASXL1 expression was associated with high mortality {10/18 (56%) vs. 1/17; (6%) P < 0 .002}. Low ASXL1 expressers showed better OS {740 days vs. 579 days; log-rank P= < 0.023; HR 7.54 (0.98-54.1)}. The association between high ASXL1 expression and epigenetic modifiers is interesting but unexplained and require further investigation. High ASXL1 expression is associated with BAP1 and its target genes. Patients with high ASXL1 expression showed poor OS without any association with a conventional molecular prognostic marker.

Keywords:  ASXL1 expression; Acute myeloid leukemia; epigenetic modifiers; prognosis

DOI:  https://doi.org/10.1080/08880018.2021.1901808
Cancer Discov. 2021 Mar 26.

WGS Outshines Cytogenetics in Myeloid Cancers.

A recent study involving patients with acute myeloid leukemia or myelodysplastic syndromes finds that whole-genome sequencing can detect more chromosomal alterations than traditional cytogenetics. In addition, whole-genome sequencing could improve the accuracy of prognoses. The study also found that the technique was faster than cytogenetics with a similar cost.

DOI: https://doi.org/10.1158/2159-8290.CD-NB2021-0328
Leuk Lymphoma. 2021 Mar 22. 1-4

Effect of post-treatment MRD status on subsequent outcomes according to chemotherapy intensity in acute myeloid leukemia (AML).

Michael J Hochman, Megan Othus, Roland B Walter, Carole Shaw, Kelda Gardner, Mary-Elizabeth M Percival, Anna B Halpern, Paul C Hendrie, Brenda M Sandmaier, Elihu H Estey.

DOI: https://doi.org/10.1080/10428194.2021.1885658
Bone Marrow Transplant. 2021 Mar 25.

Prognostic impact of the adverse molecular-genetic profile on long-term outcomes following allogeneic hematopoietic stem cell transplantation in acute myeloid leukemia.

Georgina Daher-Reyes, TaeHyung Kim, Igor Novitzky-Basso, Kyuoung Ha Kim, Adam Smith, Tracy Stockley, Jose-Mario Capochichi, Zeyad Al-Shaibani, Ivan Pasic, Arjun Law, Wilson Lam, Fotios V Michelis, Armin Gerbitz, Auro Viswabandya, Jeffrey Lipton, Rajat Kumar, Jonas Mattsson, Aaron Schimmer, Caroline McNamara, Tracy Murphy, Dawn Maze, Vikas Gupta, Hassan Sibai, Steven Chan, Karen Yee, Mark Minden, Zhaolei Zhang, Andre Schuh, Dennis D H Kim.

The impact of adverse risk genetic profiles on outcomes in acute myeloid leukemia (AML) patients following allogeneic hematopoietic stem cell transplantation (HCT) has not been fully elucidated. Accordingly, we have profiled somatic mutations at diagnosis using next-generation sequencing (NGS) in 178 AML patients who received allogeneic HCT. NGS revealed 598 somatic mutations in 165/178 patients (92.7%). Frequently mutated genes include DNMT3A, TET2, NPM1, RUNX1, IDH2, and FLT3. Commonly detected cytogenetic profiles include normal karyotype, trisomy 8, monosomal karyotype (MK), deletion 5, complex karyotype (CK), and monosomy 7. In univariate analyses, TP53 mutation, MK, CK, and monosomy 7 were associated with decreased overall survival (OS), relapse-free survival (RFS), and a higher relapse incidence (RI). We defined adverse molecular-genetic profile as harboring at least one of the molecular/genetic abnormalities of TP53 mutation, MK, CK, monosomy 7, and deletion 5. The patients harboring adverse molecular-genetic profile (n = 30) showed a lower 2-year OS (24.9% vs. 57.9%; p = 0.003), RFS (23.7% vs. 57.9%; p = 0.002), and higher RI (47.2% and 17.2%; p = 0.001) after HCT when compared to patients without those lesions. Multivariate analysis confirmed adverse molecular-genetic profile as an independent prognostic factor, associated with decreased OS (HR 2.19), RFS (HR 2.23), and higher RI (HR 2.94).

DOI: https://doi.org/10.1038/s41409-021-01255-4
Cell Metab. 2021 Mar 23. pii: S1550-4131(21)00110-8. [Epub ahead of print]

Malic enzyme 2 connects the Krebs cycle intermediate fumarate to mitochondrial biogenesis.

Yi-Ping Wang, Azeem Sharda, Shuang-Nian Xu, Nick van Gastel, Cheuk Him Man, Una Choi, Wei Zhong Leong, Xi Li, David T Scadden.

  Mitochondria have an independent genome (mtDNA) and protein synthesis machinery that coordinately activate for mitochondrial generation. Here, we report that the Krebs cycle intermediate fumarate links metabolism to mitobiogenesis through binding to malic enzyme 2 (ME2). Mechanistically, fumarate binds ME2 with two complementary consequences. First, promoting the formation of ME2 dimers, which activate deoxyuridine 5'-triphosphate nucleotidohydrolase (DUT). DUT fosters thymidine generation and an increase of mtDNA. Second, fumarate-induced ME2 dimers abrogate ME2 monomer binding to mitochondrial ribosome protein L45, freeing it for mitoribosome assembly and mtDNA-encoded protein production. Methylation of the ME2-fumarate binding site by protein arginine methyltransferase-1 inhibits fumarate signaling to constrain mitobiogenesis. Notably, acute myeloid leukemia is highly dependent on mitochondrial function and is sensitive to targeting of the fumarate-ME2 axis. Therefore, mitobiogenesis can be manipulated in normal and malignant cells through ME2, an unanticipated governor of mitochondrial biomass production that senses nutrient availability through fumarate.

Keywords:  acute myeloid leukemia; arginine methylation; deoxyuridine 5′-triphosphate nucleotidohydrolase; fumarate; malic enzyme 2; mitobiogenesis; mitochondrial ribosome; mitochondrial ribosome protein L45; protein arginine methyltransferase 1

DOI:  https://doi.org/10.1016/j.cmet.2021.03.003
Blood. 2021 Mar 24. pii: blood.2020009676. [Epub ahead of print]

YBX1 is required for maintaining myeloid leukemia cell survival by regulating BCL2 stability in an m6A-dependent manner.

Mengdie Feng, Xueqin Xie, Guoqiang Han, Tiantian Zhang, Yashu Li, Yicun Li, Rong Yin, Qifan Wang, Tong Zhang, Peipei Wang, Jin Hu, Ying Cheng, Zhuying Gao, Jing Wang, Jiwei Chang, Manman Cui, Kexin Gao, Jihua Chai, Weidong Liu, Chengli Guo, Shaoguang Li, Lingbo Liu, Fuling Zhou, Jianjun Chen, Haojian Zhang.

RNA-binding proteins (RBPs) are critical regulators of transcription and translation that are often dysregulated in cancer. Although RBPs are increasingly appreciated as being important for normal hematopoiesis and for hematological malignancies as oncogenes or tumor suppressors, essential RBPs for leukemia maintenance and survival remain elusive. Here we show that YBX1 is specifically required for maintaining myeloid leukemia cell survival in an m6A-dependent manner. We found that expression of YBX1 is significantly upregulated in myeloid leukemia cells, and deletion of YBX1 dramatically induces apoptosis, promotes differentiation, coupled with reduced proliferation and impaired leukemic capacity of primary human and mouse acute myeloid leukemia (AML) cells in vitro and in vivo. Loss of YBX1 does not obviously affect normal hematopoiesis. Mechanistically, YBX1 interacts with IGF2BPs and stabilizes m6A-tagged RNA. Moreover, YBX1 deficiency dysregulates the expression of apoptosis-related genes, and promotes mRNA decay of MYC and BCL2 in an m6A-dependent manner, which contributes to the defective survival due to YBX1 deletion. Thus, our findings uncover a selective and critical role of YBX1 in maintaining myeloid leukemia survival that might provide a rationale for the therapeutic targeting of YBX1 in myeloid leukemia.

DOI: https://doi.org/10.1182/blood.2020009676
Best Pract Res Clin Haematol. 2021 Mar;pii: S1521-6926(21)00019-0. [Epub ahead of print]34(1): 101254

What are the molecular mechanisms driving the switch from MPNs to leukemia?

Xiaoli Wang, Ronald Hoffman.

  Myeloproliferative neoplasm-blast phase (MPN-BP) is a form of acute leukemia which is distinct from de novo acute myeloid leukemia with each entity being characterized by specific complex cytogenetic abnormalities and myeloid gene mutational patterns. MPN-BP patients have a particularly dismal prognosis with a medium overall survival of 5.8 months with currently available therapies. Large-scale sequencing studies have unraveled the mutational landscape of the chronic MPNs and MPN-BP, demonstrating importance of clonal heterogeneity and the role of somatic mutations in disease progression and their use to determine patient outcomes. JAK inhibitors represent the standard of care for intermediate/high-risk MF patients and have been shown to improve clinical symptoms. However, this therapeutic approach leads to a modest reduction in the variant allele frequency of the known MPN driver mutations in most patients and does not substantially delay or prevent the evolution to MPN-BP. In this article, we will review molecular mechanisms driving the progression from chronic MPNs to a BP, the impact of genetic changes on MPN-BP evolution, and the role of clonal evolution in response to JAK inhibitor therapy and disease progression. We will also discuss our ongoing functional studies of cells responsible for the development of MPN-BP.

Keywords:  Acute myeloid leukemia; Blast phase; JAK inhibitor; Leukemic transformation; Molecular mechanism; Myeloproliferative neoplasm; Stem cell

DOI:  https://doi.org/10.1016/j.beha.2021.101254
Blood. 2021 Mar 25. 137(12): 1565-1567

Modeling acute erythroid leukemia via CRISPR.

Jian-Ping Zhang, Tao Cheng.

DOI: https://doi.org/10.1182/blood.2020010544
J Exp Med. 2021 May 03. pii: e20201974. [Epub ahead of print]218(5):

Nuclear DEK preserves hematopoietic stem cells potential via NCoR1/HDAC3-Akt1/2-mTOR axis.

Zhe Chen, Dawei Huo, Lei Li, Zhilong Liu, Zhigang Li, Shuangnian Xu, Yongxiu Huang, Weiru Wu, Chengfang Zhou, Yuanyuan Liu, Mei Kuang, Feng Wu, Hui Li, Pengxu Qian, Guanbin Song, Xudong Wu, Jieping Chen, Yu Hou.

The oncogene DEK is found fused with the NUP214 gene creating oncoprotein DEK-NUP214 that induces acute myeloid leukemia (AML) in patients, and secreted DEK protein functions as a hematopoietic cytokine to regulate hematopoiesis; however, the intrinsic role of nuclear DEK in hematopoietic stem cells (HSCs) remains largely unknown. Here, we show that HSCs lacking DEK display defects in long-term self-renew capacity, eventually resulting in impaired hematopoiesis. DEK deficiency reduces quiescence and accelerates mitochondrial metabolism in HSCs, in part, dependent upon activating mTOR signaling. At the molecular level, DEK recruits the corepressor NCoR1 to repress acetylation of histone 3 at lysine 27 (H3K27ac) and restricts the chromatin accessibility of HSCs, governing the expression of quiescence-associated genes (e.g., Akt1/2, Ccnb2, and p21). Inhibition of mTOR activity largely restores the maintenance and potential of Dek-cKO HSCs. These findings highlight the crucial role of nuclear DEK in preserving HSC potential, uncovering a new link between chromatin remodelers and HSC homeostasis, and have clinical implications.

DOI: https://doi.org/10.1084/jem.20201974
Blood Cancer J. 2021 Mar 22. 11(3): 64

EVI1 dysregulation: impact on biology and therapy of myeloid malignancies.

Christine Birdwell, Warren Fiskus, Tapan M Kadia, Courtney D DiNardo, Christopher P Mill, Kapil N Bhalla.

Ecotropic viral integration site 1 (Evi1) was discovered in 1988 as a common site of ecotropic viral integration resulting in myeloid malignancies in mice. EVI1 is an oncogenic zinc-finger transcription factor whose overexpression contributes to disease progression and an aggressive phenotype, correlating with poor clinical outcome in myeloid malignancies. Despite progress in understanding the biology of EVI1 dysregulation, significant improvements in therapeutic outcome remain elusive. Here, we highlight advances in understanding EVI1 biology and discuss how this new knowledge informs development of novel therapeutic interventions. EVI1 is overexpression is correlated with poor outcome in some epithelial cancers. However, the focus of this review is the genetic lesions, biology, and current therapeutics of myeloid malignancies overexpressing EVI1.

DOI: https://doi.org/10.1038/s41408-021-00457-9
Blood Adv. 2021 Mar 23. 5(6): 1757-1759

Azacitidine maintenance after allogeneic hematopoietic cell transplantation for MDS and AML.

Firas El Chaer, Uma Borate, Rémy Duléry, Shernan G Holtan, Arjun Datt Law, Lori Muffly, Samah Nassereddine, Rory M Shallis, Kate Stringaris, Justin Taylor, Steven M Devine, Mohamad Mohty, Christopher S Hourigan.

DOI: https://doi.org/10.1182/bloodadvances.2020003839
Nat Commun. 2021 03 23. 12(1): 1826

Mutant ASXL1 induces age-related expansion of phenotypic hematopoietic stem cells through activation of Akt/mTOR pathway.

Takeshi Fujino, Susumu Goyama, Yuki Sugiura, Daichi Inoue, Shuhei Asada, Satoshi Yamasaki, Akiko Matsumoto, Kiyoshi Yamaguchi, Yumiko Isobe, Akiho Tsuchiya, Shiori Shikata, Naru Sato, Hironobu Morinaga, Tomofusa Fukuyama, Yosuke Tanaka, Tsuyoshi Fukushima, Reina Takeda, Keita Yamamoto, Hiroaki Honda, Emi K Nishimura, Yoichi Furukawa, Tatsuhiro Shibata, Omar Abdel-Wahab, Makoto Suematsu, Toshio Kitamura.

Somatic mutations of ASXL1 are frequently detected in age-related clonal hematopoiesis (CH). However, how ASXL1 mutations drive CH remains elusive. Using knockin (KI) mice expressing a C-terminally truncated form of ASXL1-mutant (ASXL1-MT), we examined the influence of ASXL1-MT on physiological aging in hematopoietic stem cells (HSCs). HSCs expressing ASXL1-MT display competitive disadvantage after transplantation. Nevertheless, in genetic mosaic mouse model, they acquire clonal advantage during aging, recapitulating CH in humans. Mechanistically, ASXL1-MT cooperates with BAP1 to deubiquitinate and activate AKT. Overactive Akt/mTOR signaling induced by ASXL1-MT results in aberrant proliferation and dysfunction of HSCs associated with age-related accumulation of DNA damage. Treatment with an mTOR inhibitor rapamycin ameliorates aberrant expansion of the HSC compartment as well as dysregulated hematopoiesis in aged ASXL1-MT KI mice. Our findings suggest that ASXL1-MT provokes dysfunction of HSCs, whereas it confers clonal advantage on HSCs over time, leading to the development of CH.

DOI: https://doi.org/10.1038/s41467-021-22053-y
Nat Commun. 2021 03 22. 12(1): 1808

The origins and genetic interactions of KRAS mutations are allele- and tissue-specific.

Joshua H Cook, Giorgio E M Melloni, Doga C Gulhan, Peter J Park, Kevin M Haigis.

Mutational activation of KRAS promotes the initiation and progression of cancers, especially in the colorectum, pancreas, lung, and blood plasma, with varying prevalence of specific activating missense mutations. Although epidemiological studies connect specific alleles to clinical outcomes, the mechanisms underlying the distinct clinical characteristics of mutant KRAS alleles are unclear. Here, we analyze 13,492 samples from these four tumor types to examine allele- and tissue-specific genetic properties associated with oncogenic KRAS mutations. The prevalence of known mutagenic mechanisms partially explains the observed spectrum of KRAS activating mutations. However, there are substantial differences between the observed and predicted frequencies for many alleles, suggesting that biological selection underlies the tissue-specific frequencies of mutant alleles. Consistent with experimental studies that have identified distinct signaling properties associated with each mutant form of KRAS, our genetic analysis reveals that each KRAS allele is associated with a distinct tissue-specific comutation network. Moreover, we identify tissue-specific genetic dependencies associated with specific mutant KRAS alleles. Overall, this analysis demonstrates that the genetic interactions of oncogenic KRAS mutations are allele- and tissue-specific, underscoring the complexity that drives their clinical consequences.

DOI: https://doi.org/10.1038/s41467-021-22125-z
J Clin Oncol. 2021 Mar 25. JCO2002619

Phase III, Randomized, Placebo-Controlled Trial of CC-486 (Oral Azacitidine) in Patients With Lower-Risk Myelodysplastic Syndromes.

Guillermo Garcia-Manero, Valeria Santini, Antonio Almeida, Uwe Platzbecker, Anna Jonasova, Lewis R Silverman, Jose Falantes, Gianluigi Reda, Francesco Buccisano, Pierre Fenaux, Rena Buckstein, Maria Diez Campelo, Stephen Larsen, David Valcarcel, Paresh Vyas, Valentina Giai, Esther Natalie Olíva, Jake Shortt, Dietger Niederwieser, Moshe Mittelman, Luana Fianchi, Ignazia La Torre, Jianhua Zhong, Eric Laille, Daniel Lopes de Menezes, Barry Skikne, C L Beach, Aristoteles Giagounidis.

PURPOSE: Treatment options are limited for patients with lower-risk myelodysplastic syndromes (LR-MDS). This phase III, placebo-controlled trial evaluated CC-486 (oral azacitidine), a hypomethylating agent, in patients with International Prognostic Scoring System LR-MDS and RBC transfusion-dependent anemia and thrombocytopenia.
METHODS: Patients were randomly assigned 1:1 to CC-486 300-mg or placebo for 21 days/28-day cycle. The primary end point was RBC transfusion independence (TI).
RESULTS: Two hundred sixteen patients received CC-486 (n = 107) or placebo (n = 109). The median age was 74 years, median platelet count was 25 × 109/L, and absolute neutrophil count was 1.3 × 109/L. In the CC-486 and placebo arms, 31% and 11% of patients, respectively, achieved RBC-TI (P = .0002), with median durations of 11.1 and 5.0 months. Reductions of ≥ 4 RBC units were attained by 42.1% and 30.6% of patients, respectively, with median durations of 10.0 and 2.3 months, and more CC-486 patients had ≥ 1.5 g/dL hemoglobin increases from baseline (23.4% v 4.6%). Platelet hematologic improvement rate was higher with CC-486 (24.3% v 6.5%). Underpowered interim overall survival analysis showed no difference between CC-486 and placebo (median, 17.3 v 16.2 months; P = .96). Low-grade GI events were the most common adverse events in both arms. In the CC-486 and placebo arms, 90% and 73% of patients experienced a grade 3-4 adverse event. Overall death rate was similar between arms, but there was an imbalance in deaths during the first 56 days (CC-486, n = 16; placebo, n = 6), most related to infections; the median pretreatment absolute neutrophil count for the 16 CC-486 patients was 0.57 × 109/L.
CONCLUSION: CC-486 significantly improved RBC-TI rate and induced durable bilineage improvements in patients with LR-MDS and high-risk disease features. More early deaths occurred in the CC-486 arm, most related to infections in patients with significant pretreatment neutropenia. Further evaluation of CC-486 in MDS is needed.

DOI: https://doi.org/10.1200/JCO.20.02619
Blood. 2021 Mar 22. pii: blood.2020010586. [Epub ahead of print]

HLA class I allele-lacking leukocytes predict rare clonal evolution to MDS/AML in patients with acquired aplastic anemia.

Kohei Hosokawa, Hiroki Mizumaki, Takeshi Yoroidaka, Hiroyuki Maruyama, Tatsuya Imi, Noriaki Tsuji, Ryota Urushihara, Mikoto Tanabe, Yoshitaka Zaimoku, Mai Anh Thi Nguyen, Dung Cao Tran, Ken Ishiyama, Hirohito Yamazaki, Takamasa Katagiri, Hiroyuki Takamatsu, Kazuyoshi Hosomichi, Atsushi Tajima, Fumihiro Azuma, Seishi Ogawa, Shinji Nakao.

DOI: https://doi.org/10.1182/blood.2020010586
Oncol Lett. 2021 May;21(5): 351

A drug targeting 5-lipoxygenase enhances the activity of a JAK2 inhibitor in CD34+ bone marrow cells from patients with JAK2V617F-positive polycythemia vera in vitro.

Yuan Chen, Hu Zhao, Jing Luo, Youping Liao, Kui Tan, Guoyu Hu.

  Janus kinase 2 (JAK2) inhibitors, the first targeted treatments for myeloproliferative neoplasms (MPNs), provide substantial benefits, including a marked reduction in splenomegaly and MPN-associated symptoms. However, these drugs rarely induce molecular remission in patients with MPNs. Zileuton, a 5-lipoxygenase (5-LO) inhibitor, has been demonstrated to selectively deplete hematopoietic stem cells (HSCs) expressing a JAK2 point mutation (JAK2V617F) in mouse models of JAK2V617F-induced polycythemia vera (PV). To determine the potential activity of 5-LO inhibitors in combination with JAK inhibitors against human PV HSCs, the present study first analyzed 5-LO expression in CD34+ bone marrow cells from patients with JAK2V617F-positive PV using western blotting and reverse transcription-quantitative PCR, and then examined the effect of zileuton combined with ruxolitinib on colony formation using a colony formation assay. Furthermore, cell cycle and apoptosis in CD34+ cells from patients with PV and healthy volunteers were determined by flow cytometry. In the present study, 5-LO expression was upregulated in CD34+ cells from patients with PV compared with in CD34+ cells from healthy volunteers. Higher levels of leukotriene B4, a product of the 5-LO signaling pathway, were detected in patients with PV compared with in healthy volunteers. Zileuton treatment suppressed the colony formation of CD34+ cells from patients with PV in a dose-dependent manner. Furthermore, zileuton and ruxolitinib exerted their anticancer effects by suppressing hematopoietic colony formation, inducing apoptosis and arresting the cell cycle of human CD34+ cells from patients with PV. The combination of these two drugs exerted a more beneficial effect than either agent alone. Based on these data, zileuton enhanced the antitumor activity of low-dose ruxolitinib in hematopoietic progenitor cells from patients with PV, providing conceptual validation for further clinical applications of combination treatment with ruxolitinib and zileuton for patients with PV.

Keywords:  5-lipoxygenase; apoptosis; cell cycle; polycythemia vera; ruxolitinib; zileuton

DOI:  https://doi.org/10.3892/ol.2021.12612
Front Oncol. 2021 ;11 608932

High Expression of CLEC11A Predicts Favorable Prognosis in Acute Myeloid Leukemia.

Chengliang Yin, Junyan Zhang, Wei Guan, Liping Dou, Yuchen Liu, Ming Shen, Xiaodong Jia, Lu Xu, Rilige Wu, Yan Li.

   Background: Acute myeloid leukemia (AML) is a heterogeneous disease of the hematopoietic system, for which identification of novel molecular markers is potentially important for clinical prognosis and is an urgent need for treatment optimization.
Methods: We selected C-type lectin domain family 11, member A (CLEC11A) for study via several public databases, comparing expression among a variety of tumors and normal samples as well as different organs and tissues. To investigated the relationship between CLEC11A expression and clinical characteristics, we derived an AML cohort from The Cancer Genome Atlas (TCGA); we also investigated the Bloodspot and HemaExplorer databases. The Kaplan-Meier method and log-rank test were used to evaluate the associations between CLEC11A mRNA expression, as well as DNA methylation, and overall survival (OS), event-free survival (EFS), and relapse-free survival (RFS). DNA methylation levels of CLEC11A from our own 28 de novo AML patients were assessed and related to chemotherapeutic outcomes. Bioinformatics analysis of CLEC11A was carried out using public databases.
Results: Multiple public databases revealed that CLEC11A expression was higher in leukemia. The TCGA data revealed that high CLEC11A expression was linked with favorable prognosis (OS p-value = 2e-04; EFS p-value = 6e-04), which was validated in GSE6891 (OS p-value = 0; EFS p-value = 0; RFS p-value = 2e-03). Methylation of CLEC11A was negatively associated with CLEC11A expression, and high CLEC11A methylation level group was linked to poorer prognosis (OS p-value = 1e-02; EFS p-value = 2e-02). Meanwhile, CLEC11A hypermethylation was associated with poor induction remission rate and dismal survival. Bioinformatic analysis also showed that CLEC11A was an up-regulated gene in leukemogenesis.
Conclusion: CLEC11A may be used as a prognostic biomarker, and could do benefit for AML patients by providing precise treatment indications, and its unique gene pattern should aid in further understanding the heterogeneous AML mechanisms.

Keywords:  CLEC11A; acute myeloid leukemia; biomarker; expression; methylation; prognosis

DOI:  https://doi.org/10.3389/fonc.2021.608932
Br J Haematol. 2021 Mar 25.

Distinct bone marrow immunophenotypic features define the splicing factor 3B subunit 1 (SF3B1)-mutant myelodysplastic syndromes subtype.

Carolien Duetz, Theresia M Westers, Florentien E M In 't Hout, Eline M P Cremers, Canan Alhan, Bianca Venniker-Punt, Heleen A Visser-Wisselaar, Dana A Chitu, Aniek O de Graaf, Linda Smit, Joop H Jansen, Arjan A van de Loosdrecht.

  Splicing factor 3B subunit 1 (SF3B1) mutations define a distinct myelodysplastic syndromes (MDS) patient group with a relatively favourable disease course and high response rates to luspatercept. Few data are available on bone marrow phenotype beyond ring sideroblasts in this subgroup of patients with MDS. In the present study, we identified immunophenotypic erythroid, myelomonocyte and progenitor features associated with SF3B1 mutations. In addition, we illustrate that SF3B1-mutation type is associated with distinct immunophenotypic features, and show the impact of co-occurrence of a SF3B1 mutation and a deletion of chromosome 5q on bone marrow immunophenotype. These genotype-phenotype associations and phenotypic subtypes within SF3B1-MDS provide leads that may further refine prognostication and therapeutic strategies for this particular MDS subgroup.

Keywords:   SF3B1 ; diagnostic haematology; flow cytometry; mutational analysis; myelodysplastic syndromes

DOI:  https://doi.org/10.1111/bjh.17414