ABSTRACT
The widespread emergence of antibiotic resistance, including multidrug resistance in Gram-negative (G-) bacterial pathogens, poses a critical challenge to the current antimicrobial armamentarium. Antibody-drug conjugates (ADCs), primarily used in anticancer therapy, offer a promising treatment alternative due to their ability to deliver a therapeutic molecule while simultaneously activating the host immune response. The Cloudbreak platform is being used to develop ADCs to treat infectious diseases, composed of a therapeutic targeting moiety (TM) attached via a noncleavable linker to an effector moiety (EM) to treat infectious diseases. In this proof-of-concept study, 21 novel dimeric peptidic molecules (TMs) were evaluated for activity against a screening panel of G- pathogens. The activities of the TMs were not impacted by existing drug resistance. Potent TMs were conjugated to the Fc fragment of human IgG1 (EM), resulting in 4 novel ADCs. These ADCs were evaluated for immunoprophylactic efficacy in a neutropenic mouse model of deep thigh infection. In colistin-sensitive infections, 3 of the 4 ADCs offered protection similar to that of therapeutically dosed colistin, while CTC-171 offered enhanced protection. The efficacy of these ADCs was unchanged in colistin-resistant infections. Together, these results indicate that the ADCs used here are capable of potent binding to G- pathogens regardless of lipopolysaccharide (LPS) modifications that otherwise lead to antibiotic resistance and support further exploration of ADCs in the treatment of infections caused by drug-resistant G- bacteria.
Subject(s)
Colistin , Gram-Negative Bacterial Infections , Animals , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Disease Models, Animal , Drug Resistance, Multiple, Bacterial , Gram-Negative Bacteria , Gram-Negative Bacterial Infections/drug therapy , Lipopolysaccharides , MiceABSTRACT
A series of potent and bacteria-selective threonyl-tRNA synthetase (ThrRS) inhibitors have been identified using structure-based drug design. These compounds occupied the substrate binding site of ThrRS and showed excellent binding affinities for all of the bacterial orthologues tested. Some of the compounds displayed greatly improved bacterial selectivity. Key residues responsible for potency and bacteria/human ThrRS selectivity have been identified. Antimicrobial activity has been achieved against wild-type Haemophilus influenzae and efflux-deficient mutants of Escherichia coli and Burkholderia thailandensis.
Subject(s)
Anti-Bacterial Agents/chemistry , Bacterial Proteins/antagonists & inhibitors , Threonine-tRNA Ligase/antagonists & inhibitors , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/pharmacology , Bacterial Proteins/chemistry , Binding Sites , Burkholderia/drug effects , Crystallography, X-Ray , Drug Resistance, Bacterial , Escherichia coli/drug effects , Escherichia coli/genetics , Escherichia coli Proteins/antagonists & inhibitors , Escherichia coli Proteins/chemistry , Haemophilus influenzae/drug effects , Humans , Microbial Sensitivity Tests , Models, Molecular , Molecular Structure , Mutation , Protein Binding , Quinazolines/chemical synthesis , Quinazolines/chemistry , Quinazolines/pharmacology , Stereoisomerism , Structure-Activity Relationship , Substrate Specificity , Threonine-tRNA Ligase/chemistry , Yersinia pestis/drug effectsABSTRACT
We identified a new benzothiophene containing Rho kinase inhibitor scaffold in an ultra high-throughput enzymatic activity screen. SAR studies, driven by a novel label-free cellular impedance assay, were used to derive 39, which substantially reduced intraocular pressure in a monkey model of glaucoma-associated ocular hypertension.
Subject(s)
Disease Models, Animal , Glaucoma/enzymology , Ocular Hypertension/enzymology , Protein Kinase Inhibitors/pharmacology , Thiophenes/pharmacology , rho-Associated Kinases/antagonists & inhibitors , Animals , Glaucoma/physiopathology , Haplorhini , HeLa Cells , Humans , Intraocular Pressure/drug effects , Ocular Hypertension/physiopathologyABSTRACT
The discovery and optimization of a novel class of carbon-linked dihydropyrones as allosteric HCV NS5B polymerase inhibitors are presented. Replacement of the sulfur linker atom with carbon reduced compound acidity and greatly increased cell permeation. Further structure-activity relationship (SAR) studies led to the identification of compounds, exemplified by 23 and 24, with significantly improved antiviral activities in the cell-based replicon assay and favorable pharmacokinetic profiles.
Subject(s)
Antiviral Agents/chemical synthesis , Hepacivirus/enzymology , Pyrones/chemical synthesis , Viral Nonstructural Proteins/antagonists & inhibitors , Administration, Oral , Allosteric Regulation , Animals , Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Biological Availability , Caco-2 Cells , Cell Line, Tumor , Half-Life , Humans , Permeability , Pyrones/chemistry , Pyrones/pharmacology , Rats , Stereoisomerism , Structure-Activity Relationship , Viral Nonstructural Proteins/geneticsABSTRACT
A novel class of non-nucleoside HCV NS5B polymerase inhibitors has been identified from screening. A co-crystal structure revealed an allosteric binding site in the protein that required a unique conformational change to accommodate inhibitor binding. Herein we report the structure-activity relationships (SARs) of this novel class of dihydropyrone-containing compounds that show potent inhibitory activities against the HCV RNA polymerase in biochemical assays.
