bims-tremyl 2023-11-26 papers

on Therapy resistance biology in myeloid leukemia

Issue of 2023–11–26
thirty-one papers selected by
Paolo Gallipoli, Barts Cancer Institute, Queen Mary University of London

Tamoxifen for the treatment of myeloproliferative neoplasms: A Phase II clinical trial and exploratory analysis.
The lifelong natural history of clonal hematopoiesis and its links to myeloid malignancy.
Phase Ib study of sabatolimab (MBG453), a novel immunotherapy targeting TIM-3 antibody, in combination with decitabine or azacitidine in high- or very high-risk myelodysplastic syndromes.
Transcriptional and Functional Consequences of Oncostatin M Signaling on Young Dnmt3a-Mutant Hematopoietic Stem Cells.
Allosteric SHP2 inhibition increases apoptotic dependency on BCL2 and synergizes with venetoclax in FLT3- and KIT-mutant AML.
Acute myeloid leukemia with NUP98::HOXA9 mimicking acute promyelocytic leukemia.
An alternative NURF complex sustains acute myeloid leukemia by regulating the accessibility of insulator regions.
Genomic DNA-based measurable residual disease monitoring in pediatric acute myeloid leukemia: unselected consecutive cohort study.
Sequential vs myeloablative vs reduced intensity conditioning for patients with myelodysplastic syndromes with an excess of blasts at time of allogeneic haematopoietic cell transplantation: a retrospective study by the chronic malignancies working party of the EBMT.
An atypical GABARAP binding module drives the pro-autophagic potential of the AML-associated NPM1c variant.
Reversal of MYB-dependent suppression of MAFB expression overrides leukaemia phenotype in MLL-rearranged AML.
Therapeutic targeting of EP300/CBP by bromodomain inhibition in hematologic malignancies.
A 19-color single-tube full spectrum flow cytometry assay for the detection of measurable residual disease in acute myeloid leukemia.
Is clonal hematopoiesis 'mostly harmless'?
N-(3-Methoxyphenyl)-6-(7-(1-methyl-1H-pyrazol-4-yl)imidazo[1,2-a]pyridin-3-yl)pyridin-2-amine is an inhibitor of the FLT3-ITD and BCR-ABL pathways, and potently inhibits FLT3-ITD/D835Y and FLT3-ITD/F691L secondary mutants.
Transfusion avoidance in myelodysplastic neoplasms.
Mutation order in acute myeloid leukemia identifies uncommon patterns of evolution and illuminates phenotypic heterogeneity.
Cost-effective and scalable clonal hematopoiesis assay provides insight into clonal dynamics.
Longitudinal Clinical Data Improves Survival Prediction after Hematopoietic Cell Transplantation Using Machine Learning.
Very short insertions in the FLT3 gene are of therapeutic significance in acute myeloid leukemia.
A PERK-Specific Inhibitor Blocks Metastatic Progression by Limiting Integrated Stress Response-Dependent Survival of Quiescent Cancer Cells.
Mutations in DEAD/H-box helicase 11 correlate with increased relapse risk in adults with acute myeloid leukaemia with normal cytogenetics.
Real-world outcomes with fedratinib therapy in patients who discontinued ruxolitinib for primary myelofibrosis.
Clinical Outcomes in Patients With Refractory Anemia With Excess Blasts (RAEB) Who Receive Hypomethylating Agents (HMAs).
Standardization of Molecular MRD Levels in AML Using an Integral Vector Bearing ABL and the Mutation of Interest.
Development of resistance to type II JAK2 inhibitors in MPN depends on AXL kinase and is targetable.
Burden of AML, 1990-2019: Estimates From the Global Burden of Disease Study.
Wei AH, Panayiotidis P, Montesinos P, et al. Long-term follow-up of VIALE-C in patients with untreated AML ineligible for intensive chemotherapy. Blood. 2022;140(25):2754-2756.
STAT5B mutations in myeloid neoplasms differ by disease subtypes but characterize a subset of chronic myeloid neoplasms with eosinophilia and/or basophilia.
Chronic myeloid leukemia (CML) in children and adolescents-Clinicopathological findings.
DOT1L interaction partner AF10 controls patterning of H3K79 methylation and RNA polymerase II to maintain cell identity.

Nat Commun. 2023 Nov 25. 14(1): 7725

Tamoxifen for the treatment of myeloproliferative neoplasms: A Phase II clinical trial and exploratory analysis.

Zijian Fang, Giuditta Corbizi Fattori, Thomas McKerrell, Rebecca H Boucher, Aimee Jackson, Rachel S Fletcher, Dorian Forte, Jose-Ezequiel Martin, Sonia Fox, James Roberts, Rachel Glover, Erica Harris, Hannah R Bridges, Luigi Grassi, Alba Rodriguez-Meira, Adam J Mead, Steven Knapper, Joanne Ewing, Nauman M Butt, Manish Jain, Sebastian Francis, Fiona J Clark, Jason Coppell, Mary F McMullin, Frances Wadelin, Srinivasan Narayanan, Dragana Milojkovic, Mark W Drummond, Mallika Sekhar, Hesham ElDaly, Judy Hirst, Maike Paramor, E Joanna Baxter, Anna L Godfrey, Claire N Harrison, Simón Méndez-Ferrer.

Current therapies for myeloproliferative neoplasms (MPNs) improve symptoms but have limited effect on tumor size. In preclinical studies, tamoxifen restored normal apoptosis in mutated hematopoietic stem/progenitor cells (HSPCs). TAMARIN Phase-II, multicenter, single-arm clinical trial assessed tamoxifen's safety and activity in patients with stable MPNs, no prior thrombotic events and mutated JAK2V617F, CALRins5 or CALRdel52 peripheral blood allele burden ≥20% (EudraCT 2015-005497-38). 38 patients were recruited over 112w and 32 completed 24w-treatment. The study's A'herns success criteria were met as the primary outcome ( ≥ 50% reduction in mutant allele burden at 24w) was observed in 3/38 patients. Secondary outcomes included ≥25% reduction at 24w (5/38), ≥50% reduction at 12w (0/38), thrombotic events (2/38), toxicities, hematological response, proportion of patients in each IWG-MRT response category and ELN response criteria. As exploratory outcomes, baseline analysis of HSPC transcriptome segregates responders and non-responders, suggesting a predictive signature. In responder HSPCs, longitudinal analysis shows high baseline expression of JAK-STAT signaling and oxidative phosphorylation genes, which are downregulated by tamoxifen. We further demonstrate in preclinical studies that in JAK2V617F+ cells, 4-hydroxytamoxifen inhibits mitochondrial complex-I, activates integrated stress response and decreases pathogenic JAK2-signaling. These results warrant further investigation of tamoxifen in MPN, with careful consideration of thrombotic risk.

DOI: https://doi.org/10.1038/s41467-023-43175-5
Blood. 2023 Nov 22. pii: blood.2023019964. [Epub ahead of print]

The lifelong natural history of clonal hematopoiesis and its links to myeloid malignancy.

Margarete A Fabre, George S Vassiliou.

The study of somatic mutations and the associated clonal mosaicism across the human body has transformed our understanding of ageing and its links to cancer. In proliferative human tissues, stem cells compete for dominance and those with an advantage expand clonally in relation to their peers. In the hematopoietic system, such expansion is termed clonal hematopoiesis (CH). The forces driving competition, namely heterogeneity of the hematopoietic stem cell (HSC) pool and attrition of the HSC environment, become increasingly prominent with age. As a result, CH becomes progressively more common through life, to the point of becoming essentially ubiquitous. We are beginning to unravel the specific intra- and extra-cellular factors underpinning clonal behavior, with somatic mutations in specific driver genes, inflammation, telomere maintenance, extraneous exposures and inherited genetic variation among the important players. The inevitability of CH with age, combined with its unequivocal links to myeloid cancers, poses a scientific and clinical challenge. Specifically, we need to decipher the factors determining clonal behavior and to develop prognostic tools to identify those at high risk of malignant progression, for whom preventive interventions may be warranted. Here, we discuss how recent advances in our understanding of the natural history of CH have provided important insights into these processes and helped define future avenues of investigation.

DOI: https://doi.org/10.1182/blood.2023019964
Am J Hematol. 2023 Nov 22.

Phase Ib study of sabatolimab (MBG453), a novel immunotherapy targeting TIM-3 antibody, in combination with decitabine or azacitidine in high- or very high-risk myelodysplastic syndromes.

Andrew M Brunner, Jordi Esteve, Kimmo Porkka, Steve Knapper, Elie Traer, Sebastian Scholl, Guillermo Garcia-Manero, Norbert Vey, Martin Wermke, Jeroen J W M Janssen, Rupa Narayan, Shaun Fleming, Sun Loo, Natalia Tovar, Mika Kontro, Oliver G Ottmann, Purushotham Naidu, Haiying Sun, May Han, Roisin White, Na Zhang, Anisa Mohammed, Catherine A Sabatos-Peyton, David P Steensma, Mikael L Rinne, Uma M Borate, Andrew H Wei.

The safety and efficacy of sabatolimab, a novel immunotherapy targeting T-cell immunoglobulin domain and mucin domain-3 (TIM-3), was assessed in combination with hypomethylating agents (HMAs) in patients with HMA-naive revised International Prognostic System Score (IPSS-R) high- or very high-risk myelodysplastic syndromes (HR/vHR-MDS) or chronic myelomonocytic leukemia (CMML). Sabatolimab + HMA had a safety profile similar to that reported for HMA alone and demonstrated durable clinical responses in patients with HR/vHR-MDS. These results support the ongoing evaluation of sabatolimab-based combination therapy in MDS, CMML, and acute myeloid leukemia.

DOI: https://doi.org/10.1002/ajh.27161
Exp Hematol. 2023 Nov 22. pii: S0301-472X(23)01768-X. [Epub ahead of print]

Transcriptional and Functional Consequences of Oncostatin M Signaling on Young Dnmt3a-Mutant Hematopoietic Stem Cells.

Logan S Schwartz, Kira A Young, Timothy M Stearns, Nathan Boyer, Kristina D Mujica, Jennifer J Trowbridge.

Age-associated clonal hematopoiesis (CH) occurs due to somatic mutations accrued in hematopoietic stem cells (HSCs) that confer a selective growth advantage in the context of aging. The mechanisms by which CH-mutant HSCs gain this advantage with aging are not comprehensively understood. Using unbiased transcriptomic approaches, we identified Oncostatin M (OSM) signaling as a candidate contributor to age-related Dnmt3a-mutant CH. We found that Dnmt3a-mutant HSCs from young adult mice (3-6 months old) subjected to acute OSM stimulation do not demonstrate altered proliferation, apoptosis, hematopoietic engraftment, or myeloid differentiation. Dnmt3a-mutant HSCs from young mice do transcriptionally upregulate an inflammatory cytokine network in response to acute in vitro OSM stimulation as evidenced by significant upregulation of the genes encoding IL-6, IL-1β and TNFα. OSM-stimulated Dnmt3a-mutant HSCs also demonstrate upregulation of the anti-inflammatory genes Socs3, Atf3 and Nr4a1. In the context of an aged bone marrow (BM) microenvironment, Dnmt3a-mutant HSCs upregulate pro-inflammatory genes but not the anti-inflammatory genes Socs3, Atf3 and Nr4a1. The results from our studies suggest that aging may exhaust the regulatory mechanisms that HSCs employ to resolve inflammatory states in response to factors such as OSM.

DOI: https://doi.org/10.1016/j.exphem.2023.11.005
Cell Rep Med. 2023 Nov 21. pii: S2666-3791(23)00484-6. [Epub ahead of print]4(11): 101290

Allosteric SHP2 inhibition increases apoptotic dependency on BCL2 and synergizes with venetoclax in FLT3- and KIT-mutant AML.

Bogdan Popescu, Carlos Stahlhut, Theodore C Tarver, Sydney Wishner, Bianca J Lee, Cheryl A C Peretz, Cuyler Luck, Paul Phojanakong, Juan Antonio Camara Serrano, Henry Hongo, Jose M Rivera, Simayijiang Xirenayi, John A Chukinas, Veronica Steri, Sarah K Tasian, Elliot Stieglitz, Catherine C Smith.

  Mutations in the receptor tyrosine kinases (RTKs) FLT3 and KIT are frequent and associated with poor outcomes in acute myeloid leukemia (AML). Although selective FLT3 inhibitors (FLT3i) are clinically effective, remissions are short-lived due to secondary resistance characterized by acquired mutations constitutively activating the RAS/MAPK pathway. Hereby, we report the pre-clinical efficacy of co-targeting SHP2, a critical node in MAPK signaling, and BCL2 in RTK-driven AML. The allosteric SHP2 inhibitor RMC-4550 suppresses proliferation of AML cell lines with FLT3 and KIT mutations, including cell lines with acquired resistance to FLT3i. We demonstrate that pharmacologic SHP2 inhibition unveils an Achilles' heel of RTK-driven AML, increasing apoptotic dependency on BCL2 via MAPK-dependent mechanisms, including upregulation of BMF and downregulation of MCL1. Consequently, RMC-4550 and venetoclax are synergistically lethal in AML cell lines and in clinically relevant xenograft models. Our results provide mechanistic rationale and pre-clinical evidence for co-targeting SHP2 and BCL2 in RTK-driven AML.

Keywords:  FLT3; SHP2; acute myeloid leukemia; apoptosis; cancer; drug synergy; targeted therapies

DOI:  https://doi.org/10.1016/j.xcrm.2023.101290
Blood. 2023 Nov 23. 142(21): 1845

Acute myeloid leukemia with NUP98::HOXA9 mimicking acute promyelocytic leukemia.

Elisa Lin, Weina Chen.

DOI: https://doi.org/10.1182/blood.2023022102
EMBO J. 2023 Nov 21. e114221

An alternative NURF complex sustains acute myeloid leukemia by regulating the accessibility of insulator regions.

Aliaksandra Radzisheuskaya, Isabel Peña-Rømer, Eugenia Lorenzini, Richard Koche, Yingqian Zhan, Pavel V Shliaha, Alexandra J Cooper, Zheng Fan, Daria Shlyueva, Jens V Johansen, Ronald C Hendrickson, Kristian Helin.

  Efficient treatment of acute myeloid leukemia (AML) patients remains a challenge despite recent therapeutic advances. Here, using a CRISPRi screen targeting chromatin factors, we identified the nucleosome-remodeling factor (NURF) subunit BPTF as an essential regulator of AML cell survival. We demonstrate that BPTF forms an alternative NURF chromatin remodeling complex with SMARCA5 and BAP18, which regulates the accessibility of a large set of insulator regions in leukemic cells. This ensures efficient CTCF binding and boundary formation between topologically associated domains that is essential for maintaining the leukemic transcriptional programs. We also demonstrate that the well-studied PHD2-BROMO chromatin reader domains of BPTF, while contributing to complex recruitment to chromatin, are dispensable for leukemic cell growth. Taken together, our results uncover how the alternative NURF complex contributes to leukemia and provide a rationale for its targeting in AML.

Keywords:  BPTF; SMARCA5; acute myeloid leukemia; chromatin remodeling; insulator regions

DOI:  https://doi.org/10.15252/embj.2023114221
Leukemia. 2023 Nov 24.

Genomic DNA-based measurable residual disease monitoring in pediatric acute myeloid leukemia: unselected consecutive cohort study.

Marketa Zaliova, Jan Zuna, Lucie Winkowska, Iveta Janotova, Justina Skorepova, Julius Lukes, Claus Meyer, Rolf Marschalek, Zbynek Novak, Jiri Domansky, Jan Stary, Lucie Sramkova, Jan Trka.

Measurable residual disease (MRD) monitoring in childhood acute myeloid leukemia (AML) is used to assess response to treatment and for early detection of imminent relapse. In childhood AML, MRD is typically evaluated using flow cytometry, or by quantitative detection of leukemia-specific aberrations at the mRNA level. Both methods, however, have significant limitations. Recently, we demonstrated the feasibility of MRD monitoring in selected subgroups of AML at the genomic DNA (gDNA) level. To evaluate the potential of gDNA-based MRD monitoring across all AML subtypes, we conducted a comprehensive analysis involving 133 consecutively diagnosed children. Integrating next-generation sequencing into the diagnostic process, we identified (presumed) primary genetic aberrations suitable as MRD targets in 97% of patients. We developed patient-specific quantification assays and monitored MRD in 122 children. The gDNA-based MRD monitoring via quantification of primary aberrations with a sensitivity of at least 10-4 was possible in 86% of patients; via quantification with sensitivity of 5 × 10-4, of secondary aberrations, or at the mRNA level in an additional 8%. Importantly, gDNA-based MRD exhibited independent prognostic value at early time-points in patients stratified to intermediate-/high-risk treatment arms. Our study demonstrates the broad applicability, feasibility, and clinical significance of gDNA-based MRD monitoring in childhood AML.

DOI: https://doi.org/10.1038/s41375-023-02083-9
Bone Marrow Transplant. 2023 Nov 22.

Sequential vs myeloablative vs reduced intensity conditioning for patients with myelodysplastic syndromes with an excess of blasts at time of allogeneic haematopoietic cell transplantation: a retrospective study by the chronic malignancies working party of the EBMT.

V Potter, L Gras, L Koster, N Kroger, K Sockel, A Ganser, J Finke, H Labussiere-Wallet, R Peffault de Latour, Y Koc, U Salmenniemi, L Smidstrup Friis, P Jindra, T Schroeder, J Tischer, M Arat, M Pascual Cascon, L C de Wreede, P Hayden, K Raj, J Drozd-Sokolowska, C Scheid, D P McLornan, M Robin, I Yakoub-Agha.

The optimal conditioning for patients with higher risk MDS receiving potentially curative allogeneic haematopoietic stem cell transplant(allo-HCT) remains to be defined. This is particularly the case for patients with excess of blasts at time of allo-HCT. Sequential (Seq) conditioning, whereby chemotherapy is followed rapidly by transplant conditioning, offers an opportunity to decrease disease burden, potentially improving outcomes allo-HCT outcomes. Herein we present the only analysis comparing Seq to myeloablative (MAC) and reduced intensity conditioning (RIC) specifically focussed on MDS patients with excess of blasts at allo-HCT. 303 patients were identified in the EBMT registry, receiving RIC (n = 158), Seq (n = 105), and MAC (n = 40). Median follow-up was 67.2 months and median age at allo-HCT was 59.5 years (IQR 53.5-65.6). For the entire cohort, 3 y overall survival (OS) was 50% (95% CI 45-56%) and relapse free survival (RFS) 45% (95% CI 40-51%). No significant differences in OS (log-rank p = 0.13) and RFS (log-rank p = 0.18) were observed between conditioning protocols. On multivariable analysis, lower performance status, worse IPSS-R cytogenetics, sibling donor (compared to 8/8 MUD) and ≥20% blasts at allo-HCT were associated with worse outcomes. In conclusion, the Seq protocol did little to influence the outcome in this high-risk group of patients, with outcomes mostly determined by baseline disease risk and patient characteristics such as performance status.

DOI: https://doi.org/10.1038/s41409-023-02111-3
Cell Rep. 2023 Nov 22. pii: S2211-1247(23)01496-1. [Epub ahead of print]42(12): 113484

An atypical GABARAP binding module drives the pro-autophagic potential of the AML-associated NPM1c variant.

Hannah Mende, Anshu Khatri, Carolin Lange, Sergio Alejandro Poveda-Cuevas, Georg Tascher, Adriana Covarrubias-Pinto, Frank Löhr, Sebastian E Koschade, Ivan Dikic, Christian Münch, Anja Bremm, Lorenzo Brunetti, Christian H Brandts, Hannah Uckelmann, Volker Dötsch, Vladimir V Rogov, Ramachandra M Bhaskara, Stefan Müller.

  The nucleolar scaffold protein NPM1 is a multifunctional regulator of cellular homeostasis, genome integrity, and stress response. NPM1 mutations, known as NPM1c variants promoting its aberrant cytoplasmic localization, are the most frequent genetic alterations in acute myeloid leukemia (AML). A hallmark of AML cells is their dependency on elevated autophagic flux. Here, we show that NPM1 and NPM1c induce the autophagy-lysosome pathway by activating the master transcription factor TFEB, thereby coordinating the expression of lysosomal proteins and autophagy regulators. Importantly, both NPM1 and NPM1c bind to autophagy modifiers of the GABARAP subfamily through an atypical binding module preserved within its N terminus. The propensity of NPM1c to induce autophagy depends on this module, likely indicating that NPM1c exerts its pro-autophagic activity by direct engagement with GABARAPL1. Our data report a non-canonical binding mode of GABARAP family members that drives the pro-autophagic potential of NPM1c, potentially enabling therapeutic options.

Keywords:  AML; ATG8; Autophagy; CP: Cancer; CP: Molecular biology; GABARAP; LC3; NPM1; NPM1c; TFEB; atypical LIR; lysosome

DOI:  https://doi.org/10.1016/j.celrep.2023.113484
Cell Death Dis. 2023 Nov 23. 14(11): 763

Reversal of MYB-dependent suppression of MAFB expression overrides leukaemia phenotype in MLL-rearranged AML.

A Negri, C Ward, A Bucci, G D'Angelo, P Cauchy, A Radesco, A B Ventura, D S Walton, M Clarke, B Mandriani, S A Pappagallo, P Mondelli, K Liao, G Gargano, G M Zaccaria, L Viggiano, F M Lasorsa, A Ahmed, D Di Molfetta, G Fiermonte, M Cives, A Guarini, M C Vegliante, S Ciavarella, J Frampton, G Volpe.

The transcription factor MYB plays a pivotal role in haematopoietic homoeostasis and its aberrant expression is involved in the genesis and maintenance of acute myeloid leukaemia (AML). We have previously demonstrated that not all AML subtypes display the same dependency on MYB expression and that such variability is dictated by the nature of the driver mutation. However, whether this difference in MYB dependency is a general trend in AML remains to be further elucidated. Here, we investigate the role of MYB in human leukaemia by performing siRNA-mediated knock-down in cell line models of AML with different driver lesions. We show that the characteristic reduction in proliferation and the concomitant induction of myeloid differentiation that is observed in MLL-rearranged and t(8;21) leukaemias upon MYB suppression is not seen in AML cells with a complex karyotype. Transcriptome analyses revealed that MYB ablation produces consensual increase of MAFB expression in MYB-dependent cells and, interestingly, the ectopic expression of MAFB could phenocopy the effect of MYB suppression. Accordingly, in silico stratification analyses of molecular data from AML patients revealed a reciprocal relationship between MYB and MAFB expression, highlighting a novel biological interconnection between these two factors in AML and supporting new rationales of MAFB targeting in MLL-rearranged leukaemias.

DOI: https://doi.org/10.1038/s41419-023-06276-z
Cancer Cell. 2023 Nov 17. pii: S1535-6108(23)00366-5. [Epub ahead of print]

Therapeutic targeting of EP300/CBP by bromodomain inhibition in hematologic malignancies.

Luciano Nicosia, Gary J Spencer, Nigel Brooks, Fabio M R Amaral, Naseer J Basma, John A Chadwick, Bradley Revell, Bettina Wingelhofer, Alba Maiques-Diaz, Oliver Sinclair, Francesco Camera, Filippo Ciceri, Daniel H Wiseman, Neil Pegg, Will West, Tomasz Knurowski, Kris Frese, Karen Clegg, Victoria L Campbell, James Cavet, Mhairi Copland, Emma Searle, Tim C P Somervaille.

CCS1477 (inobrodib) is a potent, selective EP300/CBP bromodomain inhibitor which induces cell-cycle arrest and differentiation in hematologic malignancy model systems. In myeloid leukemia cells, it promotes rapid eviction of EP300/CBP from an enhancer subset marked by strong MYB occupancy and high H3K27 acetylation, with downregulation of the subordinate oncogenic network and redistribution to sites close to differentiation genes. In myeloma cells, CCS1477 induces eviction of EP300/CBP from FGFR3, the target of the common (4; 14) translocation, with redistribution away from IRF4-occupied sites to TCF3/E2A-occupied sites. In a subset of patients with relapsed or refractory disease, CCS1477 monotherapy induces differentiation responses in AML and objective responses in heavily pre-treated multiple myeloma. In vivo preclinical combination studies reveal synergistic responses to treatment with standard-of-care agents. Thus, CCS1477 exhibits encouraging preclinical and early-phase clinical activity by disrupting recruitment of EP300/CBP to enhancer networks occupied by critical transcription factors.

DOI: https://doi.org/10.1016/j.ccell.2023.11.001
Cytometry A. 2023 Nov 20.

A 19-color single-tube full spectrum flow cytometry assay for the detection of measurable residual disease in acute myeloid leukemia.

Hendrik Fokken, Julian Waclawski, Nadine Kattre, Arnold Kloos, Sebastian Müller, Max Ettinger, Tim Kacprowski, Michael Heuser, Tobias Maetzig, Adrian Schwarzer.

Multiparameter flow cytometry (MFC) has emerged as a standard method for quantifying measurable residual disease (MRD) in acute myeloid leukemia (AML). However, the limited number of available channels on conventional flow cytometers requires the division of a diagnostic sample into several tubes, restricting the number of cells and the complexity of immunophenotypes that can be analyzed. Full spectrum flow cytometers overcome this limitation by enabling the simultaneous use of up to 40 fluorescent markers. Here, we used this approach to develop a good laboratory practice-conform single-tube 19-color MRD detection assay that complies with recommendations of the European LeukemiaNet Flow-MRD Working Party. We based our assay on clinically-validated antibody clones and evaluated its performance on an IVD-certified full spectrum flow cytometer. We measured MRD and normal bone marrow samples and compared the MRD data to a widely used reference MRD-MFC panel generating highly concordant results. Using our newly developed single-tube panel, we established reference values in healthy bone marrow for 28 consensus leukemia-associated immunophenotypes and introduced a semi-automated dimensionality-reduction, clustering and cell type identification approach that aids the unbiased detection of aberrant cells. In summary, we provide a comprehensive full spectrum MRD-MFC workflow with the potential for rapid implementation for routine diagnostics due to reduced cell requirements and ease of data analysis with increased reproducibility in comparison to conventional Flow-MRD routines. This article is protected by copyright. All rights reserved.

DOI: https://doi.org/10.1002/cyto.a.24811
Nat Genet. 2023 Nov 23.

Is clonal hematopoiesis 'mostly harmless'?

DOI: https://doi.org/10.1038/s41588-023-01556-y
Bioorg Chem. 2023 Nov 11. pii: S0045-2068(23)00627-2. [Epub ahead of print]143 106966

N-(3-Methoxyphenyl)-6-(7-(1-methyl-1H-pyrazol-4-yl)imidazo[1,2-a]pyridin-3-yl)pyridin-2-amine is an inhibitor of the FLT3-ITD and BCR-ABL pathways, and potently inhibits FLT3-ITD/D835Y and FLT3-ITD/F691L secondary mutants.

Xiuqi Wang, Rosa Anna DeFilippis, Yuet-Kin Leung, Neil P Shah, Hong-Yu Li.

  Activating mutations within FLT3 make up 30 % of all newly diagnosed acute myeloid leukemia (AML) cases, with the most common mutation being an internal tandem duplication (FLT3-ITD) in the juxtamembrane region (25 %). Currently, two generations of FLT3 kinase inhibitors have been developed, with three inhibitors clinically approved. However, treatment of FLT3-ITD mutated AML is limited due to the emergence of secondary clinical resistance, caused by multiple mechanism including on-target FLT3 secondary mutations - FLT3-ITD/D835Y and FLT3-ITD/F691L being the most common, as well as the off-target activation of alternative pathways including the BCR-ABL pathway. Through the screening of imidazo[1,2-a]pyridine derivatives, N-(3-methoxyphenyl)-6-(7-(1-methyl-1H-pyrazol-4-yl)imidazo[1,2-a]pyridin-3-yl)pyridin-2-amine (compound 1) was identified as an inhibitor of both the FLT3-ITD and BCR-ABL pathways. Compound 1 potently inhibits clinically related leukemia cell lines driven by FLT3-ITD, FLT3-ITD/D835Y, FLT3-ITD/F691L, or BCR-ABL. Studies indicate that it mediates proapoptotic effects on cells by inhibiting FLT3 and BCR-ABL pathways, and other possible targets. Compound 1 is more potent against FLT3-ITD than BCR-ABL, and it may have other possible targets; however, compound 1 is first step for further optimization for the development of a balanced FLT3-ITD/BCR-ABL dual inhibitor for the treatment of relapsed FLT3-ITD mutated AML with multiple secondary clinical resistant subtypes such as FLT3-ITD/D835Y, FLT3-ITD/F691L, and cells co-expressing FLT3-ITD and BCR-ABL.

Keywords:  AML; BCR-ABL; Cancer; FLT3-ITD; Secondary mutants

DOI:  https://doi.org/10.1016/j.bioorg.2023.106966
Curr Opin Hematol. 2023 Nov 17.

Transfusion avoidance in myelodysplastic neoplasms.

Elizabeth A Griffiths.

PURPOSE OF REVIEW: Myelodysplastic neoplasms (MDS) are diseases of stem cell aging associated with complications from inadequate hematopoiesis (red cells, neutrophils and platelets) and variable risk for transformation to acute myeloid leukemia. Those with low-risk disease also suffer and die from MDS-related complications. Among the most challenging is development of anemia and transfusion dependence, which impacts quality of life and is associated with reduced survival. Appreciating and measuring the quality-of-life impact, preventing (if possible), treating, and managing the complications from anemia in MDS are of critical importance.
RECENT FINDINGS: Recent developments in basic science highlight the potential deleterious impact of iron overload within the developing red cell niche. Iron overload can compromise red cell maturation from healthy as well as malignant clones and produces an environment favoring expansion of mutant clonal cells, potentially driving disease progression. Observational studies in nontransfusion dependent MDS highlight that iron overload occurs even in the nontransfusion dependent. The newly approved (and established) therapies for management of MDS-related anemia work best when begun before patients become heavily transfusion-dependent.
SUMMARY: Iron overload is detrimental to hematopoiesis. Understanding the benefit afforded by transfusion is critical to optimal application and patient reported outcomes can inform this. Recently developed therapies are active and optimized application may improve response.

DOI: https://doi.org/10.1097/MOH.0000000000000794
Res Sq. 2023 Nov 06. pii: rs.3.rs-3516536. [Epub ahead of print]

Mutation order in acute myeloid leukemia identifies uncommon patterns of evolution and illuminates phenotypic heterogeneity.

Ravi Majeti, Matthew Schwede, Katharina Jahn, Jack Kuipers, Linde Miles, Robert Bowman, Troy Robinson, Ken Furudate, Hidetaka Uryu, Tomoyuki Tanaka, Yuya Sasaki, Asiri Ediriwickrema, Brooks Benard, Andrew Gentles, Ross Levine, Niko Beerenwinkel, Koichi Takahashi.

Acute myeloid leukemia (AML) has a poor prognosis and a heterogeneous mutation landscape. Although common mutations are well-studied, little research has characterized how the sequence of mutations relates to clinical features. Using published, single-cell DNA sequencing data from three institutions, we compared clonal evolution patterns in AML to patient characteristics, disease phenotype, and outcomes. Mutation trees, which represent the order of select mutations, were created for 207 patients from targeted panel sequencing data using 1 639 162 cells, 823 mutations, and 275 samples. In 224 distinct orderings of mutated genes, mutations related to DNA methylation typically preceded those related to cell signaling, but signaling-first cases did occur, and had higher peripheral cell counts, increased signaling mutation homozygosity, and younger patient age. Serial sample analysis suggested that NPM1 and DNA methylation mutations provide an advantage to signaling mutations in AML. Interestingly, WT1 mutation evolution shared features with signaling mutations, such as WT1-early being proliferative and occurring in younger individuals, trends that remained in multivariable regression. Some mutation orderings had a worse prognosis, but this was mediated by unfavorable mutations, not mutation order. These findings add a dimension to the mutation landscape of AML, identifying uncommon patterns of leukemogenesis and shedding light on heterogenous phenotypes.

DOI: https://doi.org/10.21203/rs.3.rs-3516536/v1
medRxiv. 2023 Nov 09. pii: 2023.11.08.23298270. [Epub ahead of print]

Cost-effective and scalable clonal hematopoiesis assay provides insight into clonal dynamics.

Taralynn Mack, Caitlyn Vlasschaert, Kelly von Beck, Alexander J Silver, J Brett Heimlich, Hannah Poisner, Henry Robert Condon, Jessica Ulloa, Andrew L Sochacki, Travis P Spaulding, Ashwin Kishtagari, Cosmin A Bejan, Yaomin Xu, Michael R Savona, Angela Jones, Alexander Bick.

Clonal hematopoiesis of indeterminate potential (CHIP) is a common age-related phenomenon that occurs when hematopoietic stem cells acquire mutations in a select set of genes commonly mutated in myeloid neoplasia which then expand clonally. Current sequencing assays to detect CHIP are not optimized for the detection of these variants and can be cost-prohibitive when applied to large cohorts or serial sequencing. Here, we present and validate a CHIP targeted sequencing assay that is affordable (∼$8/sample), accurate and highly scalable. To demonstrate the utility of this assay, we detected CHIP in a cohort of 456 individuals with DNA collected at multiple timepoints in the Vanderbilt BioVU biobank and quantified clonal expansion rates over time. A total of 101 individuals with CHIP were identified, and individual-level clonal expansion rate was calculated using the variant allele fraction (VAF) at both timepoints. Differences in clonal expansion rate by driver gene were observed, but there was also significant individual-level heterogeneity, emphasizing the multifactorial nature of clonal expansion. We further describe the mutation co-occurrence and clonal competition between multiple driver mutations.

DOI: https://doi.org/10.1101/2023.11.08.23298270
Blood Adv. 2023 Nov 22. pii: bloodadvances.2023011752. [Epub ahead of print]

Longitudinal Clinical Data Improves Survival Prediction after Hematopoietic Cell Transplantation Using Machine Learning.

Yiwang Zhou, Jesse Smith, Dinesh Keerthi, Cai Li, Yilun Sun, Suraj Sarvode Mothi, David Shyr, Barbara Spitzer, Andrew C Harris, Avijit Chatterjee, Subrata Chatterjee, Roni Shouval, Swati Naik, Alice Bertaina, Jaap Jan Boelens, Brandon M Triplett, Li Tang, Akshay Sharma.

Serial prognostic evaluation of patients after allogeneic hematopoietic cell transplantation (alloHCT) might help identify patients at high risk of developing potentially lethal organ dysfunction. Current prediction algorithms are based on models that do not incorporate changes to the patients' clinical condition that occur after alloHCT in the model development, which limits their predictive ability. We developed and validated a robust risk-prediction algorithm to predict short-term and long-term survival after alloHCT in pediatric patients that includes baseline biological variables, as well as changes in the patients' clinical status after alloHCT. The model was developed using clinical data from children and young adults treated at a single academic quaternary-care referral center. The model was created using a randomly split training dataset (70% of the cohort), internally validated (remaining 30% of the cohort from the same center), and then externally validated on patient data from another tertiary-care referral center. Repeated clinical measurements performed from 30 days before alloHCT to 30 days afterwards were extracted from the electronic medical record and incorporated into the model to predict survival at 100 days, 1-year, and 2-years after alloHCT. Of the 738 patients who underwent their first alloHCT at our institution between 2000 and 2020, 517 (70%) were randomly included in the training dataset and 221 (30%) constituted the validation dataset. When compared with models constructed from baseline variables alone, the naïve-Bayes machine learning models incorporating longitudinal data were significantly better at predicting whether patients would be alive or deceased at the given timepoints. This proof-of-concept study demonstrates that unlike traditional prognostic tools that use fixed variables for risk assessment, incorporating dynamic variability using clinical and laboratory data improves the prediction of mortality in patients undergoing alloHCT.

DOI: https://doi.org/10.1182/bloodadvances.2023011752
Blood Adv. 2023 Nov 21. pii: bloodadvances.2023011916. [Epub ahead of print]

Very short insertions in the FLT3 gene are of therapeutic significance in acute myeloid leukemia.

Jérôme Tamburini, Sarah Mouche, Clement Larrue, Nicolas Duployez, Audrey Bidet, Auriane Salotti, Pierre Hirsch, Lucie Rigolot, Sylvain Carras, Marie Temple, Fabrizia Favale, Pascale Flandrin-Gresta, Yannick Le Bris, Anne-Sophie Alary, Laurent Mauvieux, Sylvie Tondeur, Eric Delabesse, Francois Delhommeau, Pierre Sujobert, Olivier Kosmider.

DOI: https://doi.org/10.1182/bloodadvances.2023011916
Clin Cancer Res. 2023 Nov 20. OF1-OF18

A PERK-Specific Inhibitor Blocks Metastatic Progression by Limiting Integrated Stress Response-Dependent Survival of Quiescent Cancer Cells.

Veronica Calvo, Wei Zheng, Anna Adam-Artigues, Kirk A Staschke, Xin Huang, Julie F Cheung, Ana Rita Nobre, Sho Fujisawa, David Liu, Maria Fumagalli, David Surguladze, Michael E Stokes, Ari Nowacek, Mark Mulvihill, Eduardo F Farias, Julio A Aguirre-Ghiso.

PURPOSE: The integrated stress response (ISR) kinase PERK serves as a survival factor for both proliferative and dormant cancer cells. We aim to validate PERK inhibition as a new strategy to specifically eliminate solitary disseminated cancer cells (DCC) in secondary sites that eventually reawake and originate metastasis.
EXPERIMENTAL DESIGN: A novel clinical-grade PERK inhibitor (HC4) was tested in mouse syngeneic and PDX models that present quiescent/dormant DCCs or growth-arrested cancer cells in micro-metastatic lesions that upregulate ISR.
RESULTS: HC4 significantly blocks metastasis, by killing quiescent/slow-cycling ISRhigh, but not proliferative ISRlow DCCs. HC4 blocked expansion of established micro-metastasis that contained ISRhigh slow-cycling cells. Single-cell gene expression profiling and imaging revealed that a significant proportion of solitary DCCs in lungs were indeed dormant and displayed an unresolved ER stress as revealed by high expression of a PERK-regulated signature. In human breast cancer metastasis biopsies, GADD34 expression (PERK-regulated gene) and quiescence were positively correlated. HC4 effectively eradicated dormant bone marrow DCCs, which usually persist after rounds of therapies. Importantly, treatment with CDK4/6 inhibitors (to force a quiescent state) followed by HC4 further reduced metastatic burden. In HNSCC and HER2+ cancers HC4 caused cell death in dormant DCCs. In HER2+ tumors, PERK inhibition caused killing by reducing HER2 activity because of sub-optimal HER2 trafficking and phosphorylation in response to EGF.
CONCLUSIONS: Our data identify PERK as a unique vulnerability in quiescent or slow-cycling ISRhigh DCCs. The use of PERK inhibitors may allow targeting of pre-existing or therapy-induced growth arrested "persister" cells that escape anti-proliferative therapies.

DOI: https://doi.org/10.1158/1078-0432.CCR-23-1427
Leukemia. 2023 Nov 22.

Mutations in DEAD/H-box helicase 11 correlate with increased relapse risk in adults with acute myeloid leukaemia with normal cytogenetics.

Ya-Lan Zhou, Ming-Yue Zhao, Robert Peter Gale, Hao Jiang, Qian Jiang, Li-Xia Liu, Jia-Yue Qin, Shan-Bo Cao, Feng Lou, Lan-Ping Xu, Xiao-Hui Zhang, Xiao-Jun Huang, Guo-Rui Ruan.

DOI: https://doi.org/10.1038/s41375-023-02085-7
Future Oncol. 2023 Nov 22.

Real-world outcomes with fedratinib therapy in patients who discontinued ruxolitinib for primary myelofibrosis.

Francesco Passamonti, Youbei Lou, Manoj Chevli, Pranav Abraham.

  Aim: Fedratinib is an oral selective JAK2 inhibitor approved in the USA for the treatment of adult patients with intermediate-2 or high-risk primary or secondary myelofibrosis (MF). Methods: This observational study assessed adult US patients who received ruxolitinib for primary MF (Flatiron Health database: 1 January 2011-31 October 2020). Patients were stratified by post-ruxolitinib treatment (fedratinib vs non-fedratinib). Results: Characteristics were comparable between fedratinib (n=70) and non-fedratinib (n=159) groups (median age: 71.0 vs 70.0 years; females: 55.7 vs 50.3%; median follow-up: 7.0 vs 6.0 months). Median overall survival (not reached vs 17 months) and 12 month survival (71.6 vs 53.5%) were improved with fedratinib versus the non-fedratinib therapies. Conclusion: In MF patients who received frontline ruxolitinib, survival was improved with subsequent fedratinib versus non-fedratinib care.

Keywords:  fedratinib; myelofibrosis; overall survival; real-world outcomes; ruxolitinib

DOI:  https://doi.org/10.2217/fon-2022-1256
Clin Lymphoma Myeloma Leuk. 2023 Oct 30. pii: S2152-2650(23)02158-4. [Epub ahead of print]

Clinical Outcomes in Patients With Refractory Anemia With Excess Blasts (RAEB) Who Receive Hypomethylating Agents (HMAs).

Amer M Zeidan, Elizabeth S Mearns, Carmen D Ng, Anuj Shah, Neil Lamarre, Archibong Yellow-Duke, Neda Alrawashdh, Baiyu Yang, Wei-Han Cheng, Cat N Bui, Anders Svensson.

   BACKGROUND: We sought to understand the clinical effectiveness associated with use of hypomethylating agents (HMAs) azacitidine (AZA) and decitabine (DEC) for patients with refractory anemia with excess blasts (RAEB; an established proxy for higher-risk myelodysplastic syndromes/neoplasms) in contemporary and representative real-world settings.
PATIENTS AND METHODS: We used the Surveillance, Epidemiology and End Results (SEER)-Medicare database, a linkage of cancer registry and Medicare claims data, to identify patients aged ≥ 66 years diagnosed with RAEB, between 2009 and 2017 in the United States, and who received AZA or DEC as first-line therapy. Outcomes measured were overall survival (OS), event-free survival (EFS), and incidence of progression-related acute myeloid leukemia (AML).
RESULTS: Of 973 eligible patients, 738 (75.8%) received AZA and 235 (24.2%) received DEC; 6.4% received hematopoietic cell transplantation during follow-up. In the overall population, median OS was 13.9 months (95% confidence interval [CI]: 12.9-15.0), median EFS was 5.2 months (95% CI: 4.9-5.7), and 38.0% of patients progressed to AML. Incidences of AML progression and death were 25.6% and 29.9%, respectively, at Year 1, and 34.3% and 44.8%, respectively, at Year 2. There were no significant differences in clinical benefits between AZA and DEC.
CONCLUSION: Median OS with both HMAs remained significantly shorter than in the AZA-001 clinical trial, highlighting how patient outcomes vary between clinical and real-world settings. Further research is required to understand why these disparities exist.

Keywords:  Azacitidine; Decitabine; HR MDS; SEER-Medicare

DOI:  https://doi.org/10.1016/j.clml.2023.10.010
Cancers (Basel). 2023 Nov 10. pii: 5360. [Epub ahead of print]15(22):

Standardization of Molecular MRD Levels in AML Using an Integral Vector Bearing ABL and the Mutation of Interest.

Boaz Nachmias, Svetlana Krichevsky, Moshe E Gatt, Noa Gross Even-Zohar, Adir Shaulov, Arnon Haran, Shlomzion Aumann, Vladimir Vainstein.

  Quantitative PCR for specific mutation is being increasingly used in Acute Myeloid Leukemia (AML) to assess Measurable Residual Disease (MRD), allowing for more tailored clinical decisions. To date, standardized molecular MRD is limited to typical NPM1 mutations and core binding factor translocations, with clear prognostic and clinical implications. The monitoring of other identified mutations lacks standardization, limiting its use and incorporation in clinical trials. To overcome this problem, we designed a plasmid bearing both the sequence of the mutation of interest and the ABL reference gene. This allows the use of commercial standards for ABL to determine the MRD response in copy number. We provide technical aspects of this approach as well as our experience with 19 patients with atypical NPM1, RUNX1 and IDH1/2 mutations. In all cases, we demonstrate a correlation between response and copy number. We further demonstrate how copy number monitoring can modulate the clinical management. Taken together, we provide proof of concept of a novel yet simple tool, which allows in-house MRD monitoring for identified mutations, with ABL-based commercial standards. This approach would facilitate large multi-center studies assessing the clinical relevance of selected MRD monitoring.

Keywords:  acute myeloid leukemia; measurable residual disease; plasmid base

DOI:  https://doi.org/10.3390/cancers15225360
Clin Cancer Res. 2023 Nov 22.

Development of resistance to type II JAK2 inhibitors in MPN depends on AXL kinase and is targetable.

Tamara Codilupi, Jakub Szybinski, Stefanie Arunasalam, Sarah Jungius, Andrew C Dunbar, Simona Stivala, Sime Brkic, Camille Albrecht, Lenka Vokalova, Julie L Yang, Katarzyna Buczak, Nilabh Ghosh, Jakob R Passweg, Alicia Rovo, Anne Angelillo-Scherrer, Dmitry Pankov, Stephan Dirnhofer, Ross L Levine, Richard Koche, Sara C Meyer.

PURPOSE: Myeloproliferative neoplasms (MPN) dysregulate JAK2 signaling. Since clinical JAK2 inhibitors have limited disease-modifying effects, type II JAK2 inhibitors such as CHZ868 stabilizing inactive JAK2 and reducing MPN clones, gain interest. We studied whether MPN cells escape from type ll inhibition.
METHODS: MPN cells were continuously exposed to CHZ868. We used phosphoproteomic analyses and ATAC-/RNA-sequencing to characterize acquired resistance to type II JAK2 inhibition, and targeted candidate mediators in MPN cells and mice.
RESULTS: MPN cells showed increased IC50 and reduced apoptosis upon CHZ868 reflecting acquired resistance to JAK2 inhibition. Among >2500 differential phospho-sites, MAPK pathway activation was most prominent, while JAK2-STAT3/5 remained suppressed. Altered histone occupancy promoting AP-1/GATA binding motif exposure associated with upregulated AXL kinase and enriched RAS target gene profiles. AXL knockdown resensitized MPN cells and combined JAK2/AXL inhibition using bemcentinib or gilteritinib reduced IC50 to levels of sensitive cells. While resistant cells induced tumor growth in NSG mice despite JAK2 inhibition, JAK2/AXL inhibition largely prevented tumor progression. Since inhibitors of MAPK pathway kinases such as MEK are clinically used in other malignancies, we evaluated JAK2/MAPK inhibition with trametinib to interfere with AXL-MAPK-induced resistance. Tumor growth was halted similarly to JAK2/AXL inhibition and in a systemic cell line-derived mouse model, marrow infiltration was decreased supporting dependency on AXL-MAPK.
CONCLUSIONS: We report on a novel mechanism of AXL-MAPK-driven escape from type II JAK2 inhibition, which is targetable at different nodes. This highlights AXL as mediator of acquired resistance warranting inhibition to enhance sustainability of JAK2 inhibition in MPN.

DOI: https://doi.org/10.1158/1078-0432.CCR-23-0163
JCO Glob Oncol. 2023 Sep;9 e2300229

Burden of AML, 1990-2019: Estimates From the Global Burden of Disease Study.

Chinmay T Jani, Alaaeldin Ahmed, Harpreet Singh, Christian Mouchati, Omar Al Omari, Padmanabh S Bhatt, Rajesh Sharma, Minaam Farooq, Weitao Liu, Joseph Shalhoub, Dominic Marshall, Justin D Salciccioli, Jeremy L Warner, Prudence Lam.

PURPOSE: AML accounts for 80% of acute leukemia in adults. While progress has been made in treating younger patients in the past 2 decades, there has been limited improvement for older patients until recently. This study examines the global and European Union (EU) 15+ trends in AML between 1990 and 2019.
METHODS: We extracted age-standardized incidence rates (ASIRs), age-standardized death rates (ASMRs), and disability-adjusted life years, stratified by sex from the Global Burden of Disease Study database, and mortality-to-incidence ratio (MIR) were computed. Trends were compared using Joinpoint regression.
RESULTS: The findings show a global increase in AML incidence for both sexes from 1990 to 2019. In the EU15+ countries, most countries exhibited an increase in ASIR for both sexes. Joinpoint revealed that globally for male patients, ASIR steadily increased until 2010, remained stable until 2015 followed by a decline till 2019. Similar trends were observed in female patients. For ASMR, although there was an increase globally and in most EU15+ countries, there was a statistically significant decrease in mortality rates globally and in the majority of EU15+ countries in recent years. MIR improved in both sexes globally. On age stratification, AML burden was highest among older groups (55 years and older), while the lowest rates were observed in younger than 20 years.
CONCLUSION: The findings from our study indicate a global rise in AML incidence and mortality in both sexes and decrease in MIR from 1990 to 2019 suggesting a better survival. However, on Joinpoint analysis, there is no change in MIR in women in the past decade and past 4 years in men indicating plateau in survival trends despite recent advances.

DOI: https://doi.org/10.1200/GO.23.00229
Blood. 2023 Nov 23. 142(21): 1846-1847

Wei AH, Panayiotidis P, Montesinos P, et al. Long-term follow-up of VIALE-C in patients with untreated AML ineligible for intensive chemotherapy. Blood. 2022;140(25):2754-2756.

DOI: https://doi.org/10.1182/blood.2023022753
Haematologica. 2023 Nov 16.

STAT5B mutations in myeloid neoplasms differ by disease subtypes but characterize a subset of chronic myeloid neoplasms with eosinophilia and/or basophilia.

C Cameron Yin, Wayne Tam, Serena M Walker, Amandeep Kaur, Madhu M Ouseph, Wei Xie, Olga K Weinberg, Peng Li, Zhuang Zuo, Mark J Routbort, Simon Chen, L Jeffrey Medeiros, Tracy I George, Attilio Orazi, Daniel A Arber, Adam Bagg, Robert P Hasserjian, Sa A Wang.

STAT5B has been reported as a recurrent mutation in myeloid neoplasms (MNs) with eosinophilia, but the overall frequency and importance across a spectrum of MNs are largely unknown. We conducted a multicenter study on a series of 82 MNs with STAT5B mutations detected by next-generation sequencing. The estimated frequency of STAT5B mutation in MNs was low.

DOI: https://doi.org/10.3324/haematol.2023.284311
Eur J Haematol. 2023 Nov 20.

Chronic myeloid leukemia (CML) in children and adolescents-Clinicopathological findings.

Louis Nevejan, Veerle Labarque, Nancy Boeckx.

   BACKGROUND: Barely two per million Belgian children/adolescents are diagnosed with chronic myeloid leukemia (CML) annually. In this retrospective study, we aimed to investigate the diagnostic features, clinical and laboratory characteristics, and treatment outcome of this rare entity.
METHODS: Medical records of all pediatric CML patients (age ≤ 17 years) diagnosed at the University Hospitals Leuven between 1986 and 2021 were reviewed.
RESULTS: Fourteen patients (median age at diagnosis 12.5 years) were included, all presenting in chronic phase. Five patients were diagnosed before 2003; main therapy included hydroxyurea (n = 5/5), interferon-alfa (n = 3/5) and allogeneic hematopoietic stem cell transplantation (allo-Tx) (n = 3/5). Complete hematologic response (CHR), complete cytogenetic response (CCyR) and major molecular response (MMR) was reached in resp. 4/5, 4/5 and in 2/3 of evaluable patients. Three patients progressed to accelerated/blast phase (median time 19 months) and 1/5 is alive and disease-free at last follow-up. Nine patients were diagnosed after 2003 and were treated with first generation (1°G) tyrosine kinase inhibitors (TKI): 3/9 subsequently underwent an allo-Tx, 4/9 were switched to 2°G TKI, one patient was additionally switched to 3°G TKI. CHR, CCyR and MMR was reached in 9/9, 9/9 and 8/9 of these patients. No progression to accelerated/blast phase was observed and none of these patients deceased. At last follow-up, 7/9 patients were in MMR or disease free, the two remaining patients did not reach or lost MMR, both related to compliance issues.
CONCLUSION: Our study confirmed that TKI significantly improved the prognosis of pediatric CML. However, drug compliance poses a considerable challenge.

Keywords:  chronic; drug compliance; imatinib mesylate; leukemia; myelogenous; pediatrics

DOI:  https://doi.org/10.1111/ejh.14137
Stem Cell Reports. 2023 Nov 08. pii: S2213-6711(23)00420-4. [Epub ahead of print]

DOT1L interaction partner AF10 controls patterning of H3K79 methylation and RNA polymerase II to maintain cell identity.

Coral K Wille, Edwin N Neumann, Aniruddha J Deshpande, Rupa Sridharan.

Histone 3 lysine 79 methylation (H3K79me) is enriched on gene bodies proportional to gene expression levels and serves as a strong barrier for the reprogramming of somatic cells to induced pluripotent stem cells (iPSCs). DOT1L is the sole histone methyltransferase that deposits all three orders-mono (me1), di (me2), and tri (me3) methylation-at H3K79. Here, we leverage genetic and chemical approaches to parse the specific functions of orders of H3K79me in maintaining cell identity. DOT1L interacts with AF10 (Mllt10), which recognizes unmodified H3K27 and boosts H3K79me2/3 methylation. AF10 deletion evicts H3K79me2/3 and reorganizes H3K79me1 to the transcription start site to facilitate iPSC formation in the absence of steady-state transcriptional changes. Instead, AF10 loss redistributes RNA polymerase II to a uniquely pluripotent pattern at highly expressed, rapidly transcribed housekeeping genes. Taken together, we reveal a specific mechanism for H3K79me2/3 located at the gene body in reinforcing cell identity.

DOI: https://doi.org/10.1016/j.stemcr.2023.10.017