Discovery of the Clinical Candidate MAK683: An EED-Directed, Allosteric, and Selective PRC2 Inhibitor for the Treatment of Advanced Malignancies

Expanding the ligand spaces for E3 ligases for the design of protein degraders

Targeted protein degradation (TPD) has recently emerged as an exciting new drug modality. However, the strategy of developing small molecule-based protein degraders has evolved over the past two decades and has now established molecular tags that are already in clinical use, as well as chimeric molecules, PROteolysis TArgeting Chimeras (PROTACs), based mainly on ligand systems developed for the two E3 ligases CRBN and VHL. The large size of the human E3 ligase family suggests that PROTACs can be developed by targeting a large diversity of E3 ligases, some of which have restricted expression patterns with the potential to design disease- or tissue-specific degraders. Indeed, many new E3 ligands have been published recently, confirming the druggability of E3 ligases. This review summarises recent data on E3 ligases and highlights the challenges in developing these molecules into efficient PROTACs rivalling the established degrader systems.

Chemical inhibitors targeting histone methylation readers

Histone methylation reader domains are protein modules that recognize specific histone methylation marks, such as methylated or unmethylated lysine or arginine residues on histones. These reader proteins play crucial roles in the epigenetic regulation of gene expression, chromatin structure, and DNA damage repair. Dysregulation of these proteins has been linked to various diseases, including cancer, neurodegenerative diseases, and developmental disorders. Therefore, targeting these proteins with chemical inhibitors has emerged as an attractive approach for therapeutic intervention, and significant progress has been made in this area. In this review, we will summarize the development of inhibitors targeting histone methylation readers, including MBT domains, chromodomains, Tudor domains, PWWP domains, PHD fingers, and WD40 repeat domains. For each domain, we will briefly discuss its identification and biological/biochemical functions, and then focus on the discovery of inhibitors tailored to target this domain, summarizing the property and potential application of most inhibitors. We will also discuss the structural basis for the potency and selectivity of these inhibitors, which will aid in further lead generation and optimization. Finally, we will also address the challenges and strategies involved in the development of these inhibitors. It should facilitate the rational design and development of novel chemical scaffolds and new targeting strategies for histone methylation reader domains with the help of this body of data.

BMP-ACVR1 Axis is Critical for Efficacy of PRC2 Inhibitors in B-Cell Lymphoma

EZH2 is the catalytic subunit of the histone methyltransferase Polycomb Repressive Complex 2 (PRC2), and its somatic activating mutations drive lymphoma, particularly the germinal center B-cell type. Although PRC2 inhibitors, such as tazemetostat, have demonstrated anti-lymphoma activity in patients, the clinical efficacy is not limited to EZH2-mutant lymphoma. In this study, Activin A Receptor Type 1 (ACVR1), a type I Bone Morphogenetic Protein (BMP) receptor, is identified as critical for the anti-lymphoma efficacy of PRC2 inhibitors through a whole-genome CRISPR screen. BMP6, BMP7, and ACVR1 are repressed by PRC2-mediated H3K27me3, and PRC2 inhibition upregulates their expression and signaling in cell and patient-derived xenograft models. Through BMP-ACVR1 signaling, PRC2 inhibitors robustly induced cell cycle arrest and B cell lineage differentiation in vivo. Remarkably, blocking ACVR1 signaling using an inhibitor or genetic depletion significantly compromised the in vitro and in vivo efficacy of PRC2 inhibitors. Furthermore, high levels of BMP6 and BMP7, along with ACVR1, are associated with longer survival in lymphoma patients, underscoring the clinical relevance of this study. Altogether, BMP-ACVR1 exhibits anti-lymphoma function and represents a critical PRC2-repressed pathway contributing to the efficacy of PRC2 inhibitors.

Epigenetic regulation of bone remodeling and bone metastasis

Bone remodeling is a continuous and dynamic process of bone formation and resorption to maintain its integrity and homeostasis. Bone marrow is a source of various cell lineages, including osteoblasts and osteoclasts, which are involved in bone formation and resorption, respectively, to maintain bone homeostasis. Epigenetics is one of the elementary regulations governing the physiology of bone remodeling. Epigenetic modifications, mainly DNA methylation, histone modifications, and non-coding RNAs, regulate stable transcriptional programs without causing specific heritable alterations. DNA methylation in CpG-rich promoters of the gene is primarily correlated with gene silencing, and histone modifications are associated with transcriptional activation/inactivation. However, non-coding RNAs regulate the metastatic potential of cancer cells to metastasize at secondary sites. Deregulated or altered epigenetic modifications are often seen in many cancers and interwound with bone-specific tropism and cancer metastasis. Histone acetyltransferases, histone deacetylase, and DNA methyltransferases are promising targets in epigenetically altered cancer. High throughput epigenome mapping and targeting specific epigenetics modifiers will be helpful in the development of personalized epi-drugs for advanced and bone metastasis cancer patients. This review aims to discuss and gather more knowledge about different epigenetic modifications in bone remodeling and metastasis. Further, it provides new approaches for targeting epigenetic changes and therapy research.

DCAF1-based PROTACs with activity against clinically validated targets overcoming intrinsic- and acquired-degrader resistance

Targeted protein degradation (TPD) mediates protein level through small molecule induced redirection of E3 ligases to ubiquitinate neo-substrates and mark them for proteasomal degradation. TPD has recently emerged as a key modality in drug discovery. So far only a few ligases have been utilized for TPD. Interestingly, the workhorse ligase CRBN has been observed to be downregulated in settings of resistance to immunomodulatory inhibitory drugs (IMiDs). Here we show that the essential E3 ligase receptor DCAF1 can be harnessed for TPD utilizing a selective, non-covalent DCAF1 binder. We confirm that this binder can be functionalized into an efficient DCAF1-BRD9 PROTAC. Chemical and genetic rescue experiments validate specific degradation via the CRL4DCAF1 E3 ligase. Additionally, a dasatinib-based DCAF1 PROTAC successfully degrades cytosolic and membrane-bound tyrosine kinases. A potent and selective DCAF1-BTK-PROTAC (DBt-10) degrades BTK in cells with acquired resistance to CRBN-BTK-PROTACs while the DCAF1-BRD9 PROTAC (DBr-1) provides an alternative strategy to tackle intrinsic resistance to VHL-degrader, highlighting DCAF1-PROTACS as a promising strategy to overcome ligase mediated resistance in clinical settings.

Insight into the Inhibitory Mechanism of Embryonic Ectoderm Development Subunit by Triazolopyrimidine Derivatives as Inhibitors through Molecular Dynamics Simulation

Inhibition of the Embryonic Ectoderm Development (EED) subunit in Polycomb Repressive Complex 2 (PRC2) can inhibit tumor growth. In this paper, we selected six experimentally designed EED competitive Inhibitors of the triazolopyrimidine derivatives class. We investigated the difference in the binding mode of the natural substrate to the Inhibitors and the effects of differences in the parent nuclei, heads, and tails of the Inhibitors on the inhibitory capacity. The results showed that the binding free energy of this class of Inhibitors was close to or lower compared to the natural substrate, providing an energetic basis for competitive inhibition. For the Inhibitors, the presence of a strong negatively charged group at the 6-position of the parent nucleus or the 8'-position of the head would make the hydrogen atom on the head imino group prone to flip, resulting in the vertical movement of the parent nucleus, which significantly decreased the inhibitory ability. When the 6-position of the parent nucleus was a nonpolar group, the parent nucleus would move horizontally, slightly decreasing the inhibitory ability. When the 8'-position of the head was methylene, it formed an intramolecular hydrophobic interaction with the benzene ring on the tail, resulting in a significant increase in inhibition ability.

Exploring the therapeutic potential of targeting polycomb repressive complex 2 in lung cancer

The pathogenesis of lung cancer (LC) is a multifaceted process that is influenced by a variety of factors. Alongside genetic mutations and environmental influences, there is increasing evidence that epigenetic mechanisms play a significant role in the development and progression of LC. The Polycomb repressive complex 2 (PRC2), composed of EZH1/2, SUZ12, and EED, is an epigenetic silencer that controls the expression of target genes and is crucial for cell identity in multicellular organisms. Abnormal expression of PRC2 has been shown to contribute to the progression of LC through several pathways. Although targeted inhibition of EZH2 has demonstrated potential in delaying the progression of LC and improving chemotherapy sensitivity, the effectiveness of enzymatic inhibitors of PRC2 in LC is limited, and a more comprehensive understanding of PRC2's role is necessary. This paper reviews the core subunits of PRC2 and their interactions, and outlines the mechanisms of aberrant PRC2 expression in cancer and its role in tumor immunity. We also summarize the important role of PRC2 in regulating biological behaviors such as epithelial mesenchymal transition, invasive metastasis, apoptosis, cell cycle regulation, autophagy, and PRC2-mediated resistance to LC chemotherapeutic agents in LC cells. Lastly, we explored the latest breakthroughs in the research and evaluation of medications that target PRC2, as well as the latest findings from clinical studies investigating the efficacy of these drugs in the treatment of various human cancers.

Nicardipine is a putative EED inhibitor and has high selectivity and potency against chemoresistant prostate cancer in preclinical models

BACKGROUND

It is imperative to develop novel therapeutics to overcome chemoresistance, a significant obstacle in the clinical management of prostate cancer (PCa) and other cancers.

METHODS

A phenotypic screen was performed to identify novel inhibitors of chemoresistant PCa cells. The mechanism of action of potential candidate(s) was investigated using in silico docking, and molecular and cellular assays in chemoresistant PCa cells. The in vivo efficacy was evaluated in mouse xenograft models of chemoresistant PCa.

RESULTS

Nicardipine exhibited high selectivity and potency against chemoresistant PCa cells via inducing apoptosis and cell cycle arrest. Computational, molecular, and cellular studies identified nicardipine as a putative inhibitor of embryonic ectoderm development (EED) protein, and the results are consistent with a proposed mechanism of action that nicardipine destabilised enhancer of zeste homologue 2 (EZH2) and inhibited key components of noncanonical EZH2 signalling, including transducer and activator of transcription 3, S-phase kinase-associated protein 2, ATP binding cassette B1, and survivin. As a monotherapy, nicardipine effectively inhibited the skeletal growth of chemoresistant C4-2B-TaxR tumours. As a combination regimen, nicardipine synergistically enhanced the in vivo efficacy of docetaxel against C4-2 xenografts.

CONCLUSION

Our findings provided the first preclinical evidence supporting nicardipine as a novel EED inhibitor that has the potential to be promptly tested in PCa patients to overcome chemoresistance and improve clinical outcomes.

Inhibition of Ezh2 redistributes bivalent domains within transcriptional regulators associated with WNT and Hedgehog pathways in osteoblasts

Bivalent epigenomic regulatory domains containing both activating histone 3 lysine 4 (H3K4me3) and repressive lysine 27 (H3K27me3) trimethylation are associated with key developmental genes. These bivalent domains repress transcription in the absence of differentiation signals but maintain regulatory genes in a poised state to allow for timely activation. Previous studies demonstrated that enhancer of zeste homolog 2 (Ezh2), a histone 3 lysine 27 (H3K27) methyltransferase, suppresses osteogenic differentiation and that inhibition of Ezh2 enhances commitment of osteoblast progenitors in vitro and bone formation in vivo. Here, we examined the mechanistic effects of Tazemetostat (EPZ6438), an Food and Drug Administration approved Ezh2 inhibitor for epithelioid sarcoma treatment, because this drug could potentially be repurposed to stimulate osteogenesis for clinical indications. We find that Tazemetostat reduces H3K27me3 marks in bivalent domains in enhancers required for bone formation and stimulates maturation of MC3T3 preosteoblasts. Furthermore, Tazemetostat activates bivalent genes associated with the Wingless/integrated (WNT), adenylyl cyclase (cAMP), and Hedgehog (Hh) signaling pathways based on transcriptomic (RNA-seq) and epigenomic (chromatin immunoprecipitation [ChIP]-seq) data. Functional analyses using selective pathway inhibitors and silencing RNAs demonstrate that the WNT and Hh pathways modulate osteogenic differentiation after Ezh2 inhibition. Strikingly, we show that loss of the Hh-responsive transcriptional regulator Gli1, but not Gli2, synergizes with Tazemetostat to accelerate osteoblast differentiation. These studies establish epigenetic cooperativity of Ezh2, Hh-Gli1 signaling, and bivalent regulatory genes in suppressing osteogenesis. Our findings may have important translational ramifications for anabolic applications requiring bone mass accrual and/or reversal of bone loss.

Targeting EZH2 in SMARCB1-deficient sarcomas: Advances and opportunities to potentiate the efficacy of EZH2 inhibitors

Soft tissue sarcomas (STSs) are rare mesechymal malignancies characterized by distintive molecular, histological and clinical features. Many STSs are considered as predominatly epigenetic diseases due to underlying chromatin deregulation. Discovery of deregulated functional antagonism between the chromatin remodeling BRG1/BRM-associated (BAFs) and the histone modifying Polycomb repressor complexes (PRCs) has provided novel actionable targets. In epithelioid sarcoma (ES), extracranial, extrarenal malignant rhabdoid tumors (eMRTs) and synovial sarcoma (SS), the total or partial loss of the BAF core subunit SMARCB1, driven by different alterations, is associated with PRC2 deregulation and dependency on its enzymatic subunit, EZH2. In these SMARCB1-deficient STSs, aberrant EZH2 expression and/or activity emerged as a druggable vulnerability. Although preclinical investigation supported EZH2 targeting as a promising therapeutic option, clinical studies demonstrated a variable response to EZH2 inhibitors. Actually, whereas the clinical benefit recorded in ES patients prompted the FDA approval of the EZH2 inhibitor tazemetostat, the modest and sporadic responses observed in eMRT and SS patients highlighted the need to deepen mechanistic as well as pharmacological investigations to improve drug effectiveness. We summarize the current knowledge of different mechanisms driving SMARCB1 deficiency and EZH2 deregulation in ES, eMRT and SS along with preclinical and clinical studies of EZH2-targeting agents. Possible implication of the PRC2- and enzymatic-independent functions of EZH2 and of its homolog, EZH1, in the response to anti-EZH2 agents will be discussed together with combinatorial strategies under investigation to improve the efficacy of EZH2 targeting in these tumors.

The roles of EZH2 in cancer and its inhibitors

The enhancer of zeste homolog 2 (EZH2) is encoded by the Enhancer of zeste 2 polycomb repressive complex 2 subunit gene. EZH2 is involved in the cell cycle, DNA damage repair, cell differentiation, autophagy, apoptosis, and immunological modulation. The main function of EZH2 is to catalyze the methylation of H3 histone of H3K27Me3, which inhibits the transcription of target genes, such as tumor suppressor genes. EZH2 also forms complexes with transcriptions factors or directly binds to the promoters of target genes, leading to regulate gene transcriptions. EZH2 has been as a prominent target for cancer therapy and a growing number of potential targeting medicines have been developed. This review summarized the mechanisms that EZH2 regulates gene transcription and the interactions between EZH2 and important intracellular signaling molecules (Wnt, Notch, MEK, Akt) and as well the clinical applications of EZH2-targeted drugs.

Triazole-fused pyrimidines in target-based anticancer drug discovery

In recent decades, the development of targeted drugs has featured prominently in the treatment of cancer, which is among the major causes of mortality globally. Triazole-fused pyrimidines, a widely-used class of heterocycles in medicinal chemistry, have attracted considerable interest as potential anticancer agents that target various cancer-associated targets in recent years, demonstrating them as valuable templates for discovering novel anticancer candidates. The current review concentrates on the latest advancements of triazole-pyrimidines as target-based anticancer agents, including works published between 2007 and the present (2007-2022). The structure-activity relationships (SARs) and multiple pathways are also reviewed to shed light on the development of more effective and biotargeted anticancer candidates.

Novel insights into histone lysine methyltransferases in cancer therapy: From epigenetic regulation to selective drugs

The reversible and precise temporal and spatial regulation of histone lysine methyltransferases (KMTs) is essential for epigenome homeostasis. The dysregulation of KMTs is associated with tumor initiation, metastasis, chemoresistance, invasiveness, and the immune microenvironment. Therapeutically, their promising effects are being evaluated in diversified preclinical and clinical trials, demonstrating encouraging outcomes in multiple malignancies. In this review, we have updated recent understandings of KMTs' functions and the development of their targeted inhibitors. First, we provide an updated overview of the regulatory roles of several KMT activities in oncogenesis, tumor suppression, and immune regulation. In addition, we summarize the current targeting strategies in different cancer types and multiple ongoing clinical trials of combination therapies with KMT inhibitors. In summary, we endeavor to depict the regulation of KMT-mediated epigenetic landscape and provide potential epigenetic targets in the treatment of cancers.

Structure-Based Design of the Indole-Substituted Triazolopyrimidines as New EED-H3K27me3 Inhibitors for the Treatment of Lymphoma

Interrupting the embryonic ectoderm development (EED)-H3K27me3 interaction represents a promising strategy to allosterically inhibit polycomb repressive complex 2 (PRC2) for cancer therapy. In this work, we report the structure-based design of new triazolopyrimidine-based EED inhibitors, which structurally feature the electron-rich indole ring at the C8 position. Particularly, ZJH-16 directly binds to EED (HTRF IC₅₀ = 2.72 nM, BLI K_D = 4.4 nM) and potently inhibits the growth of KARPAS422 and Pfeiffer cells. In both cells, ZJH-16 is selectively engaged with EED and reduces H3K27 trimethylation levels. ZJH-16 inhibits the gene silencing function of PRC2 in KARPAS422 cells. ZJH-16 possesses favorable pharmacokinetic (PK) profiles with an excellent oral bioavailability (F = 94.7%). More importantly, ZJH-16 shows robust tumor regression in the KARPAS422 xenograft model after oral administration with the tumor growth inhibition reaching nearly 100%. The robust antitumor efficacy and favorable PK profiles of ZJH-16 warrant further advanced preclinical development for lymphoma treatment.

EZH2: An Accomplice of Gastric Cancer

Gastric cancer is the fifth most common cancer and the third leading cause of cancer deaths worldwide. Understanding the factors influencing the therapeutic effects in gastric cancer patients and the molecular mechanism behind gastric cancer is still facing challenges. In addition to genetic alterations and environmental factors, it has been demonstrated that epigenetic mechanisms can also induce the occurrence and progression of gastric cancer. Enhancer of zeste homolog 2 (EZH2) is the catalytic subunit of the polycomb repressor complex 2 (PRC2), which trimethylates histone 3 at Lys-27 and regulates the expression of downstream target genes through epigenetic mechanisms. It has been found that EZH2 is overexpressed in the stomach, which promotes the progression of gastric cancer through multiple pathways. In addition, targeted inhibition of EZH2 expression can effectively delay the progression of gastric cancer and improve its resistance to chemotherapeutic agents. Given the many effects of EZH2 in gastric cancer, there are no studies to comprehensively describe this mechanism. Therefore, in this review, we first introduce EZH2 and clarify the mechanisms of abnormal expression of EZH2 in cancer. Secondly, we summarize the role of EZH2 in gastric cancer, which includes the association of the EZH2 gene with genetic susceptibility to GC, the correlation of the EZH2 gene with gastric carcinogenesis and invasive metastasis, the resistance to chemotherapeutic drugs of gastric cancer mediated by EZH2 and the high expression of EZH2 leading to poor prognosis of gastric cancer patients. Finally, we also clarify some of the current statuses of drug development regarding targeted inhibition of EZH2/PRC2 activity.

The pleiotropic roles of EZH2 in T-cell immunity and immunotherapy

EZH2 is a histone methyltransferase. It catalyzes trimethylation of histone H3 at lysine 27 (H3K27me3) to control gene transcription critical for cell proliferation, differentiation, expansion, and function. For instance, EZH2 plays a central role in regulating T-cell immune responses. EZH2 restrains terminal differentiation of effector CD8 T cells, promotes formation of precursor and mature memory CD8 T cells, regulates appropriate lineage-specification and identity maintenance of helper CD4 T cells, and maintains survival of differentiated antigen-specific T cells. Most importantly, EZH2 is shown to be important for reinvigoration of exhausted chimeric antigen receptor (CAR) T cells. Dysregulated EZH2 function has been linked to many forms of cancer, including lymphomas and solid tumors. In B-cell lymphoid malignancies, EZH2 is overexpressed to drive tumorigenesis. These specific effects of EZH2, in the context of its roles in catalyzing H3K27me3 and orchestrating gene transcription programs in both normal and malignant cells, establishes EZH2 as a unique target for drug development. Here, we will discuss Ezh2 regulation of T-cell immunity, EZH2-mediated lymphomagenesis, and therapeutic benefits of EZH2 inhibitors to the treatment of lymphoma.

Dual-Acting Peptides Target EZH2 and AR: A New Paradigm for Effective Treatment of Castration-Resistant Prostate Cancer

Prostate cancer starts as a treatable hormone-dependent disease, but often ends in a drug-resistant form called castration-resistant prostate cancer (CRPC). Despite the development of the antiandrogens enzalutamide and abiraterone for CRPC, which target the androgen receptor (AR), drug resistance usually develops within 6 months and metastatic CRPC (mCRPC) leads to lethality. EZH2, found with SUZ12, EED, and RbAP48 in Polycomb repressive complex 2 (PRC2), has emerged as an alternative target for the treatment of deadly mCRPC. Unfortunately, drugs targeting EZH2 have shown limited efficacy in mCRPC. To address these failures, we have developed novel, dual-acting peptide inhibitors of PRC2 that uniquely target the SUZ12 protein component, resulting in the inhibition of both PRC2 canonical and noncanonical functions in prostate cancer. These peptides were found to inhibit not only the EZH2 methylation activity, but also block its positive effect on AR gene expression in prostate cancer cells. Since the peptide effect on AR levels is transcriptional, the inhibitory peptides can block the expression of both full-length AR and its splicing variants including AR-V7, which plays a significant role in the development of drug resistance. This dual-mode action provides the peptides with the capability to kill enzalutamide-resistant CRPC cells. These peptides are also more cytotoxic to prostate cancer cells than the combination of enzalutamide and an EZH2 inhibitory drug, which was recently suggested to be an effective treatment of mCRPC disease. Our data show that such a dual-acting therapeutic approach can be more effective than the existing front-line drug therapies for treating deadly mCRPC.

Efficient synthesis and evaluation of novel 6-arylamino-[1,2,4]triazolo[4,3-a]pyridine derivatives as antiproliferative agents

Based on our previous work, a series of novel 6-arylamino-[1,2,4]triazolo[4,3-a]pyridine derivatives were synthesized, and evaluated for antiproliferative activities. SAR studies revealed that inserting an amino linkage between 6‑aryl group and [1,2,4]triazolo[4,3-a]pyridine core led to amuch broaderantitumorspectrum, and the most promising compound 8 l exerted potent andbroad-spectrum antiproliferative activity toward HeLa, HCT116, MCF-7, and A549 cell lines, with IC₅₀ values in the micromolar range of 5.98-12.58 μM, which were more active than the positive control 5-FU. The mechanism investigation illustrated that 8 l dose-dependently caused cell cycle arrest at the G₂/M phase, and induced cell apoptosis in HeLa cells. Consequently, these findings suggest the 6-arylamino-[1,2,4]triazolo[4,3-a]pyridines afford significant potential for the discovery of a new highly efficient anticancer agents.

Critical Roles of Polycomb Repressive Complexes in Transcription and Cancer

Polycomp group (PcG) proteins are members of highly conserved multiprotein complexes, recognized as gene transcriptional repressors during development and shown to play a role in various physiological and pathological processes. PcG proteins consist of two Polycomb repressive complexes (PRCs) with different enzymatic activities: Polycomb repressive complexes 1 (PRC1), a ubiquitin ligase, and Polycomb repressive complexes 2 (PRC2), a histone methyltransferase. Traditionally, PRCs have been described to be associated with transcriptional repression of homeotic genes, as well as gene transcription activating effects. Particularly in cancer, PRCs have been found to misregulate gene expression, not only depending on the function of the whole PRCs, but also through their separate subunits. In this review, we focused especially on the recent findings in the transcriptional regulation of PRCs, the oncogenic and tumor-suppressive roles of PcG proteins, and the research progress of inhibitors targeting PRCs.

Chemical biology and pharmacology of histone lysine methylation inhibitors

Histone lysine methylation is a post-translational modification that plays a key role in the epigenetic regulation of a broad spectrum of biological processes. Moreover, the dysregulation of histone lysine methyltransferases (KMTs) has been implicated in the pathogenesis of several diseases particularly cancer. Due to their pathobiological importance, KMTs have garnered immense attention over the last decade as attractive therapeutic targets. These endeavors have culminated in tens of chemical probes that have been used to interrogate many aspects of histone lysine methylation. Besides, over a dozen inhibitors have been advanced to clinical trials, including the EZH2 inhibitor tazemetostat approved for the treatment of follicular lymphoma and advanced epithelioid sarcoma. In this Review, we highlight the chemical biology and pharmacology of KMT inhibitors and targeted protein degraders focusing on the clinical development of EZH1/2, DOT1L, Menin-MLL, and WDR5-MLL inhibitors. We also briefly discuss the pharmacologic targeting of other KMTs.