bims-tremyl 2022-04-10 papers

bims-tremyl

Biomed News

on Therapy resistance biology in myeloid leukemia

Issue of 2022‒04‒10
27 papers selected by
Paolo Gallipoli
Barts Cancer Institute, Queen Mary University of London

Impact of IDH1 and IDH2 mutation detection at diagnosis and in remission in patients with AML receiving allogeneic transplantation.
TP53 Copy Number and Protein Expression Inform Mutation Status across Risk Categories in Acute Myeloid Leukemia.
NADPH metabolism determines the leukemogenic capacity and drug resistance of AML cells.
The Irreversible FLT3 Inhibitor FF-10101 Is Active Against a Diversity of FLT3 Inhibitor Resistance Mechanisms.
VCP inhibition induces an unfolded protein response and apoptosis in human acute myeloid leukemia cells.
Point Mutations in the FLT3-ITD Region Are Rare but Recurrent Alterations in Adult AML and Associated With Concomitant KMT2A-PTD.
Txnip Enhances Fitness of Dnmt3a-Mutant Hematopoietic Stem Cells via p21.
Bone marrow stroma cells promote induction of a chemoresistant and prognostic unfavorable S100A8/A9high AML cell subset.
Acute Myeloid Leukemia Cells Functionally Compromise Hematopoietic Stem/Progenitor Cells Inhibiting Normal Hematopoiesis Through the Release of Extracellular Vesicles.
Identification of a c-MYB-directed therapeutic for acute myeloid leukemia.
Prediction of Survival with Intensive Chemotherapy in Acute Myeloid Leukemia.
Toll like receptor and cytokine expression throughout the bone marrow differs between patients with low- and high-risk myelodysplastic syndromes.
The Coming of Age of Preclinical Models of MDS.
Impact of IDH1 c.315C>T SNP on Outcomes in Acute Myeloid Leukemia: A Propensity Score-Adjusted Cohort Study.
Role of the bone marrow immune microenvironment in chronic myelomonocytic leukemia pathogenesis: novel mechanisms and insights into clonal propagation.
Augmented FLAMSA-Bu versus FluBu2 reduced-intensity conditioning in patients with active relapsed/refractory acute myeloid leukemia: an EBMT analysis.
Comprehensive analysis of genetic factors predicting overall survival in Myelodysplastic syndromes.
MGUS and clonal hematopoiesis show unrelated clinical and biological trajectories in an older population cohort.
Targeting matrix metallopeptidase 2 by hydroxyurea selectively kills acute myeloid mixed-lineage leukemia.
A randomised comparison of FLAG-Ida versus daunorubicin combined with clofarabine in relapsed or refractory acute myeloid leukaemia: Results from the UK NCRI AML17 trial.
Cancer stem cells: The adventurous journey from hematopoietic to leukemic stem cells.
Mendelian randomization supports bidirectional causality between telomere length and clonal hematopoiesis of indeterminate potential.
Infectious complications of targeted drugs and biotherapies in acute leukemia. Clinical practice guidelines by the European Conference on Infections in Leukemia (ECIL), a joint venture of the European Group for Blood and Marrow Transplantation (EBMT), the European Organization for Research and Treatment of Cancer (EORTC), the International Immunocompromised Host Society (ICHS) and the European Leukemia Net (ELN).
Longitudinal study of 2 patients with cyclic thrombocytopenia, STAT3, and MPL mutations.
The role of clonal hematopoiesis as driver of therapy-related myeloid neoplasms after autologous stem cell transplantation.
Treatment-free remission in chronic myeloid leukemia patients treated front-line with nilotinib: 10-year follow-up of the GIMEMA CML 0307 study.
CRISPR-free base editors with enhanced activity and expanded targeting scope in mitochondrial and nuclear DNA.

Blood Adv. 2022 Apr 05. pii: bloodadvances.2021005789. [Epub ahead of print]

Impact of IDH1 and IDH2 mutation detection at diagnosis and in remission in patients with AML receiving allogeneic transplantation.

Marius Bill, Madlen Jentzsch, Lara Bischof, Jessica Kohlschmidt, Juliane Grimm, Laura Katharina Schmalbrock, Donata Backhaus, Dominic Brauer, Karoline Goldmann, Georg-Nikolaus Franke, Vladan Vucinic, Dietger Niederwieser, Alice S Mims, Uwe Platzbecker, Ann-Kathrin Eisfeld, Sebastian Schwind.

Somatic mutations in the isocitrate dehydrogenase 1 and 2 genes (IDH1 and IDH2) are common in acute myeloid leukemia (AML). The prognostic impact of the presence of IDH mutations may be influenced by the co-mutational status, the specific location of the mutation (i.e., IDH1 R132, IDH2 R140, and IDH2 R172) at diagnosis and the dynamics of the mutation burden during disease course. Even though many IDH mutated AML patients are consolidated by hematopoietic stem cell transplantation (HSCT), the underlying biology and prognostic consequences remain largely unknown. Here we present a large analysis of 292 AML patients who received HSCT in complete remission (CR) or CR with incomplete peripheral recovery (CRi) in which we assessed the IDH mutation status at diagnosis and at HSCT as a potential marker for measurable residual disease (MRD). About a quarter of all patients were IDH mutated at diagnosis. The diagnostic presence of IDH mutations in AML did not have a significant prognostic impact when consolidated with HSCT. However, IDH1 R132 and IDH2 R172 MRD positivity in remission at HSCT associated with an increased risk of relapse, while IDH2 R140 mutations did not. The IDH2 R140 variant allele frequency (VAF) at diagnosis was higher - clustering around 50% - and the mutation clearance at HSCT in morphologic remission was much lower compared to IDH1 R132 and IDH2 R172. In our cohort, IDH2 R140 mutations behaved more like a clonal hematopoiesis related abberation, while IDH1 R132 and IDH2 R172 habored AML disease specific features.

DOI: https://doi.org/10.1182/bloodadvances.2021005789
Blood. 2022 Apr 07. pii: blood.2021013983. [Epub ahead of print]

TP53 Copy Number and Protein Expression Inform Mutation Status across Risk Categories in Acute Myeloid Leukemia.

Mehrnoosh Tashakori, Tapan M Kadia, Sanam Loghavi, Naval G Daver, Rashmi Kanagal-Shamanna, Sherry R Pierce, Dawen Sui, Peng Wei, Farnoosh Khodakarami, Zhenya Tang, Mark Routbort, Carol Bivins, Elias J Jabbour, L Jeffrey Medeiros, Kapil N Bhalla, Hagop M Kantarjian, Farhad Ravandi, Joseph D Khoury.

Mutant TP53 is an adverse risk factor in acute myeloid leukemia (AML), but large-scale integrated genomic-proteomic analyses of p53 alterations in AML patients remain limited. We analyzed TP53 mutational status, copy number (CN), and protein expression data in AML (N=528) and provide a compilation of mutation sites and types across disease subgroups among treated and untreated patients. Our analysis shows differential hotspots in subsets of AML and uncovered novel pathogenic variants involving TP53 splice sites. In addition, we identified TP53 CN loss in 70.2% of TP53-mutated AML, which had more deleterious TP53 mutations and copy neutral loss of heterozygosity in 5/32 (15.6%) AML patients who had intact TP53 CN. Importantly, we demonstrate that mutant p53 protein expression patterns by immunohistochemistry evaluated using digital image-assisted analysis provide a robust readout that integrates TP53 mutation and allelic states in patients with AML (sensitivity=94.49%, specificity=90.48%). Protein expression of p53 by immunohistochemistry informed mutation status irrespective of TP53 CN status. Genomic analysis of co-mutations in TP53-mutant AML showed a muted landscape that encompassed primarily mutations in genes involved in epigenetic regulation (DNMT3A and TET2), RAS/MAPK signaling (NF1, KRAS/NRAS, PTPN11), and RNA splicing (SRSF2). In summary, our data provides a rationale to refine risk stratification of AML patients on the basis of integrated molecular and protein-level TP53 analyses.

DOI: https://doi.org/10.1182/blood.2021013983
Cell Rep. 2022 Apr 05. pii: S2211-1247(22)00355-2. [Epub ahead of print]39(1): 110607

NADPH metabolism determines the leukemogenic capacity and drug resistance of AML cells.

Chiqi Chen, Xiaoyun Lai, Yaping Zhang, Li Xie, Zhuo Yu, Sijia Dan, Yu Jiang, Weicai Chen, Ligen Liu, Yi Yang, Dan Huang, Yuzheng Zhao, Junke Zheng.

  The mechanism by which redox metabolism regulates the fates of acute myeloid leukemia (AML) cells remains largely unknown. Using a highly sensitive, genetically encoded fluorescent sensor of nicotinamide adenine dinucleotide phosphate (NADPH), iNap1, we find three heterogeneous subpopulations of AML cells with different cytosolic NADPH levels in an MLL-AF9-induced murine AML model. The iNap1-high AML cells have enhanced proliferation capacities both in vitro and in vivo and are enriched for more functional leukemia-initiating cells than iNap1-low counterparts. The iNap1-high AML cells prefer localizing in the bone marrow endosteal niche and are resistant to methotrexate treatment. Furthermore, iNap1-high human primary AML cells have enhanced proliferation abilities both in vitro and in vivo. Mechanistically, the MTHFD1-mediated folate cycle regulates NADPH homeostasis to promote leukemogenesis and methotrexate resistance. These results provide important clues for understanding mechanisms by which redox metabolism regulates cancer cell fates and a potential metabolic target for AML treatments.

Keywords:  CP: Cancer; NADPH metabolism; acute myeloid leukemia; endosteal niche; folate cycle; leukemia-initiating cells; metabolic sensor; methotrexate resistance; methylenetetrahydrofolate dehydrogenase; tetrahydrofolic acid; vascular niche

DOI:  https://doi.org/10.1016/j.celrep.2022.110607
Mol Cancer Ther. 2022 Apr 08. OF1-OF11

The Irreversible FLT3 Inhibitor FF-10101 Is Active Against a Diversity of FLT3 Inhibitor Resistance Mechanisms.

Timothy T Ferng, Daisuke Terada, Makoto Ando, Theodore C Tarver, Fihr Chaudhary, Kimberly C Lin, Aaron C Logan, Catherine C Smith.

Small-molecule FLT3 inhibitors have recently improved clinical outcomes for patients with FLT3-mutant acute myeloid leukemia (AML) after many years of development, but resistance remains an important clinical problem. FF-10101 is the first irreversible, covalent inhibitor of FLT3 which has previously shown activity against FLT3 tyrosine kinase inhibitor resistance-causing FLT3 F691L and D835 mutations. We report that FF-10101 is also active against an expanded panel of clinically identified FLT3 mutations associated with resistance to other FLT3 inhibitors. We also demonstrate that FF-10101 can potentially address resistance mechanisms associated with growth factors present in the bone marrow microenvironment but is vulnerable to mutation at C695, the amino acid required for covalent FLT3 binding. These data suggest that FF-10101 possesses a favorable resistance profile that may contribute to improved single-agent efficacy when used in patients with FLT3-mutant AML.

DOI: https://doi.org/10.1158/1535-7163.MCT-21-0317
PLoS One. 2022 ;17(4): e0266478

VCP inhibition induces an unfolded protein response and apoptosis in human acute myeloid leukemia cells.

Paweł P Szczęśniak, Jan B Heidelberger, Hubert Serve, Petra Beli, Sebastian A Wagner.

Acute myeloid leukemia (AML) is a heterogeneous malignancy characterized by the accumulation of undifferentiated white blood cells (blasts) in the bone marrow. Valosin-containing protein (VCP) is an abundant molecular chaperone that extracts ubiquitylated substrates from protein complexes and cellular compartments prior to their degradation by the proteasome. We found that treatment of AML cell lines with the VCP inhibitor CB-5083 leads to an accumulation of ubiquitylated proteins, activation of unfolded protein response (UPR) and apoptosis. Using quantitative mass spectrometry-based proteomics we assessed the effects of VCP inhibition on the cellular ubiquitin-modified proteome. We could further show that CB-5083 decreases the survival of the AML cell lines THP-1 and MV4-11 in a concentration-dependent manner, and acts synergistically with the antimetabolite cytarabine and the BH3-mimetic venetoclax. Finally, we showed that prolonged treatment of AML cells with CB-5083 leads to development of resistance mediated by mutations in VCP. Taken together, inhibition of VCP leads to a lethal unfolded protein response in AML cells and might be a relevant therapeutic strategy for treatment of AML, particularly when combined with other drugs. The toxicity and development of resistance possibly limit the utility of VCP inhibitors and have to be further explored in animal models and clinical trials.

DOI: https://doi.org/10.1371/journal.pone.0266478
Front Oncol. 2022 ;12 862991

Point Mutations in the FLT3-ITD Region Are Rare but Recurrent Alterations in Adult AML and Associated With Concomitant KMT2A-PTD.

Sebastian Stasik, Michael Kramer, Sven Zukunft, Christoph Röllig, Claudia D Baldus, Uwe Platzbecker, Hubert Serve, Carsten Müller-Tidow, Kerstin Schäfer-Eckart, Martin Kaufmann, Stefan Krause, Tim Sauer, Mathias Hänel, Andreas Neubauer, Gerhard Ehninger, Martin Bornhäuser, Johannes Schetelig, Jan M Middeke, Christian Thiede.

  FLT3-ITD mutations are common druggable alterations in patients with acute myeloid leukemia (AML) and associated with poor prognosis. Beside typical ITD mutations, point mutations and deletions in the juxtamembrane domain (JMD) have been observed. However, due to the low frequency of these alterations, there is only limited information on molecular and clinical associations. To evaluate the prognostic impact of non-ITD mutations in the FLT3 JMD region, we analyzed a large cohort of 1,539 adult AML patients treated in different protocols of the Study Alliance Leukemia, using next-generation sequencing. Non-ITD point mutations and deletions within the FLT3 JMD were identified with a prevalence of ~1.23% (n = 19). Both FLT3-ITD and non-ITD mutations were associated with a higher rate of NPM1 (42%-61%; p < 0.001) and DNMT3A mutations (37%-43%; p < 0.001), as well as an increased percentage of peripheral blood (54%-65%) and bone marrow blast cells (74%; p < 0.001), compared to FLT3-wild-type patients. Most significantly, AML patients with FLT3 non-ITD mutations had a higher rate of concomitant KMT2A-PTD mutations (37.5%; p < 0.001) as compared to FLT3-ITD (7%) or FLT3-wild-type cases (4.5%). In a multivariable analysis, FLT3 non-ITD mutations were not an independent prognostic factor. However, patients with dual FLT3 non-ITD and KMT2A-PTD mutations showed a trend for inferior outcome, which points at a functional interaction in this subset of AML.

Keywords:  FLT3-ITD; KMT2A-PTD; acute myeloid leukemia (AML); clinical outcome; point mutations

DOI:  https://doi.org/10.3389/fonc.2022.862991
Blood Cancer Discov. 2022 Apr 08. OF1-OF20

Txnip Enhances Fitness of Dnmt3a-Mutant Hematopoietic Stem Cells via p21.

Christine R Zhang, Elizabeth L Ostrander, Ostap Kukhar, Cates Mallaney, Jiameng Sun, Emily Haussler, Hamza Celik, Won Kyun Koh, Katherine Y King, Paul Gontarz, Grant A Challen.

Clonal hematopoiesis (CH) refers to the age-related expansion of specific clones in the blood system, and manifests from somatic mutations acquired in hematopoietic stem cells (HSCs). Most CH variants occur in the gene DNMT3A, but while DNMT3A-mutant CH becomes almost ubiquitous in aging humans, a unifying molecular mechanism to illuminate how DNMT3A-mutant HSCs outcompete their counterparts is lacking. Here, we used interferon gamma (IFNγ) as a model to study the mechanisms by which Dnmt3a mutations increase HSC fitness under hematopoietic stress. We found Dnmt3a-mutant HSCs resist IFNγ-mediated depletion, and IFNγ-signaling is required for clonal expansion of Dnmt3a-mutant HSCs in vivo. Mechanistically, DNA hypomethylation-associated overexpression of Txnip in Dnmt3a-mutant HSCs leads to p53 stabilization and upregulation of p21. This preserves the functional potential of Dnmt3a-mutant HSCs through increased quiescence and resistance to IFNγ-induced apoptosis. These data identify a previously undescribed mechanism to explain increased fitness of DNMT3A-mutant clones under hematopoietic stress.SIGNIFICANCE: DNMT3A mutations are common variants in clonal hematopoiesis, and recurrent events in blood cancers. Yet the mechanisms by which these mutations provide hematopoietic stem cells a competitive advantage as a precursor to malignant transformation remain unclear. Here, we use inflammatory stress to uncover molecular mechanisms leading to this fitness advantage. See related article by De Dominici and James DeGregori .

DOI: https://doi.org/10.1158/2643-3230.BCD-21-0132
Blood Adv. 2022 Apr 07. pii: bloodadvances.2021005938. [Epub ahead of print]

Bone marrow stroma cells promote induction of a chemoresistant and prognostic unfavorable S100A8/A9high AML cell subset.

Martin Böttcher, Konstantinos Panagiotidis, Heiko Bruns, Martina Stumpf, Simon Völkl, Stefanie Geyh, Barbara Dietel, Thomas Schroeder, Andreas Mackensen, Dimitrios Mougiakakos.

The bone marrow (BM) stroma represents a protective niche for acute myeloid leukemia (AML) cells. However, the complex underlying mechanisms remain to be fully elucidated. We found 2 small intracellular calcium-sensing molecules, S100A8 and S100A9, among the top genes being upregulated in primary AML blasts upon stromal contact. As members of the S100 protein family they can modulate cellular processes like proliferation, migration, and differentiation. Dysregulation of S100 proteins is described in different human cancers including increased S100A8 expression in de novo AML as a predictor of poor survival. Thus, we aimed to decipher the underlying pathways of stroma-mediated S100A8/A9 induction as well as its functional consequences. Upregulation of S100A8/A9 following stromal crosstalk was validated in AML cell lines, was contact-independent and reversible, and resulted in accumulation of S100A8/A9highcells. Accordingly, frequency of S100A8/A9high AML blasts was higher in the patients' BM as compared to peripheral blood. This S100A8/A9high AML cell population displayed an enhanced utilization of free fatty acids, features of a more mature myeloid phenotype, and increased resilience towards chemotherapeutics and BCL2 inhibition. We could identify stromal cell-derived interleukin-6 (IL-6) as the trigger for a Jak/STAT3 signaling-mediated S100A8/A9 induction. Interfering with fatty acid uptake and the IL-6-Jak/STAT3 pathway antagonized formation of S100A8/A9high cells and therapeutic resistance, which could have therapeutic implications as a strategy to interfere with the AML-niche dynamics.

DOI: https://doi.org/10.1182/bloodadvances.2021005938
Front Oncol. 2022 ;12 824562

Acute Myeloid Leukemia Cells Functionally Compromise Hematopoietic Stem/Progenitor Cells Inhibiting Normal Hematopoiesis Through the Release of Extracellular Vesicles.

Stefania Trino, Ilaria Laurenzana, Daniela Lamorte, Giovanni Calice, Angelo De Stradis, Michele Santodirocco, Alessandro Sgambato, Antonella Caivano, Luciana De Luca.

  Acute myeloid leukemia (AML) is an aggressive and heterogeneous clonal disorder of hematopoietic stem/progenitor cells (HSPCs). It is not well known how leukemia cells alter hematopoiesis promoting tumor growth and leukemic niche formation. In this study, we investigated how AML deregulates the hematopoietic process of HSPCs through the release of extracellular vesicles (EVs). First, we found that AML cells released a heterogeneous population of EVs containing microRNAs involved in AML pathogenesis. Notably, AML-EVs were able to influence the fate of HSPCs modifying their transcriptome. In fact, gene expression profile of AML-EV-treated HSPCs identified 923 down- and 630 up-regulated genes involved in hematopoiesis/differentiation, inflammatory cytokine production and cell movement. Indeed, most of the down-regulated genes are targeted by AML-EV-derived miRNAs. Furthermore, we demonstrated that AML-EVs were able to affect HSPC phenotype, modifying several biological functions, such as inhibiting cell differentiation and clonogenicity, activating inflammatory cytokine production and compromising cell movement. Indeed, a redistribution of HSPC populations was observed in AML-EV treated cells with a significant increase in the frequency of common myeloid progenitors and a reduction in granulocyte-macrophage progenitors and megakaryocyte-erythroid progenitors. This effect was accompanied by a reduction in HSPC colony formation. AML-EV treatment of HSPCs increased the levels of CCL3, IL-1B and CSF2 cytokines, involved in the inflammatory process and in cell movement, and decreased CXCR4 expression associated with a reduction of SDF-1 mediated-migration. In conclusion, this study demonstrates the existence of a powerful communication between AML cells and HSPCs, mediated by EVs, which suppresses normal hematopoiesis and potentially contributes to create a leukemic niche favorable to neoplastic development.

Keywords:  acute myeloid leukemia; clonogenicity; differentiation; extracellular vesicles; hematopoiesis; hematopoietic stem progenitor cells; inflammatory cytokines; microRNAs

DOI:  https://doi.org/10.3389/fonc.2022.824562
Leukemia. 2022 Apr 02.

Identification of a c-MYB-directed therapeutic for acute myeloid leukemia.

Katherine Clesham, Vanessa Walf-Vorderwülbecke, Luca Gasparoli, Clemence Virely, Sandra Cantilena, Alexia Tsakaneli, Sarah Inglott, Stuart Adams, Sujith Samarasinghe, Jack Bartram, Gareth Williams, Jasper de Boer, Owen Williams.

A significant proportion of patients suffering from acute myeloid leukemia (AML) cannot be cured by conventional chemotherapy, relapsed disease being a common problem. Molecular targeting of essential oncogenic mediators is an attractive approach to improving outcomes for this disease. The hematopoietic transcription factor c-MYB has been revealed as a central component of complexes maintaining aberrant gene expression programs in AML. We have previously screened the Connectivity Map database to identify mebendazole as an anti-AML therapeutic targeting c-MYB. In the present study we demonstrate that another hit from this screen, the steroidal lactone withaferin A (WFA), induces rapid ablation of c-MYB protein and consequent inhibition of c-MYB target gene expression, loss of leukemia cell viability, reduced colony formation and impaired disease progression. Although WFA has been reported to have pleiotropic anti-cancer effects, we demonstrate that its anti-AML activity depends on c-MYB modulation and can be partially reversed by a stabilized c-MYB mutant. c-MYB ablation results from disrupted HSP/HSC70 chaperone protein homeostasis in leukemia cells following induction of proteotoxicity and the unfolded protein response by WFA. The widespread use of WFA in traditional medicines throughout the world indicates that it represents a promising candidate for repurposing into AML therapy.

DOI: https://doi.org/10.1038/s41375-022-01554-9
Am J Hematol. 2022 Apr 05.

Prediction of Survival with Intensive Chemotherapy in Acute Myeloid Leukemia.

Koji Sasaki, Farhad Ravandi, Tapan Kadia, Courtney DiNardo, Gautam Borthakur, Nicholas Short, Nitin Jain, Naval Daver, Elias Jabbour, Guillermo Garcia-Manero, Joseph Khoury, Sergej Konoplev, Sanam Loghavi, Keyur Patel, Guillermo Montalban Bravo, Lucia Masarova, Marina Konopleva, Hagop Kantarjian.

Progress with intensive chemotherapy and supportive care measures has improved survival in newly diagnosed acute myeloid leukemia (AML). Predicting outcome helps in treatment decision making. We analyzed survival as the treatment endpoint in 3728 patients with newly diagnosed AML treated with intensive chemotherapy from 1980 to 2021. We divided the total study group (3:1 basis) into a training (n=2790) and a validation group (n=938). The associations between survival and 27 characteristics were investigated. In the training cohort, the multivariate analysis identified 12 consistent adverse prognostic variables independently associated with worse survival: older age, therapy-related myeloid neoplasm, worse performance status, cardiac comorbidity, leukocytosis, anemia, thrombocytopenia, elevated creatinine and lactate dehydrogenase, cytogenetic abnormalities, and the presence of infection at diagnosis except fever of unknown origin. We categorized patients into four prognostic groups, favorable (7%), intermediate (43%), poor (39%) and very poor (11%) with estimated 5-year survival rates of 69%, 36%, 13%, and 3% respectively (p<0.001). The predictive model was validated in an independent cohort. In a subset of patients with molecular mutation profiles, adding the mutation profiles after accounting for the effects of previous factors identified NPM1 (favorable), PTPN11, and TP53 (both unfavorable) mutations as molecular prognostic factors. The new proposed predictive model for survival with intensive chemotherapy in patients with AML is robust and can be used to advise patients regarding their prognosis, to modify therapy in remission (e.g. proposing allogeneic stem cell transplantation in first remission), and to compare outcome and benefits on future investigational therapies. This article is protected by copyright. All rights reserved.

DOI: https://doi.org/10.1002/ajh.26557
Exp Hematol. 2022 Mar 31. pii: S0301-472X(22)00131-X. [Epub ahead of print]

Toll like receptor and cytokine expression throughout the bone marrow differs between patients with low- and high-risk myelodysplastic syndromes.

Luana Chiquetto Paracatu, Darlene A Monlish, Zev J Greenberg, Daniel A C Fisher, Matthew J Walter, Stephen T Oh, Laura G Schuettpelz.

Myelodysplastic syndromes (MDS) are hematopoietic stem cell disorders, the pathogenesis of which involves enhanced immune signaling that promotes or selects for mutant hematopoietic stem and progenitor cells (HSPCs). In particular, toll like receptor (TLR) expression and signaling is enhanced in MDS, and its inhibition is an attractive therapeutic strategy. While prior studies have shown increased expression of TLR2 and its binding partners TLR1 and TLR6 in the CD34+ cells of patients with MDS (especially those with low-risk disease), TLR expression in other cell types throughout the bone marrow is largely unknown. To address this, we used mass cytometry to assess the expression of TLRs 1, 2, 6 and cytokines in the bone marrow hematopoietic cells of 6 low/intermediate-risk and 6 high-risk unmatched MDS bone marrow samples, as well as healthy controls, both at baseline and in response to TLR agonists. We observed several consistent differences between the groups. Most notably, TLR expression was upregulated in multiple cell populations in the low/intermediate-risk, but not high-risk, patients. In addition, many cytokines, including IL-6, IL-8, TNFα, TGFβ, MIP1β and granzyme B were highly expressed from various cell types in low/intermediate-risk patients. However, these same cytokines, with the exception of TGFβ, were expressed at lower levels in high-risk MDS. Together, these findings highlight the differential role of inflammation, and specifically TLR expression, in low/intermediate- versus high-risk MDS, and suggest that elevated TLR expression and cytokine production in multiple cell types likely influences the pathogenesis of MDS in lower-risk patients.

DOI: https://doi.org/10.1016/j.exphem.2022.03.011
Front Oncol. 2022 ;12 815037

The Coming of Age of Preclinical Models of MDS.

Wei Liu, Patric Teodorescu, Stephanie Halene, Gabriel Ghiaur.

  Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal bone-marrow diseases with ineffective hematopoiesis resulting in cytopenias and morphologic dysplasia of hematopoietic cells. MDS carry a wide spectrum of genetic abnormalities, ranging from chromosomal abnormalities such as deletions/additions, to recurrent mutations affecting the spliceosome, epigenetic modifiers, or transcription factors. As opposed to AML, research in MDS has been hindered by the lack of preclinical models that faithfully replicate the complexity of the disease and capture the heterogeneity. The complex molecular landscape of the disease poses a unique challenge when creating transgenic mouse-models. In addition, primary MDS cells are difficult to manipulate ex vivo limiting in vitro studies and resulting in a paucity of cell lines and patient derived xenograft models. In recent years, progress has been made in the development of both transgenic and xenograft murine models advancing our understanding of individual contributors to MDS pathology as well as the complex primary interplay of genetic and microenvironment aberrations. We here present a comprehensive review of these transgenic and xenograft models for MDS and future directions.

Keywords:  humanized mouse models; immunodeficient mouse models; myelodysplastic syndromes (MDS); transgenic mouse models; xenograft animal model

DOI:  https://doi.org/10.3389/fonc.2022.815037
Front Oncol. 2022 ;12 804961

Impact of IDH1 c.315C>T SNP on Outcomes in Acute Myeloid Leukemia: A Propensity Score-Adjusted Cohort Study.

Elizabeth M Corley, Moaath K Mustafa Ali, Hanan Alharthy, Kathryn A F Kline, Danielle Sewell, Jennie Y Law, Seung Tae Lee, Sandrine Niyongere, Vu H Duong, Maria R Baer, Ashkan Emadi.

  Acute myeloid leukemia (AML) is the common type of acute leukemia in adults. Definitive prognostic significance of variants of unknown significance lacks for many commonly mutated genes, including the isocitrate dehydrogenase 1 (IDH1) synonymous single nucleotide polymorphism (SNP) variant c.315C>T. In this retrospective cohort study of 248 AML patients at the University of Maryland Greenebaum Comprehensive Cancer Center, we show that the IDH1 c.315C>T SNP, previously reported to be associated with poor prognosis by other studies with conflicting data, does not confer worse prognosis, with a median overall survival (OS) of 17.1 months compared to 15.1 months for patients without this SNP (P=0.57). The lack of negative effect on prognosis by IDH1 SNP c.315C>T is consistent with the absence of amino acid alteration (p.Gly105Gly).

Keywords:  AML; IDH1 c.315C>T SNP; Myeloid mutations; prognosis; survival

DOI:  https://doi.org/10.3389/fonc.2022.804961
Leuk Lymphoma. 2022 Apr 04. 1-9

Role of the bone marrow immune microenvironment in chronic myelomonocytic leukemia pathogenesis: novel mechanisms and insights into clonal propagation.

Abhishek A Mangaonkar, Mrinal M Patnaik.

  Recent studies in chronic myelomonocytic leukemia (CMML) involving clonal dendritic cell (DC) aggregates and association with systemic immune dysregulation have highlighted novel and potentially targetable pathways of disease progression. CMML DC aggregates are populated by heterogeneous cell types such as CD123+ plasmacytoid dendritic cells (pDCs), CD11c + myeloid-derived DCs (mDCs), myeloid-derived suppressor cells (MDSCs), monocytes, and associate with an immune checkpoint called indoleamine 2,3-dioxygenase (IDO). Systemically, these IDO + DC aggregates are associated with immune tolerance marked by regulatory T cell expansion, likely mediated by aberrant DC-T cell interactions occurring within the bone marrow (BM) microenvironment. Somatic mutational events in CMML such as ASXL1 and NRAS mutations cooperate to induce T cell exhaustion and contribute toward disease progression to acute myeloid leukemia (AML). In this review, we explore the role of aging-induced alterations in the BM immune microenvironment, aberrant innate immune and proinflammatory signaling, and the adaptive immune system in CMML.

Keywords:  CMML; dendritic cell biology; immune microenvironment; immunotherapy; myeloid leukemias and dysplasias; tumor microenvironment

DOI:  https://doi.org/10.1080/10428194.2022.2056175
Bone Marrow Transplant. 2022 Apr 07.

Augmented FLAMSA-Bu versus FluBu2 reduced-intensity conditioning in patients with active relapsed/refractory acute myeloid leukemia: an EBMT analysis.

Eduardo Rodríguez-Arbolí, Myriam Labopin, Matthias Eder, Arne Brecht, Igor Wolfgang Blau, Anne Huynh, Edouard Forcade, Johanna Tischer, Wolfgang Bethge, Sergey Bondarenko, Mareike Verbeek, Claude Eric Bulabois, Hermann Einsele, Friedrich Stölzel, Bipin Savani, Alexandros Spyridonidis, Ali Bazarbachi, Sebastian Giebel, Eolia Brissot, Christoph Schmid, Arnon Nagler, Mohamad Mohty.

Comparative data of fludarabine, cytarabine and amsacrine (FLAMSA) chemotherapy followed by busulfan (Bu)-based reduced-intensity conditioning (RIC) (FLAMSA-Bu) versus RIC regimens are lacking in patients with active relapsed/refractory (R/R) acute myeloid leukemia (AML) at the time of allogeneic hematopoietic stem cell transplantation (alloSCT). Here, we retrospectively analyzed outcomes after FLAMSA-Bu versus fludarabine/busulfan (FluBu2) conditioning in this patient population. A total of 476 patients fulfilled the inclusion criteria, of whom 257 received FluBu2 and 219 FLAMSA-Bu. Median follow-up was 41 months. Two-year non-relapse mortality (21%), graft-versus-host disease-free, relapse-free survival (24%) and chronic graft-versus-host disease (GVHD) (29%) were not statistically different between cohorts. FLAMSA-Bu was associated with lower 2-year relapse incidence (RI) (38 vs 49% after FluBu2, p = 0.004), and increased leukemia-free survival (LFS) (42 vs 29%, p = 0.001), overall survival (47 vs 39%, p = 0.008) and grades II-IV acute GVHD (36 vs 20%, p = 0.001). In the multivariate analysis, FLAMSA-Bu remained associated with lower RI (HR 0.69, p = 0.042), increased LFS (HR 0.74, p = 0.048) and a higher risk of acute GVHD (HR 2.06, p = 0.005). Notwithstanding the limitations inherent in this analysis, our data indicate that FLAMSA-Bu constitutes a tolerable conditioning strategy, resulting in a long-term benefit in a subset of patients reaching alloSCT with active disease.

DOI: https://doi.org/10.1038/s41409-022-01611-y
Sci Rep. 2022 Apr 08. 12(1): 5925

Comprehensive analysis of genetic factors predicting overall survival in Myelodysplastic syndromes.

Nehakumari Maurya, Purvi Mohanty, Somprakash Dhangar, Purvi Panchal, Farah Jijina, S Leo Prince Mathan, Chandrakala Shanmukhaiah, Manisha Madkaikar, Babu Rao Vundinti.

Myelodysplastic syndromes (MDS) are a group of clonal hematological disease with high risk of progression to AML. Accurate risk stratification is of importance for the proper management of MDS. Genetic lesions (Cytogenetic and Molecular mutations) are known to help in prognosticating the MDS patients. We have studied 152 MDS patients using cytogenetics and next generation sequencing (NGS). These patients were evaluated and as per cytogenetic prognostic group, majority (92.1%) of the patients classified as good (81.6%) and intermediate (10.5%) group. The NGS identified 38 different gene mutations in our cohort. Among 111 MDS patients with mutations, the most frequent mutated genes were SF3B1 (25.2%), SRSF2 (19%) U2AF1 (14.4%) ASXL1 (9.9%) RUNX1 (9.9%) TET2 (9%), TP53 (9%), ATM (6.3%), NRAS (5.4%) and JAK2/3 (5.4%). The survival analysis revealed that the mutations in TP53, JAK2/3, KRAS, NRAS and ASXL1 were significantly (P < 0.05) associated with poor survival of the patients. The univariate cox and multivariate cox analysis of our study suggested that the age, marrow morphology, cytogenetic and gene mutations with IPSS-R should be considered for prognosticating the MDS patients. We have proposed M-IPSS-R which changed the risk stratification i.e. 66.3% patients had decreased risk whereas 33.75% showed increased risk compared to IPSS-R. The survival analysis also showed that the M-IPSS-R were more significant in separating the patients as per their risk than the IPSS-R alone. The change in risk stratification could help in proper strategy for the treatment planning.

DOI: https://doi.org/10.1038/s41598-022-09864-9
Blood Adv. 2022 Apr 07. pii: bloodadvances.2021006498. [Epub ahead of print]

MGUS and clonal hematopoiesis show unrelated clinical and biological trajectories in an older population cohort.

Matteo Claudio Da Vià, Marta Lionetti, Alessio Marella, Antonio Matera, Erica Travaglino, Elena Signaroldi, Alessia Antonella Galbussera, Ugo Lucca, Sara Mandelli, Emma Riva, Mauro Tettamanti, Loredana Pettine, Alessandra Pompa, Luca Baldini, Antonino Neri, Matteo Giovanni Della Porta, Niccolo Bolli.

Monoclonal gammopathy of undetermined significance (MGUS) and clonal hematopoiesis (CH) are 2 preclinical clonal expansions of hematopoietic cells, whose prevalence rises with age reaching almost 10% in people of 70 years and older. The increased risk of myeloid malignancies in patients with myeloma is well defined, and the study of the association between these CH and MGUS could help explain this phenomenon. Here, we analyzed a fully clinically annotated dataset of 777 older subjects (median age, 91 years-old) previously screened for prevalence of CH. The prevalence of MGUS and CH was 9.6% and 17.3%, respectively. We detected CH in 9.7% of the MGUS patients, and MGUS in 5.5% of the CH patients. We did not find a significant correlation between the presence of MGUS and CH. Furthermore, the 2 conditions showed a differential association with clinical and laboratory covariates, suggesting that MGUS and CH may represent age-associated unrelated clonal drifts of hematopoietic cells. Confirmatory studies are needed to assess the relevance of CH in plasma cell disorders.

DOI: https://doi.org/10.1182/bloodadvances.2021006498
Cell Death Discov. 2022 Apr 08. 8(1): 180

Targeting matrix metallopeptidase 2 by hydroxyurea selectively kills acute myeloid mixed-lineage leukemia.

Ruiheng Wang, Shufeng Xie, Shouhai Zhu, Yong Sun, Bowen Shi, Dan Li, Ting Kang, Yuanli Wang, Zhenshu Xu, Han Liu.

Oncogene-induced tumorigenesis results in the variation of epigenetic modifications, and in addition to promoting cell immortalization, cancer cells undergo more intense cellular stress than normal cells and depend on other support genes for survival. Chromosomal translocations of mixed-lineage leukemia (MLL) induce aggressive leukemias with an inferior prognosis. Unfortunately, most MLL-rearranged (MLL-r) leukemias are resistant to conventional chemotherapies. Here, we showed that hydroxyurea (HU) could kill MLL-r acute myeloid leukemia (AML) cells through the necroptosis process. HU target these cells by matrix metallopeptidase 2 (MMP2) deficiency rather than subordinate ribonucleotide reductase regulatory subunit M2 (RRM2) inhibition, where MLL directly regulates MMP2 expression and is decreased in most MLL-r AMLs. Moreover, iron chelation of HU is also indispensable for inducing cell stress, and MMP2 is the support factor to protect cells from death. Our preliminary study indicates that MMP2 might play a role in the nonsense-mediated mRNA decay pathway that prevents activation of unfolding protein response under innocuous endoplasmic reticulum stress. Hence, these results reveal a possible strategy of HU application in MLL-r AML treatment and shed new light upon HU repurposing.

DOI: https://doi.org/10.1038/s41420-022-00989-4
Br J Haematol. 2022 Apr 06.

A randomised comparison of FLAG-Ida versus daunorubicin combined with clofarabine in relapsed or refractory acute myeloid leukaemia: Results from the UK NCRI AML17 trial.

Nigel H Russell, Robert K Hills, Lars Kjeldsen, Richard E Clark, Sahra Ali, Paul Cahalin, Ian F Thomas, Alan K Burnett.

  The prognosis for younger patients with relapsed acute myeloid leukaemia (AML) is generally dismal. Allogeneic stem cell transplantation is the preferred therapy for these patients. As part of the UK NCRI AML17 trial, daunorubicin/clofarabine (DClo) was compared with fludarabine, cytarabine, granulocyte colony-stimulating factor with idarubicin (FLAG-Ida) in 311 patients designated high-risk following course one of induction therapy, which has previously been reported. We now report the results of the same randomisation in patients who were refractory to two induction courses or subsequently relapsed. A total of 94 relapsed or refractory AML patients, usually less than 60 years of age and with mainly favourable or intermediate-risk cytogenetics, were randomised to receive up to three courses of DClo or FLAG-Ida, with the aim of proceeding to transplant. Complete remission was achieved in 74% of patients with no difference between the arms. Overall, 57% of patients received a transplant with no difference between the arms, likewise overall survival at five years showed no significant difference (21% for DClo vs. 22% for FLAG-Ida). No patient who did not receive a transplant survived beyond 21months. A stratified analysis including the 311 post course 1 high-risk patients who underwent the same randomisation showed a consistent treatment benefit for FLAG-Ida.

Keywords:  CLL lymphocytes; chronic lymphocytic leukaemia; morphology

DOI:  https://doi.org/10.1111/bjh.18195
Cell. 2022 Apr 03. pii: S0092-8674(22)00335-X. [Epub ahead of print]

Cancer stem cells: The adventurous journey from hematopoietic to leukemic stem cells.

Andreas Trumpp, Simon Haas.

This year's Gairdner Foundation Award for Biomedical Research is awarded to John Dick for the discovery of leukemic stem cells and the hierarchical organization of acute myeloid leukemias. His work laid the foundation for the cancer stem cell model with numerous clinical implications for hematopoietic malignancies and solid tumors.

DOI: https://doi.org/10.1016/j.cell.2022.03.025
Sci Adv. 2022 Apr 08. 8(14): eabl6579

Mendelian randomization supports bidirectional causality between telomere length and clonal hematopoiesis of indeterminate potential.

Samoan Obesity, Lifestyle and Genetic Adaptations Study (OLaGA) Group

Human genetic studies support an inverse causal relationship between leukocyte telomere length (LTL) and coronary artery disease (CAD), but directionally mixed effects for LTL and diverse malignancies. Clonal hematopoiesis of indeterminate potential (CHIP), characterized by expansion of hematopoietic cells bearing leukemogenic mutations, predisposes both hematologic malignancy and CAD. TERT (which encodes telomerase reverse transcriptase) is the most significantly associated germline locus for CHIP in genome-wide association studies. Here, we investigated the relationship between CHIP, LTL, and CAD in the Trans-Omics for Precision Medicine (TOPMed) program (n = 63,302) and UK Biobank (n = 47,080). Bidirectional Mendelian randomization studies were consistent with longer genetically imputed LTL increasing propensity to develop CHIP, but CHIP then, in turn, hastens to shorten measured LTL (mLTL). We also demonstrated evidence of modest mediation between CHIP and CAD by mLTL. Our data promote an understanding of potential causal relationships across CHIP and LTL toward prevention of CAD.

DOI: https://doi.org/10.1126/sciadv.abl6579
Leukemia. 2022 Apr 02.

Infectious complications of targeted drugs and biotherapies in acute leukemia. Clinical practice guidelines by the European Conference on Infections in Leukemia (ECIL), a joint venture of the European Group for Blood and Marrow Transplantation (EBMT), the European Organization for Research and Treatment of Cancer (EORTC), the International Immunocompromised Host Society (ICHS) and the European Leukemia Net (ELN).

Georg Maschmeyer, Lars Bullinger, Carolina Garcia-Vidal, Raoul Herbrecht, Johan Maertens, Pierantonio Menna, Livio Pagano, Anne Thiebaut-Bertrand, Thierry Calandra.

The 9th web-based European Conference on Infections in Leukemia (ECIL-9), held September 16-17, 2021, reviewed the risk of infections and febrile neutropenia associated with more recently approved immunotherapeutic agents and molecular targeted drugs for the treatment of acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). Novel antibody based treatment approaches (inotuzumab ozogamicin, gemtuzumab ozogamicin, flotetuzumab), isocitrate dehydrogenases inhibitors (ivosidenib, enasidenib, olutasidenib), FLT3 kinase inhibitors (gilteritinib, midostaurin, quizartinib), a hedgehog inhibitor (glasdegib) as well as a BCL2 inhibitor (venetoclax) were reviewed with respect to their mode of action, their immunosuppressive potential, their current approval and the infectious complications and febrile neutropenia reported from clinical studies. Evidence-based recommendations for prevention and management of infectious complications and specific alerts regarding the potential for drug-drug interactions were developed and discussed in a plenary session with the panel of experts until consensus was reached. The set of recommendations was posted on the ECIL website for a month for comments from members of EBMT, EORTC, ICHS and ELN before final approval by the panelists. While a majority of these agents are not associated with a significantly increased risk when used as monotherapy, caution is required with combination therapy such as venetoclax plus hypomethylating agents, gemtuzumab ozogamicin plus cytotoxic drugs or midostaurin added to conventional AML chemotherapy.

DOI: https://doi.org/10.1038/s41375-022-01556-7
Blood Adv. 2022 Apr 05. pii: bloodadvances.2021006701. [Epub ahead of print]

Longitudinal study of 2 patients with cyclic thrombocytopenia, STAT3, and MPL mutations.

Haiyu Zhang, May Chien, Yu Hou, William Shomali, Rondeep Brar, Chandler Ho, Panpan Han, Danfei Xu, Bing M Zhang, Xiangqian Guo, Lorna Tolentino, Nancy C Wu, Albert G Tsai, Jing Jin, Wesley Holbrook Witteles, Zhenping Chen, Parveen Abidi, Diwash Jangam, Madison S Krieger, Morgan Craig, James B Bussel, Jason R Gotlib, James L Zehnder.

Cyclic thrombocytopenia (CTP) is a rare disease of periodic platelet count oscillations. The pathogenesis of CTP remains elusive. To study the underlying pathophysiology and genetic and cellular associations with CTP, we applied systems biology approaches to two patients with stable platelet cycling and reciprocal thrombopoietin (TPO) cycling at multiple time points through 2 cycles. Blood transcriptome analysis revealed cycling of platelet-specific genes, which are in parallel with and precede platelet count oscillation, indicating that cyclical platelet production leads platelet count cycling in both patients. Additionally, neutrophil and erythrocyte-specific genes also showed fluctuations correlating with platelet count changes, consistent with TPO effects on hematopoietic progenitors. Moreover, we found novel genetic associations with CTP. One patient had a novel germline heterozygous loss-of-function (LOF) thrombopoietin receptor (MPL) c.1210G>A mutation, and both had pathogenic somatic gain-of-function (GOF) variants in signal transducer and activator of transcription 3 (STAT3). In addition, both patients had clonal T-cell populations that remained stable throughout platelet count cycles. These mutations and clonal T cells may potentially involve in the pathogenic baseline in these patients rendering exaggerated persistent thrombopoiesis oscillations of their intrinsic rhythm upon homeostatic perturbations. This work provides new insights into the pathophysiology of CTP and possible therapies.

DOI: https://doi.org/10.1182/bloodadvances.2021006701
Ann Hematol. 2022 Apr 05.

The role of clonal hematopoiesis as driver of therapy-related myeloid neoplasms after autologous stem cell transplantation.

Doriana Gramegna, Diego Bertoli, Chiara Cattaneo, Camillo Almici, Alessandro Re, Angelo Belotti, Erika Borlenghi, Gaetana Lanzi, Silvana Archetti, Rosanna Verardi, Duilio Brugnoni, Margherita Sciumè, Rosa Daffini, Aldo M Roccaro, Alessandra Tucci, Giuseppe Rossi.

  Therapy-related myeloid neoplasm (t-MN) is a threatening complication of autologous stem cell transplantation (ASCT). Detecting clonal hematopoiesis (CH) mutations in cryopreserved cells before ASCT has been associated with a higher risk of t-MN, but the evolution of molecular abnormalities from pre-ASCT to t-MN, within the same patient, remains to be elucidated. We evaluated the mutational profile of 19 lymphoma/myeloma patients, at both pre-ASCT and t-MN diagnosis, using a targeted NGS approach; 26 non-developing t-MN control patients were also studied pre-ASCT. At ASCT, we found a higher frequency of CH in patients developing t-MN (58%) than in those who did not (23%) (P = 0.029); mutations in epigenetic (DNMT3A, TET2, and ASXL1) and DNA repair genes (PPM1D, RAD21, TP53, and STAG2) were the most represented. At t-MN, CH increased to 82% of patients. Cumulative mutational burden and variant allele frequency (VAF) also increased at t-MN. CH clones detected at ASCT were found at t-MN in eight out of 16 patients, mainly with stable VAF. Among the new driver mutations appeared at t-MN, TP53 increased from one to 13 mutations, in nine patients; being associated with complex karyotype. Mutations in transcription factor (RUNX1, CEBPA) and intracellular signaling genes (FLT3, RAS genes) also increased from three to 17 mutations in eight patients, presenting with a normal karyotype. Overall, we found that preexisting CH at ASCT rarely causes t-MN directly, but may rather facilitate the appearance of new mutations, especially those involving TP53, RUNX1, and RAS, that can drive the evolution to t-MN of at least two distinct types.

Keywords:  Autologous stem cell transplantation; Clonal hematopoiesis; Next-generation sequencing; Therapy-related myeloid neoplasms

DOI:  https://doi.org/10.1007/s00277-022-04806-x
Haematologica. 2022 Apr 07.

Treatment-free remission in chronic myeloid leukemia patients treated front-line with nilotinib: 10-year follow-up of the GIMEMA CML 0307 study.

Gabriele Gugliotta, Fausto Castagnetti, Massimo Breccia, Luciano Levato, Tamara Intermesoli, Mariella D'Adda, Marzia Salvucci, Fabio Stagno, Giovanna Rege-Cambrin, Mario Tiribelli, Bruno Martino, Monica Bocchia, Michele Cedrone, Elena Trabacchi, Francesco Cavazzini, Ferdinando Porretto, Federica Sorà, Maria Pina Simula, Francesco Albano, Simona Soverini, Robin Foà, Fabrizio Pane, Michele Cavo, Giuseppe Saglio, Michele Baccarani, Gianantonio Rosti.

We report the final analysis, with a 10-year follow-up, of the phase II study GIMEMA CML 0307 (NCT00481052), which enrolled 73 adult patients (median age 51 years, range 18-83) with newly diagnosed chronic-phase (CP)-chronic myeloid leukemia (CML) to investigate the efficacy and the toxicity of front-line treatment with nilotinib (NIL). The initial dose was 400 mg twice daily; the dose was reduced to 300 mg twice daily as soon as this dose was approved and registered. The 10-year overall survival and progression-free survival were 94.5%. At the last contact, 36 (49.3%) patients were continuing NIL (22 patients at 300 mg twice daily, 14 at lower doses), 18 (24.7%) patients were in treatment-free remission (TFR), 14 (19.2%) were receiving other tyrosinekinase inhibitors and 4 (5.5%) patients have died. The rates of major (MMR) and deep (MR4) molecular responses by 10 years were 96% and 83%, respectively. The median time to MMR and MR4 were 6 and 18 months, respectively. After a median duration of NIL treatment of 88 months, 24 (32.9%) patients discontinued NIL while in stable deep molecular response. In these patients, the 2-years estimated treatment-free survival was 72.6%. The overall TFR rate, calculated on all enrolled patients, was 24.7% (18/73 patients). Seventeen patients (23.3%), at a median age of 69 years, had at least one arterial obstructive event. In conclusion, the use of NIL front-line in CP-CML can induce a stable TFR in a relevant number of patients, although cardiovascular toxicity remains of concern.

DOI: https://doi.org/10.3324/haematol.2021.280175
Nat Biotechnol. 2022 Apr 04.

CRISPR-free base editors with enhanced activity and expanded targeting scope in mitochondrial and nuclear DNA.

Beverly Y Mok, Anna V Kotrys, Aditya Raguram, Tony P Huang, Vamsi K Mootha, David R Liu.

The all-protein cytosine base editor DdCBE uses TALE proteins and a double-stranded DNA-specific cytidine deaminase (DddA) to mediate targeted C•G-to-T•A editing. To improve editing efficiency and overcome the strict TC sequence-context constraint of DddA, we used phage-assisted non-continuous and continuous evolution to evolve DddA variants with improved activity and expanded targeting scope. Compared to canonical DdCBEs, base editors with evolved DddA6 improved mitochondrial DNA (mtDNA) editing efficiencies at TC by 3.3-fold on average. DdCBEs containing evolved DddA11 offered a broadened HC (H = A, C or T) sequence compatibility for both mitochondrial and nuclear base editing, increasing average editing efficiencies at AC and CC targets from less than 10% for canonical DdCBE to 15-30% and up to 50% in cell populations sorted to express both halves of DdCBE. We used these evolved DdCBEs to efficiently install disease-associated mtDNA mutations in human cells at non-TC target sites. DddA6 and DddA11 substantially increase the effectiveness and applicability of all-protein base editing.

DOI: https://doi.org/10.1038/s41587-022-01256-8