Potent, Gut-Restricted Inhibitors of Divalent Metal Transporter 1: Preclinical Efficacy against Iron Overload and Safety Evaluation.

Divalent metal transporter 1 (DMT1) cotransports ferrous iron and protons and is the primary mechanism for uptake of nonheme iron by enterocytes. Inhibitors are potentially useful as therapeutic agents to treat iron overload disorders such as hereditary hemochromatosis or ß-thalassemia intermedia, provided that inhibition can be restricted to the duodenum. We used a calcein quench assay to identify human DMT1 inhibitors. Dimeric compounds were made to generate more potent compounds with low systemic exposure. Direct block of DMT1 was confirmed by voltage clamp measurements. The lead compound, XEN602, strongly inhibits dietary nonheme iron uptake in both rats and pigs yet has negligible systemic exposure. Efficacy is maintained for >2 weeks in a rat subchronic dosing assay. Doses that lowered iron content in the spleen and liver by >50% had no effect on the tissue content of other divalent cations except for cobalt. XEN602 represents a powerful pharmacological tool for understanding the physiologic function of DMT1 in the gut. SIGNIFICANCE STATEMENT: This report introduces methodology to develop potent, gut-restricted inhibitors of divalent metal transporter 1 (DMT1) and identifies XEN602 as a suitable compound for in vivo studies. We also report novel animal models to quantify the inhibition of dietary uptake of iron in both rodents and pigs. This research shows that inhibition of DMT1 is a promising means to treat iron overload disorders.

Targeting AXL kinase sensitizes leukemic stem and progenitor cells to venetoclax treatment in acute myeloid leukemia.

The abundance of genetic abnormalities and phenotypic heterogeneities in acute myeloid leukemia (AML) poses significant challenges to the development of improved treatments. Here, we demonstrated that a key growth arrest-specific gene 6/AXL axis is highly activated in cells from patients with AML, particularly in stem/progenitor cells. We developed a potent selective AXL inhibitor that has favorable pharmaceutical properties and efficacy against preclinical patient-derived xenotransplantation (PDX) models of AML. Importantly, inhibition of AXL sensitized AML stem/progenitor cells to venetoclax treatment, with strong synergistic effects in vitro and in PDX models. Mechanistically, single-cell RNA-sequencing and functional validation studies uncovered that AXL inhibition, alone or in combination with venetoclax, potentially targets intrinsic metabolic vulnerabilities of AML stem/progenitor cells and shows a distinct transcriptomic profile and inhibits mitochondrial oxidative phosphorylation. Inhibition of AXL or BCL-2 also differentially targets key signaling proteins to synergize in leukemic cell killing. These findings have a direct translational impact on the treatment of AML and other cancers with high AXL activity.

[Analysis of genetic variants in a patient with Familial hemophagocytic lymphohistiocytosis].

OBJECTIVE: To explore the genetic basis for a patient with Familial hemophagocytic lymphohistiocytosis (FHL). METHODS: A 35-day-old male infant who was admitted to the Oriental Hospital Affiliated to Xiamen University on August 3, 2021 due to fever for over 7 hours was selected as the study subject. Whole exome sequencing (WES) was carried out for the proband and his parents, and candidate variants were selected based on the clinical phenotypes of the proband and confirmed by Sanger sequencing. RESULTS: WES and Sanger sequencing results revealed that the proband had harbored compound heterozygous c.67_71delinsGCCC and c.65delC variants of the PRF1 gene, which were respectively inherited from his mother and father. The c.67_71delinsGCCC variant was unreported previously. Based on the guidelines of American College of Medical Genetics and Genomics and clinical manifestations, it was classified as pathogenic (PVS1+PM2_Supporting+PM3+PP4). c.65delC was a known pathogenic variant (PVS1+PM2_Supporting+PM3_Strong+PP4). CONCLUSION: The compound heterozygous variants of c.67_71delinsGCCC and c.65delC of the PRF1 gene probably underlay the disease in the proband. The identification of the novel variant has expanded the mutational spectrum of the PRF1 gene.

Effect of Remote Ischemic Conditioning vs Usual Care on Neurologic Function in Patients With Acute Moderate Ischemic Stroke: The RICAMIS Randomized Clinical Trial.

Importance: Preclinical and clinical studies have suggested a neuroprotective effect of remote ischemic conditioning (RIC), which involves repeated occlusion/release cycles on bilateral upper limb arteries; however, robust evidence in patients with ischemic stroke is lacking. Objective: To assess the efficacy of RIC for acute moderate ischemic stroke. Design, Setting, and Participants: This multicenter, open-label, blinded-end point, randomized clinical trial including 1893 patients with acute moderate ischemic stroke was conducted at 55 hospitals in China from December 26, 2018, through January 19, 2021, and the date of final follow-up was April 19, 2021. Interventions: Eligible patients were randomly assigned within 48 hours after symptom onset to receive treatment with RIC (using a pneumatic electronic device and consisting of 5 cycles of cuff inflation for 5 minutes and deflation for 5 minutes to the bilateral upper limbs to 200 mm Hg) for 10 to 14 days as an adjunct to guideline-based treatment (n = 922) or guideline-based treatment alone (n = 971). Main Outcomes and Measures: The primary end point was excellent functional outcome at 90 days, defined as a modified Rankin Scale score of 0 to 1. All end points had blinded assessment and were analyzed on a full analysis set. Results: Among 1893 eligible patients with acute moderate ischemic stroke who were randomized (mean [SD] age, 65 [10.3] years; 606 women [34.1%]), 1776 (93.8%) completed the trial. The number with excellent functional outcome at 90 days was 582 (67.4%) in the RIC group and 566 (62.0%) in the control group (risk difference, 5.4% [95% CI, 1.0%-9.9%]; odds ratio, 1.27 [95% CI, 1.05-1.54]; P = .02). The proportion of patients with any adverse events was 6.8% (59/863) in the RIC group and 5.6% (51/913) in the control group. Conclusions and Relevance: Among adults with acute moderate ischemic stroke, treatment with remote ischemic conditioning compared with usual care significantly increased the likelihood of excellent neurologic function at 90 days. However, these findings require replication in another trial before concluding efficacy for this intervention. Trial Registration: ClinicalTrials.gov Identifier: NCT03740971.

Applications of amide isosteres in medicinal chemistry.

Isosteric replacement of amide groups is a classic practice in medicinal chemistry. This digest highlights the applications of most commonly employed amide isosteres in drug design aiming at improving potency and selectivity, optimizing physicochemical and pharmacokinetic properties, eliminating or modifying toxicophores, as well as providing novel intellectual property of lead compounds.

[Genetic evolution and substitution frequency of avian influenza virus HA gene in chicken H9N2 subtype in China in the last 20 years].

OBJECTIVE: Low pathogenic avian influenza (LPAI) H9N2 subtype virus has been prevalent in domestic poultry in China over two decades. This study was to determine the genetic evolution trend of H9N2 avian influenza virus (AIV) under immune pressure of vaccine. METHODS: H9 HA sequences of 40 isolates from the present study and 136 pandemic strains and 7 classical strains from China downloaded from GenBank, were genetically analyzed to determine evolution, molecular characteristic, and mutation frequency. RESULTS: Phylogenetic trees analysis suggested that H9N2 subtypes AIV could be clustered into 5 distinct lineages: G1-like, BJ94-like, Y280-like, S2-like and Americans lineages. Most H9N2 isolates in 2005-2014 belonged to S2-like sub-genotype, suggesting that this genotype was the dominate isolates in China. Further more, comparison based on the amino acid sequence showed that different lineages have their distinct characteristics, and significant accumulations of amino acid variation were also found. In addition, in comparison with reference Ck/BJ/1/1994 HA gene, average annual substitution rates of H9N2 pandemic strain nucleotide and amino acid were 5.73 x 10⁻³ and 4.25 x 10⁻³ from 1994 to 2014, respectively. Substitution rate during 2011-2014 were 6.35 x 10⁻³ and 5.32 x 10⁻³, higher than that during the period of 2006-2010 (5.22 x 10⁻³ and 3.70 x 10⁻³) and even much higher than that during the 1999-2005 (0.74 x 10⁻³ and 0.50 x 10⁻³), when the vaccines were initially applied in the field. CONCLUSION: Overall, these data indicate that the mismatch between H9N2 vaccine strains and pandemic strains drives the virus to quickly mutate.

Discovery of triazolone derivatives as novel, potent stearoyl-CoA desaturase-1 (SCD1) inhibitors.

Stearoyl-CoA desaturase-1 (SCD1) plays an important role in lipid metabolism. Inhibition of SCD1 activity represents a potential novel approach for the treatment of metabolic diseases such as obesity, type 2 diabetes and dyslipidemia, as well as skin diseases, acne and cancer. Herein, we report the synthesis and structure-activity relationships (SAR) of a series of novel triazolone derivatives, culminating in the identification of pyrazolyltriazolone 17a, a potent SCD1 inhibitor, which reduced plasma C16:1/C16:0 triglycerides desaturation index (DI) in an acute Lewis rat model in a dose dependent manner, with an ED50 of 4.6 mg/kg. In preliminary safety studies, compound 17a did not demonstrate adverse effects related to SCD1 inhibition after repeat dosing at 100mg/kg. Together, these data suggest that sufficient safety margins can be achieved with certain SCD1 inhibitors, thus allowing exploration of clinical utility in metabolic disease settings.

The discovery of benzenesulfonamide-based potent and selective inhibitors of voltage-gated sodium channel Na(v)1.7.

The voltage gated sodium channel Nav1.7 represents an interesting target for the treatment of pain. Human genetic studies have identified the crucial role of Nav1.7 in pain signaling. Herein, we report the design and synthesis of a novel series of benzenesulfonamide-based Nav1.7 inhibitors. Structural-activity relationship (SAR) studies were undertaken towards improving Nav1.7 activity and minimizing CYP inhibition. These efforts resulted in the identification of compound 12k, a highly potent Nav1.7 inhibitor with a thousand-fold selectivity over Nav1.5 and negligible CYP inhibition.

Systematic evaluation of amide bioisosteres leading to the discovery of novel and potent thiazolylimidazolidinone inhibitors of SCD1 for the treatment of metabolic diseases.

Several five- and six-membered heterocycles were introduced to replace the C2-position amide bond of the original 2-aminothiazole-based hit compound 5. Specifically, replacement of the amide bond with an imidazolidinone moiety yielded a novel and potent thiazolylimidazolidinone series of SCD1 inhibitors. XEN723 (compound 22) was identified after optimization of the thiazolylimidazolidinone series. This compound demonstrated a 560-fold improvement in in vitro potency and reduced plasma desaturation indices in a dose dependent manner, with an EC50 of 4.5 mg/kg.

Discovery of thiazolylpyridinone SCD1 inhibitors with preferential liver distribution and reduced mechanism-based adverse effects.

We discovered a series of novel and potent thiazolylpyridinone-based SCD1 inhibitors based on a 2-aminothiazole HTS hit by replacing the amide bond with a pyridinone moiety. Compound 19 demonstrated good potency against SCD1 in vitro and in vivo. The mouse liver microsomal SCD1 in vitro potency for 19 was improved by more than 240-fold compared to the original HTS hit. Furthermore, 19 demonstrated a dose-dependent reduction of plasma desaturation index with an ED50 of 6.3 mg/kg. Compound 19 demonstrated high liver to plasma and liver to eyelid exposures, indicating preferential liver distribution. The preliminary toxicology study with compound 19 did not demonstrate adverse effects related to SCD1 inhibition, suggesting a wide safety margin with respect to other known SCD1 inhibitors with wider distribution profiles.

Tenecteplase Plus Butyphthalide for Stroke Within 4.5-6 Hours of Onset (EXIT-BT): a Phase 2 Study.

To date, the benefit of intravenous thrombolysis is confined to within 4.5 h of onset for acute ischemic stroke (AIS) without advanced neuroimaging selection. The current trial aimed to investigate the safety and efficacy of intravenous tenecteplase (TNK) plus Dl-3-n-Butylphthalide (NBP) in AIS within 4.5 to 6 h of onset. In this randomized, multicenter trial, eligible AIS patients were randomly assigned to receive intravenous TNK (0.25 mg/kg) plus NBP or NBP within 4.5 to 6 h of onset. The primary endpoint was symptomatic intracranial hemorrhage (sICH). Secondary endpoints included excellent functional outcome defined as a modified Rankin Scale score of 0 to 1 at 90 days. 100 patients diagnosed by non-contrast CT (NCCT) were enrolled, including 50 in TNK group and 50 in control group. sICH occurred in 2.0% (1/50) in TNK group and 0.0% (0/49) in control group with no difference (unadjusted P = 0.998). The proportion of excellent functional outcome was 77.6% (38/49) in TNK group and 69.4% (34/49) in control group with non-significance (absolute difference 8.2%, P = 0.36). A significant decrease in NIHSS score at 24 h (P = 0.004) and more early neurological improvement (20.4% vs 4.1%; P = 0.026) was observed in TNK vs control group, but there was no difference in other secondary outcomes. This phase 2 study suggests that intravenous TNK with adjuvant NBP seems safe, feasible and may improve early neurological function in AIS patients within 4.5 to 6 h of symptom onset selected using NCCT.Clinical Trials Registration: This trial was registered with ClinicalTrials.gov (NCT05189509).

Discovery of XEN445: a potent and selective endothelial lipase inhibitor raises plasma HDL-cholesterol concentration in mice.

Endothelial lipase (EL) activity has been implicated in HDL metabolism and in atherosclerotic plaque development; inhibitors are proposed to be efficacious in the treatment of dyslipidemia related cardiovascular disease. We describe here the discovery of a novel class of anthranilic acids EL inhibitors. XEN445 (compound 13) was identified as a potent and selective EL inhibitor, that showed good ADME and PK properties, and demonstrated in vivo efficacy in raising plasma HDLc concentrations in mice.

UBE4A catalyzes NRF1 ubiquitination and facilitates DDI2-mediated NRF1 cleavage.

The transcription factor nuclear factor erythroid 2 like 1 (NFE2L1 or NRF1) regulates constitutive and inducible expression of proteasome subunits and assembly chaperones. The precursor of NRF1 is integrated into the endoplasmic reticulum (ER) and can be retrotranslocated from the ER to the cytosol where it is processed by ubiquitin-directed endoprotease DDI2. DDI2 cleaves and activates NRF1 only when NRF1 is highly polyubiquitinated. It remains unclear how retrotranslocated NRF1 is primed with large amount of ubiquitin and/or very long polyubiquitin chain for subsequent processing. Here, we report that E3 ligase UBE4A catalyzes ubiquitination of retrotranslocated NRF1 and promotes its cleavage. Depletion of UBE4A reduces the amount of ubiquitin modified on NRF1, shortens the average length of polyubiquitin chain, decreases NRF1 cleavage efficiency and causes accumulation of non-cleaved, inactivated NRF1. Expression of a UBE4A mutant lacking ligase activity impairs the cleavage, likely due to a dominant negative effect. UBE4A interacts with NRF1 and the recombinant UBE4A can promote ubiquitination of retrotranslocated NRF1 in vitro. In addition, knocking out UBE4A reduces transcription of proteasomal subunits in cells. Our results indicate that UBE4A primes NRF1 for DDI2-mediated activation to facilitate expression of proteasomal genes.

Intravenous Tenecteplase for Acute Ischemic Stroke Within 4.5-24 Hours of Onset (ROSE-TNK): A Phase 2, Randomized, Multicenter Study.

BACKGROUND AND PURPOSE: Intravenous tenecteplase (TNK) efficacy has not been well demonstrated in acute ischemic stroke (AIS) beyond 4.5 hours after onset. This study aimed to determine the effect of intravenous TNK for AIS within 4.5 to 24 hours of onset. METHODS: In this pilot trial, eligible AIS patients with diffusion-weighted imaging (DWI)-fluid attenuated inversion recovery (FLAIR) mismatch were randomly allocated to intravenous TNK (0.25 mg/kg) or standard care within 4.5-24 hours of onset. The primary endpoint was excellent functional outcome at 90 days (modified Rankin Scale [mRS] score of 0-1). The primary safety endpoint was symptomatic intracranial hemorrhage (sICH). RESULTS: Of the randomly assigned 80 patients, the primary endpoint occurred in 52.5% (21/40) of TNK group and 50.0% (20/40) of control group, with no significant difference (unadjusted odds ratio, 1.11; 95% confidence interval 0.46-2.66; P=0.82). More early neurological improvement occurred in TNK group than in control group (11 vs. 3, P=0.03), but no significant differences were found in other secondary endpoints, such as mRS 0-2 at 90 days, shift analysis of mRS at 90 days, and change in National Institutes of Health Stroke Scale score at 24 hours and 7 days. There were no cases of sICH in this trial; however, asymptomatic intracranial hemorrhage occurred in 3 of the 40 patients (7.5%) in the TNK group. CONCLUSION: This phase 2, randomized, multicenter study suggests that intravenous TNK within 4.5-24 hours of onset may be safe and feasible in AIS patients with a DWI-FLAIR mismatch.

Optimizing variant-specific therapeutic SARS-CoV-2 decoys using deep-learning-guided molecular dynamics simulations.

Treatment of COVID-19 with a soluble version of ACE2 that binds to SARS-CoV-2 virions before they enter host cells is a promising approach, however it needs to be optimized and adapted to emerging viral variants. The computational workflow presented here consists of molecular dynamics simulations for spike RBD-hACE2 binding affinity assessments of multiple spike RBD/hACE2 variants and a novel convolutional neural network architecture working on pairs of voxelized force-fields for efficient search-space reduction. We identified hACE2-Fc K31W and multi-mutation variants as high-affinity candidates, which we validated in vitro with virus neutralization assays. We evaluated binding affinities of these ACE2 variants with the RBDs of Omicron BA.3, Omicron BA.4/BA.5, and Omicron BA.2.75 in silico. In addition, candidates produced in Nicotiana benthamiana, an expression organism for potential large-scale production, showed a 4.6-fold reduction in half-maximal inhibitory concentration (IC50) compared with the same variant produced in CHO cells and an almost six-fold IC50 reduction compared with wild-type hACE2-Fc.

Synthesis and biological evaluation of substituted pyrazoles as blockers of divalent metal transporter 1 (DMT1).

Three distinct series of substituted pyrazole blockers of divalent metal transporter 1 (DMT1) were elaborated from the high-throughput screening pyrazolone hit 1. Preliminary hit-to-lead efforts revealed a preference for electron-withdrawing substituents in the 4-amido-5-hydroxypyrazole series 6a-l. In turn, this preference was more pronounced in a series of 4-aryl-5-hydroxypyrazoles 8a-j. The representative analogs 6f and 12f were found to be efficacious in a rodent model of acute iron hyperabsorption. These three series represent promising starting points for lead optimization efforts aimed at the discovery of DMT1 blockers as iron overload therapeutics.

Discovery of benzylisothioureas as potent divalent metal transporter 1 (DMT1) inhibitors.

Inhibition of intestinal brush border DMT1 offers a novel therapeutic approach to the prevention and treatment of disorders of iron overload. Several series of diaryl and tricyclic benzylisothiourea compounds as novel and potent DMT1 inhibitors were discovered from the original hit compound 1. These compounds demonstrated in vitro potency against DMT1, desirable cell permeability properties and a dose-dependent inhibition of iron uptake in an acute rat model of iron hyperabsorption. Tricyclic compounds increased the in vitro potency by up to 16-fold versus the original hit. Diaryl compounds 6b and 14a demonstrated significant iron absorption inhibition in vivo with both 25 and 50 mg/kg doses. The diaryl and tricyclic compounds described in this report represent promising structural templates for further optimization.

Inhibition of Carbonic Anhydrase Using SLC-149: Support for a Noncatalytic Function of CAIX in Breast Cancer.

Carbonic anhydrase IX (CAIX) is considered a target for therapeutic intervention in solid tumors. In this study, the efficacy of the inhibitor, 4-(3-(2,4-difluorophenyl)-oxoimidazolidin-1-yl)benzenesulfonamide (SLC-149), is evaluated on CAIX and a CAIX-mimic. We show that SLC-149 is a better inhibitor than acetazolamide against CAIX. Binding of SLC-149 thermally stabilizes CAIX-mimic at lower concentrations compared to that of CAII. Structural examinations of SLC-149 bound to CAIX-mimic and CAII explain binding preferences. In cell culture, SLC-149 is a more effective inhibitor of CAIX activity in a triple-negative breast cancer cell line than previously studied sulfonamide inhibitors. SLC-149 is also a better inhibitor of activity in cells expressing CAIX versus CAXII. However, SLC-149 has little effect on cytotoxicity, and high concentrations are required to inhibit cell growth, migration, and invasion. These data support the hypothesis that CAIX activity, shown to be important in regulating extracellular pH, does not underlie its ability to control cell growth.

A Phase 1 Study of SLC-0111, a Novel Inhibitor of Carbonic Anhydrase IX, in Patients With Advanced Solid Tumors.

OBJECTIVES: SLC-0111 is an ureido-substituted benzenesulfonamide small molecule inhibitor of carbonic anhydrase IX. The objectives of this first-in-human Phase 1 study were to determine the safety and tolerability of SLC-0111 in patients with advanced solid tumors and to establish the recommended Phase 2 dose for future clinical investigations. MATERIALS AND METHODS: Using a 3+3 design, dose escalation started at 500 mg oral daily dosing of SLC-0111 in cohort 1 and increased to 1000 and 2000 mg in cohorts 2 and 3. Drug-related adverse events (AEs) were monitored to determine safety and tolerability. Pharmacokinetic analyses assessed plasma concentrations of single and repeated doses of SLC-0111. RECIST 1.1 criteria were used to assess disease progression. RESULTS: No dose-limiting toxicities were reported and patients dosed at ≤1000 mg exhibited fewer drug-related AEs ≥ grade 3 and fewer AEs such as nausea and vomiting, compared with the 2000-mg cohort. Forty-one percent of patients experienced dose interruptions or discontinuation and the majority (71%) of these occurred in the 2000-mg cohort. Mean Cmax and AUC(0-24) values for single doses were similar at the 1000-mg and 2000-mg dose levels. Mean Tmax and T1/2 values of SLC-0111 were similar after single and repeated dosing. Power-law analysis of Cmax and AUC0-24 showed that exposure to SLC-0111 was generally dose proportional. No objective responses were observed, but stable disease >24 weeks was observed in 2 patients. CONCLUSIONS: SLC-0111 was safe in patients with previously treated, advanced solid tumors. The safety and pharmacokinetic data support 1000 mg/d as the recommended phase 2 dose for SLC-0111.

[99mTc]Technetium labelled PnAo-azomycin glucuronides: a novel class of imaging markers of tissue hypoxia.

Azomycin glucuronate was coupled to a PnAO ligand to create azomycin-based ligands that would form water-soluble 99mTc-azomycin complexes for imaging hypoxic tissue. 1-beta-D-(2-Nitroimidazolyl)glucuronic acid, (see structure in text), was synthesized by coupling 2-nitroimidazole with 1-alpha-bromo-2,3,4-tri-O-acetyl-6-methyl glucuronate, followed by deprotection. Reaction of (see structure in text) with 6-methyl-6-methylamino-HMPnAO (Pn-44) in the presence of BOP reagent in anhydrous dimethyl sulfoxide afforded the PnAO-glucuronides (see structure in text) and (see structure in text). Compound (see structure in text) was isolated in three rotomeric forms. Biological evaluation of (see structure in text) (99mTc-5) indicated selective binding to hypoxic EMT-6 cells, and cytotoxicity to fibroblasts and HeLa, sk24, sk23, and g361 cancer cell lines, at an IC20 <2.5 microgram/ml. In vivo biodistribution of two formulations of (see structure in text) in Balb/c mice with EMT-6 tumor produced diverse results, with one formulation showing no tumor preference, and the other providing a tumor/blood ratio of 2.3 at 4 h post-injection. The latter formulation delineated tumor, large intestine and liver in scintigraphic images.