Discovery of the TLR7/8 Antagonist MHV370 for Treatment of Systemic Autoimmune Diseases

Toll-like receptor (TLR) 7 and TLR8 are endosomal sensors of the innate immune system that are activated by GU-rich single stranded RNA (ssRNA). Multiple genetic and functional lines of evidence link chronic activation of TLR7/8 to the pathogenesis of systemic autoimmune diseases (sAID) such as Sjögren's syndrome (SjS) and systemic lupus erythematosus (SLE). This makes targeting TLR7/8-induced inflammation with small-molecule inhibitors an attractive approach for the treatment of patients suffering from systemic autoimmune diseases. Here, we describe how structure-based optimization of compound 2 resulted in the discovery of 34 (MHV370, (S)-N-(4-((5-(1,6-dimethyl-1H-pyrazolo[3,4-b]pyridin-4-yl)-3-methyl-4,5,6,7-tetrahydro-1H-pyrazolo[4,3-c]pyridin-1-yl)methyl)bicyclo[2.2.2]octan-1-yl)morpholine-3-carboxamide). Its in vivo activity allows for further profiling toward clinical trials in patients with autoimmune disorders, and a Phase 2 proof of concept study of MHV370 has been initiated, testing its safety and efficacy in patients with Sjögren's syndrome and mixed connective tissue disease.

JDQ443, a Structurally Novel, Pyrazole-Based, Covalent Inhibitor of KRASG12C for the Treatment of Solid Tumors

Rapid emergence of tumor resistance via RAS pathway reactivation has been reported from clinical studies of covalent KRASG12C inhibitors. Thus, inhibitors with broad potential for combination treatment and distinct binding modes to overcome resistance mutations may prove beneficial. JDQ443 is an investigational covalent KRASG12C inhibitor derived from structure-based drug design followed by extensive optimization of two dissimilar prototypes. JDQ443 is a stable atropisomer containing a unique 5-methylpyrazole core and a spiro-azetidine linker designed to position the electrophilic acrylamide for optimal engagement with KRASG12C C12. A substituted indazole at pyrazole position 3 results in novel interactions with the binding pocket that do not involve residue H95. JDQ443 showed PK/PD activity in vivo and dose-dependent antitumor activity in mouse xenograft models. JDQ443 is now in clinical development, with encouraging early phase data reported from an ongoing Phase Ib/II clinical trial (NCT04699188).

Structure-Based Optimization of a Fragment-like TLR8 Binding Screening Hit to an In Vivo Efficacious TLR7/8 Antagonist

Inappropriate activation of TLR7 and TLR8 is linked to several autoimmune diseases, such as lupus erythematosus. Here we report on the efficient structure-based optimization of the inhibition of TLR8, starting from a co-crystal structure of a small screening hit. Further optimization of the physicochemical properties for cellular potency and expansion of the structure-activity relationship for dual potency finally resulted in a highly potent TLR7/8 antagonist with demonstrated in vivo efficacy after oral dosing.

Development of autotaxin inhibitors: A series of tetrazole cinnamides

A series of inhibitors of Autotaxin (ATX) have been developed from a high throughput screening hit, 1a, which shows an alternative binding mode to known catalytic site inhibitors. Selectivity over the hERG channel and microsomal clearance were dependent on the lipophilicity of the compounds, and this was optimised by reduction of clogD whilst maintaining high affinity ATX inhibition. Compound 15a shows good oral exposure, and concentration dependent inhibition of formation of LPA in vivo, as shown in pharmacokinetic-pharmacodynamic (PK/PD) experiments.

Comparison of Two High-End Ultrasound Systems for Contrast-Enhanced Ultrasound Quantification of Mural Microvascularity in Crohn's Disease

PURPOSE

To verify the reproducibility of contrast-enhanced ultrasound (CEUS) quantification results of two different high-end ultrasound systems and to evaluate the clinical utility of the method in patients with Crohn's disease (CD).

MATERIALS AND METHODS

18 patients with histologically confirmed CD (36.8 % women, 63.2 % men; mean age 43.7 ± 14.1 years) and wall segments thicker than 5 mm were recruited. CEUS quantification and conventional ultrasound investigation were performed under standardized settings using Toshiba Aplio500 and Siemens Acuson S3000 high-end ultrasound systems. CEUS was performed at a low mechanical index of 0.1 after bolus application of 4.8 ml of SonoVue(®) contrast medium. The recorded DICOM clips were quantified using VueBox(®) (version 4.3) calculating 11 quantitative parameters. Subsequently, CEUS quantification and conventional ultrasound results were analyzed.

RESULTS

Correlation of quantitative parameters between the Aplio500 and AcusonS3000 systems for peak enhancement (PE), rise time (RT), wash-in-rate (WiR) and quality of fit (QOF) yielded significance levels of p < 0.05 and p < 0.0001 for wash-in-wash-out area under the curve (WiWoAUC). Spearman rank test showed moderate levels of correlation for PE, RT, WiR and QOF (r = 0.5, 0.49, 0.49 and 0.5 respectively), and high correlation for WiWoAUC (r = 0.89) between the two ultrasound systems.

CONCLUSION

Due to multiple uncontrollable affecting factors, the method of CEUS quantification by VueBox in the intestine cannot be recommended for device-independent multicenter studies. Therefore we suggest to use identical ultrasound systems and probes as well as to establish adequate reference ROIS, like a AIF-ROI.

Genome-wide meta-analysis reveals common splice site acceptor variant in CHRNA4 associated with nicotine dependence

We conducted a 1000 Genomes-imputed genome-wide association study (GWAS) meta-analysis for nicotine dependence, defined by the Fagerström Test for Nicotine Dependence in 17 074 ever smokers from five European-ancestry samples. We followed up novel variants in 7469 ever smokers from five independent European-ancestry samples. We identified genome-wide significant association in the alpha-4 nicotinic receptor subunit (CHRNA4) gene on chromosome 20q13: lowest P=8.0 × 10(-9) across all the samples for rs2273500-C (frequency=0.15; odds ratio=1.12 and 95% confidence interval=1.08-1.17 for severe vs mild dependence). rs2273500-C, a splice site acceptor variant resulting in an alternate CHRNA4 transcript predicted to be targeted for nonsense-mediated decay, was associated with decreased CHRNA4 expression in physiologically normal human brains (lowest P=7.3 × 10(-4)). Importantly, rs2273500-C was associated with increased lung cancer risk (N=28 998, odds ratio=1.06 and 95% confidence interval=1.00-1.12), likely through its effect on smoking, as rs2273500-C was no longer associated with lung cancer after adjustment for smoking. Using criteria for smoking behavior that encompass more than the single 'cigarettes per day' item, we identified a common CHRNA4 variant with important regulatory properties that contributes to nicotine dependence and smoking-related consequences.

Genomic analysis of Xanthomonas oryzae isolates from rice grown in the United States reveals substantial divergence from known X. oryzae pathovars

The species Xanthomonas oryzae is comprised of two designated pathovars, both of which cause economically significant diseases of rice in Asia and Africa. Although X. oryzae is not considered endemic in the United States, an X. oryzae-like bacterium was isolated from U.S. rice and southern cutgrass in the late 1980s. The U.S. strains were weakly pathogenic and genetically distinct from characterized X. oryzae pathovars. In the current study, a draft genome sequence from two U.S. Xanthomonas strains revealed that the U.S. strains form a novel clade within the X. oryzae species, distinct from all strains known to cause significant yield loss. Comparative genome analysis revealed several putative gene clusters specific to the U.S. strains and supported previous reports that the U.S. strains lack transcriptional activator-like (TAL) effectors. In addition to phylogenetic and comparative analyses, the genome sequence was used for designing robust U.S. strain-specific primers, demonstrating the usefulness of a draft genome sequence in the rapid development of diagnostic tools.

Crystal Structure of Human BACE2 in Complex with a Hydroxyethylamine Transition-state Inhibitor

BACE2 is a membrane-bound aspartic protease of the A1 family with a high level of sequence homology to BACE1. While BACE1 is involved in the generation of amyloid plaques in Alzheimer's disease by cleaving Abeta-peptides from the amyloid precursor protein, the physiological function of BACE2 is not well understood. BACE2 appears to be associated with the early onset of dementia in patients with Down's syndrome, and it has been shown to be highly expressed in breast cancers. Further, it may participate in the function of normal and abnormal processes of human muscle biology. Similar to other aspartic proteases, BACE2 is expressed as an inactive zymogen requiring the cleavage of its pro-sequence during the maturation process. We have produced mature BACE2 by expression of pro-BACE2 in Escherichia coli as inclusion bodies, followed by refolding and autocatalytic activation at pH 3.4. Using a C and N-terminally truncated BACE2 variant, we were able to crystallize and determine the crystal structure of mature BACE2 in complex with a hydroxyethylamine transition-state mimetic inhibitor at 3.1 angstroms resolution. The structure of BACE2 follows the general fold of A1 aspartic proteases. However, similar to BACE1, its C-terminal domain is significantly larger than that of the other family members. Furthermore, the structure of BACE2 reveals differences in the S3, S2, S1' and S2' active site substrate pockets as compared to BACE1, and allows, therefore, for a deeper understanding of the structural features that may facilitate the design of selective BACE1 or BACE2 inhibitors.

A regional convolution kernel algorithm for scatter correction in dual-energy images: comparison to single-kernel algorithms

Single kernel scatter correction algorithms are based on the model that the scatter field can be predicted by convolution of the primary intensity (Iprim) with a spatially invariant scatter point-spread function (PSF). Practical limitations (Iprim unknown) suggest the substitution of the total detected intensity (Idet) for Iprim as the source image in the convolution. In regions of high scatter fraction (SF), Idet is a poor approximation of Iprim, thereby causing an overestimation of scatter originating in the region. This contributes to errors in estimating detected scatter in the mediastinum and neighboring regions. A technique using a regionally variable point-spread function that significantly reduces RMS error in estimation of the primary image as compared to the single PSF method is investigated. The regionally variable convolution method employs a larger PSF in the mediastinum and a smaller PSF in the lungs to reduce the error in estimating the scatter throughout the image. The method to allow for patient differences has also been expanded and various implementations of these methods have been compared. Results show that the dual-kernel algorithm is always more effective than an equivalent single-kernel algorithm. The dual-kernel algorithm using a predicted scatter fraction curve gives an overall RMS error in the primary of as low as 20.8% which is equivalent to 8.7% RMS error in the scatter. The dual-kernel method using a predicted scatter fraction curve approaches the accuracy of the single-kernel method using patient specific scatter measurements. Because using individual scatter measurements is a less desirable method for clinical use, we feel that the dual-kernel algorithm which uses two regions specific convolution kernels and a variable scatter fraction curve is the preferable method.