Somatic gain-of-function mutations in isocitrate dehydrogenases (
) 1 and 2 are found in multiple hematologic and solid tumors, leading to accumulation of the oncometabolite (
)-2-hydroxyglutarate ...(2HG). 2HG competitively inhibits α-ketoglutarate-dependent dioxygenases, including histone demethylases and methylcytosine dioxygenases of the TET family, causing epigenetic dysregulation and a block in cellular differentiation.
studies have provided proof of concept for mutant IDH inhibition as a therapeutic approach. We report the discovery and characterization of AG-221, an orally available, selective, potent inhibitor of the mutant IDH2 enzyme. AG-221 suppressed 2HG production and induced cellular differentiation in primary human
mutation-positive acute myeloid leukemia (AML) cells
and in xenograft mouse models. AG-221 also provided a statistically significant survival benefit in an aggressive IDH2
-mutant AML xenograft mouse model. These findings supported initiation of the ongoing clinical trials of AG-221 in patients with
mutation-positive advanced hematologic malignancies.
Mutations in
are identified in approximately 20% of patients with AML and contribute to leukemia via a block in hematopoietic cell differentiation. We have shown that the targeted inhibitor AG-221 suppresses the mutant IDH2 enzyme in multiple preclinical models and induces differentiation of malignant blasts, supporting its clinical development.
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Transcription and pre-mRNA splicing are key steps in the control of gene expression and mutations in genes regulating each of these processes are common in leukaemia
. Despite the frequent overlap of ...mutations affecting epigenetic regulation and splicing in leukaemia, how these processes influence one another to promote leukaemogenesis is not understood and, to our knowledge, there is no functional evidence that mutations in RNA splicing factors initiate leukaemia. Here, through analyses of transcriptomes from 982 patients with acute myeloid leukaemia, we identified frequent overlap of mutations in IDH2 and SRSF2 that together promote leukaemogenesis through coordinated effects on the epigenome and RNA splicing. Whereas mutations in either IDH2 or SRSF2 imparted distinct splicing changes, co-expression of mutant IDH2 altered the splicing effects of mutant SRSF2 and resulted in more profound splicing changes than either mutation alone. Consistent with this, co-expression of mutant IDH2 and SRSF2 resulted in lethal myelodysplasia with proliferative features in vivo and enhanced self-renewal in a manner not observed with either mutation alone. IDH2 and SRSF2 double-mutant cells exhibited aberrant splicing and reduced expression of INTS3, a member of the integrator complex
, concordant with increased stalling of RNA polymerase II (RNAPII). Aberrant INTS3 splicing contributed to leukaemogenesis in concert with mutant IDH2 and was dependent on mutant SRSF2 binding to cis elements in INTS3 mRNA and increased DNA methylation of INTS3. These data identify a pathogenic crosstalk between altered epigenetic state and splicing in a subset of leukaemias, provide functional evidence that mutations in splicing factors drive myeloid malignancy development, and identify spliceosomal changes as a mediator of IDH2-mutant leukaemogenesis.
D-2-hydroxyglutaric aciduria type II (D2HGA2) is a severe inborn disorder of metabolism caused by heterozygous R140 mutations in the IDH2 (isocitrate dehydrogenase 2) gene. Here we report the results ...of treatment of two children with D2HGA2, one of whom exhibited severe dilated cardiomyopathy, with the selective mutant IDH2 enzyme inhibitor enasidenib. In both children, enasidenib treatment led to normalization of D-2-hydroxyglutarate (D-2-HG) concentrations in body fluids. At doses of 50 mg and 60 mg per day, no side effects were observed, except for asymptomatic hyperbilirubinemia. For the child with cardiomyopathy, chronic D-2-HG inhibition was associated with improved cardiac function, and for both children, therapy was associated with improved daily functioning, global motility and social interactions. Treatment of the child with cardiomyopathy led to therapy-coordinated changes in serum phospholipid levels, which were partly recapitulated in cultured fibroblasts, associated with complex effects on lipid and redox-related gene pathways. These findings indicate that targeted inhibition of a mutant enzyme can partly reverse the pathology of a chronic neurometabolic genetic disorder.
IDH mutants cause aberrant DNA and histone methylation and contribute to hematological and neural malignancies. In this issue of Cancer Cell, Inoue et al. describe a potential specific effect of IDH1 ...mutations that reduces Atm expression via inhibition of H3K9 demethylases, which may represent a first step toward cellular transformation.
IDH mutants cause aberrant DNA and histone methylation and contribute to hematological and neural malignancies. In this issue of Cancer Cell, Inoue et al. describe a potential specific effect of IDH1 mutations that reduces Atm expression via inhibition of H3K9 demethylases, which may represent a first step toward cellular transformation.
Somatic point mutations at a key arginine residue (R132) within the active site of the metabolic enzyme isocitrate dehydrogenase 1 (IDH1) confer a novel gain of function in cancer cells, resulting in ...the production of d-2-hydroxyglutarate (2-HG), an oncometabolite. Elevated 2-HG levels are implicated in epigenetic alterations and impaired cellular differentiation. IDH1 mutations have been described in an array of hematologic malignancies and solid tumors. Here, we report the discovery of AG-120 (ivosidenib), an inhibitor of the IDH1 mutant enzyme that exhibits profound 2-HG lowering in tumor models and the ability to effect differentiation of primary patient AML samples ex vivo. Preliminary data from phase 1 clinical trials enrolling patients with cancers harboring an IDH1 mutation indicate that AG-120 has an acceptable safety profile and clinical activity.
The nucleoporin gene NUP98 is rearranged in more than 27 chromosomal abnormalities observed in childhood and adult, de novo and therapy-related acute leukemias of myeloid and T-lymphoid origins, ...resulting in the creation of fusion genes and the expression of chimeric proteins. We report here the functional analysis of the NUP98-coiled-coil domain-containing protein 28A (NUP98-CCDC28A) fusion protein, expressed as the consequence of a recurrent t(6;11)(q24.1;p15.5) translocation.
To gain insight into the function of the native CCDC28A gene, we collected information on any differential expression of CCDC28A among normal hematologic cell types and within subgroups of acute leukemia. To assess the in vivo effects of the NUP98-CCDC28A fusion, NUP98-CCDC28A or full length CCDC28A were retrovirally transduced into primary murine bone marrow cells and transduced cells were next transplanted into sub-lethally irradiated recipient mice.
Our in silico analyses supported a contribution of CCDC28A to discrete stages of murine hematopoietic development. They also suggested selective enrichment of CCDC28A in the French-American-British M6 class of human acute leukemia. Primary murine hematopoietic progenitor cells transduced with NUP98-CCDC28A generated a fully penetrant and transplantable myeloproliferative neoplasm-like myeloid leukemia and induced selective expansion of granulocyte/macrophage progenitors in the bone marrow of transplanted recipients, showing that NUP98-CCDC28A promotes the proliferative capacity and self-renewal potential of myeloid progenitors. In addition, the transformation mediated by NUP98-CCDC28A was not associated with deregulation of the Hoxa-Meis1 pathway, a feature shared by a diverse set of NUP98 fusions.
Our results demonstrate that the recurrent NUP98-CCDC28A is an oncogene that induces a rapid and transplantable myeloid neoplasm in recipient mice. They also provide additional evidence for an alternative leukemogenic mechanism for NUP98 oncogenes.
Abstract Our purpose is to identify stromal-derived signals required for IDH1/2-mut hematopoietic stem cells (HSCs) to become leukemogenic. Mutations in IDH genes are found in 20% of acute myeloid ...leukemia (AML) patients and are not transformative. They produce the oncometabolite 2HG which inhibits key epigenetic regulators. We explored whether epigenetic changes in the bone marrow (BM) niche could provide cooperative signals to IDH-mut HSCs leading to their transformation and disease development. We found that 2HG is elevated in the BM plasma of MDS/AML patients with IDH1/2 mutations as compared to IDH-wt patients. Interestingly, 2HG is taken up by BM stromal cells (BMSCs) suggesting it may induce aberrant methylation patterns in them. Indeed, methylome analysis showed hypermethylation in BMSCs of AML patients with IDH1/2 mutations compared to wt. Among the most hypermethylated genes in the IDH-mut stroma are AXIN1, AXIN2 and NDK2, all negative regulators of β-catenin; this pathway activation was previously shown to cause MDS/AML in mice and present in 38% of patients. In agreement with these findings βcat activation in the stroma of IDH-mut vs IDH-wt AML patients showed a strong positive correlation as 50% of IDH-mut patients had activated βcat in their BMSCs. Inquiring whether stroma methylation precedes HSC transformation, we analyzed samples from healthy individuals with IDH-mut clonal hematopoiesis. They exhibited increased global and AXIN1 promoter methylation compared to samples without such clones, but not active βcat in osteoblasts, indicating this might be a later step along with disease development. In fact, transplantation of HSCs from Idh2-mut mice to recipients expressing active βcat in osteoblasts led to increase in blasts and shortened survival compared to wt mice transplanted with Idh2-mut HSCs. As many patients relapse following treatment with IDH inhibitors, we investigated a potential role for βcat signaling in treatment outcome. IDH-mut AML patients who do not respond to treatment with the IDHi present more frequently with activated βcat in osteoblasts compared to responders. Analyzing samples from the same patient pre- and post-treatment with IDHi, we found before treatment most patients were positive for βcat stromal activation, whereas after treatment, all patients with complete response were negative, while patients with progressive disease remained positive. Our model suggests IDH-mut HSCs secrete 2HG inducing epigenetic alterations in the niche, some of which cause activation of the βcat pathway. In turn, this additional signal leads to the transformation of HSCs to dysplastic cells and MDS/AML development. This work uncovers a new mechanism for transformation to MDS/AML and resistance to IDHi treatment. Thus, targeting βcat activation in the stroma, in combination with IDHi, could improve treatment outcome. Citation Format: Paraskevi Vgenopoulou, Luis Flores, Ioanna Mosialou, Junfei Zhao, X. Shawn Liu, Pamela Sung, Virginie Penard-Lacronique, Martin Carroll, Stavroula Kousteni. Aberrant β-catenin signaling from the bone marrow niche leads to transformation of IDH1/2-mutant hematopoietic stem cells and compromises response to IDH1/2 inhibitors abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 280.
The leukemia-associated TEL-Jak2 fusion protein possesses a constitutive tyrosine kinase activity and transforming properties in hematopoietic cell lines and animal models. In the murine pro-B Ba/F3 ...cell line, this fusion constitutively activates the Signal Transducer and Activator of Transcription 5 (Stat5) factors and, as a consequence, induces the sustained expression of various Stat5-target genes including the Cytokine Inducible SH2-containing protein (Cis) gene, which codes for a member of the Suppressor of Cytokine Signaling (Socs) protein family. In TEL-Jak2-transformed Ba/F3 cells, we also observed the upregulation of the Socs1 gene, whose product has been reported to negatively regulate the Jak kinase activity. In transient transfection experiments, Socs1 physically interacts with TEL-Jak2 and interferes with the TEL-Jak2-induced phosphorylation and activation of Stat5 factors, probably through the Socs1-induced proteasome-mediated degradation of the fusion protein. Interestingly, TEL-Jak2-expressing Ba/F3 cells were found to be resistant to the anti-proliferative activities of gamma interferon (IFN-gamma) seemingly as a consequence of Socs1 constitutive expression. These results indicate that the Socs1-dependent cytokine feedback loop, although active, is bypassed by the TEL-Jak2 fusion, but may play a role in the leukemogenic process by altering the cytokine responses of the leukemic cells. Our results also suggest that Socs1 plays a role in shutting down the signaling from the normally activated Jak2 kinase by inducing its proteasome-dependent degradation.
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