bims-tremyl 2021-01-17 papers

bims-tremyl

Biomed News

on Therapy resistance biology in myeloid leukemia

Issue of 2021–01–17
thirty papers selected by
Paolo Gallipoli, Barts Cancer Institute, Queen Mary University of London

Serine biosynthesis is a metabolic vulnerability in FLT3-ITD-driven acute myeloid leukaemia.
Phosphotyrosine-based Phosphoproteomics for Target Identification and Drug Response Prediction in AML Cell Lines.
A review of FDA-approved acute myeloid leukemia therapies beyond "7 + 3".
FLT3 Mutations in Acute Myeloid Leukemia: Key Concepts and Emerging Controversies.
Eprenetapopt (APR-246) and Azacitidine in TP53-Mutant Myelodysplastic Syndromes.
Surface antigen-guided CRISPR screens identify regulators of myeloid leukemia differentiation.
Enriching for human acute myeloid leukemia stem cells using reactive oxygen species-based cell sorting.
BRD4-mediated repression of p53 is a target for combination therapy in AML.
High-throughput Identification of FLT3 Wild-type and Mutant Kinase Substrate Preferences and Application to Design of Sensitive In Vitro Kinase Assay Substrates.
Phase 2 study of lenalidomide maintenance for patients with high-risk acute myeloid leukemia in remission.
Key Event-Informed Risk Models for Benzene-induced Acute Myeloid Leukaemia.
Imaging dynamic mTORC1 pathway activity in vivo reveals marked shifts that support time-specific inhibitor therapy in AML.
A Phase II Trial of Imatinib Mesylate as Maintenance Therapy for Patients With Newly Diagnosed C-kit-positive Acute Myeloid Leukemia.
Current and emerging strategies for management of myelodysplastic syndromes.
Clinical and genomic characterization of patients diagnosed with the provisional entity Acute myeloid leukemia with BCR-ABL1, a Swedish population-based study.
Nucleoside and Non-Nucleoside DOT1L Inhibitors：Dawn of MLLrearranged Leukemia.
Targeting NAT10 Induces Apoptosis Associated With Enhancing Endoplasmic Reticulum Stress in Acute Myeloid Leukemia Cells.
Treatment patterns and outcomes in patients with myelodysplastic syndromes treated with hypomethylating agents: a SEER-Medicare analysis.
Relationships between AML1-ETO and MLL-AF9 fusion gene expressions and hematological parameters in acute myeloid leukemia.
Different methylation signatures at diagnosis in patients with high-risk myelodysplastic syndromes and secondary acute myeloid leukemia predict azacitidine response and longer survival.
The adverse events of haematopoietic stem cell transplantation are associated with gene polymorphism within human leukocyte antigen region.
Overexpression of Hmga2 activates Igf2bp2 and remodels transcriptional program of Tet2-deficient stem cells in myeloid transformation.
Altered Spatial Composition of the Immune Cell Repertoire in Association to CD34+ Blasts in Myelodysplastic Syndromes and Secondary Acute Myeloid Leukemia.
Clinical features and outcomes of hypocellular acute myeloid leukemia in adults: A Korean AML registry data.
Interplay between chromosomal alterations and gene mutations shapes the evolutionary trajectory of clonal hematopoiesis.
Developmental Stage-Specific Changes in Protein Synthesis Differentially Sensitize Hematopoietic Stem Cells and Erythroid Progenitors to Impaired Ribosome Biogenesis.
Venetoclax and donor lymphocyte infusion for early relapsed acute myeloid leukemia after allogeneic hematopoietic cell transplantation. A retrospective multicenter trial.
Lenalidomide-Epoetin Alfa Versus Lenalidomide Monotherapy in Myelodysplastic Syndromes Refractory to Recombinant Erythropoietin.
Concerted roles of PTEN and ATM in controlling hematopoietic stem cell fitness and dormancy.
Chaperone-mediated autophagy sustains haematopoietic stem-cell function.

Cancer Discov. 2021 Jan 12. pii: candisc.0738.2020. [Epub ahead of print]

Serine biosynthesis is a metabolic vulnerability in FLT3-ITD-driven acute myeloid leukaemia.

Stefan Bjelosevic, Emily Gruber, Andrea Newbold, Carolyn Shembrey, Jennifer R Devlin, Simon J Hogg, Lev Kats, Izabela Todorovski, Zheng Fan, Thomas C Abrehart, Giovanna Pomilio, Andrew Wei, Gareth P Gregory, Stephin J Vervoort, Kristin K Brown, Ricky W Johnstone.

Internal tandem duplication of the FMS-like tyrosine kinase 3 gene (FLT3-ITD) occurs in 30% of poor prognosis acute myeloid leukaemias (AMLs). Limited clinical efficacy of FLT3 inhibitors highlights the need for alternative therapeutic modalities in this subset of disease. Using human and murine models of FLT3-ITD-driven AML, we demonstrate that FLT3-ITD promotes serine synthesis and uptake via ATF4-dependent transcriptional regulation of genes in the de novo serine biosynthesis pathway and neutral amino acid transport. Genetic or pharmacological inhibition of PHGDH, the rate-limiting enzyme of de novo serine biosynthesis, selectively inhibited proliferation of FLT3-ITD AMLs in vitro and in vivo. Moreover, pharmacological inhibition of PHGDH sensitised FLT3-ITD AMLs to the standard of care chemotherapeutic cytarabine. Collectively, these data reveal novel insights into FLT3-ITD-induced metabolic reprogramming and reveal a targetable vulnerability in FLT3-ITD AML.

DOI: https://doi.org/10.1158/2159-8290.CD-20-0738
Mol Cell Proteomics. 2020 May;pii: S1535-9476(20)35010-6. [Epub ahead of print]19(5): 884-899

Phosphotyrosine-based Phosphoproteomics for Target Identification and Drug Response Prediction in AML Cell Lines.

Carolien van Alphen, Jacqueline Cloos, Robin Beekhof, David G J Cucchi, Sander R Piersma, Jaco C Knol, Alex A Henneman, Thang V Pham, Johan van Meerloo, Gert J Ossenkoppele, Henk M W Verheul, Jeroen J W M Janssen, Connie R Jimenez.

  Acute myeloid leukemia (AML) is a clonal disorder arising from hematopoietic myeloid progenitors. Aberrantly activated tyrosine kinases (TK) are involved in leukemogenesis and are associated with poor treatment outcome. Kinase inhibitor (KI) treatment has shown promise in improving patient outcome in AML. However, inhibitor selection for patients is suboptimal. In a preclinical effort to address KI selection, we analyzed a panel of 16 AML cell lines using phosphotyrosine (pY) enrichment-based, label-free phosphoproteomics. The Integrative Inferred Kinase Activity (INKA) algorithm was used to identify hyperphosphorylated, active kinases as candidates for KI treatment, and efficacy of selected KIs was tested. Heterogeneous signaling was observed with between 241 and 2764 phosphopeptides detected per cell line. Of 4853 identified phosphopeptides with 4229 phosphosites, 4459 phosphopeptides (4430 pY) were linked to 3605 class I sites (3525 pY). INKA analysis in single cell lines successfully pinpointed driver kinases (PDGFRA, JAK2, KIT and FLT3) corresponding with activating mutations present in these cell lines. Furthermore, potential receptor tyrosine kinase (RTK) drivers, undetected by standard molecular analyses, were identified in four cell lines (FGFR1 in KG-1 and KG-1a, PDGFRA in Kasumi-3, and FLT3 in MM6). These cell lines proved highly sensitive to specific KIs. Six AML cell lines without a clear RTK driver showed evidence of MAPK1/3 activation, indicative of the presence of activating upstream RAS mutations. Importantly, FLT3 phosphorylation was demonstrated in two clinical AML samples with a FLT3 internal tandem duplication (ITD) mutation. Our data show the potential of pY-phosphoproteomics and INKA analysis to provide insight in AML TK signaling and identify hyperactive kinases as potential targets for treatment in AML cell lines. These results warrant future investigation of clinical samples to further our understanding of TK phosphorylation in relation to clinical response in the individual patient.

Keywords:  Tyrosine kinases; acute myeloid leukemia; cell signaling; drug targets; kinase inhibitors; mass spectrometry; molecular biology; personalized medicine; phosphoproteome; phosphoproteomics; receptor tyrosine kinases

DOI:  https://doi.org/10.1074/mcp.RA119.001504
Expert Rev Hematol. 2021 Jan 11.

A review of FDA-approved acute myeloid leukemia therapies beyond "7 + 3".

Alexandre Bazinet, Sarit Assouline.

   INTRODUCTION: The standard anthracycline and cytarabine-based chemotherapy for acute myeloid leukemia (AML) has changed relatively little since the 1970s and produces unsatisfactory outcomes in many patients. In the past two decades, a better understanding of the pathophysiology and heterogeneity of this disease has led to promising new therapies, resulting in a flurry of new drug approvals.
AREAS COVERED: The MEDLINE database, ClinicalTrials.gov and conference proceedings were reviewed for the most salient literature concerning FDA-approved drugs for AML beyond standard chemotherapy: gemtuzumab ozogamicin, hypomethylating agents, Fms-like tyrosine kinase 3 (FLT3) inhibitors, isocitrate dehydrogenase (IDH) inhibitors, venetoclax, liposomal cytarabine and daunorubicin (CPX-351), and hedgehog pathway inhibitors. Key evidence for their efficacy is discussed. For each drug category, indications, typical usage and responses, major toxicities, and future directions for research are highlighted.
EXPERT OPINION: The treatment paradigm for AML is rapidly evolving. Promising new drugs targeting driver mutations have improved outcomes in specific AML subgroups. In parallel, advances in low-intensity therapies have allowed patients unfit for standard induction chemotherapy to achieve meaningful disease control. Further work is ongoing to identify synergistic drug combinations as well as optimal treatment selection guided by individual patient and disease features.

Keywords:  Acute myeloid leukemia; CPX-351; FLT3 inhibitors; IDH inhibitors; gemtuzumab ozogamicin; glasdegib; hypomethylating agents; low-intensity therapy; molecular targeted therapy; venetoclax

DOI:  https://doi.org/10.1080/17474086.2021.1875814
Front Oncol. 2020 ;10 612880

FLT3 Mutations in Acute Myeloid Leukemia: Key Concepts and Emerging Controversies.

Vanessa E Kennedy, Catherine C Smith.

  The FLT3 receptor is overexpressed on the majority of acute myeloid leukemia (AML) blasts. Mutations in FLT3 are the most common genetic alteration in AML, identified in approximately one third of newly diagnosed patients. FLT3 internal tandem duplication mutations (FLT3-ITD) are associated with increased relapse and inferior overall survival. Multiple small molecule inhibitors of FLT3 signaling have been identified, two of which (midostaurin and gilteritinib) are currently approved in the United States, and many more of which are in clinical trials. Despite significant advances, resistance to FLT3 inhibitors through secondary FLT3 mutations, upregulation of parallel pathways, and extracellular signaling remains an ongoing challenge. Novel therapeutic strategies to overcome resistance, including combining FLT3 inhibitors with other antileukemic agents, development of new FLT3 inhibitors, and FLT3-directed immunotherapy are in active clinical development. Multiple questions regarding FLT3-mutated AML remain. In this review, we highlight several of the current most intriguing controversies in the field including the role of FLT3 inhibitors in maintenance therapy, the role of hematopoietic cell transplantation in FLT3-mutated AML, use of FLT3 inhibitors in FLT3 wild-type disease, significance of non-canonical FLT3 mutations, and finally, emerging concerns regarding clonal evolution.

Keywords:  Acute Myeloid Leukemia; FLT3 inhibitor; FLT3 inhibitor maintenance; FLT3 resistance; non-canonical FLT3 mutation

DOI:  https://doi.org/10.3389/fonc.2020.612880
J Clin Oncol. 2021 Jan 15. JCO2002341

Eprenetapopt (APR-246) and Azacitidine in TP53-Mutant Myelodysplastic Syndromes.

David A Sallman, Amy E DeZern, Guillermo Garcia-Manero, David P Steensma, Gail J Roboz, Mikkael A Sekeres, Thomas Cluzeau, Kendra L Sweet, Amy McLemore, Kathy L McGraw, John Puskas, Ling Zhang, Jiqiang Yao, Qianxing Mo, Lisa Nardelli, Najla H Al Ali, Eric Padron, Greg Korbel, Eyal C Attar, Hagop M Kantarjian, Jeffrey E Lancet, Pierre Fenaux, Alan F List, Rami S Komrokji.

PURPOSE: Approximately 20% of patients with TP53-mutant myelodysplastic syndromes (MDS) achieve complete remission (CR) with hypomethylating agents. Eprenetapopt (APR-246) is a novel, first-in-class, small molecule that restores wild-type p53 functions in TP53-mutant cells.
METHODS: This was a phase Ib/II study to determine the safety, recommended phase II dose, and efficacy of eprenetapopt administered in combination with azacitidine in patients with TP53-mutant MDS or acute myeloid leukemia (AML) with 20%-30% marrow blasts (ClinicalTrials.gov identifier: NCT03072043).
RESULTS: Fifty-five patients (40 MDS, 11 AML, and four MDS/myeloproliferative neoplasms) with at least one TP53 mutation were treated. The overall response rate was 71% with 44% achieving CR. Of patients with MDS, 73% (n = 29) responded with 50% (n = 20) achieving CR and 58% (23/40) a cytogenetic response. The overall response rate and CR rate for patients with AML was 64% (n = 7) and 36% (n = 4), respectively. Patients with only TP53 mutations by next-generation sequencing had higher rates of CR (69% v 25%; P = .006). Responding patients had significant reductions in TP53 variant allele frequency and p53 expression by immunohistochemistry, with 21 (38%) achieving complete molecular remission (variant allele frequency < 5%). Median overall survival was 10.8 months with significant improvement in responding versus nonresponding patients by landmark analysis (14.6 v 7.5 months; P = .0005). Overall, 19/55 (35%) patients underwent allogeneic hematopoietic stem-cell transplant, with a median overall survival of 14.7 months. Adverse events were similar to those reported for azacitidine or eprenetapopt monotherapy, with the most common grade ≥ 3 adverse events being febrile neutropenia (33%), leukopenia (29%), and neutropenia (29%).
CONCLUSION: Combination treatment with eprenetapopt and azacitidine is well-tolerated yielding high rates of clinical response and molecular remissions in patients with TP53-mutant MDS and oligoblastic AML.

DOI: https://doi.org/10.1200/JCO.20.02341
Cell Stem Cell. 2021 Jan 08. pii: S1934-5909(20)30589-0. [Epub ahead of print]

Surface antigen-guided CRISPR screens identify regulators of myeloid leukemia differentiation.

Eric Wang, Hua Zhou, Bettina Nadorp, Geraldine Cayanan, Xufeng Chen, Anna H Yeaton, Sofia Nomikou, Matthew T Witkowski, Sonali Narang, Andreas Kloetgen, Palaniraja Thandapani, Niklas Ravn-Boess, Aristotelis Tsirigos, Iannis Aifantis.

Lack of cellular differentiation is a hallmark of many human cancers, including acute myeloid leukemia (AML). Strategies to overcome such a differentiation blockade are an approach for treating AML. To identify targets for differentiation-based therapies, we applied an integrated cell surface-based CRISPR platform to assess genes involved in maintaining the undifferentiated state of leukemia cells. Here we identify the RNA-binding protein ZFP36L2 as a critical regulator of AML maintenance and differentiation. Mechanistically, ZFP36L2 interacts with the 3' untranslated region of key myeloid maturation genes, including the ZFP36 paralogs, to promote their mRNA degradation and suppress terminal myeloid cell differentiation. Genetic inhibition of ZFP36L2 restores the mRNA stability of these targeted transcripts and ultimately triggers myeloid differentiation in leukemia cells. Epigenome profiling of several individuals with primary AML revealed enhancer modules near ZFP36L2 that associated with distinct AML cell states, establishing a coordinated epigenetic and post-transcriptional mechanism that shapes leukemic differentiation.

DOI: https://doi.org/10.1016/j.stem.2020.12.005
STAR Protoc. 2021 Mar 19. 2(1): 100248

Enriching for human acute myeloid leukemia stem cells using reactive oxygen species-based cell sorting.

Brett M Stevens, Cristiana O'Brien, Craig T Jordan, Courtney L Jones.

  Isolation of leukemia stem cells presents a challenge due to the heterogeneity of the immunophenotypic markers commonly used to identify blood stem cells. Several studies have reported that relative levels of reactive oxygen species (ROS) can be used to enrich for stem cell populations, suggesting a potential alternative to surface antigen-based methods. Here, we describe a protocol to enrich for stem cells from human acute myeloid leukemia specimens using relative levels of ROS. This protocol provides consistent enrichment of leukemia stem cells. For complete details on the use and execution of this protocol, please refer to Lagadinou et al. (2013) and Pei et al. (2018).

Keywords:  Cancer; Flow cytometry/mass cytometry; Metabolism; Stem cells

DOI:  https://doi.org/10.1016/j.xpro.2020.100248
Nat Commun. 2021 01 11. 12(1): 241

BRD4-mediated repression of p53 is a target for combination therapy in AML.

Anne-Louise Latif, Ashley Newcombe, Sha Li, Kathryn Gilroy, Neil A Robertson, Xue Lei, Helen J S Stewart, John Cole, Maria Terradas Terradas, Loveena Rishi, Lynn McGarry, Claire McKeeve, Claire Reid, William Clark, Joana Campos, Kristina Kirschner, Andrew Davis, Jonathan Lopez, Jun-Ichi Sakamaki, Jennifer P Morton, Kevin M Ryan, Stephen W G Tait, Sheela A Abraham, Tessa Holyoake, Brian Higgins, Xu Huang, Karen Blyth, Mhairi Copland, Timothy J T Chevassut, Karen Keeshan, Peter D Adams.

Acute myeloid leukemia (AML) is a typically lethal molecularly heterogeneous disease, with few broad-spectrum therapeutic targets. Unusually, most AML retain wild-type TP53, encoding the pro-apoptotic tumor suppressor p53. MDM2 inhibitors (MDM2i), which activate wild-type p53, and BET inhibitors (BETi), targeting the BET-family co-activator BRD4, both show encouraging pre-clinical activity, but limited clinical activity as single agents. Here, we report enhanced toxicity of combined MDM2i and BETi towards AML cell lines, primary human blasts and mouse models, resulting from BETi's ability to evict an unexpected repressive form of BRD4 from p53 target genes, and hence potentiate MDM2i-induced p53 activation. These results indicate that wild-type TP53 and a transcriptional repressor function of BRD4 together represent a potential broad-spectrum synthetic therapeutic vulnerability for AML.

DOI: https://doi.org/10.1038/s41467-020-20378-8
Mol Cell Proteomics. 2019 Mar;pii: S1535-9476(20)31852-1. [Epub ahead of print]18(3): 477-489

High-throughput Identification of FLT3 Wild-type and Mutant Kinase Substrate Preferences and Application to Design of Sensitive In Vitro Kinase Assay Substrates.

Minervo Perez, John Blankenhorn, Kevin J Murray, Laurie L Parker.

  Acute myeloid leukemia (AML) is an aggressive disease that is characterized by abnormal increase of immature myeloblasts in blood and bone marrow. The FLT3 receptor tyrosine kinase plays an integral role in hematopoiesis, and one third of AML diagnoses exhibit gain-of-function mutations in FLT3, with the juxtamembrane domain internal tandem duplication (ITD) and the kinase domain D835Y variants observed most frequently. Few FLT3 substrates or phosphorylation sites are known, which limits insight into FLT3's substrate preferences and makes assay design particularly challenging. We applied in vitro phosphorylation of a cell lysate digest (adaptation of the Kinase Assay Linked with Phosphoproteomics (KALIP) technique and similar methods) for high-throughput identification of substrates for three FLT3 variants (wild-type, ITD mutant, and D835Y mutant). Incorporation of identified substrate sequences as input into the KINATEST-ID substrate preference analysis and assay development pipeline facilitated the design of several peptide substrates that are phosphorylated efficiently by all three FLT3 kinase variants. These substrates could be used in assays to identify new FLT3 inhibitors that overcome resistant mutations to improve FLT3-positive AML treatment.

Keywords:  Acute Myeloid Leukemia; Assay development; FLT3; FLT3-ITD; KINATEST-ID; Kinase Assay-Linked with Phosphoproteomics; Mass Spectrometry; Phosphorylation; Substrate identification; Tyrosine Kinases*

DOI:  https://doi.org/10.1074/mcp.RA118.001111
Cancer. 2021 Jan 15.

Phase 2 study of lenalidomide maintenance for patients with high-risk acute myeloid leukemia in remission.

Iman Abou Dalle, Hagop M Kantarjian, Farhad Ravandi, Naval Daver, Xuemei Wang, Elias Jabbour, Zeev Estrov, Courtney D DiNardo, Naveen Pemmaraju, Alessandra Ferrajoli, Nitin Jain, Sa A Wang, Nadya Jammal, Gautam Borthakur, Kiran Naqvi, Sarah Pelletier, Sherry Pierce, Michael Andreeff, Guillermo Garcia-Manero, Jorge E Cortes, Tapan M Kadia.

   BACKGROUND: New drug combinations have led to significant improvements in remission rates for patients with acute myeloid leukemia (AML). However, many patients with high-risk AML who respond to their initial treatment and are not candidates for allogeneic stem cell transplantation (ASCT) will eventually relapse with poor outcomes.
METHODS: In this phase 2 trial, the efficacy of lenalidomide maintenance was evaluated in patients with high-risk AML who had achieved their first or second remission after induction chemotherapy and at least 1 consolidation cycle and who were not candidates for immediate ASCT. Lenalidomide was given orally at 10 to 20 mg daily on days 1 to 28 of a 28-day cycle for up to 24 cycles.
RESULTS: A total of 28 patients were enrolled in this study with a median age of 61 years (range, 24-87 years). The median number of cycles was 8 (range, 1-24 cycles). Ten patients (36%) completed 24 months of maintenance treatment. With a median follow-up of 22.5 months (range, 2.6-55 months), 12 patients (43%) relapsed after a median of 3 months (range, 0.7-23 months). The median duration of remission for all patients was 18.7 months (range, 0.7-55.1 months). The 2-year overall survival and relapse-free survival rates from the time of enrollment were 63% and 50%, respectively. Overall, lenalidomide was well tolerated; serious adverse events of grade 3 or 4, including rash (n = 5), thrombocytopenia (n = 4), neutropenia (n = 4), and fatigue (n = 2), were observed in 13 patients (46%).
CONCLUSIONS: Lenalidomide is a safe and feasible maintenance strategy in patients with high-risk AML who are not candidates for ASCT, and it has beneficial effects for patients with negative measurable residual disease.

Keywords:  acute myeloid leukemia (AML); immunomodulation; lenalidomide; maintenance

DOI:  https://doi.org/10.1002/cncr.33409
Toxicol Lett. 2021 Jan 08. pii: S0378-4274(21)00004-7. [Epub ahead of print]

Key Event-Informed Risk Models for Benzene-induced Acute Myeloid Leukaemia.

Colin M North, A Robert Schnatter, Martijn Rooseboom, Neslihan Aygun Kocabas, Abigail Dalzell, Stephen D Williams.

  Occupational exposure to benzene at levels of 10 ppm or more has been associated with increased risk of acute myeloid leukaemia (AML). The mode of action (MOA) for AML development leading to mortality is anticipated to include multiple earlier key events, which can be observed in hematotoxicity and genetic toxicity in peripheral blood of exposed workers. Prevention of these early events would lead to prevention of the apical, adverse outcomes, the morbidity and mortality caused by the myelodysplastic syndromes (MDS) and AML. Incorporation of key event information should modify the risk model, but few modification approaches have been suggested. To that end, two approaches to risk model modification are described that use sub-linear and segmented linear increases in risk below key events, while maintaining a linear increase in AML mortality risk beginning at 2 ppm, the lowest observed adverse effect concentration (LOAEC) identified for hemato- and geno- toxicity in high quality studies of human occupational exposure. Below 2 ppm two different modification approaches to quantitative risk models were applied: a continuously decreasing slope model and a segmented modification in slope. These two approaches provide greater flexibility to incorporate MOA information in risk model development and selection.

Keywords:  acute myeloid leukemia; benzene; dose response modelling; exposure response modelling; genotoxicity; hematotoxicity; key event; mortality; occupational; risk model

DOI:  https://doi.org/10.1016/j.toxlet.2021.01.003
Nat Commun. 2021 01 11. 12(1): 245

Imaging dynamic mTORC1 pathway activity in vivo reveals marked shifts that support time-specific inhibitor therapy in AML.

Toshihiko Oki, Francois Mercier, Hiroki Kato, Yookyung Jung, Thomas O McDonald, Joel A Spencer, Michael C Mazzola, Nick van Gastel, Charles P Lin, Franziska Michor, Toshio Kitamura, David T Scadden.

Acute myeloid leukemia (AML) is a high remission, high relapse fatal blood cancer. Although mTORC1 is a master regulator of cell proliferation and survival, its inhibitors have not performed well as AML treatments. To uncover the dynamics of mTORC1 activity in vivo, fluorescent probes are developed to track single cell proliferation, apoptosis and mTORC1 activity of AML cells in the bone marrow of live animals and to quantify these activities in the context of microanatomical localization and intra-tumoral heterogeneity. When chemotherapy drugs commonly used clinically are given to mice with AML, apoptosis is rapid, diffuse and not preferentially restricted to anatomic sites. Dynamic measurement of mTORC1 activity indicated a decline in mTORC1 activity with AML progression. However, at the time of maximal chemotherapy response, mTORC1 signaling is high and positively correlated with a leukemia stemness transcriptional profile. Cell barcoding reveals the induction of mTORC1 activity rather than selection of mTORC1 high cells and timed inhibition of mTORC1 improved the killing of AML cells. These data define the real-time dynamics of AML and the mTORC1 pathway in association with AML growth, response to and relapse after chemotherapy. They provide guidance for timed intervention with pathway-specific inhibitors.

DOI: https://doi.org/10.1038/s41467-020-20491-8
Clin Lymphoma Myeloma Leuk. 2020 Dec 03. pii: S2152-2650(20)30660-1. [Epub ahead of print]

A Phase II Trial of Imatinib Mesylate as Maintenance Therapy for Patients With Newly Diagnosed C-kit-positive Acute Myeloid Leukemia.

Anjali S Advani, William Tse, Hong Li, Xuefei Jia, Paul Elson, Brenda Cooper, Francis Ali-Osman, Jino Park, Arati V Rao, David A Rizzieri, Eunice S Wang, Claudiu V Cotta, Matt Kalaycio, Ronald M Sobecks, Basel Rouphail, Jaroslaw P Maciejewski, Jaime Fensterl, Jennifer S Carew, Bethany Foster, Mary Lynn Rush, Barbara Tripp, Donna Adams, Donna Corrigan, Elizabeth A Griffiths, Mikkael A Sekeres.

   INTRODUCTION: Adults with acute myeloid leukemia (AML) have a high rate of remission; however, more than 50% relapse. C-kit is expressed in approximately 60% of patients with de novo AML and represents a potential therapeutic target.
MATERIALS AND METHODS: Patients with newly diagnosed AML received 12 months of imatinib mesylate as maintenance therapy after the completion of post-remission therapy. The primary objective was to determine whether this approach improved progression-free survival (defined as no relapse and no death) compared with historical controls.
RESULTS: The median progression-free survival of patients < 60 years of age was 52.1 months (historical control, 13 months) and for patients ≥ 60 years of age was 10.7 months (historical control, 8 months). The median level of AF1q expression was high (9.59), and 84% of patients had moderate or high levels of drug-resistance factors.
CONCLUSIONS: Imatinib maintenance therapy may improve the outcome of newly diagnosed patients with AML who are < 60 years of age.

Keywords:  AF1q; CD117; Prognosis; Survival; Targeted

DOI:  https://doi.org/10.1016/j.clml.2020.11.018
Blood Rev. 2020 Dec 27. pii: S0268-960X(20)30141-7. [Epub ahead of print] 100791

Current and emerging strategies for management of myelodysplastic syndromes.

Caner Saygin, Hetty E Carraway.

  Myelodysplastic syndromes (MDS) are characterized by ineffective hematopoiesis with varying degrees of dysplasia and peripheral cytopenias. MDS are driven by structural chromosomal alterations and somatic mutations in neoplastic myeloid cells, which are supported by a tumorigenic and a proinflammatory marrow microenvironment. Current treatment strategies for lower-risk MDS focus on improving quality of life and cytopenias, while prolonging survival and delaying disease progression is the focus for higher-risk MDS. Several promising drugs are in the horizon, including the hypoxia-inducible factor stabilizer roxadustat, telomerase inhibitor imetelstat, oral hypomethylating agents (CC-486), TP53 modulators (APR-246 and ALRN-6924), and the anti-CD47 antibody magrolimab. Targeted therapies approved for acute myeloid leukemia treatment, such as isocitrate dehdyrogenase inhibitors and venetoclax, are also being studied for use in MDS. In this review, we provide a brief overview of pathogenesis and current treatment strategies in MDS followed by a discussion of newer agents that are under clinical investigation.

Keywords:  APR-246; Checkpoint inhibitor; Guadecitabine; H3B-8800; HMA; Imetelstat; Luspatercept; MDS; Magrolimab; Rigosertib; Roxadustat; Venetoclax

DOI:  https://doi.org/10.1016/j.blre.2020.100791
Genes Chromosomes Cancer. 2021 Jan 12.

Clinical and genomic characterization of patients diagnosed with the provisional entity Acute myeloid leukemia with BCR-ABL1, a Swedish population-based study.

Christina Orsmark-Pietras, Niklas Landberg, Fryderyk Lorenz, Bertil Uggla, Martin Höglund, Sören Lehmann, Åsa Derolf, Stefan Deneberg, Petar Antunovic, Jörg Cammenga, Lars Möllgård, Lovisa Wennström, Henrik Lilljebjörn, Marianne Rissler, Thoas Fioretos, Vladimir Lj Lazarevic.

  Acute myeloid leukemia (AML) with t(9;22)(q34;q11), also known as AML with BCR-ABL1, is a rare, provisional entity in the WHO 2016 classification and is considered a high-risk disease according to the European LeukemiaNet 2017 risk stratification. We here present a retrospective, population-based study of this disease entity from the Swedish Acute Leukemia Registry. By strict clinical inclusion criteria we aimed to identify genetic markers further distinguishing AML with t(9;22) as a separate entity. Twenty-five patients were identified and next-generation sequencing using a 54-gene panel was performed in 21 cases. Interestingly, no mutations were found in NPM1, FLT3 or DNMT3A, three frequently mutated genes in AML. Instead, RUNX1 was the most commonly mutated gene, with aberrations present in 38% of the cases compared to around 10% in de novo AML. Additional mutations were identified in genes involved in RNA splicing (SRSF2, SF3B1) and chromatin regulation (ASXL1, STAG2, BCOR, BCORL1). Less frequently, mutations were found in IDH2, NRAS, TET2 and TP53. The mutational landscape exhibited a similar pattern as recently described in patients with chronic myeloid leukemia (CML) in myeloid blast crisis (BC). Despite the concomitant presence of BCR-ABL1 and RUNX mutations in our cohort, both features of high-risk AML, the RUNX-mutated cases showed a superior overall survival compared to RUNX1 wildtype cases. Our results suggest that the molecular characteristics of AML with t(9;22)/BCR-ABL1 and CML in myeloid BC are similar and do not support a distinction of the two disease entities based on their underlying molecular alterations. This article is protected by copyright. All rights reserved.

Keywords:  AML; BCR-ABL1; CML BC; RUNX1; t(9;22)

DOI:  https://doi.org/10.1002/gcc.22936
Mini Rev Med Chem. 2021 Jan 11.

Nucleoside and Non-Nucleoside DOT1L Inhibitors：Dawn of MLLrearranged Leukemia.

Meng Cao, Tong Li, Yuxiang Chen, Xin Zhai.

  Herein, the underlying role of disruptor of telomeric silencing 1-like (DOT1L) as a therapeutic target for mixed lineage leukemia (MLL)-rearranged were comprehensively clarified. DOT1L can be aberrantly recruited by MLL fusion partner, thereby occasion several leukemia relevant genes over-expression, and eventually lead to leukemia. As the unique histone methyltransferase (HMT), DOT1L possessed the function to specifically methylate H3K79, which was identified as hallmark of active transcription. Accordingly, blockading of DOT1L has been recognized as an effective approach for cancer treatment. Currently, nucleoside DOT1L inhibitors have been developed successfully with the only EPZ5676 entering phase Ⅰ clinical trial in 2013, which was validated as 'orphan drug' toward MLL-rearranged leukemia by FDA. In order to find compounds with better pharmacokinetic properties as DOT1L inhibitors, other types of non-nucleoside skeletons have also been reported successively.

Keywords:  DOT1L; Epigenetics; MLL-rearranged leukemia; Non-nucleoside inhibitors; Nucleoside inhibitors; Post-translational modification of histone

DOI:  https://doi.org/10.2174/1389557521666210111144357
Front Oncol. 2020 ;10 598107

Targeting NAT10 Induces Apoptosis Associated With Enhancing Endoplasmic Reticulum Stress in Acute Myeloid Leukemia Cells.

Jie Zi, Qi Han, Siyu Gu, Mary McGrath, Shriya Kane, Chunhua Song, Zheng Ge.

  N-acetyltransferase 10 (NAT10) has oncogenic properties in many tumors through its role in different cellular biological processes. NAT10 is also a potential biomarker in acute myeloid leukemia (AML); however, the mechanisms underlying NAT10's contribution to disease states and the effect of targeting NAT10 as a therapeutic target remain unclear. NAT10 was found to be highly expressed in patients with AML, and increased NAT10 expression was associated with poor outcomes. Additionally, targeting NAT10 via the shRNA knockdown and its pharmacotherapeutic inhibitor resulted in inhibition of cell proliferation, induction of cell cycle arrest in the G1 phase, and apoptosis in AML cells. Moreover, NAT10 induces cell cycle arrest by decreasing expression of CDK2, CDK4, CyclinD1, Cyclin E while simultaneously increasing the expression of p16 and p21. Targeting NAT10 induces ER stress through the increased expression of GRP78 and the cleavage of caspase 12, which are classical markers of ER stress. This triggered the Unfolded Protein Response (UPR) pathway by consequently increasing IRE1, CHOP, and PERK expression, all of which play crucial roles in the UPR pathway. Targeting NAT10 also activated the classical apoptotic pathway through the upregulation of the Bax/bak and the concurrent downregulation of Bcl-2. In summary, our data indicate that targeting NAT10 promotes ER stress, triggers the UPR pathway, and activates the Bax/Bcl-2 axis in AML cells. Our results thus indicate a novel mechanism underlying the induction of NAT10 inhibition-mediated apoptosis and reveal the potential for the therapeutic effect of a NAT10 specific inhibitor in AML.

Keywords:  N-acetyltransferase; NAT10; acute myeloid leukemia; apoptosis; remodelin hydrobromide

DOI:  https://doi.org/10.3389/fonc.2020.598107
Leuk Lymphoma. 2021 Jan 11. 1-16

Treatment patterns and outcomes in patients with myelodysplastic syndromes treated with hypomethylating agents: a SEER-Medicare analysis.

Eytan M Stein, Gaetano Bonifacio, Dominick Latremouille-Viau, Sherry Shi, Annie Guerin, Eric Q Wu, Islam Sadek, Xiting Cao.

  To describe real-world treatment patterns and outcomes among adult patients with myelodysplastic syndromes (MDS) treated with hypomethylating agents (HMA), patients were identified in the SEER-Medicare database (01/2006-12/2016); 3,046 patients with MDS treated with HMA were included. An algorithm was developed to categorize patients into MDS risk groups: the majority of patients were classified as Higher-risk (70.9%), 8.0% as Intermediate-risk, and 21.1% as Unknown-risk. Overall, 77.4% of patients initiated azacitidine and 22.6% decitabine; they received an average of 5.1 index-HMA cycles, of which 90.9% were complete with a median cycle duration of 28 days. Median survival was 11.6, 18.4, and 19.1 months for the Higher-risk, Intermediate-risk, and Unknown-risk groups, respectively. Median time-to-AML transformation was 19.3 months for the Higher-risk group and 50.4 months for the Intermediate-risk group (not reached for Unknown-risk). Data highlight the unmet medical needs of patients with MDS treated with HMA, particularly for the Higher-risk MDS group.

Keywords:  Myelodysplastic syndromes; acute myeloid leukemia transformation; claims database; hypomethylating agents; overall survival; treatment patterns

DOI:  https://doi.org/10.1080/10428194.2020.1869959
Gulf J Oncolog. 2020 Sep;1(34): 65-69

Relationships between AML1-ETO and MLL-AF9 fusion gene expressions and hematological parameters in acute myeloid leukemia.

Abdel Rahim Mahmoud Muddathir, Tarig A M Hamid, Elwaleed Mohamed Elamin, Omar F Khabour.

BACKGROUND: Acute myeloid leukemia (AML) is a malignant disease of the myeloid line that caused by several chromosomal aberrations that include AML1 -ETO and MLL-AF9. In the current study, the correlations of fusion gene quantitative RT-PCR and hematological parameters in patients with AML were examined to determine their prognostic value in clinical practice.
METHODOLOGY: This study was conducted at Alzaeim Alazhari University, Khartoum, Sudan. A total of 82 patients with AML (51 AML1-ETO and 31 MLL-AF9) were participated in the study. Quantitative RT-PCR was used to determine types of fusion genes Results: The expression of MLL-AF9 was significantly higher than that for AML1-ETO (P < 0.01). In addition, with respect to FAB classification M2/M3 types were dominated in patients with AML1-ETO gene fusion, whereas M4/M5 types were dominated in MLL-AF9 subjects (P < 0.01). Finally, neither AML1-ETO nor MLL-AF9 quantitative RT-PCR gene expressions were correlated with the examined hematological parameters including: hemoglobin, total white blood count, platelets and blast cells (P > 0.05).
CONCLUSIONS: Significant variations in AML1-ETO and MLL-AF9 expression were observed in AML. No correlations between the expression of fusion genes and hematological parameters were detected.
Clin Epigenetics. 2021 Jan 14. 13(1): 9

Different methylation signatures at diagnosis in patients with high-risk myelodysplastic syndromes and secondary acute myeloid leukemia predict azacitidine response and longer survival.

CETLAM group

   BACKGROUND: Epigenetic therapy, using hypomethylating agents (HMA), is known to be effective in the treatment of high-risk myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) patients who are not suitable for intensive chemotherapy and/or allogeneic stem cell transplantation. However, response rates to HMA are low and there is an unmet need in finding prognostic and predictive biomarkers of treatment response and overall survival. We performed global methylation analysis of 75 patients with high-risk MDS and secondary AML who were included in CETLAM SMD-09 protocol, in which patients received HMA or intensive treatment according to age, comorbidities and cytogenetic.
RESULTS: Unsupervised analysis of global methylation pattern at diagnosis did not allow patients to be differentiated according to the cytological subtype, cytogenetic groups, treatment response or patient outcome. However, after a supervised analysis we found a methylation signature defined by 200 probes, which allowed differentiating between patients responding and non-responding to azacitidine (AZA) treatment and a different methylation pattern also defined by 200 probes that allowed to differentiate patients according to their survival. On studying follow-up samples, we confirmed that AZA decreases global DNA methylation, but in our cohort the degree of methylation decrease did not correlate with the type of response. The methylation signature detected at diagnosis was not useful in treated samples to distinguish patients who were going to relapse or progress.
CONCLUSIONS: Our findings suggest that in a subset of specific CpGs, altered DNA methylation patterns at diagnosis may be useful as a biomarker for predicting AZA response and survival.

Keywords:  Azacitidine; DNA methylation; Epigenetic drugs; Hypomethylating agents; Myelodysplastic syndromes; Prognostic factors; Secondary acute myeloid leukemia

DOI:  https://doi.org/10.1186/s13148-021-01002-y
Sci Rep. 2021 Jan 14. 11(1): 1475

The adverse events of haematopoietic stem cell transplantation are associated with gene polymorphism within human leukocyte antigen region.

Ding-Ping Chen, Ying-Hao Wen, Po-Nan Wang, Ai-Ling Hour, Wei-Tzu Lin, Fang-Ping Hsu, Wei-Ting Wang.

Adverse reactions may still occur in some patients after receiving haematopoietic stem cell transplantation (HSCT), even when choosing a human leukocyte antigen (HLA)-matched donor. The adverse reactions of transplantation include disease relapse, graft-versus-host disease (GVHD), mortality and CMV infection. However, only the relapse was discussed in our previous study. Therefore, in this study, we investigated the correlation between the gene polymorphisms within the HLA region and the adverse reactions of post-HSCT in patients with acute leukaemia (n = 176), where 72 patients were diagnosed with acute lymphocytic leukaemia (ALL) and 104 were acute myeloid leukaemia (AML). The candidate single nucleotide polymorphisms were divided into three models: donor, recipient, and donor-recipient pairs and the data of ALL and AML were analysed individually. Based on the results, we found 16 SNPs associated with the survival rates, the risk of CMV infection, or the grade of GVHD in either donor, recipient, or donor-recipient matching models. In the ALL group, the rs209132 of TRIM27 in the donor group was related to CMV infection (p = 0.021), the rs213210 of RING1 in the recipient group was associated with serious GVHD (p = 0.003), and the rs2227956 of HSPA1L in the recipient group correlated with CMV infection (p = 0.001). In the AML group, the rs3130048 of BAG6 in the donor-recipient pairs group was associated with serious GVHD (p = 0.048). Moreover, these SNPs were further associated with the duration time of survival after transplantation. These results could be applied to select the best donor in HSCT.

DOI: https://doi.org/10.1038/s41598-020-79369-w
Oncogene. 2021 Jan 15.

Overexpression of Hmga2 activates Igf2bp2 and remodels transcriptional program of Tet2-deficient stem cells in myeloid transformation.

Jie Bai, Takako Yokomizo-Nakano, Sho Kubota, Yuqi Sun, Akinori Kanai, Mihoko Iimori, Hironori Harada, Atsushi Iwama, Goro Sashida.

High Mobility Group AT-hook 2 (HMGA2) is a chromatin modifier and its overexpression has been found in patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Level of Hmga2 expression is fine-tuned by Lin28b-Let-7 axis and Polycomb Repressive Complex 2, in which deletion of Ezh2 leads to activation of Hmga2 expression in hematopoietic stem cells. To elucidate the mechanisms by which the overexpression of HMGA2 helps transformation of stem cells harboring a driver mutation of TET2, we generated an Hmga2-expressing Tet2-deficient mouse model showing the progressive phenotypes of MDS and AML. The overexpression of Hmga2 remodeled the transcriptional program of Tet2-deficient stem and progenitor cells, leading to the impaired differentiation of myeloid cells. Furthermore, Hmga2 was bound to a proximal region of Igf2bp2 oncogene, and activated its transcription, leading to enhancing self-renewal of Tet2-deficient stem cells that was suppressed by inhibition of the DNA binding of Hmga2. These combinatory effects on the transcriptional program and cellular function were not redundant to those in Tet2-deficient cells. The present results elucidate that Hmga2 targets key oncogenic pathways during the transformation and highlight the Hmga2-Igf2bp2 axis as a potential target for therapeutic intervention.

DOI: https://doi.org/10.1038/s41388-020-01629-w
Cancers (Basel). 2021 Jan 07. pii: E186. [Epub ahead of print]13(2):

Altered Spatial Composition of the Immune Cell Repertoire in Association to CD34+ Blasts in Myelodysplastic Syndromes and Secondary Acute Myeloid Leukemia.

Marcus Bauer, Christoforos Vaxevanis, Haifa Kathrin Al-Ali, Nadja Jaekel, Christin Le Hoa Naumann, Judith Schaffrath, Achim Rau, Barbara Seliger, Claudia Wickenhauser.

  Background: Myelodysplastic syndromes (MDS) are caused by a stem cell failure and often include a dysfunction of the immune system. However, the relationship between spatial immune cell distribution within the bone marrow (BM), in relation to genetic features and the course of disease has not been analyzed in detail. Methods: Histotopography of immune cell subpopulations and their spatial distribution to CD34+ hematopoietic cells was determined by multispectral imaging (MSI) in 147 BM biopsies (BMB) from patients with MDS, secondary acute myeloid leukemia (sAML), and controls. Results: In MDS and sAML samples, a high inter-tumoral immune cell heterogeneity in spatial proximity to CD34+ blasts was found that was independent of genetic alterations, but correlated to blast counts. In controls, no CD8+ and FOXP3+ T cells and only single MUM1p+ B/plasma cells were detected in an area of ≤10 μm to CD34+ HSPC. Conclusions: CD8+ and FOXP3+ T cells are regularly seen in the 10 μm area around CD34+ blasts in MDS/sAML regardless of the course of the disease but lack in the surrounding of CD34+ HSPC in control samples. In addition, the frequencies of immune cell subsets in MDS and sAML BMB differ when compared to control BMB providing novel insights in immune deregulation.

Keywords:  CD34+ blasts; MDS; immune cell repertoire; multiplex immunohistochemistry; prognosis

DOI:  https://doi.org/10.3390/cancers13020186
Medicine (Baltimore). 2021 Jan 08. 100(1): e24185

Clinical features and outcomes of hypocellular acute myeloid leukemia in adults: A Korean AML registry data.

Ik-Chan Song, Deog-Yeon Jo, Hyeoung-Joon Kim, Yoo-Hong Min, Dae Sik Hong, Won-Sik Lee, Ho-Jin Shin, Je-Hwan Lee, Jinny Park, Hee-Je Kim.

ABSTRACT: The hypocellular variant of acute myeloid leukemia (AML) is defined as bone marrow cellularity of <20% in a biopsy specimen at presentation. We performed a retrospective analysis of the clinical features and survival outcomes of hypocellular AML in a Korean population. We reviewed the medical records of all patients diagnosed with AML at nine hospitals participating in the Korean AML registry from 2006 to 2012. Overall survival (OS) and event-free survival (EFS) rates were calculated from the time of diagnosis until death or an event, respectively. In total, 2110 patients were enrolled and 102 (4.8%) were identified as having hypocellular AML. Patients with hypocellular AML were older than those with non-hypocellular AML (median age: 59 vs 49 years; P < .001) and presented with leukopenia more frequently (mean white blood cell count: 5810/μL vs 40549/μL; P < .001). There was no difference between patients with and without hypocellular AML in terms of the presence of antecedent hematologic disorders (5.9% vs 5.3%; P = .809). FLT3-ITD and NPM1 mutations were less common in hypocellular than non-hypocellular AML (FLT3-ITD mutations: 1.2% vs 14.3%, P < .001; NPM1 mutations: 0% vs 9.5%, P = .019). No differences were seen between the hypocellular and non-hypocellular AML groups in the complete remission rate (53.9% vs 61.3%, P = .139) or early death rate (defined as any death before 8 weeks; 14.7% vs 13.0%, P = .629). The OS and EFS did not differ between the hypocellular and non-hypocellular AML groups (median OS: 16 vs 23 months, P = .169; median EFS: 6 vs 9 months, P = .215). Hypocellular AML is more frequently observed in older-aged patients and have fewer FLT3-ITD and NPM1 mutation, but the clinical outcomes of hypocellular AML do not differ from those of non-hypocellular AML.

DOI: https://doi.org/10.1097/MD.0000000000024185
Nat Commun. 2021 01 12. 12(1): 338

Interplay between chromosomal alterations and gene mutations shapes the evolutionary trajectory of clonal hematopoiesis.

Teng Gao, Ryan Ptashkin, Kelly L Bolton, Maria Sirenko, Christopher Fong, Barbara Spitzer, Kamal Menghrajani, Juan E Arango Ossa, Yangyu Zhou, Elsa Bernard, Max Levine, Juan S Medina Martinez, Yanming Zhang, Sebastià Franch-Expósito, Minal Patel, Lior Z Braunstein, Daniel Kelly, Mariko Yabe, Ryma Benayed, Nicole M Caltabellotta, John Philip, Ederlinda Paraiso, Simon Mantha, David B Solit, Luis A Diaz, Michael F Berger, Virginia Klimek, Ross L Levine, Ahmet Zehir, Sean M Devlin, Elli Papaemmanuil.

Stably acquired mutations in hematopoietic cells represent substrates of selection that may lead to clonal hematopoiesis (CH), a common state in cancer patients that is associated with a heightened risk of leukemia development. Owing to technical and sample size limitations, most CH studies have characterized gene mutations or mosaic chromosomal alterations (mCAs) individually. Here we leverage peripheral blood sequencing data from 32,442 cancer patients to jointly characterize gene mutations (n = 14,789) and mCAs (n = 383) in CH. Recurrent composite genotypes resembling known genetic interactions in leukemia genomes underlie 23% of all detected autosomal alterations, indicating that these selection mechanisms are operative early in clonal evolution. CH with composite genotypes defines a patient group at high risk of leukemia progression (3-year cumulative incidence 14.6%, CI: 7-22%). Multivariable analysis identifies mCA as an independent risk factor for leukemia development (HR = 14, 95% CI: 6-33, P < 0.001). Our results suggest that mCA should be considered in conjunction with gene mutations in the surveillance of patients at risk of hematologic neoplasms.

DOI: https://doi.org/10.1038/s41467-020-20565-7
Stem Cell Reports. 2021 Jan 12. pii: S2213-6711(20)30465-3. [Epub ahead of print]16(1): 20-28

Developmental Stage-Specific Changes in Protein Synthesis Differentially Sensitize Hematopoietic Stem Cells and Erythroid Progenitors to Impaired Ribosome Biogenesis.

Jeffrey A Magee, Robert A J Signer.

  Adult hematopoietic stem cell (HSC) self-renewal requires precise control of protein synthesis, but fetal and adult HSCs have distinct self-renewal mechanisms and lineage outputs. This raises the question of whether protein synthesis rates change with age. Here, we show that protein synthesis rates decline during HSC ontogeny, yet erythroid protein synthesis rates increase. A ribosomal mutation that impairs ribosome biogenesis (Rpl24Bst/+) disrupts both fetal and adult HSC self-renewal. However, the Rpl24Bst/+ mutation selectively impairs fetal erythropoiesis at differentiation stages that exhibit fetal-specific attenuation of protein synthesis. Developmental changes in protein synthesis thus differentially sensitize hematopoietic stem and progenitor cells to impaired ribosome biogenesis.

Keywords:  erythroid; erythropoiesis; hematopoiesis; hematopoietic stem cell; progenitor; protein synthesis; proteostasis; ribosome; ribosomopathy; translation

DOI:  https://doi.org/10.1016/j.stemcr.2020.11.017
Ann Hematol. 2021 Jan 13.

Venetoclax and donor lymphocyte infusion for early relapsed acute myeloid leukemia after allogeneic hematopoietic cell transplantation. A retrospective multicenter trial.

Odelia Amit, Yael Bar On, Galit Perez, Liat Shargian-Alon, Moshe Yeshurun, Ron Ram.

  Prognosis in patients with post allogeneic HCT-early relapse of acute myeloid leukemia (<6 months post HCT) is dismal and response to salvage treatment is < 20%. In addition, majority of patients at this early point are unable to withstand intensive salvage chemotherapy. We hypothesized that the combination of donor lymphocyte infusion (DLI) and venetoclax may result in increased response in this difficult to treat patient group. We retrospectively analyzed 22 patients from February 2017-December 2019, who were given the Venetoclax/DLI combination. Median age was 65 (43-75) years. There were no cases of tumor lysis syndrome. Microbiology documented infections occurred in 8 patients (36%). Majority were able to tolerate the protocol without admissions. Acute GVHD was observed in 4 (18%) patients and cGVHD was observed in 6 (27%) patients. Overall response was observed in 11 (50%) patients (CR, n = 4; CRi, n = 1; CRp, n = 4; MLFS n = 2). Median time to response was 28 (18-67) days and median cycles of venetoclax 2 [1-8] and duration of response were 135 (31-564) days. Median survival was 6.1 months (95% CI .73-11.4). Cox regression model for survival showed decreased WBC at relapse, GVHD and better performance status were associated with better survival. These results may endorse the hypothesis that enhancing alloreactivity combined with venetoclax is safe and efficacious and should be further investigated in prospective trials.

Keywords:  AML; Allogeneic HCT; DLI; Relapse; Venetoclax

DOI:  https://doi.org/10.1007/s00277-021-04398-y
J Clin Oncol. 2021 Jan 13. JCO2001691

Lenalidomide-Epoetin Alfa Versus Lenalidomide Monotherapy in Myelodysplastic Syndromes Refractory to Recombinant Erythropoietin.

Alan F List, Zhuoxin Sun, Amit Verma, John M Bennett, Rami S Komrokji, Kathy McGraw, Jaroslaw Maciejewski, Jessica K Altman, Puneet S Cheema, David F Claxton, Selina M Luger, Ryan J Mattison, Timothy R Wassenaar, Andrew S Artz, Charles A Schiffer, Mark R Litzow, Martin S Tallman.

PURPOSE: Impaired response to erythropoietin underlies ineffective erythropoiesis and anemia in myelodysplastic syndromes (MDS). We investigated whether treatment with lenalidomide (LEN), which augments erythropoietin receptor signaling in vitro, can restore and improve hemoglobin response to epoetin (EPO) alfa in patients with lower-risk, non-del(5q) MDS who have anemia that is refractory to or have low probability of benefit from treatment with recombinant erythropoietin.
METHODS: In a phase III, US intergroup trial, we randomly assigned patients to receive either LEN and EPO alfa or LEN alone following stratification by serum erythropoietin concentration and prior erythropoietin treatment.
RESULTS: A total of 195 evaluable patients were randomly assigned: 99 patients to the LEN-EPO alfa cohort and 96 to LEN alone. After four cycles of treatment, the primary end point of major erythroid response (MER) was significantly higher (28.3%) with the combination compared with LEN alone (11.5%) (P = .004). Among 136 patients who completed 16 weeks of study treatment, 38.9% and 15.6% achieved MER, respectively (P = .004). Additionally, minor erythroid response was achieved in 18.2% and 20.8% of patients, for an overall erythroid response rate of 46.5% versus 32.3%. Among LEN nonresponders, 38 crossed over to the addition of EPO alfa with 10 patients (26.3%) achieving a MER. Responses to the combined treatment were highly durable with a median MER duration of 23.8 months compared with 13 months with LEN alone.
CONCLUSION: LEN restores sensitivity to recombinant erythropoietin in growth factor-insensitive, lower-risk, non-del(5q) MDS, to yield a significantly higher rate and duration of MER compared with LEN alone (funded by the National Cancer Institute; E2905 ClinicalTrials.gov identifier: NCT02048813).

DOI: https://doi.org/10.1200/JCO.20.01691
J Clin Invest. 2021 Jan 14. pii: 131698. [Epub ahead of print]

Concerted roles of PTEN and ATM in controlling hematopoietic stem cell fitness and dormancy.

Jerome Fortin, Christian Bassi, Parameswaran Ramachandran, Wanda Y Li, Ruxiao Tian, Ida Zarrabi, Graham Hill, Bryan E Snow, Jillian Haight, Chantal Tobin, Kelsey Hodgson, Andrew Wakeham, Vuk Stambolic, Tak W Mak.

  In order to sustain proficient life-long hematopoiesis, hematopoietic stem cells (HSCs) must possess robust mechanisms to preserve their quiescence and genome integrity. DNA-damaging stress can perturb HSC homeostasis by affecting their survival, self-renewal and differentiation. Ablation of the kinase ATM, a master regulator of the DNA damage response, impairs HSC fitness. Paradoxically, we show here that loss of a single allele of Atm enhances HSC functionality in mice. To explain this observation, we explored a possible link between ATM and the tumor suppressor PTEN, which also regulates HSC function. We generated and analyzed a knock-in mouse line (PtenS398A/S398A), in which PTEN cannot be phosphorylated by ATM. Similar to Atm+/-, PtenS398A/S398A HSCs have enhanced hematopoietic reconstitution ability, accompanied by resistance to apoptosis induced by genotoxic stress. Single-cell transcriptomic analyses and functional assays revealed that dormant PtenS398A/S398A HSCs aberrantly tolerate elevated mitochondrial activity and the accumulation of reactive oxygen species, which are normally associated with HSC priming for self-renewal or differentiation. Our results unveil a molecular connection between ATM and PTEN, which couples the response to genotoxic stress and dormancy in HSC.

Keywords:  DNA repair; Hematology; Hematopoietic stem cells; Stem cells

DOI:  https://doi.org/10.1172/JCI131698
Nature. 2021 Jan 13.

Chaperone-mediated autophagy sustains haematopoietic stem-cell function.

Shuxian Dong, Qian Wang, Yun-Ruei Kao, Antonio Diaz, Inmaculada Tasset, Susmita Kaushik, Victor Thiruthuvanathan, Aliona Zintiridou, Edward Nieves, Monika Dzieciatkowska, Julie A Reisz, Evripidis Gavathiotis, Angelo D'Alessandro, Britta Will, Ana Maria Cuervo.

The activation of mostly quiescent haematopoietic stem cells (HSCs) is a prerequisite for life-long production of blood cells1. This process requires major molecular adaptations to allow HSCs to meet the regulatory and metabolic requirements for cell division2-4. The mechanisms that govern cellular reprograming upon stem-cell activation, and the subsequent return of stem cells to quiescence, have not been fully characterized. Here we show that chaperone-mediated autophagy (CMA)5, a selective form of lysosomal protein degradation, is involved in sustaining HSC function in adult mice. CMA is required for protein quality control in stem cells and for the upregulation of fatty acid metabolism upon HSC activation. We find that CMA activity in HSCs decreases with age and show that genetic or pharmacological activation of CMA can restore the functionality of old mouse and human HSCs. Together, our findings provide mechanistic insights into a role for CMA in sustaining quality control, appropriate energetics and overall long-term HSC function. Our work suggests that CMA may be a promising therapeutic target for enhancing HSC function in conditions such as ageing or stem-cell transplantation.

DOI: https://doi.org/10.1038/s41586-020-03129-z