A Monovalent Fab Affinity-Capture and Elution Bridging Immunoassay Overcomes Rheumatoid Factor Interference while Accurately Detecting Antidrug Antibodies.

BACKGROUND: Rheumatoid factor (RF) consists of autoantibodies that bind the fragment crystallizable (Fc) region of human immunoglobulin G (IgG) and present in sera of rheumatoid arthritis (RA) patients. Immunoassays to detect antidrug antibodies (ADA) in RA patient samples may experience interference due to RF binding and crosslinking Fc regions of the capture and detection antibody reagents. To overcome this interference, a novel Fab affinity-capture and elution (ACE)-bridging immunoassay (Fab ACE-Bridge) was developed with monovalent-recombinant Fab to avoid RF interference. METHODS: ACE and ACE-Bridge assays were developed to detect ADA against a therapeutic monoclonal antibody using samples from healthy donors, psoriasis patients, and RA patients. The performance of these assays was compared to a novel Fab ACE-Bridge assay, in which monoclonal antibody was replaced with monovalent Fab. RESULTS: High screening signals in the ACE and ACE-Bridge assays were detected in RA patient samples but not in samples from healthy donors or psoriasis patients. The high screening signals in RA samples did not inhibit to the expected extent in the confirmatory assay, a consistent feature of false-positive screening results. Further investigation revealed RF as the interferent affecting assay performance. Modification of the ACE-Bridge assay by using monovalent Fab eliminated RF interference while allowing for sensitive and drug-tolerant detection of authentic ADA. CONCLUSIONS: RF interfered significantly in traditional ACE and ACE-Bridge assays. Implementation of a novel monovalent Fab ACE-Bridge assay overcame RF interference. The use of monovalent Fab is recommended for immunogenicity assays when assessing ADA in RA patient samples.

Structure-Based Design of Active-Site-Directed, Highly Potent, Selective, and Orally Bioavailable Low-Molecular-Weight Protein Tyrosine Phosphatase Inhibitors.

Protein tyrosine phosphatases constitute an important class of drug targets whose potential has been limited by the paucity of drug-like small-molecule inhibitors. We recently described a class of active-site-directed, moderately selective, and potent inhibitors of the low-molecular-weight protein tyrosine phosphatase (LMW-PTP). Here, we report our extensive structure-based design and optimization effort that afforded inhibitors with vastly improved potency and specificity. The leading compound inhibits LMW-PTP potently and selectively (Ki = 1.2 nM, >8000-fold selectivity). Many compounds exhibit favorable drug-like properties, such as low molecular weight, weak cytochrome P450 inhibition, high metabolic stability, moderate to high cell permeability (Papp > 0.2 nm/s), and moderate to good oral bioavailability (% F from 23 to 50% in mice), and therefore can be used as in vivo chemical probes to further dissect the complex biological as well as pathophysiological roles of LMW-PTP and for the development of therapeutics targeting LMW-PTP.

The method history report: an adaptable tool for communicating immunogenicity assay development and validation.

Over the developmental lifetime of a therapeutic protein, the immunogenicity assay validation history can become substantial, frustrating review of clinical immunogenicity within the biologics license application. In our experience, this can lead to questions by regulators, resulting in numerous information requests during the review process. To address this, we propose a new document, the method history report (MHR), which can comprehensively present the history of the immunogenicity assay for regulators, including assay development and validation. The flexibility of the MHR allows for adaptation to the specific needs of each therapeutic program, while maintaining a consistent template. Here, we detail the rationale, general outline and template for the MHR and recommend others consider adopting it for their biologics license application-related activities.

Synthesis and Pharmacological Characterization of 2-(2,6-Dichlorophenyl)-1-((1S,3R)-5-(3-hydroxy-3-methylbutyl)-3-(hydroxymethyl)-1-methyl-3,4-dihydroisoquinolin-2(1H)-yl)ethan-1-one (LY3154207), a Potent, Subtype Selective, and Orally Available Positive Allosteric Modulator of the Human Dopamine D1 Receptor.

Clinical development of catechol-based orthosteric agonists of the dopamine D1 receptor has thus far been unsuccessful due to multiple challenges. To address these issues, we identified LY3154207 (3) as a novel, potent, and subtype selective human D1 positive allosteric modulator (PAM) with minimal allosteric agonist activity. Conformational studies showed LY3154207 adopts an unusual boat conformation, and a binding pose with the human D1 receptor was proposed based on this observation. In contrast to orthosteric agonists, LY3154207 showed a distinct pharmacological profile without a bell-shaped dose-response relationship or tachyphylaxis in preclinical models. Identification of a crystalline form of free LY3154207 from the discovery lots was not successful. Instead, a novel cocrystal form with superior solubility was discovered and determined to be suitable for development. This cocrystal form was advanced to clinical development as a potential first-in-class D1 PAM and is now in phase 2 studies for Lewy body dementia.

Synthesis and biological evaluation of aryl-oxadiazoles as inhibitors of Mycobacterium tuberculosis.

Despite increased research efforts to find new treatments for tuberculosis in recent decades, compounds with novel mechanisms of action are still required. We previously identified a series of novel aryl-oxadiazoles with anti-tubercular activity specific for bacteria using butyrate as a carbon source. We explored the structure activity relationship of this series. Structural modifications were performed in all domains to improve potency and physico-chemical properties. A number of compounds displayed sub-micromolar activity against M. tuberculosis utilizing butyrate, but not glucose as the carbon source. Compounds showed no or low cytotoxicity against eukaryotic cells. Three compounds were profiled in mouse pharmacokinetic studies. Plasma clearance was low to moderate but oral exposure suggested solubility-limited drug absorption in addition to first pass metabolism. The presence of a basic nitrogen in the linker slightly increased solubility, and salt formation optimized aqueous solubility. Our findings suggest that the 1,3,4-oxadiazoles are useful tools and warrant further investigation.

Difference in the Pharmacokinetics and Hepatic Metabolism of Antidiabetic Drugs in Zucker Diabetic Fatty and Sprague-Dawley Rats.

The Zucker diabetic fatty (ZDF) rat, an inbred strain of obese Zucker fatty rat, develops early onset of insulin resistance and displays hyperglycemia and hyperlipidemia. The phenotypic changes resemble human type 2 diabetes associated with obesity and therefore the strain is used as a pharmacological model for type 2 diabetes. The aim of the current study was to compare the pharmacokinetics and hepatic metabolism in male ZDF and Sprague-Dawley (SD) rats of five antidiabetic drugs that are known to be cleared via various mechanisms. Among the drugs examined, metformin, cleared through renal excretion, and rosiglitazone, metabolized by hepatic cytochrome P450 2C, did not exhibit differences in the plasma clearance in ZDF and SD rats. In contrast, glibenclamide, metabolized by hepatic CYP3A, canagliflozin, metabolized mainly by UDP-glucuronosyltransferases (UGT), and troglitazone, metabolized by sulfotransferase and UGT, exhibited significantly lower plasma clearance in ZDF than in SD rats after a single intravenous administration. To elucidate the mechanisms for the difference in the drug clearance, studies were performed to characterize the activity of hepatic drug-metabolizing enzymes using liver S9 fractions from the two strains. The results revealed that the activity for CYP3A and UGT was decreased in ZDF rats using the probe substrates, and decreased unbound intrinsic clearance in vitro for glibenclamide, canagliflozin, and troglitazone was consistent with lower plasma clearance in vivo. The difference in pharmacokinetics of these two strains may complicate pharmacokinetic/pharmacodynamic correlations, given that ZDF is used as a pharmacological model, and SD rat as the pharmacokinetics and toxicology strain.