Evolution of AML genome and epigenome with IDH inhibitors and their association with clinical response and resistance [methylation]
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ABSTRACT: Allosteric inhibitors of mutant IDH1 or IDH2 induce terminal differentiation in mutant leukemic blasts and may provide durable clinical responses in approximately 40% of acute myeloid leukemia (AML) patients with the mutations. However, most responders eventually relapse. To understand the molecular underpinnings of clinical resistance, we performed multipronged genomic analyses (DNA sequencing, RNA sequencing and cytosine methylation profiling) in longitudinally collected specimens from 68 IDH1/IDH2-mutant AML patients treated with IDH inhibitors (IDHi), and described the evolution of AML genome and epigenome during the therapy and its association with clinical response and relapse. Co-occurrence of mutations in RUNX1/CEBPA or RAS-RTK pathway genes were associated with poor response to IDHi. The same group of mutations were also frequently selected or acquired at relapse. In addition, acquired mutations in BCOR, reciprocal IDH gene, and TET2 were also implicated at relapse. DNA methylation changes largely mirrored plasma 2HG dynamics and had little association with clinical response to IDHi. The mapping of mutation dynamics and methylation changes in longitudinal samples revealed the interplay between AML genome and epigenome with IDHi therapy. While the alteration in RAS-RTK signaling genes and RUNX1/CEBPA were the key molecular pathways involved in clinical resistance to IDHi, diverse molecular pathways were involved in IDHi resistance. The data highlights the role of clonal heterogeneity in therapeutic resistance in AML and implicates opportunities for novel combination strategies.
Project description:Allosteric inhibitors of mutant IDH1 or IDH2 induce terminal differentiation in mutant leukemic blasts and may provide durable clinical responses in approximately 40% of acute myeloid leukemia (AML) patients with the mutations. However, most responders eventually relapse. To understand the molecular underpinnings of clinical resistance, we performed multipronged genomic analyses (DNA sequencing, RNA sequencing and cytosine methylation profiling) in longitudinally collected specimens from 68 IDH1/IDH2-mutant AML patients treated with IDH inhibitors (IDHi), and described the evolution of AML genome and epigenome during the therapy and its association with clinical response and relapse. Co-occurrence of mutations in RUNX1/CEBPA or RAS-RTK pathway genes were associated with poor response to IDHi. The same group of mutations were also frequently selected or acquired at relapse. In addition, acquired mutations in BCOR, reciprocal IDH gene, and TET2 were also implicated at relapse. DNA methylation changes largely mirrored plasma 2HG dynamics and had little association with clinical response to IDHi. The mapping of mutation dynamics and methylation changes in longitudinal samples revealed the interplay between AML genome and epigenome with IDHi therapy. While the alteration in RAS-RTK signaling genes and RUNX1/CEBPA were the key molecular pathways involved in clinical resistance to IDHi, diverse molecular pathways were involved in IDHi resistance. The data highlights the role of clonal heterogeneity in therapeutic resistance in AML and implicates opportunities for novel combination strategies.
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: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: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.
Project description:To study the effects of IDH mutations, we collected and performed gene expression microarray analysis with tumor specimens from patients with grade II-III oligodendroglioma. Sequencing for mutations of IDH1 and IDH2 was done. Gene expression was compared between IDH wildtype vs. mutant samples
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:Gene expression of mouse hepatoblasts (HBs) expressing IDH1 WT, IDH1 R132C, IDH2 WT, R172K and empty vector controls (N=2 cultures for each condition) grown on collagen-coated plates and IDH1 R132C and empty vector controls on uncoated plates were evaluated using Affymetrix Mouse 430Av2 DNA microarrays that were processed at the Dana-Farber Cancer Institute core facility (http://macf-web.dfci.harvard.edu/) using their standard protocol. Mutations in Isocitrate dehydrogenase 1 (IDH1) and IDH2 are among the most common genetic alterations in intrahepatic cholangiocarcinoma (IHCC), a deadly primary liver cancer. Mutant IDH proteins in IHCC and other malignancies acquire an abnormal enzymatic activity allowing them to convert alphaketoglutarate (aKG) to 2-hydroxyglutarate (2HG), which inhibits the activity of multiple aKG-dependent dioxygenases, and results in alterations in cell differentiation, survival, and extracellular matrix maturation. However, the molecular pathways by which IDH mutations lead to tumour formation remain unclear. Here we show that mutant IDH blocks primary liver progenitor cells from undergoing hepatocyte differentiation through the production of 2HG and suppression of HNF4a, a master regulator of hepatocyte identity and quiescence. Correspondingly, genetically engineered mouse models (GEMMs) expressing mutant IDH in the adult liver show aberrant response to hepatic injury, characterized by HNF4a silencing, impaired hepatocyte differentiation and markedly elevated levels of cell proliferation. Moreover, mutant IDH and activated Kras, genetic alterations that co-exist in a subset of human IHCCs, cooperate to drive the expansion of liver progenitor cells, development of premalignant biliary lesions, and progression to metastatic IHCC. These studies provide a functional link between IDH mutations, hepatic cell fate, and IHCC pathogenesis and present a novel GEMM of IDH-driven malignancy. Gene expression of HBs expressing IDH1 WT, IDH1 R132C, IDH2 WT, R172K and empty vector controls under a doxycycline-inducible system (N=2 cultures for each condition) grown on collagen-coated plates and IDH1 R132C and empty vector controls on uncoated plates were evaluated using Affymetrix Mouse 430Av2 DNA microarrays.
Project description:Cancer-associated IDH mutations are characterized by neomorphic enzyme activity and resultant 2 hydroxyglutarate (2HG) production. Mutational and epigenetic profiling of a large AML patient cohort revealed that IDH1/2-mutant AMLs display global DNA hypermethylation and a specific hypermethylation signature. Furthermore, expression of 2HG-producing IDH alleles in cells rapidly induced global DNA hypermethylation. In the AML cohort, IDH1/2 mutations were mutually exclusive with mutations in the α-ketoglutarate-dependent enzyme TET2, and TET2 loss-of function mutations associated with similar epigenetic defects as IDH1/2 mutants. Consistent with these genetic and epigenetic data, expression of IDH mutants impaired TET2 catalytic function in cells. Finally, either expression of mutant IDH1/2 or Tet2 depletion impaired hematopoietic differentiation and increased stem cell marker expression, suggesting a shared pro-leukemogenic effect. DNA methylation and gene expression profiling in IDH1/2 mutant vs. IDH1/2 wild-type AML
Project description:More than 50% of patients with chondrosarcomas exhibit gain-of-function mutations in either isocitrate dehydrogenase 1 (IDH1) or IDH2. In this study, we performed genome-wide CpG methylation sequencing of chondrosarcoma biopsies and found that IDH mutations were associated with DNA hypermethylation at CpG islands but not other genomic regions. Regions of CpG island hypermethylation were enriched for genes implicated in stem cell maintenance/differentiation and lineage specification. In murine 10T1/2 mesenchymal 20 progenitor cells, expression of mutant IDH2 led to DNA hypermethylation and an impairment in differentiation that could be reversed by treatment with DNA-hypomethylating agents. Introduction of mutant IDH2 also induced loss of contact inhibition and generated undifferentiated sarcomas in vivo. The oncogenic potential of mutant IDH2 correlated with the ability to produce 2-hydroxyglutarate. Together, these data demonstrate that neomorphic IDH2 mutations can be oncogenic in mesenchymal cells.. RRBS sequencing of (1) IDH wild type and mutant human chondrosarcomas, (2) isogenic cell lines expressing wild-type or mutant IDH.
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.