ABSTRACT
Polycomb Repressive Complex 2 (PRC2) plays an important role in transcriptional regulation during animal development and in cell differentiation, and alteration of PRC2 activity has been associated with cancer. On a molecular level, PRC2 catalyzes methylation of histone H3 lysine 27 (H3K27), resulting in mono-, di-, or trimethylated forms of H3K27, of which the trimethylated form H3K27me3 leads to transcriptional repression of polycomb target genes. Previously, we have shown that binding of the low-molecular-weight compound EED226 to the H3K27me3 binding pocket of the regulatory subunit EED can effectively inhibit PRC2 activity in cells and reduce tumor growth in mouse xenograft models. Here, we report the stepwise optimization of the tool compound EED226 toward the potent and selective EED inhibitor MAK683 (compound 22) and its subsequent preclinical characterization. Based on a balanced PK/PD profile, efficacy, and mitigated risk of forming reactive metabolites, MAK683 has been selected for clinical development.
Subject(s)
Histones , Neoplasms , Animals , Enzyme Inhibitors , Histones/metabolism , Humans , Methylation , Mice , Neoplasms/drug therapy , Polycomb Repressive Complex 2ABSTRACT
Overexpression and somatic heterozygous mutations of EZH2, the catalytic subunit of polycomb repressive complex 2 (PRC2), are associated with several tumor types. EZH2 inhibitor, EPZ-6438 (tazemetostat), demonstrated clinical efficacy in patients with acceptable safety profile as monotherapy. EED, another subunit of PRC2 complex, is essential for its histone methyltransferase activity through direct binding to trimethylated lysine 27 on histone 3 (H3K27Me3). Herein we disclose the discovery of a first-in-class potent, selective, and orally bioavailable EED inhibitor compound 43 (EED226). Guided by X-ray crystallography, compound 43 was discovered by fragmentation and regrowth of compound 7, a PRC2 HTS hit that directly binds EED. The ensuing scaffold hopping followed by multiparameter optimization led to the discovery of 43. Compound 43 induces robust and sustained tumor regression in EZH2MUT preclinical DLBCL model. For the first time we demonstrate that specific and direct inhibition of EED can be effective as an anticancer strategy.
Subject(s)
Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Polycomb Repressive Complex 2/antagonists & inhibitors , Sulfones/chemistry , Sulfones/pharmacology , Triazoles/chemistry , Triazoles/pharmacology , Animals , Antineoplastic Agents/pharmacokinetics , Antineoplastic Agents/therapeutic use , Cell Proliferation/drug effects , Crystallography, X-Ray , Dogs , Female , Haplorhini , Histones/metabolism , Humans , Lymphoma, Large B-Cell, Diffuse/drug therapy , Lymphoma, Large B-Cell, Diffuse/metabolism , Lysine/metabolism , Male , Methylation/drug effects , Mice , Mice, Inbred BALB C , Mice, Nude , Molecular Docking Simulation , Polycomb Repressive Complex 2/chemistry , Polycomb Repressive Complex 2/metabolism , Rats , Sulfones/pharmacokinetics , Sulfones/therapeutic use , Triazoles/pharmacokinetics , Triazoles/therapeutic useABSTRACT
PRC2 is a multisubunit methyltransferase involved in epigenetic regulation of early embryonic development and cell growth. The catalytic subunit EZH2 methylates primarily lysine 27 of histone H3, leading to chromatin compaction and repression of tumor suppressor genes. Inhibiting this activity by small molecules targeting EZH2 was shown to result in antitumor efficacy. Here, we describe the optimization of a chemical series representing a new class of PRC2 inhibitors which acts allosterically via the trimethyllysine pocket of the noncatalytic EED subunit. Deconstruction of a larger and complex screening hit to a simple fragment-sized molecule followed by structure-guided regrowth and careful property modulation were employed to yield compounds which achieve submicromolar inhibition in functional assays and cellular activity. The resulting molecules can serve as a simplified entry point for lead optimization and can be utilized to study this new mechanism of PRC2 inhibition and the associated biology in detail.
Subject(s)
Enzyme Inhibitors/chemistry , Epigenesis, Genetic , Methyltransferases/antagonists & inhibitors , Polycomb Repressive Complex 2/chemistry , Allosteric Regulation , Caco-2 Cells , Chromatography, Liquid , Crystallography, X-Ray , Enzyme Inhibitors/pharmacology , Humans , Inhibitory Concentration 50 , Mass Spectrometry , Molecular Structure , Proton Magnetic Resonance Spectroscopy , Structure-Activity RelationshipABSTRACT
As easy as ABCD: (-)-Jiadifenin was synthesized in eighteen reaction steps from 1-[(E)-(4'-bromo-2'-butenyl)oxy]-4-methoxybenzene. Key features of this synthesis include: 1) Ireland-Claisen rearrangement to produce the two contiguous quaternary centers at C5 and C6 simultaneously, 2) intramolecular Pauson-Khand reaction (IMPKR) to concurrently construct the A and B rings, and 3) [2+2] photo-cycloaddition to generate the all-carbon quaternary center at C9.
Subject(s)
Illicium/chemistry , Sesquiterpenes/chemical synthesis , Cycloaddition Reaction , Models, Molecular , Sesquiterpenes/chemistry , StereoisomerismABSTRACT
[reaction: see text] We describe a facile approach for effectively constructing the pentacyclic framework of subincanadine B. The seven-step assembly of tetracyclic ketone 14 featured Michael addition, Pictet-Spengler cyclization, and Dieckmann condensation. From this key ketone intermediate, two analogues of subincanadine B, i.e., 20-deethylenylated subincanadine B (27) and 19,20-dihydrosubincanadine B (31), were synthesized in four steps, respectively.
