Project description:Herein we developed a multigenic AML model with inducible expression of IDH2R140Q and constitutive expression of mutant DNMT3AR882H and NRASG12D. Using genetic de-induction and the first-in-class IDH2 inhibitor AG-221, we demonstrate that despite the presence of multiple oncogenic lesions, AML cells expressing mutant IDH2 depend on continued production of 2-HG to maintain their leukemic potential. Moreover, by comparing pharmacological inhibition and genetic depletion of IDH2R140Q we validate AG-221 as a highly on target inhibitor and identify key downstream pathways including GATA1 that are critical for disease maintenance.
Project description:Genomic studies in acute myeloid leukemias (AML) have identified mutations which drive altered DNA methylation, including TET2 and IDH. Functional studies have shown these mutations contribute to transformation, although how these mutations impact the response to epigenetic therapies is not fully delineated. Here we show AMLs with TET2/IDH2 mutations combined with FLT3ITD mutations are specifically sensitive to 5-Azacytidine or to the IDH2 inhibitor AG-221, respectively. 5-Azacytidine/AG-221 therapies induced a reduction in leukemic blasts and in stem/progenitor expansion, with attenuation of aberrant DNA hypermethylation. These therapeutic benefits were achieved through restoration of differentiation, such that normalized hematopoiesis was derived from mutant cells. Consistent with these data, at the time of clinical response to 5-Azacytidine or AG-221, most patients had mutant-derived hematopoiesis. By contrast, combined AG-221/5-Azacytidine plus FLT3 inhibition reduced disease burden and reversed epigenetic dysfunction. Our studies suggest combined targeting of signaling and epigenetic pathways can increase therapeutic response in AML.
Project description:Genomic studies in acute myeloid leukemias (AML) have identified mutations which drive altered DNA methylation, including TET2 and IDH. Functional studies have shown these mutations contribute to transformation, although how these mutations impact the response to epigenetic therapies is not fully delineated. Here we show AMLs with TET2/IDH2 mutations combined with FLT3ITD mutations are specifically sensitive to 5-Azacytidine or to the IDH2 inhibitor AG-221, respectively. 5-Azacytidine/AG-221 therapies induced a reduction in leukemic blasts and in stem/progenitor expansion, with attenuation of aberrant DNA hypermethylation. These therapeutic benefits were achieved through restoration of differentiation, such that normalized hematopoiesis was derived from mutant cells. Consistent with these data, at the time of clinical response to 5-Azacytidine or AG-221, most patients had mutant-derived hematopoiesis. By contrast, combined AG-221/5-Azacytidine plus FLT3 inhibition reduced disease burden and reversed epigenetic dysfunction. Our studies suggest combined targeting of signaling and epigenetic pathways can increase therapeutic response in AML.
Project description:Mutations in IDH1 and IDH2 are frequently observed in various cancers, including acute myeloid leukemia (AML). Mutant IDHs convert α-ketoglutarate (α-KG) to 2-hydroxyglutarate (2-HG), which dysregulates a set ofα-KG-dependent dioxygenases. To determine whether mutant IDHs are valid targets for cancer therapy, we established a mouse AML model harboring an IDH2 mutation by transplanting mice with nucleophosmin1 (NPM1)+/- mouse hematopoietic stem/progenitor cells that had been co-transduced with four mutant genes (NPMc, IDH2/R140Q, DNMT3A/R882H and FLT3/ITD) that frequently occur simultaneously in human AML patients. IDH2/R140Q is necessary for the engraftment or survival of NPMc+ cells in vivo. Gene-expression analysis indicated that NPMc increased the expression of Hoxa9, and that IDH2/R140Q increased the level of Meis1 and activated the hypoxia pathway in AML cells. Conditional deletion of IDH2/R140Q blocked 2-HG production and maintenance of leukemia stem cells, resulting in survival of the AML mice. IDH2/R140Q reversibly decreased the levels of 5hmC modification and gene expression at some differentiation inducing genes (Ebf1, Pax5 and Spib). These results indicate that the IDH2 mutation is critical for the development and maintenance of AML stem cells, and that mutant IDHs are promising targets for anticancer therapy.
Project description:Mutations in IDH1 and IDH2 are frequently observed in various cancers, including acute myeloid leukemia (AML). Mutant IDHs convert α-ketoglutarate (α-KG) to 2-hydroxyglutarate (2-HG), which dysregulates a set ofα-KG-dependent dioxygenases. To determine whether mutant IDHs are valid targets for cancer therapy, we established a mouse AML model harboring an IDH2 mutation by transplanting mice with nucleophosmin1 (NPM1)+/- mouse hematopoietic stem/progenitor cells that had been co-transduced with four mutant genes (NPMc, IDH2/R140Q, DNMT3A/R882H and FLT3/ITD) that frequently occur simultaneously in human AML patients. IDH2/R140Q is necessary for the engraftment or survival of NPMc+ cells in vivo. Gene-expression analysis indicated that NPMc increased the expression of Hoxa9, and that IDH2/R140Q increased the level of Meis1 and activated the hypoxia pathway in AML cells. Conditional deletion of IDH2/R140Q blocked 2-HG production and maintenance of leukemia stem cells, resulting in survival of the AML mice. IDH2/R140Q reversibly decreased the levels of 5hmC modification and gene expression at some differentiation inducing genes (Ebf1, Pax5 and Spib). These results indicate that the IDH2 mutation is critical for the development and maintenance of AML stem cells, and that mutant IDHs are promising targets for anticancer therapy.
Project description:<p>FLT3 mutations are commonly detected in Acute Myeloid Leukemia (AML) patients and are associated with poor prognosis. Crenolanib, a potent type I pan-FLT3 (<a href="https://www.ncbi.nlm.nih.gov/gene/?term=FLT3" target="_blank">GeneID:2322</a>) inhibitor, is effective against both internal tandem duplications (ITD) and resistance-conferring tyrosine kinase domain (TKD) mutations. While crenolanib monotherapy has demonstrated significant clinical benefit in heavily pretreated relapsed/refractory AML patients, responses are transient and relapse eventually occurs. To investigate the mechanisms of crenolanib resistance, we performed whole exome sequencing of AML patient samples before and after crenolanib treatment (122 samples from 59 patients). Unlike other FLT3 inhibitors, crenolanib did not induce FLT3 activation loop mutations, and mutations of the FLT3 "gatekeeper" residue were infrequent. Instead, mutations of NRAS (<a href="https://www.ncbi.nlm.nih.gov/gene/?term=NRAS" target="_blank">GeneID:4893</a>) and IDH2 (<a href="https://www.ncbi.nlm.nih.gov/gene/?term=IDH2" target="_blank">GeneID:3418</a>) arose, mostly as FLT3-independent subclones, while TET2 (<a href="https://www.ncbi.nlm.nih.gov/gene/?term=TET2" target="_blank">GeneID:54790</a>) and IDH1 (<a href="https://www.ncbi.nlm.nih.gov/gene/?term=IDH1" target="_blank">GeneID:3417</a>) predominantly co-occurred with the FLT3-mutant clone and were enriched in crenolanib poor-responders. The remaining patients exhibited post-crenolanib expansion of mutations associated with epigenetic regulators, transcription factors, and cohesion factors, suggesting diverse non-FLT3 genetic/epigenetic mechanisms of crenolanib resistance. Drug combinations in experimental models restored crenolanib sensitivity.</p>
Project description:IDH mutations are found in 20% of acute myeloid leukemia (AML) patients. IDH inhibitors (IDHi) have emerged as a novel treatment option. However, only 30-40% of patients respond to single drug treatment and there is an unmet need for improvement as well as identifying alternative treatment options. The overall aim of this study was therefore to gain deeper insights into the molecular signatures of IDH mutations, the effects of IDHi as well as to identify a molecular vulnerability to tailor novel therapies for AML patients with IDH mutations. Here, we have characterized the transcriptional and epigenetic landscape before and after treatment with IDH2i AG-221, using an IDH2 mutated AML cell line model and AML patient cohorts. We discovered decreased DNA hydroxymethylation in IDH2 mutated AML cells, particular in enhancers and a perturbed transcriptional regulatory network involving myeloid transcription factors. In addition, hypermethylation of the HLA I cluster caused a dramatic down-regulation of HLA genes, triggering an enhanced natural killer (NK) cell activation, and displayed an increased susceptibility to NK cell mediated killing. These responses were reverted when the AML cells were pre-exposed to IFN-gamma, resulting in up-regulation of cell surface HLA class I. Finally, analyses of DNA methylation data from IDHi-treated patients showed that non-responders continued to harbor hypermethylation in HLA class I genes, suggesting maintained susceptibility to NK cells. In conclusion, this study provides new insights into the perturbed epigenetic and transcriptional regulation in IDH mutated AML and shed light on a potential strategy for personalized medicine in AML.
Project description:IDH mutations are found in 20% of acute myeloid leukemia (AML) patients. IDH inhibitors (IDHi) have emerged as a novel treatment option. However, only 30-40% of patients respond to single drug treatment and there is an unmet need for improvement as well as identifying alternative treatment options. The overall aim of this study was therefore to gain deeper insights into the molecular signatures of IDH mutations, the effects of IDHi as well as to identify a molecular vulnerability to tailor novel therapies for AML patients with IDH mutations. Here, we have characterized the transcriptional and epigenetic landscape before and after treatment with IDH2i AG-221, using an IDH2 mutated AML cell line model and AML patient cohorts. We discovered decreased DNA hydroxymethylation in IDH2 mutated AML cells, particular in enhancers and a perturbed transcriptional regulatory network involving myeloid transcription factors. In addition, hypermethylation of the HLA I cluster caused a dramatic down-regulation of HLA genes, triggering an enhanced natural killer (NK) cell activation, and displayed an increased susceptibility to NK cell mediated killing. These responses were reverted when the AML cells were pre-exposed to IFN-gamma, resulting in up-regulation of cell surface HLA class I. Finally, analyses of DNA methylation data from IDHi-treated patients showed that non-responders continued to harbor hypermethylation in HLA class I genes, suggesting maintained susceptibility to NK cells. In conclusion, this study provides new insights into the perturbed epigenetic and transcriptional regulation in IDH mutated AML and shed light on a potential strategy for personalized medicine in AML. Methylation/hydroxymethylation profiling by array
Project description:Mutations of IDH1 (R132) and IDH2 (R172 and R140), which produce an oncometabolite 2-hydroxyglutarate (2HG), have been identified in several tumors including acute myeloid leukemia (AML). Recent studies have shown that expression of the IDH mutant enzymes results in high levels of 2HG and a block in cellular differentiation that can be reversed with IDH-mutant specific small molecule inhibitors. To further understand the role of IDH mutations in cancer, we conducted mechanistic studies in the TF-1/IDH2 R140Q erythroleukemia model system and found that IDH2 mutant expression caused both histone and genomic DNA methylation changes that can be reversed when IDH2 mutant activity is inhibited. Specifically, histone hypermethylation is rapidly reversed within days whereas reversal of DNA hypermethylation proceeds in a progressive manner over the course of weeks. Pathway enrichment analysis revealed several pathways involved in tumorigenesis of leukemia and lymphoma, indicating a selective modulation of relevant cancer genes by IDH mutations. As methylation of DNA and histones is closely linked to mRNA expression and differentiation, these results indicate that IDH2 mutant inhibition may function as a cancer therapy via short-term histone demethylation and long-term DNA demethylation at genes involved in differentiation and tumorigenesis. TF-1 cells with and without IDH2/R140Q expression were treated with DMSO or AGI-6780, an inhibitor of IDH2/R140Q for 7 to 28 days. Genomic DNA was extracted and analyzed by the Illumina 450k Methylation array.