Tuning the Reactivity of Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2) Activators for Optimal Efficacy.

Dimethyl fumarate is approved for the treatment of multiple sclerosis but is also associated with off-target activation of the niacin receptor. By using a tetrazolone or triazolone bioisostere approach to the fumarate and vinyl sulfone series of Nrf2 activators, we have optimized the electrophilicity of the double bond to tune the on-target Nrf2 activation with PK properties to achieve efficacy in animal models of multiple sclerosis. The study linked highly potent, highly electrophilic molecules to low plasma stability and, subsequently, limited efficacy.

Optimization of Pharmacokinetic and In Vitro Safety Profile of a Series of Pyridine Diamide Indirect AMPK Activators.

A set of focused analogues have been generated around a lead indirect adenosine monophosphate-activated kinase (AMPK) activator to improve the rat clearance of the molecule. Analogues were focused on inhibiting amide hydrolysis by the strategic placement of substituents that increased the steric environment about the secondary amide bond between 4-aminopiperidine and pyridine-5-carboxylic acid. It was found that placing substituents at position 3 of the piperidine ring and position 4 of the pyridine could all improve clearance without significantly impacting on-target potency.

Optimization of Pyrimidine Compounds as Potent JAK1 Inhibitors and the Discovery of R507 as a Clinical Candidate.

Janus kinases (JAK) play a critical role in JAK/signal transducer and activator of transcription (STAT) signaling pathways that mediate immune response and cell growth. From high-throughput screening (HTS) hit to lead optimization, a series of pyrimidine compounds has been discovered as potent JAK1 inhibitors with selectivity over JAK2. Cell-based assays were used as primary screening methods for evaluating potency and selectivity, the results were further assessed and confirmed by biochemical and additional cellular assays for lead molecules.

Structure activity relationships leading to the identification of the indirect activator of AMPK, R419.

Using an in-cell AMPK activation assay, we have developed structure-activity relationships around a hit pyridine dicarboxamide 5 that resulted in 40 (R419). A particular focus was to retain the on-target potency while also improving microsomal stability and reducing off-target activities, including hERG inhibition. We were able to show that removing a tertiary amino group from the piperazine unit of hit compound 5 improved microsomal stability while hERG inhibition was improved by modifying the substitution of the central core pyridine ring.

Bicyclic pyrimidine compounds as potent IRAK4 inhibitors.

Interleukin-1 receptor-associated kinase 4 (IRAK4) plays a critical role in transduction of IL-1R/TLR signaling which is responsible for innate immune response. From HTS campaign, bicyclic-pyrimidine compounds have been identified as potent IRAK4 inhibitors, exhibiting good potency in both IRAK4 biochemical and LPS induced IL-23 inhibition cell-based assays. The SAR efforts were focused on further improving on-target potency, reducing PAD activities of HTS hit molecule and improving in vivo PK profiles of early lead compounds.

Tetrazolone as an acid bioisostere: application to marketed drugs containing a carboxylic acid.

Matched molecular pair analysis was used to evaluate the ability of a tetrazolone group to act as a bioisostere of a carboxylic acid. Compound 7, a tetrazolone of the anti-hypertensive drug, telmisartan 6, was shown to be a potent AT antagonist (K = 0.14 nM), with activity comparable to telmisartan itself (K = 0.

The Selective JAK1/3-Inhibitor R507 Mitigates Obliterative Airway Disease Both With Systemic Administration and Aerosol Inhalation.

Background: The efficacy of selective Janus kinase 1/3 inhibitor R507 to prevent obliterative airway disease was analyzed in preclinical airway transplantation models.

Methods: Orthotopic trachea transplantations were performed between Lewis donors and Brown Norway rat recipients. Oral everolimus (4 mg/kg once per day) or oral respective inhaled R507 (60 mg/kg twice per day, each) was used for immunosuppression.

Exercise performance and peripheral vascular insufficiency improve with AMPK activation in high-fat diet-fed mice.

Intermittent claudication is a form of exercise intolerance characterized by muscle pain during walking in patients with peripheral artery disease (PAD). Endothelial cell and muscle dysfunction are thought to be important contributors to the etiology of this disease, but a lack of preclinical models that incorporate these elements and measure exercise performance as a primary end point has slowed progress in finding new treatment options for these patients. We sought to develop an animal model of peripheral vascular insufficiency in which microvascular dysfunction and exercise intolerance were defining features.

Significant reduction of acute cardiac allograft rejection by selective janus kinase-1/3 inhibition using R507 and R545.

Background: Selective inhibition of lymphocyte activation through abrogation of signal 3-cytokine transduction emerges as a new strategy for immunosuppression. This is the first report on the novel Janus kinase (JAK)1/3 inhibitors R507 and R545 for prevention of acute allograft rejection.

Methods: Pharmacokinetic and in vitro enzyme inhibition assays were performed to characterize the drugs.

R723, a selective JAK2 inhibitor, effectively treats JAK2V617F-induced murine myeloproliferative neoplasm.

The activating mutations in JAK2 (including JAK2V617F) that have been described in patients with myeloproliferative neoplasms (MPNs) are linked directly to MPN pathogenesis. We developed R723, an orally bioavailable small molecule that inhibits JAK2 activity in vitro by 50% at a concentration of 2nM, while having minimal effects on JAK3, TYK2, and JAK1 activity. R723 inhibited cytokine-independent CFU-E growth and constitutive activation of STAT5 in primary hematopoietic cells expressing JAK2V617F.

Metabolism of fostamatinib, the oral methylene phosphate prodrug of the spleen tyrosine kinase inhibitor R406 in humans: contribution of hepatic and gut bacterial processes to the overall biotransformation.

The metabolism of the spleen tyrosine kinase inhibitor N4-(2,2-dimethyl-3-oxo-4-pyrid[1,4]oxazin-6-yl)-5-fluoro-N2-(3,4,5-trimethyoxyphenyl)-2,4-pyrimidinediamine (R406) and its oral prodrug N4-(2,2-dimethyl-4-[(dihydrogenphosphonoxy)methyl]-3-oxo-5-pyrid[1,4]oxazin-6-yl)-5-fluoro-N2-(3,4,5-trimethyoxyphenyl)-2,4-pyrimidinediamine disodium hexahydrate (R788, fostamatinib) was determined in vitro and in humans. R788 was rapidly converted to R406 by human intestinal microsomes, and only low levels of R788 were observed in plasma of human subjects after oral administration of (14)C-R788. R406 was the major drug-related compound in plasma from human subjects, and only low levels of metabolites were observed in plasma.

Anthranilamide-based N,N-dialkylbenzamidines as potent and orally bioavailable factor Xa inhibitors: P4 SAR.

Anthranilamide-based benzamidine compound 4 and its N-substituted analogs were designed and examined as factor Xa inhibitors using substituted benzamidines as unconventional S4 binding element. A group of N,N-dialkylbenzamidines (11, 17 and 24) have been discovered as potent factor Xa inhibitors with strong anticoagulant activity and promising oral PK profiles.

Discovery of betrixaban (PRT054021), N-(5-chloropyridin-2-yl)-2-(4-(N,N-dimethylcarbamimidoyl)benzamido)-5-methoxybenzamide, a highly potent, selective, and orally efficacious factor Xa inhibitor.

Systematic SAR studies of in vitro factor Xa inhibitory activity around compound 1 were performed by modifying each of the three phenyl rings. A class of highly potent, selective, efficacious and orally bioavailable direct factor Xa inhibitors was discovered. These compounds were screened in hERG binding assays to examine the effects of substitution groups on the hERG channel affinity.

A novel JAK3 inhibitor, R348, attenuates chronic airway allograft rejection.

Background: This study aimed at investigating the role of a novel JAK3 inhibitor, R348, in the prevention of chronic airway allograft rejection.

Methods: The heterotopic rat trachea transplant model was used. Recipients were treated daily with R348 (10, 20, 40, 80 mg/kg) or rapamycin (0.

Novel immunosuppression: R348, a JAK3- and Syk-inhibitor attenuates acute cardiac allograft rejection.

Background: Janus kinase (JAK)3 is crucial for signal transduction downstream of various cytokine receptors in immune cells. This is the first report on the novel JAK3 inhibitor R348.

Methods: (1) Detailed pharmacokinetic data were obtained in rats; (2) multiple in vitro enzyme inhibition assays were performed to characterize the drug; (3) prevention of acute rejection was investigated in animals treated with different doses of R348 or rapamycin for 5 days; and (4) cardiac allograft survival after a 10-day treatment period was studied for various regimens of R348, tacrolimus, or rapamycin; combination indices were calculated to evaluate drug interactions.

R406, an orally available spleen tyrosine kinase inhibitor blocks fc receptor signaling and reduces immune complex-mediated inflammation.

Recent compelling evidence has lead to renewed interest in the role of antibodies and immune complexes in the pathogenesis of several autoimmune disorders, such as rheumatoid arthritis. These immune complexes, consisting of autoantibodies to self-antigens, can mediate inflammatory responses largely through binding and activating the immunoglobulin Fc receptors (FcRs). Using cell-based structure activity relationships with cultured human mast cells, we have identified the small molecule R406 [N4-(2,2-dimethyl-3-oxo-4H-pyrid[1,4]oxazin-6-yl)-5-fluoro-N2-(3,4,5-trimethoxyphenyl)-2,4-pyrimidinediamine] as a potent inhibitor of immunoglobulin E (IgE)- and IgG-mediated activation of Fc receptor signaling (EC(50) for degranulation = 56-64 nM).

Discovery of novel 2,8-diazaspiro[4.5]decanes as orally active glycoprotein IIb-IIIa antagonists.

In our efforts to develop orally active GPIIb-IIIa antagonists with improved pharmaceutical properties, we have utilized a novel 2,8-diazaspiro[4.5]decane scaffold as a template. We describe here our investigation of a variety of templates including spiropiperidinyl-gamma-lactams, spiropiperidinylimide, spiropiperidinylureas, and spiropiperidinylhydantoins.

Design, synthesis, and SAR of anthranilamide-based factor Xa inhibitors incorporating substituted biphenyl P4 motifs.

Anthranilamides 4 and 5 were designed and synthesized as selective and orally bioavailable factor Xa inhibitors. Structural modifications aimed at lowering their lipophilicity were performed at the central phenyl ring and at the S4 binding biphenyl region by incorporating water solublizing substituents. The resulting compounds (e.

Extubation failure in pediatric intensive care: a multiple-center study of risk factors and outcomes.

Objective: To determine a contemporary failed extubation rate, risk factors, and consequences of extubation failure in pediatric intensive care units (PICUs). Three hypotheses were investigated: a) Extubation failure is in part disease specific; b) preexisting respiratory conditions predispose to extubation failure; and c) admission acuity scoring does not affect extubation failure.

Design: Twelve-month prospective, observational, clinical study.

Inhibition of purified factor Xa amidolytic activity may not be predictive of inhibition of in vivo thrombosis: implications for identification of therapeutically active inhibitors.

Objective: In this study we test the hypothesis that blood/plasma-based prothrombinase assays, rather than inhibition of purified factor Xa (fXa), are predictive of in vivo antithrombotic activity.

Methods And Results: Six fXa inhibitors with equivalent nanomolar Ki were studied in thrombin generation assays using human plasma/blood and endogenous macromolecular substrate. In all assays, benzamidine inhibitors were more potent (100 to 800 nmol/L) than the aminoisoquinolines (5 to 58 micromol/L) or neutral inhibitors (3 to 10 micromol/L).

Design, synthesis and structure-activity relationships of benzoxazinone-based factor Xa inhibitors.

A series of benzoxazinone derivatives was designed and synthesized as factor Xa inhibitors. We demonstrated that the naphthyl moiety in the aniline-based compounds 1 and 2 can be replaced with benzene-fused heterobicycles and biaryls to give factor Xa inhibitors with improved trypsin selectivity. The P4 modifications lead to monoamidines which are moderately active.

Design and synthesis of factor Xa inhibitors and their prodrugs.

In addition to our previously reported fluoro acrylamides Xa inhibitors 2 and 3, a series of potent and novel cyclic diimide amidine compounds has been identified. In efforts to improve their oral bioavailability, replacement of the amidine group with methyl amidrazone gives compounds of moderate potency (14, IC(50)=0.028 microM).

Substituted acrylamides as factor Xa inhibitors: improving bioavailability by P1 modification.

To overcome the low bioavailability of our substituted acrylamide P1 benzamidine factor Xa inhibitors reported previously, neutral and less basic groups were used to replace the benzamidine. As a result, a series of P1 aminoisoquinoline substituted acrylamide Xa inhibitors was identified to be potent, selective, and orally bioavailable. Modification of P4 moiety of these compounds further improved their pharmacokinetic properties.

Design, synthesis, and SAR of monobenzamidines and aminoisoquinolines as factor Xa inhibitors.

Monoamidine FXa inhibitors 3 were designed and synthesized. SAR studies and molecular modeling led to the design of conformationally constrained diaryl ethers 4 and 5, as well as benzopyrrolidinone 7 as potent FXa inhibitors. The monoamidines show high efficacy in a DVT model, but lack desirable oral bioavailability.