Discovery of the first potent and selective αvβ5 integrin inhibitor based on an amide-containing core

Integrins αvβ5 and αvβ3 are closely related, proangiogenic members of the wider RGD-binding integrin family. Due to their high sequence homology, the development of αvβ5-selective compounds has remained elusive to synthetic and medicinal chemists. Herein, we describe a survey of SAR around a series of amide-containing 3-aryl-succinamic acid-based RGD mimetics. This resulted in the discovery of α,α,α-trifluorotolyl 12 which exhibits 800 × selectivity for αvβ5 versus αvβ3 with a pyrrolidine amide linker that confers selectivity for αvβ5 by positioning a key aryl ring in the SDL of αvβ5 with good complementarity; binding in this mode is disfavoured in αvβ3 due to clashes with key residues in the β3-subunit. Compound 12 exhibits selective inhibition by a cell adhesion assay, high passive permeability and solubility which enables potential use of this inhibitor as an αvβ5-selective in vitro tool compound

Design and elaboration of a tractable tricyclic scaffold to synthesize druglike inhibitors of dipeptidyl peptidase-4 (DPP-4), antagonists of the C–C Chemokine Receptor Type 5 (CCR5), and highly potent and selective phosphoinositol-3 Kinase δ (PI3Kδ) inhibitors

A novel molecular scaffold has been synthesized, and its incorporation into new analogues of biologically active molecules across multiple target classes will be discussed. In these studies, we have shown use of the tricyclic scaffold to synthesize potent inhibitors of the serine peptidase DPP-4, antagonists of the CCR5 receptor, and highly potent and selective PI3K δ isoform inhibitors. We also describe the predicted physicochemical properties of the resulting inhibitors and conclude that the tractable molecular scaffold could have potential application in future drug discovery programs

Late-Stage Functionalization by Chan–Lam Amination: Rapid Access to Potent and Selective Integrin Inhibitors

© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim A late-stage functionalization of the aromatic ring in amino acid derivatives is described. The key step is a copper-catalysed diversification of a boronate ester by amination (Chan–Lam reaction) that can be carried out on a complex β-aryl-β-amino acid scaffold. This not only considerably extends the substrate scope of amination partners, but also delivers an array of potent and selective integrin inhibitors as potential treatment agents of idiopathic pulmonary fibrosis (IPF). This versatile chemical strategy, which is amenable to high-throughput-array protocols, allows the installation of pharmaceutically valuable heteroaromatic fragments at a late stage by direct coupling to NH heterocycles, leading to compounds with drug-like attributes. It thus constitutes a useful addition to the medicinal chemist's repertoire

Core modifications of GSK3335103 toward orally bioavailable αvβ6 inhibitors with improved synthetic tractability

The α β integrin has been identified as a target for the treatment of fibrotic diseases, based on the role it has in activating TGF-β , a protein implicated in the pathogenesis of fibrosis. However, the development of orally bioavailable α β inhibitors has proven challenging due to the zwitterionic pharmacophore required to bind to the RGD binding site. This work describes the design and development of a novel, orally bioavailable series of α β inhibitors, developing on two previously published α β inhibitors, GSK3008348 and GSK3335103. Strategies to reduce the basicity of the central ring nitrogen present in GSK3008348 were employed, while avoiding the synthetic complexity of the chiral, fluorine-containing quaternary carbon center contained in GSK3335103. Following initial PK studies, this series was optimized, aided by analysis of the physicochemical and in vitro PK properties, to deliver lead molecules ( )- and as potent and orally bioavailable α β inhibitors with improved synthetic tractability

Design and development of a macrocyclic series targeting phosphoinositide 3-kinase δ

A macrocyclization approach has been explored on a series of benzoxazine phosphoinositide 3-kinase δ inhibitors, resulting in compounds with improved potency, permeability, and in vivo clearance while maintaining good solubility. The thermodynamics of binding was explored via surface plasmon resonance, and the binding of lead macrocycle 19 was found to be almost exclusively entropically driven compared with progenitor 18, which demonstrated both enthalpic and entropic contributions. The pharmacokinetics of macrocycle 19 was also explored in vivo, where it showed reduced clearance when compared with the progenitor 18. This work adds to the growing body of evidence that macrocyclization could provide an alternative and complementary approach to the design of small-molecule inhibitors, with the potential to deliver differentiated properties

Development of a small molecule that corrects misfolding and increases secretion of Z α1 -antitrypsin.

Severe α1 -antitrypsin deficiency results from the Z allele (Glu342Lys) that causes the accumulation of homopolymers of mutant α1 -antitrypsin within the endoplasmic reticulum of hepatocytes in association with liver disease. We have used a DNA-encoded chemical library to undertake a high-throughput screen to identify small molecules that bind to, and stabilise Z α1 -antitrypsin. The lead compound blocks Z α1 -antitrypsin polymerisation in vitro, reduces intracellular polymerisation and increases the secretion of Z α1 -antitrypsin threefold in an iPSC model of disease. Crystallographic and biophysical analyses demonstrate that GSK716 and related molecules bind to a cryptic binding pocket, negate the local effects of the Z mutation and stabilise the bound state against progression along the polymerisation pathway. Oral dosing of transgenic mice at 100 mg/kg three times a day for 20 days increased the secretion of Z α1 -antitrypsin into the plasma by sevenfold. There was no observable clearance of hepatic inclusions with respect to controls over the same time period. This study provides proof of principle that "mutation ameliorating" small molecules can block the aberrant polymerisation that underlies Z α1 -antitrypsin deficiency

Radiation Resistance of Sequencing Chips for in situ Life Detection

Life beyond Earth may be based on RNA or DNA if such life is related to life on Earth through shared ancestry due to meteoritic exchange, such as may be the case for Mars, or if delivery of similar building blocks to habitable environments has biased the evolution of life toward utilizing nucleic acids. In this case, in situ sequencing is a powerful approach to identify and characterize such life without the limitations or expense of returning samples to Earth, and can monitor forward contamination. A new semiconductor sequencing technology based on sensing hydrogen ions released during nucleotide incorporation can enable massively parallel sequencing in a small, robust, optics-free CMOS chip format. We demonstrate that these sequencing chips survive several analogues of space radiation at doses consistent with a 2-year Mars mission, including protons with solar particle event–distributed energy levels and 1 GeV oxygen and iron ions. We find no measurable impact of irradiation at 1 and 5 Gy doses on sequencing quality nor on low-level hardware characteristics. Further testing is required to study the impacts of soft errors as well as to characterize performance under neutron and gamma irradiation and at higher doses, which would be expected during operation in environments with significant trapped energetic particles such as during a mission to Europa. Our results support future efforts to use in situ sequencing to test theories of panspermia and/or whether life has a common chemical basis.United States. National Aeronautics and Space Administration (Astrobiology Science and Technology Instrument Development Program Grant NX08AX15G

Radiation Resistance of Sequencing Chips for in situ Life Detection

Abstract Life beyond Earth may be based on RNA or DNA if such life is related to life on Earth through shared ancestry due to meteoritic exchange, such as may be the case for Mars, or if delivery of similar building blocks to habitable environments has biased the evolution of life toward utilizing nucleic acids. In this case, in situ sequencing is a powerful approach to identify and characterize such life without the limitations or expense of returning samples to Earth, and can monitor forward contamination. A new semiconductor sequencing technology based on sensing hydrogen ions released during nucleotide incorporation can enable massively parallel sequencing in a small, robust, optics-free CMOS chip format. We demonstrate that these sequencing chips survive several analogues of space radiation at doses consistent with a 2-year Mars mission, including protons with solar particle event-distributed energy levels and 1 GeV oxygen and iron ions. We find no measurable impact of irradiation at 1 and 5 Gy doses on sequencing quality nor on low-level hardware characteristics. Further testing is required to study the impacts of soft errors as well as to characterize performance under neutron and gamma irradiation and at higher doses, which would be expected during operation in environments with significant trapped energetic particles such as during a mission to Europa. Our results support future efforts to use in situ sequencing to test theories of panspermia and/or whether life has a common chemical basis

Profile of a highly selective quaternized pyrrolidine betaine αvβ6 integrin inhibitor - (3S)-3-(3-(3,5-Dimethyl-1H-pyrazol-1-yl)phenyl)-4-((1S and 1R,3R)-1-methyl-3-(2- (5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)ethyl)pyrrolidin-1-ium-1-yl)butanoate synthesized by stereoselective methylation

A quaternary ammonium betaine 7 is described which shows exceptional potency and selectivity (1.4 to >3 logs) for the α vβ 6 integrin receptor over the other α v integrins as determined in cell adhesion assays. 7 is prepared by remarkably stereoselective methylation, the origins of which are discussed. The chemical, biological, physicochemical, and pharmacokinetic properties of 7 and its docking into α vβ 6 are described along with related analogues

Relative Binding Affinities of Integrin Antagonists by Equilibrium Dialysis and Liquid Chromatography–Mass Spectrometry

The integrin α_vβ₆ is a potential target for treatment of idiopathic pulmonary fibrosis (IPF). Equilibrium dialysis (ED) was investigated for its ability to report ligand binding in an α_vβ₆ inhibitor screening assay. As a preliminary experiment, an established peptidomimetic inhibitor of the integrin was dialyzed against α_vβ₆, and the fraction bound (<i>f</i>_b) and percentage saturation determined by liquid chromatography–mass spectrometry (LC-MS) analysis. Quantitation of the inhibitor in the two chambers of the ED cartridge revealed an uneven distribution in the presence of α_vβ₆, corresponding to near saturation binding to the protein (93 ± 3%), while the control (without integrin) showed an equal partitioning of the inhibitor on either side of the dialysis membrane. A competitive ED assay with a 12 component mixture of antagonists was conducted, and the results compared with an established cell adhesion assay for quantifying α_vβ₆ inhibition of individual antagonists. Compounds clustered into three groupings: those with p<i>IC</i>₅₀ values between ca. 5.0 and 5.5, which possessed ED <i>f</i>_b values indistinguishable from the controls, those with p<i>IC</i>₅₀s of 6.5 ± 0.2, which exhibited detectable integrin binding (<i>f</i>_b 13–25%) in the ED assay, and a single compound of p<i>IC</i>₅₀ 7.2 possessing an <i>f</i>_b value of 38%. A good correlation between ED-derived <i>f</i>_b and p<i>IC</i>₅₀ was observed despite the two assays utilizing quite different outputs. These results demonstrate that ED with LC-MS detection shows promise as a rapid α_vβ₆ integrin antagonist screening assay for mixtures of putative ligands