Xue et al., “MAP3K1 and MAP2K4 mutations are associated with sensitivity to MEK inhibitors in multiple cancer models”; Cell Res. 2018
Abstract
Despite decades of ground-breaking research in academia, organic synthesis is still a rate-limiting factor in drug-discovery projects. Here we present some current challenges in synthetic organic chemistry from the perspective of the pharmaceutical industry and highlight problematic steps that, if overcome, would find extensive application in the discovery of transformational medicines. Significant synthesis challenges arise from the fact that drug molecules typically contain amines and N-heterocycles, as well as unprotected polar groups. There is also a need for new reactions that enable non-traditional disconnections, more C–H bond activation and late-stage functionalization, as well as stereoselectively substituted aliphatic heterocyclic ring synthesis, C–X or C–C bond formation. We also emphasize that syntheses compatible with biomacromolecules will find increasing use, while new technologies such as machine-assisted approaches and artificial intelligence for synthesis planning have the potential to dramatically accelerate the drug-discovery process. We believe that increasing collaboration between academic and industrial chemists is crucial to address the challenges outlined here.
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Rees et al. “Organic synthesis provides opportunities to transform drug discovery.” Nature Chemistry., 2018
Abstract
The hit validation stage of a fragment-based drug discovery campaign involves probing the SAR around one or more fragment hits. This often requires a search for similar compounds in a corporate collection or from commercial suppliers. The Fragment Network is a graph database that allows a user to efficiently search chemical space around a compound of interest. The result set is chemically intuitive, naturally grouped by substitution pattern and meaningfully sorted according to the number of observations of each transformation in medicinal chemistry databases. This paper describes the algorithms used to construct and search the Fragment Network and provides examples of how it may be used in a drug discovery context.
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Hall et al., “The Fragment Network: A Chemistry Recommendation Engine Built Using a Graph Database.” J. Med. Chem., 2017, 60(14), pp 6440-6450, DOI: 10.1021/acs.jmedchem.7b00809
Abstract
XIAP and cIAP1 are members of the inhibitor of apoptosis protein (IAP) family and are key regulators of anti-apoptotic and pro-survival signaling pathways. Overexpression of IAPs occurs in various cancers and has been associated with tumor progression and resistance to treatment. Structure-based drug design (SBDD) guided by structural information from X-ray crystallography, computational studies, and NMR solution conformational analysis was successfully applied to a fragment-derived lead resulting in AT-IAP, a potent, orally bioavailable, dual antagonist of XIAP and cIAP1 and a structurally novel chemical probe for IAP biology.
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Tamanini et al., “Discovery of a Potent Nonpeptidomimetic, Small-Molecule Antagonist of Cellular Inhibitor of Apoptosis Protein 1 (cIAP1) and X-Linked Inhibitor of Apoptosis Protein (XIAP).” J. Med. Chem., 2017, 60(11), pp 4611-4625, DOI: 10.1021/acs.jmedchem.6b01877
Abstract
Computational fragment mapping methods aim to predict hotspots on protein surfaces where small fragments will bind. Such methods are popular for druggability assessment as well as structure-based design. However, to date researchers developing or using such tools have had no clear way of assessing the performance of these methods. Here, we introduce the first diverse, high quality validation set for computational fragment mapping. The set contains 52 diverse examples of fragment binding “hot” and “warm” spots from the Protein Data Bank (PDB). Additionally, we describe PLImap, a novel protocol for fragment mapping based on the Protein–Ligand Informatics force field (PLIff). We evaluate PLImap against the new fragment mapping test set, and compare its performance to that of simple shape-based algorithms and fragment docking using GOLD. PLImap is made publicly available from https://bitbucket.org/AstexUK/pli.
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Rathi et al., “Predicting ‘Hot’ and ‘Warm’ Spots for Fragment Binding.” J. Med. Chem., 2017, 60 (9), pp 4036-4046, DOI: 10.1021/acs.jmedchem.7b00366
Abstract
The members of the NSD subfamily of lysine methyl transferases are compelling oncology targets due to the recent characterization of gain-of-function mutations and translocations in several hematological cancers. To date, these proteins have proven intractable to small molecule inhibition. Here, we present initial efforts to identify inhibitors of MMSET (aka NSD2 or WHSC1) using solution phase and crystal structural methods. On the basis of 2D NMR experiments comparing NSD1 and MMSET structural mobility, we designed an MMSET construct with five point mutations in the N-terminal helix of its SET domain for crystallization experiments and elucidated the structure of the mutant MMSET SET domain at 2.1 Å resolution. Both NSD1 and MMSET crystal systems proved resistant to soaking or cocrystallography with inhibitors. However, use of the close homologue SETD2 as a structural surrogate supported the design and characterization of N-alkyl sinefungin derivatives, which showed low micromolar inhibition against both SETD2 and MMSET.
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Tisi et al. “Structure of the Epigenetic Oncogene MMSET and Inhibition by N-Alkyl Sinefungin Derivatives.” ACS Chem. Biol., 2016, 11 (11), pp 3093–3105, DOI: 10.1021/acschembio.6b00308
Abstract
Fragment-based drug discovery (FBDD) is now well-established as a technology for generating new chemical leads and drugs. This Miniperspective provides a tabulated overview of the fragment-to-lead literature published in the year 2015, together with a commentary on trends observed across the FBDD field during this time. It is hoped that this tabulated summary will provide a useful point of reference for both FBDD practitioners and the wider medicinal chemistry community.
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Johnson et al. “Fragment-to-Lead Medicinal Chemistry Publications in 2015.” J. Med. Chem., 2017, 60 (1), pp 89–99, DOI: 10.1021/acs.jmedchem.6b01123
Abstract
Lp-PLA2 has been explored as a target for a number of inflammation associated diseases, including cardiovascular disease and dementia. This article describes the discovery of a new fragment derived chemotype that interacts with the active site of Lp-PLA2. The starting fragment hit was discovered through an X-ray fragment screen and showed no activity in the bioassay (IC50 > 1 mM). The fragment hit was optimized using a variety of structure-based drug design techniques, including virtual screening, fragment merging, and improvement of shape complementarity. A novel series of Lp-PLA2 inhibitors was generated with low lipophilicity and a promising pharmacokinetic profile.
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Woolford et al. “Fragment-Based Approach to the Development of an Orally Bioavailable Lactam Inhibitor of Lipoprotein-Associated Phospholipase A2 (Lp-PLA2)” J. Med. Chem., 2016, 59 (23), pp 10738–10749, DOI: 10.1021/acs.jmedchem.6b01427
Summary
Selective degradation of proteins by proteolysis targeting chimeras (PROTACs) offers a promising potential alternative to protein inhibition for therapeutic intervention. Current PROTAC molecules incorporate a ligand for the target protein, a linker, and an E3 ubiquitin ligase recruiting group, which bring together target protein and ubiquitinating machinery. Such hetero-bifunctional molecules require significant linker optimization and possess high molecular weight, which can limit cellular permeation, solubility, and other drug-like properties. We show here that the hetero-bifunctional molecule can be formed intracellularly by bio-orthogonal click combination of two smaller precursors. We designed a tetrazine tagged thalidomide derivative which reacts rapidly with a trans-cyclo-octene tagged ligand of the target protein in cells to form a cereblon E3 ligase recruiting PROTAC molecule. The in-cell click-formed proteolysis targeting chimeras (CLIPTACs) were successfully used to degrade two key oncology targets, BRD4 and ERK1/2. ERK1/2 degradation was achieved using a CLIPTAC based on a covalent inhibitor. We expect this approach to be readily extendable to other inhibitor-protein systems because the tagged E3 ligase recruiter is capable of undergoing the click reaction with a suitably tagged ligand of any protein of interest to elicit its degradation.
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Lebraud et al. “Protein Degradation by In-Cell Self-Assembly of Proteolysis Targeting Chimeras.” ACS Cent. Sci.,2016, 2 (12), pp 927–934 DOI: 10.1021/acscentsci.6b00280
Summary
PURPOSE: To investigate SGI-110 as a “chemosensitizer” in ovarian cancer and to assess its effects on tumor suppressor genes (TSG) and chemoresponsiveness-associated genes silenced by DNA methylation in ovarian cancer.
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Fang et al.. “: The Novel, Small-Molecule DNA Methylation Inhibitor SGI-110 as an Ovarian Cancer Chemosensitizer.” Clin Cancer Res; 20(24) December 15, 2014
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