Blood Cancer Discovery最新文献

{"title":"The Polyamine-Hypusine Circuit Controls an Oncogenic Translational Program Essential for Malignant Conversion in MYC-Driven Lymphoma.","authors":"Shima Nakanishi, Jiannong Li, Anders E Berglund, Youngchul Kim, Yonghong Zhang, Ling Zhang, Chunying Yang, Jinming Song, Raghavendra G Mirmira, John L Cleveland","doi":"10.1158/2643-3230.BCD-22-0162","DOIUrl":"10.1158/2643-3230.BCD-22-0162","url":null,"abstract":"<p><p>The MYC oncoprotein is activated in a broad spectrum of human malignancies and transcriptionally reprograms the genome to drive cancer cell growth. Given this, it is unclear if targeting a single effector of MYC will have therapeutic benefit. MYC activates the polyamine-hypusine circuit, which posttranslationally modifies the eukaryotic translation factor eIF5A. The roles of this circuit in cancer are unclear. Here we report essential intrinsic roles for hypusinated eIF5A in the development and maintenance of MYC-driven lymphoma, where the loss of eIF5A hypusination abolishes malignant transformation of MYC-overexpressing B cells. Mechanistically, integrating RNA sequencing, ribosome sequencing, and proteomic analyses revealed that efficient translation of select targets is dependent upon eIF5A hypusination, including regulators of G1-S phase cell-cycle progression and DNA replication. This circuit thus controls MYC's proliferative response, and it is also activated across multiple malignancies. These findings suggest the hypusine circuit as a therapeutic target for several human tumor types.</p><p><strong>Significance: </strong>Elevated EIF5A and the polyamine-hypusine circuit are manifest in many malignancies, including MYC-driven tumors, and eIF5A hypusination is necessary for MYC proliferative signaling. Not-ably, this circuit controls an oncogenic translational program essential for the development and maintenance of MYC-driven lymphoma, supporting this axis as a target for cancer prevention and treatment. See related commentary by Wilson and Klein, p. 248. This article is highlighted in the In This Issue feature, p. 247.</p>","PeriodicalId":29944,"journal":{"name":"Blood Cancer Discovery","volume":"4 4","pages":"294-317"},"PeriodicalIF":11.2,"publicationDate":"2023-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10320645/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9788123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An MYC-Driven Vicious Circuit Is a Targetable Achilles' Heel in Lymphoma.","authors":"Erica B Wilson, Ulf Klein","doi":"10.1158/2643-3230.BCD-23-0053","DOIUrl":"10.1158/2643-3230.BCD-23-0053","url":null,"abstract":"<p><strong>Summary: </strong>In this issue of Blood Cancer Discovery, Nakanishi et al. uncover a critical role for the elevated activity of the translation initiation factor eIF5A in the malignant growth of MYC-driven lymphoma. eIF5A is posttranslationally modified by hypusination through MYC oncoprotein-mediated hyperactivation of the polyamine-hypusine circuit, which may represent a promising therapeutic target because an enzyme of this circuit that is required for hypusinating eIF5A proved to be essential for lymphoma development. See related article by Nakanishi et al., p. 294 (4).</p>","PeriodicalId":29944,"journal":{"name":"Blood Cancer Discovery","volume":"4 4","pages":"248-251"},"PeriodicalIF":11.2,"publicationDate":"2023-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10320646/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9853800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Role of Inflammation in the Initiation and Progression of Myeloid Neoplasms.","authors":"Juan Carlos Balandrán, Audrey Lasry, Iannis Aifantis","doi":"10.1158/2643-3230.BCD-22-0176","DOIUrl":"10.1158/2643-3230.BCD-22-0176","url":null,"abstract":"<p><p>Myeloid malignancies are devastating hematologic cancers with limited therapeutic options. Inflammation is emerging as a novel driver of myeloid malignancy, with important implications for tumor composition, immune response, therapeutic options, and patient survival. Here, we discuss the role of inflammation in normal and malignant hematopoiesis, from clonal hematopoiesis to full-blown myeloid leukemia. We discuss how inflammation shapes clonal output from hematopoietic stem cells, how inflammation alters the immune microenvironment in the bone marrow, and novel therapies aimed at targeting inflammation in myeloid disease.</p><p><strong>Significance: </strong>Inflammation is emerging as an important factor in myeloid malignancies. Understanding the role of inflammation in myeloid transformation, and the interplay between inflammation and other drivers of leukemogenesis, may yield novel avenues for therapy.</p>","PeriodicalId":29944,"journal":{"name":"Blood Cancer Discovery","volume":"4 4","pages":"254-266"},"PeriodicalIF":11.2,"publicationDate":"2023-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10320626/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"10000381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microbiota Influences on Hematopoiesis and Blood Cancers: New Horizons?","authors":"Jessica R Galloway-Peña, Christian Jobin","doi":"10.1158/2643-3230.BCD-22-0172","DOIUrl":"10.1158/2643-3230.BCD-22-0172","url":null,"abstract":"<p><p>Hematopoiesis governs the generation of immune cells through the differentiation of hematopoietic stem cells (HSC) into various progenitor cells, a process controlled by intrinsic and extrinsic factors. Among extrinsic factors influencing hematopoiesis is the microbiota, or the collection of microorganisms present in various body sites. The microbiota has a profound impact on host homeostasis by virtue of its ability to release various molecules and structural components, which promote normal organ function. In this review, we will discuss the role of microbiota in influencing hematopoiesis and how disrupting the microbiota/host network could lead to hematologic malignancies, as well as highlight important knowledge gaps to move this field of research forward.</p><p><strong>Significance: </strong>Microbiota dysfunction is associated with many pathologic conditions, including hematologic malignancies. In this review, we discuss the role of microbiota in influencing hematopoiesis and how disrupting the microbiota/host network could lead to hematologic malignancies. Understanding how the microbiota influences hematologic malignancies could have an important therapeutic impact for patients.</p>","PeriodicalId":29944,"journal":{"name":"Blood Cancer Discovery","volume":"4 4","pages":"267-275"},"PeriodicalIF":11.5,"publicationDate":"2023-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10320642/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9846734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abstract A04: Modulation of RNA splicing enhances response to BCL2 inhibition in leukemia","authors":"Eric Wang, Omar Abdel-Wahab, Robert K Bradley, Jose Mario Bello, Won Jun Kim, Carine Bossard","doi":"10.1158/2643-3249.aml23-a04","DOIUrl":"https://doi.org/10.1158/2643-3249.aml23-a04","url":null,"abstract":"Abstract Therapy resistance is a major challenge in the treatment of cancer. Here, we performed CRISPR/Cas9 screens across a broad range of therapies used in acute myeloid leukemia to identify genomic determinants of drug response. Our screens uncovered a selective dependency on RNA splicing factors whose loss preferentially enhanced response to the BCL2 inhibitor venetoclax. Loss of the splicing factor RBM10 augmented response to venetoclax in leukemia yet was completely dispensable for normal hematopoiesis. Combined RBM10 and BCL2 inhibition led to mis-splicing and inactivation of the inhibitor of apoptosis XIAP and downregulation of BCL2A1, an anti-apoptotic protein implicated in venetoclax resistance. A novel inhibitor of splicing kinase families CLKs and DYRKs led to aberrant splicing of key splicing and apoptotic factors that synergized with venetoclax and overcame resistance to BCL2 inhibition. Our findings underscore the importance of splicing in modulating response to therapies and provide a strategy to improve venetoclax-based treatments. Citation Format: Eric Wang, Omar Abdel-Wahab, Robert K Bradley, Jose Mario Bello, Won Jun Kim, Carine Bossard. Modulation of RNA splicing enhances response to BCL2 inhibition in leukemia [abstract]. In: Proceedings of the AACR Special Conference: Acute Myeloid Leukemia and Myelodysplastic Syndrome; 2023 Jan 23-25; Austin, TX. Philadelphia (PA): AACR; Blood Cancer Discov 2023;4(3_Suppl):Abstract nr A04.","PeriodicalId":29944,"journal":{"name":"Blood Cancer Discovery","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136096448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Global Shift in Alternative Splicing and Therapeutic Susceptibilities in Leukemia Driven by METTL3 Overexpression.","authors":"Maxime Janin,&nbsp;Manel Esteller","doi":"10.1158/2643-3230.BCD-23-0035","DOIUrl":"10.1158/2643-3230.BCD-23-0035","url":null,"abstract":"<p><strong>Summary: </strong>Mutations in splicing factors are commonly observed in chronic lymphocytic leukemia (CLL); however, other mechanisms can also contribute to the dysregulation of alternative splicing. One example is the overexpression of the m6A RNA methyltransferase METTL3, that by depositing the epitranscriptomic mark in spliceosome transcripts leads to aberrant splicing, but at the same time creates vulnerability to METTL3 inhibitors. See related article by Wu et al., p. 228 (8) .</p>","PeriodicalId":29944,"journal":{"name":"Blood Cancer Discovery","volume":"4 3","pages":"176-179"},"PeriodicalIF":11.2,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10150279/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9630410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abstract A26: Age and Dose Related Changes to the Bone Marrow Microenvironment after Cytotoxic Conditioning with Busulfan","authors":"J. Spencer, C. Burns, R. Verrinder, Farhad Ghazali, N. Abbasizadeh","doi":"10.1158/2643-3249.aml23-a26","DOIUrl":"https://doi.org/10.1158/2643-3249.aml23-a26","url":null,"abstract":"\u0000 Hematopoietic Cell Transplantation (HCT) is a frequently used treatment for hematologic malignancies such as acute myeloid leukemia, multiple myeloma, lymphoma and non-malignant diseases. Preparative regimens before HCT damage the Bone Marrow (BM) niche, but it is not fully known how the cytotoxic preconditioning, whether High or Low intensity, impacts bone and BM remodeling, regeneration, and subsequent hematopoietic recovery over time. In addition, the effect of recipient age on these factors has not been completely described. In this study, we sought to longitudinally investigate bone and BM remodeling after Low and High intensity Busulfan (BU) conditioning with the aim of understanding the role that BM niche alterations play in the recovery of the hematopoietic system after transplantation. Using two-photon intravital microscopy, we visualized bone and BM changes in young and adult mice on days 2, 5, and 42 post-transplantation. Both Low and High intensity conditioning were administered with injections of 40 mg/kg and 80 mg/kg busulfan, respectively. Busulfan is a DNA alkylating drug that in combination with cyclophosphamide is being clinically used to treat leukemia. Mice were then transplanted with 1 × 106 whole BM cells from a C57BL/6-Tg(UBC-GFP) mouse. During live imaging, functionality of the vascular system and hematopoietic recovery were studied. For ex vivo imaging, vascular labeling fluorescent antibodies (Alexafluor 647 conjugated to anti-CD31, CD144, and Sca-1) and calcium binding dyes (dye1; Calcein, Dye2; Alizarin) were administered before intracardiac perfusion. Then long bones were harvested, frozen, and the cortical layer was shaved to enable visualization of the BM. Vascular analysis indicated increased leakage in both Low and High intensity conditioning even after 42 days suggesting delayed endothelial recovery following conditioning. Morphological evaluation of the vascular network revealed a decrease in the frequency and increase in the size and density of the vessels at early timepoints that was partially restored by day 42 in young mice only. Bone remodeling in young mice showed a reduction in the dye1/dye2 ratio at day 5 and a more significant decrease by day 42. In the adult mice, a low ratio was observed in BU-conditioned mice only at day 42 post treatment. To further investigate, we classified the metaphyseal and epiphyseal long bone cavities as deposition type, mixed type, and resorption type based on the ratio of the two dyes. The classification analysis indicates that the reduction in dye1/dye2 ratio in BU-conditioned mice over time is primarily due to an increase in resorption type bone cavities in BU-conditioned mice compared to the control. Although donor HSC engraftment is known to be age and dose dependent, our results indicate that long-term microenvironmental changes in the bone and bone marrow may further impact hematopoietic recovery. Overall, our results demonstrate new aspects of bone remodeling and b","PeriodicalId":29944,"journal":{"name":"Blood Cancer Discovery","volume":" ","pages":""},"PeriodicalIF":11.2,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45682634","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abstract A18: STC-15, a novel METTL3 inhibitor, and its combination with Venetoclax confer anti-tumour activity in AML models","authors":"L. Vasiliauskaitė, Y. Ofir-Rosenfeld, M. Albertella, C. Hoareau-Aveilla, Jerry McMahon, Oliver Rausch","doi":"10.1158/2643-3249.aml23-a18","DOIUrl":"https://doi.org/10.1158/2643-3249.aml23-a18","url":null,"abstract":"\u0000 N6-methyladenosine (m6A) is one of the most abundant RNA modifications, which influences mRNA and lncRNA localization, half-life, translation, and splicing. The majority of m6A modifications on cellular mRNAs are deposited by the RNA methyltransferase METTL3. To date, METTL3 has been implicated in the initiation and progression of multiple cancer types, with the highest expression of METTL3 mRNA observed in acute myeloid leukemia (AML). Currently, one line of standard of care therapy for AML patients is Venetoclax, which targets the anti-apoptotic protein BCL2. It was shown that m6A, deposited by METTL3 on BCL2 transcript, affects BCL2 mRNA stability and translation. Storm Therapeutics has developed potent and selective METTL3 inhibitors, including the clinical candidate STC-15. Here, we explore pharmacological inhibition of METTL3 as monotherapy or in combination with Venetoclax in AML models in vitro and in vivo. Sulforhodamine B and CellTiterGloTM assays were used to assess the viability of AML cell lines and patient-derived xenografts (PDXs), respectively, following METTL3 inhibition in vitro. BCL2 protein level was evaluated by Western blotting. SynergyFinder software was used to assess the degree of synergy between METTL3 inhibitors and Venetoclax. Intra-tibial implantation of human-derived AML cells (AML-PDXs) in NSG mice was used to determine single agent and combination therapy efficacy. Multiple AML cells lines and AML-PDXs were sensitive to pharmacological inhibition of METTL3 in vitro, as assessed by loss of viability. Treatment with METTL3 inhibitors led to downregulation of BCL2 protein level in several AML cell lines, as previously suggested by literature. Based on these results, the synergy between METTL3 inhibition and Venetoclax was assessed. Matrix-combination experiments have shown a high degree of synergy between the two drugs (defined by a synergy score &gt;10) in THP-1 and MOLM-13 cell lines. To test METTL3 inhibition as a monotherapy and in combination with Venetoclax in vivo, three AML-PDX studies were initiated. Significantly lower spleen weight was observed in all animals treated with STC-15 or STC-15 + Venetoclax, and reduced number of circulating hCD45+ cells was observed in 2 out of the 3 models. In one of the models, STC-15 monotherapy outperformed Venetoclax (median survival 68 days vs 58 days, respectively), while the combination therapy extended median group survival to 85 days in comparison to 51.5 days in the vehicle group. In conclusion, we demonstrated that METTL3 inhibition results in anti-tumour effects across different AML models. Moreover, we demonstrated a synergistic effect between the novel METTL3 inhibitor STC-15 and Venetoclax, both in vitro and in vivo. These studies provide evidence for the utility of METTL3 inhibitor as a new therapeutic agent to treat AML. Currently, STC-15 is under clinical development (NCT05584111).\u0000 Citation Format: Lina Vasiliauskaite, Yaara Ofir-Rosenfeld, Mark Albertella, Co","PeriodicalId":29944,"journal":{"name":"Blood Cancer Discovery","volume":" ","pages":""},"PeriodicalIF":11.2,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46808001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abstract A52: IDS and SETBP1 is highly prognostic in myelodysplastic neoplasms and is a candidate stem cell signature","authors":"A. Ediriwickrema, A. Gentles, R. Majeti","doi":"10.1158/2643-3249.aml23-a52","DOIUrl":"https://doi.org/10.1158/2643-3249.aml23-a52","url":null,"abstract":"\u0000 Myelodysplastic neoplasms (MDS) are heterogenous blood disorders that arise from dysfunctional hematopoietic stem cells (HSCs) and progenitor cells (HSPCs). According to the cancer stem cell (CSC) model, MDS is organized as a cellular hierarchy that arises from the malignant transformation of HSPCs into rare CSCs. MDS-CSCs are thought to persist during treatment and regenerate disease during relapse. Prior studies have linked MDS-CSCs to MDS-HSPC (Woll et al. Cancer Cell 2014, Pang et al, PNAS 2013, Will et al, Blood 2012), however, a specific cell type has not been isolated and purified as the MDS-CSC. Prognostic gene expression signatures in MDS have also been linked to immature HSPCs (Shiozawa et al, Blood 2017), however, a cell specific signature has not been identified. There is a need to characterize a cell specific gene signature for MDS-CSCs in order to study these cells. To address this need, we performed iterative statistical analyses on MDS gene expression data in order to identify a candidate CSC signature. We hypothesized that by analyzing genes specifically up-regulated in MDS-HSPCs, we can derive a CSC specific gene signature that is not only associated with poor outcomes in MDS, but also marks a subset of cells in MDS with stem cell programs. Up-regulated genes in MDS-HSPCs compared to healthy controls were derived by re-analyzing 73 sorted samples (Woll et al, Cancer Cell 2014) using the limma (Ritchie et al, Nucleic Acids Res 2015). Using these genes, we subsequently analyzed their association with survival in a cohort of 244 MDS patients (Shiozawa et al, Blood 2017, Gerstung et al, Nat Commun 2015, Tyner et al, Nature 2018). We performed iterative Cox proportional hazard models on a training data (n=146), using single and multiple gene combinations. A 2 gene score (i.e., MDS2), comprising IDS and SETBP1, was identified as the most significantly associated feature with decreased survival in MDS compared to Age, Sex, Cytogenetic Risk, and an established MDS score (Shiozawa et al, Blood 2017). Single cell expression of MDS2 was evaluated in MDS scRNA-seq samples (Dussiau et al, BMC Biol2022), and rare cells were identified expressing high levels of MDS2, i.e., MDS2 cells. These cells were integrated with healthy HSPCs. MDS2 cells reside primarily between HSCs and MPPs on a diffusion map, following a differentiation trajectory towards GMPs and monocyte precursors. These observations are consistent with prior studies, as MDS-CSCs were shown to be enriched in HSCs and GMPs (Pang et al, PNAS 2013, Woll et al, Cancer Cell 2014). Analysis of upregulated genes in MDS2 cells revealed that antigen processing, assembly and presentation were the most enriched processes. This analysis supports our approach for identifying a cell specific gene signature, and future work will focus on further single cell analyses and evaluation of CSC content and function of MDS2 cells.\u0000 Citation Format: Asiri Ediriwickrema, Andrew Gentles, Ravindra Majeti. I","PeriodicalId":29944,"journal":{"name":"Blood Cancer Discovery","volume":" ","pages":""},"PeriodicalIF":11.2,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47387308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abstract A25: A niche directed therapy for the treatment of myelodysplasia and acute myeloid leukemia","authors":"I. Mosialou, A. Ali, Rachel Adams, A. Corper, C. Woods, Xiaomin Fan, A. Raza, S. Kousteni","doi":"10.1158/2643-3249.aml23-a25","DOIUrl":"https://doi.org/10.1158/2643-3249.aml23-a25","url":null,"abstract":"\u0000 Cells of the surrounding bone marrow microenvironment (niche) have emerged as important regulators of myeloid disease development and progression, leading to myeloproliferative neoplasms, myelodysplasia (MDS) or acute myeloid leukemia (AML). This not only highlights the complexity of the disease but may, at least in part, explain the limitations of current malignant cell targeted therapies to prevent relapse and at the same time opens new avenues for therapeutic intervention. To test this hypothesis, we examined here the therapeutic potential of targeting a potent, niche-driven oncogenic pathway, constitutive activation of b-catenin/Jagged1 signaling in osteoblasts. In humans, this pathway is activated in approximately 40% of MDS and AML patients; and also following hypermethylation of its regulators in MDS patients. Its activation levels increase with disease severity, correlate with MDS to AML transformation and with del(5q)-associated myeloid malignancies. In mice, it leads to MDS rapidly progressing to AML. To test its therapeutic potential, we inhibited Jagged1. We generated a chimeric human-mouse neutralizing antibody that efficiently and specifically binds JAG1 (anti-JAG1) and inhibits Notch1-induced signaling. Administration of anti-JAG1 in leukemic mice with activated b-catenin/Jag1 in their osteoblasts rescued anemia, thrombocytopenia, neutrophilia and lymphocytopenia, relieved myeloid differentiation block and eliminated blasts. Body weight increased with time and lethality was abrogated in treated mice. Blood chemistry profiling indicated lack of any toxicity following treatment as indicated by normal liver and kidney function and absence of inflammation, dyslipidemia or pancreatitis. In contrast, chemotherapy at a dose simulating the induction regimen used in patients, dramatically exacerbated anemia, thrombocytopenia and lymphocytopenia without decreasing blasts leading to increased lethality due to bone marrow failure. Emphasizing relevance to human disease, anti-JAG1 treatment of patient-derived samples with activated b-catenin/JAG1 in their osteoblasts, inhibited MDS and AML cell growth and survival and promoted myeloid and erythroid differentiation through its actions on osteoblasts. Responsiveness was observed across patients belonging to diverse disease subtypes and categories including patients with adverse cytogenetics and high-risk groups. Confirming the specificity of anti-JAG1 action, no effect was observed in cells from patients without activated b-catenin/JAG1 in their osteoblasts or healthy subjects and the magnitude of the response correlated with the levels of b-catenin/JAG1 activation in osteoblasts. These results suggest the therapeutic efficacy of blocking JAG1 and its superiority to chemotherapy in osteoblastic, b-catenin-driven MDS/AML that could impact 1/3 of MDS and AML patients. In addition, they suggest that targeting the niche may be an approach to avoid toxicity and overcome MDS/AML cell mutation depende","PeriodicalId":29944,"journal":{"name":"Blood Cancer Discovery","volume":" ","pages":""},"PeriodicalIF":11.2,"publicationDate":"2023-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43208476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}