Experimental hematology最新文献

{"title":"2017 – ARID1B-DEPENDENT ENHANCER REWIRING SUSTAINS KMT2A-MLLT3 LEUKEMIA AND EXPOSES A THERAPEUTIC VULNERABILITY","authors":"Jinyu Su, Sachin Pundhir, Marta Tapia, Adrija Kalvisa, Mikkel Schuster, Ying Ge, Linea Laursen, Maria Madsen, Jesper Madsen, Juerg Schwaller, Susanne Mandrup, Bo Porse","doi":"10.1016/j.exphem.2026.105545","DOIUrl":"10.1016/j.exphem.2026.105545","url":null,"abstract":"<div><div>KMT2A-rearranged acute myeloid leukemia (AML), one of the most treatment-refractory leukemic subtypes, is driven by fusion protein-mediated promoter hijacking of self-renewal genes such as HOXA9 and MEIS1. However, how these direct targets promote genome-wide transcriptional reprogramming remains incompletely resolved. Using a doxycycline-inducible KMT2A-MLLT3 mouse AML model combined with epigenomic profiling (ATAC-seq, ChIP-seq, promoter capture Hi-C), we demonstrate that KMT2A-MLLT3 supports the establishment of a two-phase oncogenic circuit by directly driving the expression of a set of core target genes, including HOXA9, MEIS1, and ARID1B, which subsequently unleashes a major remodeling of the enhancer landscape to sustain leukemogenesis. Pooled CRISPR knockout screens confirmed the functional requirement of these leukemia-activated enhancers for leukemic growth. We identify ARID1B, a subunit of the cBAF chromatin remodeling complex, as a key mediator of enhancer remodeling. Specifically, ARID1B supports accessibility at leukemia-activated enhancers, and its loss selectively collapses the enhancer program and impairs leukemic, but not normal hematopoietic, growth, across species. Clinically, high ARID1B expression correlates with earlier disease onset and leukemic stem cell transcriptional signatures. We further demonstrate that strengthening of the ARID1B-driven enhancer network is associated with BET inhibitor resistance, which can be overcome by combined cBAF and BET inhibition. Thus, our work identifies ARID1B-mediated enhancer remodeling as a key oncogenic driver in KMT2A-rearranged AML with potential clinical implications.</div></div><div>KMT2A-rearranged acute myeloid leukemia (AML), one of the most treatment-refractory leukemic subtypes, is driven by fusion protein-mediated promoter hijacking of self-renewal genes such as HOXA9 and MEIS1. However, how these direct targets promote genome-wide transcriptional reprogramming remains incompletely resolved. Using a doxycycline-inducible KMT2A-MLLT3 mouse AML model combined with epigenomic profiling (ATAC-seq, ChIP-seq, promoter capture Hi-C), we demonstrate that KMT2A-MLLT3 supports the establishment of a two-phase oncogenic circuit by directly driving the expression of a set of core target genes, including HOXA9, MEIS1, and ARID1B, which subsequently unleashes a major remodeling of the enhancer landscape to sustain leukemogenesis. Pooled CRISPR knockout screens confirmed the functional requirement of these leukemia-activated enhancers for leukemic growth. We identify ARID1B, a subunit of the cBAF chromatin remodeling complex, as a key mediator of enhancer remodeling. Specifically, ARID1B supports accessibility at leukemia-activated enhancers, and its loss selectively collapses the enhancer program and impairs leukemic, but not normal hematopoietic, growth, across species. Clinically, high ARID1B expression correlates with earlier disease onset and leukemic stem cell transcriptio","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105545"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2027 – DEVELOPMENTAL STAGE SHAPES LINEAGE FATE AND REVEALS A TARGETABLE PRELEUKEMIC STATE IN BCR::ABL1-DRIVEN LEUKEMIA","authors":"Miguel Quijada-Alamo, Grace Freed, Nikita Poddar, Saul Carcamo, Persephone Fiore, Isabella Martinez, Mimi Zhang, Ke Wang, Subrina Autar, Shayan Saniei, Clifford Chao, Lois Kelly, Zayna Diaz, Levan Mekerishvil, Franco Izzo, Dan Hasson, Elvin Wagenblast","doi":"10.1016/j.exphem.2026.105555","DOIUrl":"10.1016/j.exphem.2026.105555","url":null,"abstract":"<div><div>Clonal hematopoiesis, predominantly linked to myeloid malignancies, has established that premalignant stem cell states can precede overt disease; analogous lymphoid preleukemic states remain poorly defined. BCR::ABL1 offers a unique model to dissect how a shared lesion drives distinct phenotypes: its two major isoforms (p190, p210) preferentially associate with B-cell acute lymphoblastic leukemia (B-ALL) and chronic myeloid leukemia (CML), respectively. We generated humanized xenograft models by CRISPR/Cas9 engineering of human primary hematopoietic stem cells (HSCs) across four developmental states and performed integrated single-cell RNA-seq and ATAC-seq across >200,000 cells. BCR::ABL1-driven transformation was strikingly isoform- and developmental state-dependent: in adult HSCs, p210 induced a CML-like myeloid disease, whereas p190 promoted lymphoid-biased output. Early developmental HSCs did not support CML-like transformation, indicating that CML fate requires adults-stage HSCs and p210 signaling. Mechanistically, adult HSCs exhibited higher baseline chromatin accessibility at CEBP-family motifs than early development HSCs, further amplified by p210, supporting a model in which developmentally-defined epigenetic priming cooperates with oncogenic signaling to dictate lineage fate. Across developmental states, both isoforms expanded a distinct ProB_VDJ transcriptional state consistent with a lymphoid preleukemic maturation arrest marked by inflammatory activation (TNF-α, IFN-γ). BCR::ABL1⁺ HSCs also showed reduced quiescence and increased oxidative phosphorylation (OXPHOS); OXPHOS inhibition with metformin significantly reduced lymphoid preleukemic expansion in vivo. Together, developmental state constrains BCR::ABL1 lineage fate through chromatin accessibility and defines a conserved metabolic vulnerability of a lymphoid preleukemic stem cell state.</div></div><div>Clonal hematopoiesis, predominantly linked to myeloid malignancies, has established that premalignant stem cell states can precede overt disease; analogous lymphoid preleukemic states remain poorly defined. BCR::ABL1 offers a unique model to dissect how a shared lesion drives distinct phenotypes: its two major isoforms (p190, p210) preferentially associate with B-cell acute lymphoblastic leukemia (B-ALL) and chronic myeloid leukemia (CML), respectively. We generated humanized xenograft models by CRISPR/Cas9 engineering of human primary hematopoietic stem cells (HSCs) across four developmental states and performed integrated single-cell RNA-seq and ATAC-seq across >200,000 cells. BCR::ABL1-driven transformation was strikingly isoform- and developmental state-dependent: in adult HSCs, p210 induced a CML-like myeloid disease, whereas p190 promoted lymphoid-biased output. Early developmental HSCs did not support CML-like transformation, indicating that CML fate requires adults-stage HSCs and p210 signaling. Mechanistically, adult HSCs exhibited higher baseline chromati","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105555"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149233601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2012 – IDENTIFICATION OF CLONAL HEMATOPOIESIS ASSOCIATED-GENETIC VARIANTS THAT PERTURB REGULATORY ELEMENTS IN HEMATOPOIETIC STEM AND PROGENITOR CELLS","authors":"Trieu Nguyen, Jessica Jeejan, Takeshi Iwasaki, Susan Kales, Joyeeta Chakraborty, Chie Yanase, Aruna Shekhar, Dominika Kwasniak, Aditi Hegde, Richard Voit, Kristy Stengel, Keisuke Ito, Ryan Tewhey, Satish Nandakumar","doi":"10.1016/j.exphem.2026.105540","DOIUrl":"10.1016/j.exphem.2026.105540","url":null,"abstract":"<div><div>Clonal hematopoiesis of indeterminate potential (CHIP) is a premalignant state driven by the expansion of hematopoietic stem cell (HSC)-derived clones harboring somatic mutations. Although it is clear that germline variation contributes to CHIP risk, the underlying mechanisms remain poorly understood. A major challenge being that most genetic variants identified by genome-wide association studies (GWAS) on CHIP reside in the noncoding regions. We hypothesize that CHIP risk variants modulate enhancer elements active in HSCs. Using a massively parallel reporter assay (MPRA) with barcoded reporter constructs, we now assess regulatory effects of 1,374 noncoding variants across 51 CHIP-associated loci from the UK Biobank. We performed the lentiviral MPRA screen in CD34<sup>+</sup> fraction of MUTZ-3 cells, a HSC relevant model that enables screening at a scale currently challenging in primary HSCs. By measuring the barcode expression levels of ∼73,000 MPRA constructs, we identified 87 variants that show allele-specific enhancer activity. We used targeted genome editing to demonstrate endogenous enhancer activity across three MPRA variants that affect the transcription of NKD2, FLT3, and MSI2 in hematopoietic cells and further validated their reporter activities in primary human CD34<sup>+</sup> hematopoietic stem and progenitor cells (HSPCs). Our functional studies on MSI2 variant indicate that the presence of higher levels of MSI2 mediated by CHIP risk allele enhances the clonal expansion of murine TET2 deficient HSPCs. RNA-Seq analysis show that both MSI2 and TET2 gene networks are activated upon MSI2 upregulation in TET2 deficient HSPCs. Furthermore, by modeling the nonrisk allele we show that MSI2 expression is required for TET2-deficient hematopoietic stem and progenitor cell (HSPC) self-renewal. Taken together, our data provide a mechanistic link whereby noncoding genetic variants can influence the expansion of mutant CHIP clones.</div></div><div>Clonal hematopoiesis of indeterminate potential (CHIP) is a premalignant state driven by the expansion of hematopoietic stem cell (HSC)-derived clones harboring somatic mutations. Although it is clear that germline variation contributes to CHIP risk, the underlying mechanisms remain poorly understood. A major challenge being that most genetic variants identified by genome-wide association studies (GWAS) on CHIP reside in the noncoding regions. We hypothesize that CHIP risk variants modulate enhancer elements active in HSCs. Using a massively parallel reporter assay (MPRA) with barcoded reporter constructs, we now assess regulatory effects of 1,374 noncoding variants across 51 CHIP-associated loci from the UK Biobank. We performed the lentiviral MPRA screen in CD34<sup>+</sup> fraction of MUTZ-3 cells, a HSC relevant model that enables screening at a scale currently challenging in primary HSCs. By measuring the barcode expression levels of ∼73,000 MPRA constructs, we identified 87 variants that","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105540"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149233748","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"1010 – INFORMING THERAPEUTIC APPROACHES FOR TP53 MUTANT BLOOD CANCERS","authors":"Gemma Kelly,&nbsp;Elizabeth Lieschke,&nbsp;Zilu Wang,&nbsp;Tianwei Chen,&nbsp;Reet Bhandari,&nbsp;Andrew Kueh,&nbsp;Lin Tai,&nbsp;Marco Herold,&nbsp;Kate Sutherland,&nbsp;Andreas Strasser","doi":"10.1016/j.exphem.2026.105506","DOIUrl":"10.1016/j.exphem.2026.105506","url":null,"abstract":"<div><div>Mutations in the tumor suppressor <em>p53</em> are common in relapsed and refractory blood cancers. Despite decades of research, it is still not clear how mutant <em>p53</em> contributes to sustained tumor growth. Understanding this will inform therapeutic approaches for patients with mutant p53 blood cancers. To address this, we have generated novel mouse models in which the endogenous <em>p53</em> locus can be switched between different <em>p53</em> states (mutant, wild-type, and knock-out) at will. We have crossed these mice to lymphoma-prone mouse models to allow a systematic assessment of the role of mutant p53 in lymphoma growth and responses to therapy.</div></div><div>Mutations in the tumor suppressor <em>p53</em> are common in relapsed and refractory blood cancers. Despite decades of research, it is still not clear how mutant <em>p53</em> contributes to sustained tumor growth. Understanding this will inform therapeutic approaches for patients with mutant p53 blood cancers. To address this, we have generated novel mouse models in which the endogenous <em>p53</em> locus can be switched between different <em>p53</em> states (mutant, wild-type, and knock-out) at will. We have crossed these mice to lymphoma-prone mouse models to allow a systematic assessment of the role of mutant p53 in lymphoma growth and responses to therapy.</div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105506"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149233763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"1012 – REGENERATION OF HEALTHY AND MALIGNANT HAEMATOPOIESIS: SIMILAR SIDES OF TWO VERY DIFFERENT COINS","authors":"Cristina Lo Celso","doi":"10.1016/j.exphem.2026.105508","DOIUrl":"10.1016/j.exphem.2026.105508","url":null,"abstract":"<div><div>Hematopoietic stem cells (HSCs) maintain the turnover of all blood cells, involving the generation of billions and trillions of new cells every day in mice and humans. Although mostly quiescent, various stresses induce HSCs to increase proliferation and differentiate to cope with increased demand for differentiated progeny. These responses have been widely associated with loss of functional HSCs. Over the last few years, my group has focused on understanding the mechanisms leading to HSC damage during acute, severe infection, using natural rodent malaria models. In particular, we have focused on the role of the bone marrow microenvironment in mediating such damage and as a potential therapeutic target to safeguard HSC numbers and function. More recently, we started exploring mechanisms of regeneration.</div><div>Leukemia is a cancer of the blood, developing in the bone marrow and overtaking healthy hematopoiesis. Acute myeloid leukemia (AML) is the prime example of a stem cell-based cancer and is particularly difficult to treat due to the ability of leukemia stem cells (LSCs) to evade therapeutic interventions. Similar to healthy HSCs, LSCs are affected by inflammatory stimuli, and we have recently focused on the interplay between AML cells, bone marrow macrophages, and T cells to identify novel potential vulnerabilities that could be targeted to avoid relapse.</div></div><div>Hematopoietic stem cells (HSCs) maintain the turnover of all blood cells, involving the generation of billions and trillions of new cells every day in mice and humans. Although mostly quiescent, various stresses induce HSCs to increase proliferation and differentiate to cope with increased demand for differentiated progeny. These responses have been widely associated with loss of functional HSCs. Over the last few years, my group has focused on understanding the mechanisms leading to HSC damage during acute, severe infection, using natural rodent malaria models. In particular, we have focused on the role of the bone marrow microenvironment in mediating such damage and as a potential therapeutic target to safeguard HSC numbers and function. More recently, we started exploring mechanisms of regeneration.</div><div>Leukemia is a cancer of the blood, developing in the bone marrow and overtaking healthy hematopoiesis. Acute myeloid leukemia (AML) is the prime example of a stem cell-based cancer and is particularly difficult to treat due to the ability of leukemia stem cells (LSCs) to evade therapeutic interventions. Similar to healthy HSCs, LSCs are affected by inflammatory stimuli, and we have recently focused on the interplay between AML cells, bone marrow macrophages, and T cells to identify novel potential vulnerabilities that could be targeted to avoid relapse.</div>","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105508"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149233765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2047 – AGING ENHANCES IL-1β RESPONSIVENESS IN HUMAN BONE MARROW HEMATOPOIETIC STEM CELLS","authors":"Monica Kasbekar,&nbsp;Jun Hou Fung,&nbsp;Melissa Proven,&nbsp;Raul Rabadan,&nbsp;Emmanuelle Passegué","doi":"10.1016/j.exphem.2026.105575","DOIUrl":"10.1016/j.exphem.2026.105575","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Human hematopoietic stem cells (HSCs) demonstrate age-related molecular changes, such as increased inflammatory pathway activation; however, the functional consequences on bone marrow (BM) HSC behavior remain incompletely understood. To address this question, we characterized 104,224 human BM HSCs (CD34&lt;sup&gt;+&lt;/sup&gt;/CD38&lt;sup&gt;–&lt;/sup&gt;/CD45RA&lt;sup&gt;–&lt;/sup&gt;/CD90&lt;sup&gt;+&lt;/sup&gt;) from 20 vertebral BM samples spanning 8–66 years of age using single-cell RNA sequencing. We identified an age-dependent increase in interleukin-1 (IL-1)–mediated signaling within the HSC compartment. We next examined the effects of IL-1β on human BM HSCs across multiple model systems. Although aging diminished overall HSC expansion in liquid culture, IL-1β preferentially enhanced expansion and promoted myeloid differentiation in old HSCs relative to young. Mechanistically, we observed age-dependent augmentation of IL-1β–induced NF-κβ activation in old HSCs. Bulk RNA sequencing of IL-1β–treated HSCs demonstrated enrichment of NF-κβ target genes in old samples, and single-cell ATAC-sequencing revealed increased accessibility of NF-κβ–associated transcription factor motifs, including REL and RELA. Consistent with these findings, confocal microscopy demonstrated increased nuclear localization of p65 following IL-1β treatment in old HSCs. To evaluate in vivo relevance, we transplanted human HSCs into NSG mice and treated engrafted recipients with intraperitoneal IL-1β for 7 days. IL-1β treatment resulted in enhanced human monocytic differentiation in mice engrafted with old HSCs compared with young, consistent with the increased age-dependent myeloid differentiation observed in vitro. Collectively, these findings demonstrate age-associated hypersensitivity of human BM HSCs to IL-1β mediated by enhanced NF-κβ responsiveness, providing a framework to understand how aging may reshape hematopoietic responses during inflammatory stress.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;Human hematopoietic stem cells (HSCs) demonstrate age-related molecular changes, such as increased inflammatory pathway activation; however, the functional consequences on bone marrow (BM) HSC behavior remain incompletely understood. To address this question, we characterized 104,224 human BM HSCs (CD34&lt;sup&gt;+&lt;/sup&gt;/CD38&lt;sup&gt;–&lt;/sup&gt;/CD45RA&lt;sup&gt;–&lt;/sup&gt;/CD90&lt;sup&gt;+&lt;/sup&gt;) from 20 vertebral BM samples spanning 8–66 years of age using single-cell RNA sequencing. We identified an age-dependent increase in interleukin-1 (IL-1)–mediated signaling within the HSC compartment. We next examined the effects of IL-1β on human BM HSCs across multiple model systems. Although aging diminished overall HSC expansion in liquid culture, IL-1β preferentially enhanced expansion and promoted myeloid differentiation in old HSCs relative to young. Mechanistically, we observed age-dependent augmentation of IL-1β–induced NF-κβ activation in old HSCs. Bulk RNA sequencing of IL-1β–treated HSCs demonstrated enrichment of NF-κβ target genes in old samples, and singl","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105575"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3269 – ANTIBODY-MEDIATED INHIBITION OF ITGΒ8 MITIGATES MYELOFIBROSIS IN HUMAN BONE MARROW ORGANOIDS AND MURINE PRECLINICAL MODELS.","authors":"Melodie Doute,&nbsp;Lyudmila Tsurkan,&nbsp;Jayaram Sakthi,&nbsp;Lei Han,&nbsp;Nicholas Morchel,&nbsp;Dean Sheppard,&nbsp;Peter Vogel,&nbsp;John Crispino,&nbsp;Marta Derecka","doi":"10.1016/j.exphem.2026.105591","DOIUrl":"10.1016/j.exphem.2026.105591","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The bone marrow (BM) microenvironment and mesenchymal stromal cells (MSCs) maintain BM homeostasis and support hematopoietic cells. In blood malignancies, hematopoietic stem cells can acquire somatic mutations that create an onco-niche, disrupting hematopoiesis and driving disease progression. In myelofibrosis (MF), mutant clones carrying &lt;em&gt;MPL, CALR&lt;/em&gt;, or &lt;em&gt;JAK2&lt;/em&gt; mutations reprogram MSCs, causing BM fibrosis. Our laboratory identified the transcription factor early B-cell factor 1 (EBF1) as a key regulator of MSC fibrotic remodeling in MF. Since targeting EBF1 is therapeutically challenging, we identified integrin β8 (ITGβ8), an EBF1-regulated gene in BM MSCs, as a potential therapeutic modality. ITGβ8 is a major contributor to the activation of profibrotic transforming growth factor β (TGF-β). MSC-specific Itgβ8 deletion showed a significant decrease in BM fibrosis, highlighting its contribution in MSCs during MF. Current therapeutic strategies for MF mostly target mutant hematopoietic clones but do not address fibrosis and the damaged BM niche. We evaluated the therapeutic potential of targeting ITGβ8 during MF, using a neutralizing antibody. Although ⍺-ITGβ8 treatment did not affect normal HSC engraftment or multilineage reconstitution, it significantly diminished expansion of mutant blood clones and BM fibrosis during MF in mice. To apply our findings to human MF, we used innovative induced pluripotent stem cell (iPSC)-derived BM organoids (BMO) to study the effect of ⍺-ITGβ8 treatment in the human context. BMOs engrafted with JAK2V617F CD34+ HSPCs show hallmarks of BM fibrosis. Treatment with ⍺-ITGβ8 reduced JAK2V617F clone proliferation and diminished collagen production in BMOs, suggesting reduced fibrotic remodeling of the niche and diminished MF progression. Overall, our findings demonstrated the therapeutic potential of ⍺-ITGβ8 in MF and show that targeting ITGβ8 in MSCs reduces BM fibrosis in both mouse and human models of MF.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;The bone marrow (BM) microenvironment and mesenchymal stromal cells (MSCs) maintain BM homeostasis and support hematopoietic cells. In blood malignancies, hematopoietic stem cells can acquire somatic mutations that create an onco-niche, disrupting hematopoiesis and driving disease progression. In myelofibrosis (MF), mutant clones carrying &lt;em&gt;MPL, CALR&lt;/em&gt;, or &lt;em&gt;JAK2&lt;/em&gt; mutations reprogram MSCs, causing BM fibrosis. Our laboratory identified the transcription factor early B-cell factor 1 (EBF1) as a key regulator of MSC fibrotic remodeling in MF. Since targeting EBF1 is therapeutically challenging, we identified integrin β8 (ITGβ8), an EBF1-regulated gene in BM MSCs, as a potential therapeutic modality. ITGβ8 is a major contributor to the activation of profibrotic transforming growth factor β (TGF-β). MSC-specific Itgβ8 deletion showed a significant decrease in BM fibrosis, highlighting its contribution in MSCs during MF. Current therapeutic strategies for MF mostly targ","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105591"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3272 – DELINEATION OF ANTIGEN PRESENTATION MODULATION FOR TAILORED TREATMENTS OF INFANT AND ADULT LEUKEMIA","authors":"Sudip Ghosh,&nbsp;Johannes Nilsson,&nbsp;Rita Azevedo Sousa e Silva,&nbsp;Mina Davoudi,&nbsp;Sarvani Arza,&nbsp;Somdatta Pal,&nbsp;Louise Olsson,&nbsp;Yanan Chen,&nbsp;Joanna Watral,&nbsp;Jia'er Wang,&nbsp;Ariana Calderón,&nbsp;Melinda Rezeli,&nbsp;Charlotta Böiers,&nbsp;Filipe Pereira,&nbsp;Jenny Hansson","doi":"10.1016/j.exphem.2026.105876","DOIUrl":"10.1016/j.exphem.2026.105876","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Infant leukemia arising during the first year of life is dominated by &lt;em&gt;KMT2A&lt;/em&gt;-rearrangements and represents a highly aggressive childhood cancer. To support their own growth, leukemia cells deregulate the antigen-presentation-driven communication with the immune system, reducing immune recognition and evading immune surveillance. Recent evidence, including from our laboratory, indicates that immunostimulation of leukemic cells with proinflammatory cytokines like interferon α (IFNα) can restore major histocompatibility complex (MHC) expression and offers a strategy to overcome immune escape and to reshape the leukemic immunopeptidome. In this study, we aimed to advance our understanding of the antigen repertoires’ opportunities for alterations in infant and adult leukemia and outline a treatment strategy that combines inflammatory stimulation and targeting of leukemia-specific immunopeptides. We integrated mass spectrometry-based immunopeptidomics with whole-cell proteomics to characterize IFNα-induced alterations in protein abundance and antigen presentation in inducible mouse models of KMT2A::MLLT1- and KMT2A::AFF1-driven leukemogenesis and in infant and adult &lt;em&gt;KMT2A&lt;/em&gt;-rearranged leukemic cell lines. Bulk RNA sequencing was integrated with the proteomics and immunopeptidomics data to identify noncanonical transcripts, enabling the detection of peptides derived from the so-called “dark proteome,” unannotated genomic regions capable of generating previously uncharacterized MHC ligands. This multiomics approach revealed distinct patterns of immune modulation in leukemic cells compared with healthy cells. IFNα stimulation also induced novel, leukemia-specific immunopeptides. Together, these findings may support the development of combinatorial therapeutic strategies that enhance immunogenicity through MHC upregulation while enabling the targeted elimination of leukemic cells via unique immunopeptide signatures.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;Infant leukemia arising during the first year of life is dominated by &lt;em&gt;KMT2A&lt;/em&gt;-rearrangements and represents a highly aggressive childhood cancer. To support their own growth, leukemia cells deregulate the antigen-presentation-driven communication with the immune system, reducing immune recognition and evading immune surveillance. Recent evidence, including from our laboratory, indicates that immunostimulation of leukemic cells with proinflammatory cytokines like interferon α (IFNα) can restore major histocompatibility complex (MHC) expression and offers a strategy to overcome immune escape and to reshape the leukemic immunopeptidome. In this study, we aimed to advance our understanding of the antigen repertoires’ opportunities for alterations in infant and adult leukemia and outline a treatment strategy that combines inflammatory stimulation and targeting of leukemia-specific immunopeptides. We integrated mass spectrometry-based immunopeptidomics with whole-cell proteomics to characterize IFNα-ind","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105876"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3259 – C-TERMINAL CEBPA MUTATIONS INDUCE DOSE-DEPENDENT MYELOID DIFFERENTIATION BLOCK IN ISOGENIC IPSC MODELS","authors":"Antonio Benedetto Ventura,&nbsp;Giacomo Volpe,&nbsp;Lucia Deligio,&nbsp;Luigi Viggiano,&nbsp;Antonio Negri","doi":"10.1016/j.exphem.2026.105581","DOIUrl":"10.1016/j.exphem.2026.105581","url":null,"abstract":"&lt;div&gt;&lt;h3&gt;Background&lt;/h3&gt;&lt;div&gt;CCAAT/enhancer-binding protein α (CEBPA) encodes a leucine zipper transcription factor required for cell cycle arrest and commitment of hematopoietic stem and progenitor cells (HSPCs) to the granulocytic lineage. C-terminal in-frame mutations affecting the basic leucine zipper (bZIP) domain impair dimerization and DNA binding, contributing to the differentiation block typical of acute myeloid leukemia (AML). Since monoallelic and biallelic mutations are associated with distinct clinical outcomes, genotype-specific mechanisms remain to be clarified.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;CCAAT/enhancer-binding protein α (CEBPA) encodes a leucine zipper transcription factor required for cell cycle arrest and commitment of hematopoietic stem and progenitor cells (HSPCs) to the granulocytic lineage. C-terminal in-frame mutations affecting the basic leucine zipper (bZIP) domain impair dimerization and DNA binding, contributing to the differentiation block typical of acute myeloid leukemia (AML). Since monoallelic and biallelic mutations are associated with distinct clinical outcomes, genotype-specific mechanisms remain to be clarified.&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Aims&lt;/h3&gt;&lt;div&gt;To generate isogenic induced pluripotent stem cell (iPSC) lines carrying C-terminal CEBPA mutations and evaluate the impact of monoallelic and biallelic genotypes on HSPC maturation and myeloid differentiation.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;To generate isogenic induced pluripotent stem cell (iPSC) lines carrying C-terminal CEBPA mutations and evaluate the impact of monoallelic and biallelic genotypes on HSPC maturation and myeloid differentiation.&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Methods&lt;/h3&gt;&lt;div&gt;Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) was used to introduce C-terminal deletions in two hiPSC lines, generating wild-type (WT), monoallelic, and biallelic clones. Cells were differentiated into CD34+ HSPCs and subsequently induced toward granulocytic and monocytic lineages. Differentiation was assessed by flow cytometry and cytomorphology. CD34+ cells were analyzed using single-cell RNA sequencing (scRNA-seq) and colony-forming assays.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) was used to introduce C-terminal deletions in two hiPSC lines, generating wild-type (WT), monoallelic, and biallelic clones. Cells were differentiated into CD34+ HSPCs and subsequently induced toward granulocytic and monocytic lineages. Differentiation was assessed by flow cytometry and cytomorphology. CD34+ cells were analyzed using single-cell RNA sequencing (scRNA-seq) and colony-forming assays.&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Results&lt;/h3&gt;&lt;div&gt;All genotypes efficiently generated CD34+ HSPCs, indicating preserved early hematopoietic potential. WT clones produced mature granulocytes and monocytes, whereas monoallelic mutants showed reduced myeloid output and biallelic mutants displayed a marked differentiation block. scRNA-seq reveal","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105581"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"2010 – INTRACELLULAR CHOLESTEROL SEQUESTRATION IN MULTIVESICULAR BODIES DRIVES METABOLIC QUIESCENCE AND LSC PERSISTENCE IN DNMT3A/NPM1-MUTATED AML","authors":"Elisa Donato,&nbsp;Roberto Würth,&nbsp;Maria Puschhof,&nbsp;Nadia Correia,&nbsp;Carolin Andresen,&nbsp;Darja Karpova,&nbsp;Nesrine Aroua,&nbsp;Michele Neßling,&nbsp;Karsten Richter,&nbsp;Christopher Manring,&nbsp;Deedra Nicolet,&nbsp;Halvard Bönig,&nbsp;Christoph Röllig,&nbsp;Anna Dolnik,&nbsp;Lars Bullinger,&nbsp;Frank Buchholz,&nbsp;Christian Thiede,&nbsp;Daniel Hübschmann,&nbsp;Ann-Kathrin Eisfeld,&nbsp;Andreas Trumpp","doi":"10.1016/j.exphem.2026.105538","DOIUrl":"10.1016/j.exphem.2026.105538","url":null,"abstract":"&lt;div&gt;&lt;div&gt;AML relapse is fueled by leukemia stem cells (LSCs) whose phenotypic and metabolic plasticity enables dynamic adaptation to therapeutic pressure. By mapping the LSC metabolic landscape through therapy, we uncovered metabolic dependencies and identified actionable drivers of treatment evasion.&lt;/div&gt;&lt;div&gt;We performed integrated transcriptomic and functional profiling of 46 primary DNMT3A/NPM1-mutated diagnostic samples, stratified by clinical outcome. To resolve resistance, patient-derived xenograft (PDX) models were treated with chemotherapy, the oxidative phosphorylation (OxPHOS) inhibitor IACS-010759, or their combination, and residual persister cells were analyzed using CITE-seq.&lt;/div&gt;&lt;div&gt;High OxPHOS characterized LSCs from patients with early relapse compared with those achieving long-term remission. However, although PDX models confirmed initial sensitivity to IACS, responses were transient; rapid leukemic rebound followed drug withdrawal. CITE-seq of residual cells revealed a pre-existing persister subpopulation that survived all treatment arms. These cells show the highest LSC17 stemness scores and the lowest level of cholesterol homeostasis genes. We show that this low-cholesterol signature is associated to the physical sequestration of free intracellular cholesterol within cytoplasmic multivesicular bodies (MVBs). This sequestration acts as a metabolic shield, maintaining LSCs in a quiescent, chemoresistant state. Pharmacological disruption of these reservoirs via statins significantly impaired LSC rebound.&lt;/div&gt;&lt;div&gt;In conclusion, although high OxPHOS is a transient vulnerability, intracellular cholesterol sequestration in MVBs is a core mechanism of LSC quiescence and long-term persistence. Corroborating this, we show that statin intake correlates with improved relapse-free survival in AML patients. Targeting the MVB–cholesterol axis represents a novel strategy to sensitize persister LSCs to conventional therapy.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;AML relapse is fueled by leukemia stem cells (LSCs) whose phenotypic and metabolic plasticity enables dynamic adaptation to therapeutic pressure. By mapping the LSC metabolic landscape through therapy, we uncovered metabolic dependencies and identified actionable drivers of treatment evasion.&lt;/div&gt;&lt;div&gt;We performed integrated transcriptomic and functional profiling of 46 primary DNMT3A/NPM1-mutated diagnostic samples, stratified by clinical outcome. To resolve resistance, patient-derived xenograft (PDX) models were treated with chemotherapy, the oxidative phosphorylation (OxPHOS) inhibitor IACS-010759, or their combination, and residual persister cells were analyzed using CITE-seq.&lt;/div&gt;&lt;div&gt;High OxPHOS characterized LSCs from patients with early relapse compared with those achieving long-term remission. However, although PDX models confirmed initial sensitivity to IACS, responses were transient; rapid leukemic rebound followed drug withdrawal. CITE-seq of residual cells revealed a pre-existing persis","PeriodicalId":12202,"journal":{"name":"Experimental hematology","volume":"162 ","pages":"Article 105538"},"PeriodicalIF":2.7,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149234112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}