Characterization of clinical envelopes with lack of sensitivity to the HIV-1 inhibitors temsavir and ibalizumab.

Previous data suggest a lack of cross-resistance between the gp120-directed attachment inhibitor temsavir (active moiety of fostemsavir) and the CD4-directed post-attachment inhibitor ibalizumab. Recently, analysis of HIV-1 envelopes with reduced sensitivity to both inhibitors was undertaken to determine whether they shared genotypic correlates of resistance. Sequences from 2 envelopes with reduced susceptibility to both agents were mapped onto a temsavir-bound gp120 structure.

Novel Bent Conformation of CD4 Induced by HIV-1 Inhibitor Indirectly Prevents Productive Viral Attachment.

GSK3732394 is a multi-specific biologic inhibitor of HIV entry currently under clinical evaluation. A key component of this molecule is an adnectin (6940_B01) that binds to CD4 and inhibits downstream actions of gp160. Studies were performed to determine the binding site of the adnectin on CD4 and to understand the mechanism of inhibition.

Emergence of Resistance in HIV-1 Integrase with Dolutegravir Treatment in a Pediatric Population from the IMPAACT P1093 Study.

P1093 is a multicenter, open-label, phase I/II study of pharmacokinetics, safety, and tolerability of dolutegravir plus an optimized background regimen in pediatric participants aged 4 weeks to <18 years with HIV-1. Most participants were highly treatment experienced. We report the mechanisms of emergent integrase strand transfer inhibitor (INSTI) resistance among adolescents and children receiving dolutegravir.

Integrase Inhibitor Resistance Mechanisms and Structural Characteristics in Antiretroviral Therapy-Experienced, Integrase Inhibitor-Naive Adults with HIV-1 Infection Treated with Dolutegravir plus Two Nucleoside Reverse Transcriptase Inhibitors in the DAWNING Study.

At week 48 in the phase IIIb DAWNING study, the integrase strand transfer inhibitor (INSTI) dolutegravir plus 2 nucleoside reverse transcriptase inhibitors demonstrated superiority to ritonavir-boosted lopinavir in achieving virologic suppression in adults with HIV-1 who failed first-line therapy. Here, we report emergent HIV-1 drug resistance and mechanistic underpinnings among dolutegravir-treated adults in DAWNING. Population viral genotyping, phenotyping, and clonal analyses were performed on participants meeting confirmed virologic withdrawal (CVW) criteria on dolutegravir-containing regimens.

A knowledge-based, structural-aided discovery of a novel class of 2-phenylimidazo[1,2-a]pyridine-6-carboxamide H-PGDS inhibitors.

Through an internal virtual screen at GlaxoSmithKline a distinct class of 2-phenylimidazo[1,2-a]pyridine-6-carboxamide H-PGDS inhibitors were discovered. Careful evaluation of crystal structures and SAR led to a novel, potent, and orally active imidazopyridine inhibitor of H-PGDS, 20b. Herein, describes the identification of 2 classes of inhibitors, their syntheses, and their challenges.

Susceptibility of global HIV-1 clinical isolates to fostemsavir using the PhenoSense® Entry assay.

Background: Fostemsavir is a prodrug of a first-in-class HIV-1 attachment inhibitor, temsavir, that binds to gp120 and blocks attachment to the host-cell CD4 receptor, preventing entry and infection of the target cell. Previous studies using a limited number of clinical isolates showed that there was intrinsic variability in their susceptibility to temsavir.

Objectives: Here, an analysis was performed using all clinical isolates analysed in the Monogram Biosciences PhenoSense® Entry assay as part of the development programme.

Complementary NAD replacement strategies fail to functionally protect dystrophin-deficient muscle.

Background: Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disorder stemming from a loss of functional dystrophin. Current therapeutic options for DMD are limited, as small molecule modalities remain largely unable to decrease the incidence or mitigate the consequences of repetitive mechanical insults to the muscle during eccentric contractions (ECCs).

Methods: Using a metabolomics-based approach, we observed distinct and transient molecular phenotypes in muscles of dystrophin-deficient MDX mice subjected to ECCs.

The exploration of aza-quinolines as hematopoietic prostaglandin D synthase (H-PGDS) inhibitors with low brain exposure.

GlaxoSmithKline and Astex Pharmaceuticals recently disclosed the discovery of the potent H-PGDS inhibitor GSK2894631A 1a (IC = 9.9 nM) as part of a fragment-based drug discovery collaboration with Astex Pharmaceuticals. This molecule exhibited good murine pharmacokinetics, allowing it to be utilized to explore H-PGDS pharmacology in vivo.

The discovery of quinoline-3-carboxamides as hematopoietic prostaglandin D synthase (H-PGDS) inhibitors.

With the goal of discovering more selective anti-inflammatory drugs, than COX inhibitors, to attenuate prostaglandin signaling, a fragment-based screen of hematopoietic prostaglandin D synthase was performed. The 76 crystallographic hits were sorted into similar groups, with the 3-cyano-quinoline 1a (FP IC = 220,000 nM, LE = 0.43) being a potent member of the 6,6-fused heterocyclic cluster.

2,4-Diamino-8-quinazoline carboxamides as novel, potent inhibitors of the NAD hydrolyzing enzyme CD38: Exploration of the 2-position structure-activity relationships.

Starting from 4-amino-8-quinoline carboxamide lead 1a and scaffold hopping to the chemically more tractable quinazoline, a systematic exploration of the 2-substituents of the quinazoline ring, utilizing structure activity relationships and conformational constraint, resulted in the identification of 39 novel CD38 inhibitors. Eight of these analogs were 10-100-fold more potent human CD38 inhibitors, including the single digit nanomolar inhibitor 1am. Several of these molecules also exhibited improved therapeutic indices relative to hERG activity.

Novel secondary mutations C56S and G149A confer resistance to HIV-1 integrase strand transfer inhibitors.

Cabotegravir (CAB, S/GSK1265744) is an investigational second-generation integrase strand transfer inhibitor (INSTI) with a chemical structure similar to dolutegravir. CAB is under development as a long-acting injectable formulation for treatment of HIV-1 infection and for pre-exposure prophylaxis. We conducted an in vitro passage study of raltegravir- or elvitegravir-resistant signature mutants in the presence of CAB to characterize the resistance profile of this drug.

Discovery of 4-Amino-8-quinoline Carboxamides as Novel, Submicromolar Inhibitors of NAD-Hydrolyzing Enzyme CD38.

Starting from the micromolar 8-quinoline carboxamide high-throughput screening hit 1a, a systematic exploration of the structure-activity relationships (SAR) of the 4-, 6-, and 8-substituents of the quinoline ring resulted in the identification of approximately 10-100-fold more potent human CD38 inhibitors. Several of these molecules also exhibited pharmacokinetic parameters suitable for in vivo animal studies, including low clearances and decent oral bioavailability. Two of these CD38 inhibitors, 1ah and 1ai, were shown to elevate NAD tissue levels in liver and muscle in a diet-induced obese (DIO) C57BL/6 mouse model.

Discovery, Synthesis, and Biological Evaluation of Thiazoloquin(az)olin(on)es as Potent CD38 Inhibitors.

A series of thiazoloquin(az)olinones were synthesized and found to have potent inhibitory activity against CD38. Several of these compounds were also shown to have good pharmacokinetic properties and demonstrated the ability to elevate NAD levels in plasma, liver, and muscle tissue. In particular, compound 78c was given to diet induced obese (DIO) C57Bl6 mice, elevating NAD > 5-fold in liver and >1.

Biological and Structural Characterization of Rotamers of C-C Chemokine Receptor Type 5 (CCR5) Inhibitor GSK214096.

We recently reported the discovery of preclinical CCR5 inhibitor GSK214096, 1 (J. Med. Chem.

A pre-steady state and steady state kinetic analysis of the N-ribosyl hydrolase activity of hCD157.

hCD157 catalyzes the hydrolysis of nicotinamide riboside (NR) and nicotinic acid riboside (NAR). The release of nicotinamide or nicotinic acid from NR or NAR was confirmed by spectrophotometric, HPLC and NMR analyses. hCD157 is inactivated by a mechanism-based inhibitor, 2'-deoxy-2'-fluoro-nicotinamide arabinoside (fNR).

Discovery of a potent boronic acid derived inhibitor of the HCV RNA-dependent RNA polymerase.

A boronic acid moiety was found to be a critical pharmacophore for enhanced in vitro potency against wild-type hepatitis C replicons and known clinical polymorphic and resistant HCV mutant replicons. The synthesis, optimization, and structure-activity relationships associated with inhibition of HCV replication in a subgenomic replication system for a series of non-nucleoside boron-containing HCV RNA-dependent RNA polymerase (NS5B) inhibitors are described. A summary of the discovery of 3 (GSK5852), a molecule which entered clinical trials in subjects infected with HCV in 2011, is included.

Rational design of potent non-nucleoside inhibitors of HIV-1 reverse transcriptase.

A new series of non-nucleoside reverse transcriptase inhibitors based on an imidazole-amide biarylether scaffold has been identified and shown to possess potent antiviral activity against HIV-1, including the NNRTI-resistant Y188L mutated virus. X-ray crystallography of inhibitors bound to reverse transcriptase, including a structure of the Y188L RT protein, was used extensively to help identify and optimize the key hydrogen-bonding motif. This led directly to the design of compound 43 that exhibits remarkable antiviral activity (EC50<1 nM) against a wide range of NNRTI-resistant viruses and a favorable pharmacokinetic profile across multiple species.

Structure guided design of 5-arylindazole glucocorticoid receptor agonists and antagonists.

Glucocorticoid receptor (GR) agonists have been used for more than half a century as the most effective treatment of acute and chronic inflammatory conditions despite serious side effects that accompany their extended use that include glucose intolerance, muscle wasting, skin thinning, and osteoporosis. As a starting point for the identification of GR ligands with an improved therapeutic index, we wished to discover selective nonsteroidal GR agonists and antagonists with simplified structure compared to known GR ligands to serve as starting points for the optimization of dissociated GR modulators. To do so, we selected multiple chemical series by structure guided docking studies and evaluated GR agonist activity.

Discovery of tertiary sulfonamides as potent liver X receptor antagonists.

Tertiary sulfonamides were identified in a HTS as dual liver X receptor (LXR, NR1H2, and NR1H3) ligands, and the binding affinity of the series was increased through iterative analogue synthesis. A ligand-bound cocrystal structure was determined which elucidated key interactions for high binding affinity. Further characterization of the tertiary sulfonamide series led to the identification of high affinity LXR antagonists.

Improving the developability profile of pyrrolidine progesterone receptor partial agonists.

The previously reported pyrrolidine class of progesterone receptor partial agonists demonstrated excellent potency but suffered from serious liabilities including hERG blockade and high volume of distribution in the rat. The basic pyrrolidine amine was intentionally converted to a sulfonamide, carbamate, or amide to address these liabilities. The evaluation of the degree of partial agonism for these non-basic pyrrolidine derivatives and demonstration of their efficacy in an in vivo model of endometriosis is disclosed herein.

Discovery of orally active, pyrrolidinone-based progesterone receptor partial agonists.

We have designed and synthesized a novel series of pyrrolidinones as progesterone receptor partial agonists. Compounds from this series had improved AR selectivity, rat pharmacokinetic properties, and in vivo potency compared to the lead compound. In addition, these compounds had improved selectivity against hERG channel inhibition.

Kinase-targeted library design through the application of the PharmPrint methodology.

The PharmPrint methodology, as modified and implemented by Deanda and Stewart, was prospectively evaluated for use as a virtual high-throughput screening tool by applying it to the design of target-focused arrays. To this end, PharmPrint quantitative structure-activity relationship (QSAR) models for the prediction of AKT1, Aurora-A, and ROCK1 inhibition were constructed and used to virtually screen two large combinatorial libraries. Based on predicted activities, an Aurora-A targeted array and a ROCK1 targeted array were designed and synthesized.

The first X-ray crystal structure of the glucocorticoid receptor bound to a non-steroidal agonist.

The amino-pyrazole 2,6-dichloro-N-ethyl benzamide 1 is a selective GR agonist with dexamethasone-like in vitro potency. Its X-ray crystal structure in the GR LBD (Glucocorticoid ligand-binding domain) is described and compared to other reported structures of steroidal GR agonists in the GR LBD (3E7C).