Project description:The chromatin adaptor protein Menin (MEN1) is required by acute leukemias driven by mixed lineage leukemia 1 gene rearrangements (KMT2A-r) for sustained leukemogenesis. Menin inhibitors (MIs), which disrupt the Menin-KMT2A interface leading to downregulation of Menin-KMT2A oncogenic transcriptional programs, have shown promising results in recent clinical trials treating acute myeloid leukemia (AML). Decreased Menin protein stability has been observed following treatment with several MIs though proteasomal degradation, though the biological mechanisms that control Menin stability are not well understood. Here we interrogate and compare five clinical MIs and two pre-clinical compounds to characterize the mechanism by which MIs induce Menin degradation and demonstrate that the loss of the Menin-KMT2A interaction results in decreased protein stability of Menin and KMT2A. We have identified the HECT E3 ubiquitin ligase UBR5 as a regulator of Menin protein stability and demonstrate that UBR5 binds to similar sites as the Menin/KMT2A complex on chromatin. Loss of UBR5 leads to transcriptional rescue of Menin-KMT2A target genes leading to decreased sensitivity to all MIs. Thus, we present UBR5 as an important regulator of Menin/KMT2A complex stability and Menin destabilization/subcellular localization as a designable feature of Menin inhibition targeting KMT2A-r leukemias.
Project description:The chromatin adaptor protein Menin (MEN1) is required by acute leukemias driven by mixed lineage leukemia 1 gene rearrangements (KMT2A-r) for sustained leukemogenesis. Menin inhibitors (MIs), which disrupt the Menin-KMT2A interface leading to downregulation of Menin-KMT2A oncogenic transcriptional programs, have shown promising results in recent clinical trials treating acute myeloid leukemia (AML). Decreased Menin protein stability has been observed following treatment with several MIs though proteasomal degradation, though the biological mechanisms that control Menin stability are not well understood. Here we interrogate and compare five clinical MIs and two pre-clinical compounds to characterize the mechanism by which MIs induce Menin degradation and demonstrate that the loss of the Menin-KMT2A interaction results in decreased protein stability of Menin and KMT2A. We have identified the HECT E3 ubiquitin ligase UBR5 as a regulator of Menin protein stability and demonstrate that UBR5 binds to similar sites as the Menin/KMT2A complex on chromatin. Loss of UBR5 leads to transcriptional rescue of Menin-KMT2A target genes leading to decreased sensitivity to all MIs. Thus, we present UBR5 as an important regulator of Menin/KMT2A complex stability and Menin destabilization/subcellular localization as a designable feature of Menin inhibition targeting KMT2A-r leukemias.
Project description:Precise control of activating H3K4me3 and repressive H3K27me3 histone modifications at bivalent promoters is essential for normal development and is frequently corrupted in cancer. By coupling a cell surface readout of bivalent MHC class I gene expression with whole genome CRISPR/Cas9 screens, we identify specific roles for MTF2-PRC2.1, PCGF1-PRC1.1 and Menin- KMT2A/B complexes in maintaining bivalency. Unexpectedly, genetic loss or pharmacological inhibition of Menin phenocopies the effects of polycomb disruption, resulting in derepression of bivalent genes in both cancer cells and pluripotent stem cells. Whilst Menin and KMT2A/B contribute to H3K4me3 at active genes, a separate Menin-independent function of KMT2A/B maintains H3K4me3 and opposes polycomb-mediated repression at bivalent genes. Release of KMT2A from active genes following Menin targeting alters the balance of polycomb and KMT2A at bivalent genes, facilitating gene activation. This functional partitioning of Menin-KMT2A/B complex components reveals novel therapeutic opportunities that can be leveraged through inhibition of Menin.
Project description:Targeting critical epigenetic regulators reverses aberrant transcription in cancer, thereby restoring normal tissue function. The interaction of menin with lysine methyltransferase 2A (KMT2A), an epigenetic regulator, is a dependency in acute leukaemia caused by either rearrangement of KMT2A or mutation in Nucleophosmin 1(NPM1). KMT2A rearrangements occur in up to 10% of acute leukaemias and have an adverse prognosis whereas NPM1 mutations occur in up to 30%, forming the most common genetic alteration in acute myeloid leukaemia7,8. Here, we describe the results of the first-in-human phase 1 clinical trial investigating revumenib (SNDX-5613), a potent and selective oral inhibitor of the menin–KMT2A interaction, in patients with relapsed or refractory acute leukaemia (ClinicalTrials.gov, NCT04065399). We show that therapy with revumenib was associated with a low frequency of grade 3 or higher treatment-related adverse events and a 30% rate of complete remission or complete remission with partial haematologic recovery (CR/CRh) in the efficacy analysis population. Asymptomatic prolongation of the QT interval on electrocardiography was identified as the only dose-limiting toxicity. Remissions occurred in leukaemias refractory to multiple previous lines of therapy. We demonstrate clearance of residual disease using sensitive clinical assays and identify hallmarks of differentiation into normal haematopoietic cells, including differentiation syndrome. These data establish menin inhibition as a therapeutic strategy for susceptible acute leukaemia subtypes.
Project description:Pharmacologic targeting of epigenetic protein complexes has shown significant in vitro responses in acute myeloid leukemia (AML). Early clinical trials in KMT2A-rearranged leukemia indicate rather transient responses and development of resistance. In an effort to define functional dependencies of KMT2A-fusions in AML, we identify the catalytic immunoproteasome subunit PSMB8 as a KMT2A-complex-specific vulnerability. Genetic and pharmacologic inactivation of PSMB8 results in impaired proliferation of murine and human leukemic cells while normal hematopoietic cells remain unaffected. Disruption of immunoproteasome function results in cellular enrichment of transcription factor BASP1, and consecutive repression of KMT2A-target genes. Pharmacologic targeting of PSMB8 improves efficacy of Menin-inhibitors, eradicates leukemia in primary human xenografts and shows preserved activity against Menin-inhibitor resistance mutations. This identifies and validates a cell-intrinsic mechanism whereby selective disruption of proteostasis results in altered transcription factor abundance and repression of oncogene-specific transcriptional networks. Therapeutic targeting of PSMB8-dependent transcription in combination with Menin-inhibition could thus eradicate KMT2A-complex driven AML.
Project description:Menin inhibitors that disrupt Menin-MLL interaction hold promise for treating specific acute myeloid leukemia subtypes, including KMT2A rearrangements (KMT2A-r), yet resistance remains a challenge. Here, through systematic chromatin-focused CRISPR screens, along with genetic, epigenetic, and pharmacologic studies in a variety of human and mouse KMT2A-r AML models, we uncover a potential resistance mechanism independent of canonical Menin-MLL targets. We show that a group of non-canonical Menin targets, which are bivalently co-occupied by active Menin and repressive H2AK119ub marks, are typically downregulated following Menin inhibition. The loss of Polycomb Repressive Complex 1.1 (PRC1.1) subunits, such as PCGF1 or BCOR, leads to Menin inhibitor resistance by epigenetic reactivation of these non-canonical targets, including MYC. Genetic and pharmacological inhibition of MYC can resensitize PRC1.1-deficent leukemia cells to Menin inhibition. Moreover, we demonstrate that leukemia cells with the loss of PRC1.1 subunits exhibit reduced monocytic gene signatures and are susceptible to the BCL2 inhibition, and combinational treatment of venetoclax overcomes the resistance to Menin inhibition in PRC1.1-deficient leukemia cells. These findings highlight the important roles of PRC1.1 and its regulated non-canonical Menin targets in modulating Menin inhibitor response and provide potential strategies to treat leukemias with compromised PRC1.1 function.
Project description:Menin inhibitors that disrupt Menin-MLL interaction hold promise for treating specific acute myeloid leukemia subtypes, including KMT2A rearrangements (KMT2A-r), yet resistance remains a challenge. Here, through systematic chromatin-focused CRISPR screens, along with genetic, epigenetic, and pharmacologic studies in a variety of human and mouse KMT2A-r AML models, we uncover a potential resistance mechanism independent of canonical Menin-MLL targets. We show that a group of non-canonical Menin targets, which are bivalently co-occupied by active Menin and repressive H2AK119ub marks, are typically downregulated following Menin inhibition. The loss of Polycomb Repressive Complex 1.1 (PRC1.1) subunits, such as PCGF1 or BCOR, leads to Menin inhibitor resistance by epigenetic reactivation of these non-canonical targets, including MYC. Genetic and pharmacological inhibition of MYC can resensitize PRC1.1-deficent leukemia cells to Menin inhibition. Moreover, we demonstrate that leukemia cells with the loss of PRC1.1 subunits exhibit reduced monocytic gene signatures and are susceptible to the BCL2 inhibition, and combinational treatment of venetoclax overcomes the resistance to Menin inhibition in PRC1.1-deficient leukemia cells. These findings highlight the important roles of PRC1.1 and its regulated non-canonical Menin targets in modulating Menin inhibitor response and provide potential strategies to treat leukemias with compromised PRC1.1 function.
Project description:To investigate the effect of Menin inhibitor on UBTF-TD harboring AML. We characterized UBTF-TD interaction with KMT2A and Menin in different leukemia models including KMT2A-r, transduced and normal cbCD34+ cells as well as in primary AML cells with UBTF-TD mutation. We also analized gene expression pattern upon treatment with Menin inhibitor.
Project description:Inhibitors of the Menin-KMT2A interaction are promising agents for the treatment of KMT2A-rearranged (KMT2A-r) leukemias. We evaluated Menin inhibition in patient derived xenografts of KMT2A-r leukemias with high-risk features. Three AMLs with high-risk fusion partners (MLLT10, MLLT4) and two infant ALL samples were sensitive to Menin inhibition. We also evaluated serial samples from two patients with multiply relapsed ALL. We found that highly pretreated KMT2A::AFF1 ALL samples were much less sensitive compared to cells obtained earlier in the same patients’ disease course. Since none of the patients had been treated with a Menin inhibitor, resistance in these highly pretreated samples was acquired in the absence to Menin inhibitor exposure. Transcriptomic analysis documented sustained on-target efficacy towards the canonical targets in the Menin-inhibitor in resistant cells. Targeted genomic analysis documented the emergence of multiple co-mutations, including RAS pathway and TP53 mutations, although neither was sufficient to induce Menin-inhibitor resistance in vitro. Downregulation of KMT3D may account for resistance in one patients; inactivation of KMT2C/D has been reported to result in Menin inhibitor resistance, and KMT2C-edited cells from this patient were selected for in VTP containing growth conditions. Future studies will need to clarify more broadly which genomic/epigenomic alterations drive upfront resistance. Regardless of mechanism, our data supports using Menin-inhibitors upfront or in early lines of therapy before substantial genomic or epigenomic evolution has occurred.