Selective inhibition of BTK prevents murine lupus and antibody-mediated glomerulonephritis.

Autoantibody production and immune complex deposition within the kidney promote renal disease in patients with lupus nephritis. Thus, therapeutics that inhibit these pathways may be efficacious in the treatment of systemic lupus erythematosus. Bruton's tyrosine kinase (BTK) is a critical signaling component of both BCR and FcR signaling. We sought to assess the efficacy of inhibiting BTK in the development of lupus-like disease, and in this article describe (R)-5-amino-1-(1-cyanopiperidin-3-yl)-3-(4-[2,4-difluorophenoxy]phenyl)-1H-pyrazole-4-carboxamide (PF-06250112), a novel highly selective and potent BTK inhibitor. We demonstrate in vitro that PF-06250112 inhibits both BCR-mediated signaling and proliferation, as well as FcR-mediated activation. To assess the therapeutic impact of BTK inhibition, we treated aged NZBxW_F1 mice with PF-06250112 and demonstrate that PF-06250112 significantly limits the spontaneous accumulation of splenic germinal center B cells and plasma cells. Correspondingly, anti-dsDNA and autoantibody levels were reduced in a dose-dependent manner. Moreover, administration of PF-06250112 prevented the development of proteinuria and improved glomerular pathology scores in all treatment groups. Strikingly, this therapeutic effect could occur with only a modest reduction observed in anti-dsDNA titers, implying a critical role for BTK signaling in disease pathogenesis beyond inhibition of autoantibody production. We subsequently demonstrate that PF-06250112 prevents proteinuria in an FcR-dependent, Ab-mediated model of glomerulonephritis. Importantly, these results highlight that BTK inhibition potently limits the development of glomerulonephritis by impacting both cell- and effector molecule-mediated pathways. These data provide support for evaluating the efficacy of BTK inhibition in systemic lupus erythematosus patients.

Identification and optimization of indolo[2,3-c]quinoline inhibitors of IRAK4.

IRAK4 is responsible for initiating signaling from Toll-like receptors (TLRs) and members of the IL-1/18 receptor family. Kinase-inactive knock-ins and targeted deletions of IRAK4 in mice cause reductions in TLR induced pro-inflammatory cytokines and these mice are resistant to various models of arthritis. Herein we report the identification and optimization of a series of potent IRAK4 inhibitors. Representative examples from this series showed excellent selectivity over a panel of kinases, including the kinases known to play a role in TLR-mediated signaling. The compounds exhibited low nM potency in LPS- and R848-induced cytokine assays indicating that they are blocking the TLR signaling pathway. A key compound (26) from this series was profiled in more detail and found to have an excellent pharmaceutical profile as measured by predictive assays such as microsomal stability, TPSA, solubility, and clogP. However, this compound was found to afford poor exposure in mouse upon IP or IV administration. We found that removal of the ionizable solubilizing group (32) led to increased exposure, presumably due to increased permeability. Compounds 26 and 32, when dosed to plasma levels corresponding to ex vivo whole blood potency, were shown to inhibit LPS-induced TNFα in an in vivo murine model. To our knowledge, this is the first published in vivo demonstration that inhibition of the IRAK4 pathway by a small molecule can recapitulate the phenotype of IRAK4 knockout mice.

Imidazo[1,5-a]quinoxalines as irreversible BTK inhibitors for the treatment of rheumatoid arthritis.

Imidazo[1,5-a]quinoxalines were synthesized that function as irreversible Bruton's tyrosine kinase (BTK) inhibitors. The syntheses and SAR of this series of compounds are presented as well as the X-ray crystal structure of the lead compound 36 in complex with a gate-keeper variant of ITK enzyme. The lead compound showed good in vivo efficacy in preclinical RA models.

3D Printing of Components with Tailored Properties Through Hilbert Curve Filling of a Discretized Domain.

Owing to the localized line-by-line and layer-by-layer style of material deposition, 3D printing remains an ideal candidate for fabrication of components with tailored properties (also referred to as functionally gradient components). The present work tries to exploit this advantage, in the extrusion-based 3D printing process, to fabricate components with varying set of properties at different locations. The implementation is done using Hilbert area-filling curves with the displacement per unit force (i.e., compliance) applied being the property varying in a gradient manner. Four input parameters have been considered to study their effect on the compliance, and the single most influencing parameter has been selected using analysis of variance (ANOVA) for further study. Mapping of a selected input variable on the desired property has been discussed through numerical and experimental tests. Based on these studies, a demonstrative case study of a shoe sole has been designed and fabricated. Deflections of the fabricated component have been measured at different locations for uniform loading conditions. The deflection behavior of the fabricated component is found to be in line with the gradient force response required, thus validating the proposed approach. The current study is intended to provide the basic framework for fabrication of components tailored for force response using Hilbert curves.

Aminopyrazole Carboxamide Bruton's Tyrosine Kinase Inhibitors. Irreversible to Reversible Covalent Reactive Group Tuning.

Potent covalent inhibitors of Bruton's tyrosine kinase (BTK) based on an aminopyrazole carboxamide scaffold have been identified. Compared to acrylamide-based covalent reactive groups leading to irreversible protein adducts, cyanamide-based reversible-covalent inhibitors provided the highest combined BTK potency and EGFR selectivity. The cyanamide covalent mechanism with BTK was confirmed through enzyme kinetic, NMR, MS, and X-ray crystallographic studies. The lead cyanamide-based inhibitors demonstrated excellent kinome selectivity and rat pharmacokinetic properties.

Rational approach to highly potent and selective apoptosis signal-regulating kinase 1 (ASK1) inhibitors.

Many diseases are believed to be driven by pathological levels of reactive oxygen species (ROS) and oxidative stress has long been recognized as a driver for inflammatory disorders. Apoptosis signal-regulating kinase 1 (ASK1) has been reported to be activated by intracellular ROS and its inhibition leads to a down regulation of p38-and JNK-dependent signaling. Consequently, ASK1 inhibitors may have the potential to treat clinically important inflammatory pathologies including renal, pulmonary and liver diseases. Analysis of the ASK1 ATP-binding site suggested that Gln756, an amino acid that rarely occurs at the GK+2 position, offered opportunities for achieving kinase selectivity for ASK1 which was applied to the design of a parallel medicinal chemistry library that afforded inhibitors of ASK1 with nanomolar potency and excellent kinome selectivity. A focused optimization strategy utilizing structure-based design resulted in the identification of ASK1 inhibitors with low nanomolar potency in a cellular assay, high selectivity when tested against kinase and broad pharmacology screening panels, and attractive physicochemical properties. The compounds we describe are attractive tool compounds to inform the therapeutic potential of ASK1 inhibition.