gsk-2816126 and Neoplasms

The polycomb repressive complex 2 (PRC2), which comprised of the core subunits: Enhancer of Zeste Homolog 2 (EZH2), Suppressor of Zeste 12 (SUZ12), and Embryonic Ectoderm Development (EED), is an essential epigenetic gene silencer responsible for depositing repressive histone H3 lysine 27 trimethylation (H3K27me3) marks on chromatin. The aberrant activity of PRC2 is closely involved in tumorigenesis and progression, making its inhibition a viable strategy for epigenetic cancer therapy. Although the clinical development of small PRC2 inhibitors has made impressive progress, with one EZH2 inhibitor approved for cancer therapy and several other candidates in clinical trials, current EZH2 inhibitors are limited to treating certain hematological malignancies and have acquired drug resistance. EED is essential for PRC2 stabilization and allosterically stimulating PRC2 activity because it functions as a scaffold protein and an H3K27me3-recognizing protein. Thus, due to its novel mechanism of action, targeting EED provides a promising new strategy for inhibiting PRC2 function and exhibits the potential to overcome the issues encountered by EZH2 inhibitors. This review provides a comprehensive overview of available cancer therapy strategies that target EED, including allosteric inhibitors, protein-protein interaction (PPI) inhibitors, and proteolysis-targeting chimeras (PROTACs).

Topics: Ectoderm; Enhancer of Zeste Homolog 2 Protein; Humans; Intercellular Signaling Peptides and Proteins; Neoplasms; Polycomb Repressive Complex 2

Enhancer of zeste homolog 2 (EZH2) is a histone methyltransferase that can change the expression of downstream target genes by catalyzing the trimethylation of lysine 27 of histone H3 (H3K27me3). Studies have found that EZH2 is highly expressed in a variety of tumor tissues and is closely related to the occurrence, development, invasion, and metastasis of tumors; therefore, EZH2 is becoming a new molecular target in antitumor therapy. Tazemetostat (EPZ-6438) was approved in 2020 as the first inhibitor targeting catalytic EZH2 for the treatment of epithelioid sarcoma. In addition, a variety of EZH2 inhibitors are being investigated in basic and clinical research for the treatment of tumors, and encouraging results have been obtained. This article systematically reviews the research progress on EZH2 inhibitors and proteolysis targeting chimera (PROTAC)-based EZH2 degradation agents with a focus on their design strategies, structure-activity relationships (SARs), and safety and clinical manifestations.

Topics: Animals; Enhancer of Zeste Homolog 2 Protein; Enzyme Inhibitors; Hematologic Neoplasms; Histone Methyltransferases; Humans; Molecular Targeted Therapy; Neoplasms; Structure-Activity Relationship

EZH2, the catalytic subunit of PRC2, catalyzes histone H3 lysine 27 (H3K27) trimethylation to induce the agglutination of chromosomes and in turn represses the transcription of the target genes. Numerous reports indicate that EZH2 is overexpressed in a variety of malignant tumor tissues. Therefore, targeting EZH2 protein is a promising strategy for cancer treatment. So far, many small molecule EZH2 specific inhibitors have entered clinical trials, but many of them harbored limited clinical efficacy. New technologies and methods are imperative to enhance the anticancer activity of EZH2. In this review, the structure and biological functions of EZH2 protein will be reviewed. The internal relationship between EZH2 and various diseases will be expounded. The development status of specific inhibitors for EZH2, and the latest progress of new strategies such as drug combination, dual-target inhibitors, targeted protein degradation technology and protein-protein interactions (PPI) inhibitors will be emphatically summarized and analyzed.

Topics: Catalytic Domain; Enhancer of Zeste Homolog 2 Protein; Enzyme Inhibitors; Humans; Neoplasms

PRC2 is a histone methyltransferase complex associated with several cancer types. Tazemetostat was recently approved as the first inhibitor targeting the catalytic subunit EZH2 and several other EZH2 inhibitors are now under clinical evaluation. Beyond EZH2, researchers have also explored other approaches including PRC2 activators, dual agents inhibiting both EZH1 and EZH2, allosteric inhibitors binding to EED, and compounds which induce the degradation of PRC2 constituent proteins.. This review provides an overview of anticancer therapies targeting PRC2 during the period 2016-2020 including clinical trials, patents and the scientific literature.. The approval of tazemetostat marks the clinical validation of EZH2 for the treatment of cancer. Despite this success many questions remain; for instance, tazemetostat was briefly placed on clinical hold for safety concerns, while another EZH2 inhibitor (GSK126) demonstrated insufficient efficacy during a Phase I/II trial. It is important to understand these risks as PRC2 therapies progress through clinic evaluation. Alternative approaches to target PRC2 may offer distinct advantages over the inhibition of EZH2, including the potential to overcome EZH2 resistance mutations. However, these emerging modalities may also incur new challenges as they progress toward the clinic. Nonetheless, the diversity of agents under development represents a wealth of therapeutic options for future patients.

Topics: Animals; Antineoplastic Agents; Benzamides; Biphenyl Compounds; Drug Resistance, Neoplasm; Enhancer of Zeste Homolog 2 Protein; Humans; Indoles; Molecular Targeted Therapy; Morpholines; Mutation; Neoplasms; Patents as Topic; Polycomb Repressive Complex 2; Pyridones

Recent genomic studies have resulted in an emerging understanding of the role of chromatin regulators in the development of cancer. EZH2, a histone methyl transferase subunit of a Polycomb repressor complex, is recurrently mutated in several forms of cancer and is highly expressed in numerous others. Notably, both gain-of-function and loss-of-function mutations occur in cancers but are associated with distinct cancer types. Here we review the spectrum of EZH2-associated mutations, discuss the mechanisms underlying EZH2 function, and synthesize a unifying perspective that the promotion of cancer arises from disruption of the role of EZH2 as a master regulator of transcription. We further discuss EZH2 inhibitors that are now showing early signs of promise in clinical trials and also additional strategies to combat roles of EZH2 in cancer.

Topics: Benzamides; Biphenyl Compounds; Drug Resistance, Neoplasm; Enhancer of Zeste Homolog 2 Protein; Humans; Indazoles; Indoles; Molecular Targeted Therapy; Morpholines; Mutation; Neoplasms; Polycomb Repressive Complex 2; Polycomb-Group Proteins; Pyridones

Enhancer of zeste homolog 2 (EZH2) activity is dysregulated in many cancers.. This phase I study determined the safety, maximum-tolerated dose (MTD), pharmacokinetics, and pharmacodynamics of the intravenously administered, highly selective EZH2 inhibitor, GSK2816126, (NCT02082977). Doses of GSK2816126 ranged from 50 to 3,000 mg twice weekly, and GSK2816126 was given 3-weeks-on/1-week-off in 28-day cycles. Eligible patients had solid tumors or B-cell lymphomas with no available standard treatment regimen.. Forty-one patients (21 solid tumors, 20 lymphoma) received treatment. All patients experienced ≥1 adverse event (AE). Fatigue [22 of 41 (53.7%)] and nausea [20 of 41 (48.8%)] were the most common toxicity. Twelve (32%) patients experienced a serious AE. Dose-limiting elevated liver transaminases occurred in 2 of 7 patients receiving 3,000 mg of GSK2816126; 2,400 mg was therefore established as the MTD. Following intravenous administration of 50 to 3,000 mg twice weekly, plasma GSK2816126 levels decreased biexponentially, with a mean terminal elimination half-life of approximately 27 hours. GSK2816126 exposure (maximum observed plasma concentration and area under the plasma-time curve) increased in a dose-proportional manner. No change from baseline in H3K27me3 was seen in peripheral blood mononuclear cells. Fourteen of 41 (34%) patients had radiological best response of stable disease, 1 patient with lymphoma achieved a partial response, 21 of 41 (51%) patients had progressive disease, and 5 patients were unevaluable for antitumor response.. The MTD of GSK2816126 was established at 2,400 mg, but the dosing method and relatively short half-life limited effective exposure, and modest anticancer activity was observed at tolerable doses.

Topics: Adult; Aged; Aged, 80 and over; Antineoplastic Agents; Enhancer of Zeste Homolog 2 Protein; Female; Humans; Indoles; Lymphoma, B-Cell; Male; Maximum Tolerated Dose; Middle Aged; Neoplasms; Patient Safety; Prognosis; Pyridones; Tissue Distribution; Young Adult

The inhibition of enhancer of zeste homolog 2 (EZH2) has been suggested to be synthetic lethal with polybromo-1 (PBRM1) deficiency, rendering EZH2 to be an attractive target for the treatment of PBRM1 frequently mutated cancers. In the current study, we combined computational and biochemical approaches to establish an efficient system for the screening and validation of synthetic lethal inhibitors from a large pool of chemical compounds. Five putative EZH2 inhibitors were identified through structure-based virtual screening from 47,737 chemical compounds and analyzed with molecular dynamics. The efficacy of these compounds against EZH2 was tested using PBRM1 deficient and wide-type cell lines. The compound L501-1669 selectively inhibited the proliferation of PBRM1-deficient cells and down-regulated the tri-methylation of histone H3 at Lysine 27 (H3K27me3). Importantly, we also observed an increase in apoptotic activities in L501-1669 treated PBRM1-deficient cells. Taken together, our results demonstrate that L501-1669 is a selective EZH2 inhibitor with promising application in the targeted therapy of PBRM1-deficient cancers.

Topics: Apoptosis; Cell Line, Tumor; Cell Proliferation; DNA-Binding Proteins; Drug Screening Assays, Antitumor; Enhancer of Zeste Homolog 2 Protein; Histones; Humans; Indoles; Lysine; Methylation; Molecular Docking Simulation; Molecular Dynamics Simulation; Neoplasms; Prognosis; Pyridones; Reproducibility of Results; Synthetic Lethal Mutations; Transcription Factors

A new enhancer of zeste homolog 2 (EZH2) inhibitor series comprising a substituted phenyl ring joined to a dimethylpyridone moiety via an amide linkage has been designed. A preferential amide torsion that improved the binding properties of the compounds was identified for this series via computational analysis. Cyclization of the amide linker resulted in a six-membered lactam analogue, compound 18. This transformation significantly improved the ligand efficiency/potency of the cyclized compound relative to its acyclic analogue. Additional optimization of the lactam-containing EZH2 inhibitors focused on lipophilic efficiency (LipE) improvement, which provided compound 31. Compound 31 displayed improved LipE and on-target potency in both biochemical and cellular readouts relative to compound 18. Inhibitor 31 also displayed robust in vivo antitumor growth activity and dose-dependent de-repression of EZH2 target genes.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Cyclization; Drug Design; Enhancer of Zeste Homolog 2 Protein; Female; Humans; Isoquinolines; Lactams; Mice; Mice, SCID; Models, Molecular; Neoplasms; Pyridones

Alterations of epigenetic modifications are promising targets for cancer therapy, and several epigenetic drugs are now being clinically utilized. At the same time, individual epigenetic modifications have physiological functions in normal cells, and cancer cell specificity is considered difficult to achieve using a drug against a single epigenetic modification. To overcome this limitation, a combination of epigenetic modifications specifically or preferentially present in cancer cells is a candidate target. In this study, we aimed to demonstrate (i) the presence of a cancer cell-specific combination of epigenetic modifications by focusing on DNA methylation and trimethylation of histone H3 lysine 27 (H3K27me3) and (ii) the therapeutic efficacy of a combination of DNA demethylation and EZH2 inhibition. Analyses of DNA methylation and H3K27me3 in human colon, breast and prostate cancer cell lines revealed that 24.7±4.1% of DNA methylated genes had both DNA methylation and H3K27me3 (dual modification) in cancer cells, while it was 11.8±7.1% in normal cells. Combined treatment with a DNA demethylating agent, 5-aza-2'-deoxycytidine (5-aza-dC) and an EZH2 inhibitor, GSK126, induced marked re-expression of genes with the dual modification, including known tumor-suppressor genes such as IGFBP7 and SFRP1, and showed an additive inhibitory effect on growth of cancer cells in vitro. Finally, an in vivo combined treatment with 5-aza-dC and GSK126 inhibited growth of xenograft tumors more efficiently than a single treatment with 5-aza-dC. These results showed that the dual modification exists specifically in cancer cells and is a promising target for cancer cell-specific epigenetic therapy.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Azacitidine; Benzamides; Cell Proliferation; Decitabine; DNA Methylation; Enhancer of Zeste Homolog 2 Protein; Enzyme Inhibitors; Epigenesis, Genetic; Female; Gene Expression Regulation, Neoplastic; HCT116 Cells; Histone Deacetylase Inhibitors; Histones; Humans; Indoles; Insulin-Like Growth Factor Binding Proteins; Intercellular Signaling Peptides and Proteins; Male; MCF-7 Cells; Membrane Proteins; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasms; Polycomb Repressive Complex 2; Promoter Regions, Genetic; Pyridines; Pyridones; Xenograft Model Antitumor Assays

Although targeted therapies have revolutionized cancer treatment, overcoming acquired resistance remains a major clinical challenge. EZH2 inhibitors (EZH2i), EPZ-6438 and GSK126, are currently in the early stages of clinical evaluation and the first encouraging signs of efficacy have recently emerged in the clinic. To anticipate mechanisms of resistance to EZH2i, we used a forward genetic platform combining a mutagenesis screen with next generation sequencing technology and identified a hotspot of secondary mutations in the EZH2 D1 domain (Y111 and I109). Y111D mutation within the WT or A677G EZH2 allele conferred robust resistance to both EPZ-6438 and GSK126, but it only drove a partial resistance within the Y641F allele. EZH2 mutants required histone methyltransferase (HMT) catalytic activity and the polycomb repressive complex 2 (PRC2) components, SUZ12 and EED, to drive drug resistance. Furthermore, D1 domain mutations not only blocked the ability of EZH2i to bind to WT and A677G mutant, but also abrogated drug binding to the Y641F mutant. These data provide the first cellular validation of the mechanistic model underpinning the oncogenic function of WT and mutant EZH2. Importantly, our findings suggest that acquired-resistance to EZH2i may arise in WT and mutant EZH2 patients through a single mutation that remains targetable by second generation EZH2i.

Topics: Antineoplastic Agents; Benzamides; Biphenyl Compounds; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Enhancer of Zeste Homolog 2 Protein; Enzyme Inhibitors; HEK293 Cells; Humans; Indoles; Molecular Targeted Therapy; Morpholines; Mutation; Neoplasm Proteins; Neoplasms; Polycomb Repressive Complex 2; Protein Binding; Protein Structure, Tertiary; Pyridones; RNA Interference; Time Factors; Transcription Factors; Transfection

Human cancer genome sequencing has recently revealed that genes that encode subunits of SWI/SNF chromatin remodeling complexes are frequently mutated across a wide variety of cancers, and several subunits of the complex have been shown to have bona fide tumor suppressor activity. However, whether mutations in SWI/SNF subunits result in shared dependencies is unknown. Here we show that EZH2, a catalytic subunit of the polycomb repressive complex 2 (PRC2), is essential in all tested cancer cell lines and xenografts harboring mutations of the SWI/SNF subunits ARID1A, PBRM1, and SMARCA4, which are several of the most frequently mutated SWI/SNF subunits in human cancer, but that co-occurrence of a Ras pathway mutation is correlated with abrogation of this dependence. Notably, we demonstrate that SWI/SNF-mutant cancer cells are primarily dependent on a non-catalytic role of EZH2 in the stabilization of the PRC2 complex, and that they are only partially dependent on EZH2 histone methyltransferase activity. These results not only reveal a shared dependency of cancers with genetic alterations in SWI/SNF subunits, but also suggest that EZH2 enzymatic inhibitors now in clinical development may not fully suppress the oncogenic activity of EZH2.

Topics: Acetylation; Animals; Catalysis; Cell Line, Tumor; Chromosomal Proteins, Non-Histone; Drug Resistance, Neoplasm; Enhancer of Zeste Homolog 2 Protein; Enzyme Inhibitors; Female; Humans; Indoles; Methylation; Mice, Nude; Mutation; Neoplasms; Phosphorylation; Polycomb Repressive Complex 2; Pyridones; RNA, Small Interfering; Transcription Factors; Xenograft Model Antitumor Assays

The polycomb group protein Ezh2 is a histone methyltransferase that modifies chromatin structure to alter gene expression during embryonic development, lymphocyte activation, and tumorigenesis. The mechanism by which Ezh2 expression is regulated is not well defined. In the current study, we report that c-Rel is a critical activator of Ezh2 transcription in lymphoid cells. In activated primary murine B and T cells, plus human leukemia and multiple myeloma cell lines, recruitment of c-Rel to the first intron of the Ezh2 locus promoted Ezh2 mRNA expression. This up-regulation was abolished in activated c-Rel-deficient lymphocytes and by c-Rel knockdown in Jurkat T cells. Treatment of malignant cells with the c-Rel inhibitor pentoxifylline not only reduced c-Rel nuclear translocation and Ezh2 expression, but also enhanced their sensitivity to the Ezh2-specific drug, GSK126 through increased growth inhibition and cell death. In summary, our demonstration that c-Rel regulates Ezh2 expression in lymphocytes and malignant lymphoid cells reveals a novel transcriptional network in transformed lymphoid cells expressing high levels of Ezh2 that provides a molecular justification for combinatorial drug therapy.

Topics: Animals; Base Sequence; Cell Line, Tumor; Cell Nucleus; Cell Survival; Enhancer of Zeste Homolog 2 Protein; Gene Expression Regulation, Neoplastic; HEK293 Cells; Humans; Indoles; Jurkat Cells; Lymphocyte Activation; Lymphocytes; Mice; Mice, Inbred C57BL; Molecular Sequence Data; Neoplasms; Pentoxifylline; Polycomb Repressive Complex 2; Proto-Oncogene Proteins c-rel; Pyridones; Transcription, Genetic; Up-Regulation