Discovery of a class of highly potent Janus Kinase 1/2 (JAK1/2) inhibitors demonstrating effective cell-based blockade of IL-13 signaling.

Disruption of interleukin-13 (IL-13) signaling with large molecule antibody therapies has shown promise in diseases of allergic inflammation. Given that IL-13 recruits several members of the Janus Kinase family (JAK1, JAK2, and TYK2) to its receptor complex, JAK inhibition may offer an alternate small molecule approach to disrupting IL-13 signaling. Herein we demonstrate that JAK1 is likely the isoform most important to IL-13 signaling. Structure-based design was then used to improve the JAK1 potency of a series of previously reported JAK2 inhibitors. The ability to impede IL-13 signaling was thereby significantly improved, with the best compounds exhibiting single digit nM IC50's in cell-based assays dependent upon IL-13 signaling. Appropriate substitution was further found to influence inhibition of a key off-target, LRRK2. Finally, the most potent compounds were found to be metabolically labile, which makes them ideal scaffolds for further development as topical agents for IL-13 mediated diseases of the lungs and skin (for example asthma and atopic dermatitis, respectively).

Novel triazolo-pyrrolopyridines as inhibitors of Janus kinase 1.

The identification of a novel fused triazolo-pyrrolopyridine scaffold, optimized derivatives of which display nanomolar inhibition of Janus kinase 1, is described. Prototypical example 3 demonstrated lower cell potency shift, better permeability in cells and higher oral exposure in rat than the corresponding, previously reported, imidazo-pyrrolopyridine analogue 2. Examples 6, 7 and 18 were subsequently identified from an optimization campaign and demonstrated modest selectivity over JAK2, moderate to good oral bioavailability in rat with overall pharmacokinetic profiles comparable to that reported for an approved pan-JAK inhibitor (tofacitinib).

1H-Pyrazolo[3,4-g]hexahydro-isoquinolines as selective glucocorticoid receptor antagonists with high functional activity.

Addition of the 4-fluorophenylpyrazole group to the previously described 2-azadecalin glucocorticoid receptor (GR) antagonist 1 resulted in significantly enhanced functional activity. SAR of the bridgehead substituent indicated that whereas groups as small as methyl afforded high GR binding, GR functional activity was enhanced by larger groups such as benzyl, substituted ethers, and aminoalkyl derivatives. GR antagonists with binding and functional activity comparable to mifepristone were discovered (e.g., 52: GR binding K(i) 0.7 nM; GR reporter gene functional K(i) 0.6 nM) and found to be highly selective over other steroid receptors. Analogues 43 and 45 had >50% oral bioavailability in the dog.

Mitigation of Acetylcholine Esterase Activity in the 1,7-Diazacarbazole Series of Inhibitors of Checkpoint Kinase 1.

Checkpoint kinase 1 (ChK1) plays a key role in the DNA damage response, facilitating cell-cycle arrest to provide sufficient time for lesion repair. This leads to the hypothesis that inhibition of ChK1 might enhance the effectiveness of DNA-damaging therapies in the treatment of cancer. Lead compound 1 (GNE-783), the prototype of the 1,7-diazacarbazole class of ChK1 inhibitors, was found to be a highly potent inhibitor of acetylcholine esterase (AChE) and unsuitable for development. A campaign of analogue synthesis established SAR delineating ChK1 and AChE activities and allowing identification of new leads with improved profiles. In silico docking using a model of AChE permitted rationalization of the observed SAR. Compounds 19 (GNE-900) and 30 (GNE-145) were identified as selective, orally bioavailable ChK1 inhibitors offering excellent in vitro potency with significantly reduced AChE activity. In combination with gemcitabine, these compounds demonstrate an in vivo pharmacodynamic effect and are efficacious in a mouse p53 mutant xenograft model.

Identification of C-2 hydroxyethyl imidazopyrrolopyridines as potent JAK1 inhibitors with favorable physicochemical properties and high selectivity over JAK2.

Herein we report on the structure-based discovery of a C-2 hydroxyethyl moiety which provided consistently high levels of selectivity for JAK1 over JAK2 to the imidazopyrrolopyridine series of JAK1 inhibitors. X-ray structures of a C-2 hydroxyethyl analogue in complex with both JAK1 and JAK2 revealed differential ligand/protein interactions between the two isoforms and offered an explanation for the observed selectivity. Analysis of historical data from related molecules was used to develop a set of physicochemical compound design parameters to impart desirable properties such as acceptable membrane permeability, potent whole blood activity, and a high degree of metabolic stability. This work culminated in the identification of a highly JAK1 selective compound (31) exhibiting favorable oral bioavailability across a range of preclinical species and robust efficacy in a rat CIA model.

Discovery and optimization of novel, non-steroidal glucocorticoid receptor modulators.

A virtual screening approach comprising a 3-D similarity search based on known GR modulators was used to identify a novel series of non-steroidal glucocorticoid receptor (GR) antagonists. Optimization of the initial hit to provide potent compounds which exhibit good selectivity against other steroidal nuclear hormone receptors is described.

Identification and optimisation of a series of substituted 5-(1H-pyrazol-3-yl)-thiophene-2-hydroxamic acids as potent histone deacetylase (HDAC) inhibitors.

Optimisation of ADS100380, a sub-micromolar HDAC inhibitor identified using a virtual screening approach, led to a series of substituted 5-(1H-pyrazol-3-yl)-thiophene-2-hydroxamic acids (6a-i), that possessed significant HDAC inhibitory activity. Subsequent functionalisation of the pendent phenyl group of compounds 6f and 6g provided analogues 6j-w with further enhanced enzyme and anti-proliferative activity. Compound 6j demonstrated efficacy in a mouse xenograft experiment.

2-Benzenesulfonyl-8a-benzyl-hexahydro-2H-isoquinolin-6-ones as selective glucocorticoid receptor antagonists.

The 2-azadecalin ring system was evaluated as a scaffold for the preparation of glucocorticoid receptor (GR) antagonists. High affinity, selective GR antagonists were discovered based on a hypothetical binding mode related to the steroidal GR antagonist RU-43044. 2-Benzenesulfonyl substituted 8a-benzyl-hexahydro-2H-isoquinolin-6-ones exemplified by (R)-37 had low nanomolar affinity for GR with moderate functional activity (200 nM) in a reporter gene assay. These compounds were devoid of affinity for other steroidal receptors (ER, AR, MR, and PR). Analogues based on an alternative putative binding mode (CP-like) were found to be inactive.

Design, synthesis and characterization of a novel class of coumarin-based inhibitors of inducible nitric oxide synthase.

Inducible nitric oxide synthase (iNOS) has been implicated in various central and peripheral pathophysiological diseases. Our high throughput screening initially identified a weak inhibitor of iNOS, thiocoumarin 13. From this lead, a number of potent derivatives were prepared that demonstrate favorable potency, selectivity and kinetics. Compound 30 has an IC50 of 60 nM for mouse iNOS and 185-fold and 9-fold selectivity for bovine eNOS and rat nNOS, respectively. In cellular assays for iNOS, this compound has micromolar potency. Furthermore, two compounds (16 and 30) demonstrate a reasonable pharmacokinetic profile in rodents. The synthesis, SAR, and biological activity of this novel class of compounds is described.