Yonghan Hu

Indole Cytosolic Phospholipase A2 α Inhibitors: Discovery and in Vitro and in Vivo Characterization of 4-{3-[5-Chloro-2-(2-{[(3,4-dichlorobenzyl)sulfonyl]amino}ethyl)-1-(diphenylmethyl)-1H-indol-3-yl]propyl}benzoic Acid, Efipladib

The optimization of a class of indole cPLA 2 alpha inhibitors is described herein. The importance of the substituent at C3 and the substitution pattern of the phenylmethane sulfonamide region are highlighted. Optimization of these regions led to the discovery of 111 (efipladib) and 121 (WAY-196025), which are shown to be potent, selective inhibitors of cPLA 2 alpha in a variety of isolated enzyme assays, cell based assays, and rat and human whole blood assays. The binding of these compounds has been further examined using isothermal titration calorimetry. Finally, these compounds have shown efficacy when dosed orally in multiple acute and chronic prostaglandin and leukotriene dependent in vivo models.

Pharmacologic Inhibition of Tpl2 Blocks Inflammatory Responses in Primary Human Monocytes, Synoviocytes, and Blood

Tumor necrosis factor α (TNFα) is a pro-inflammatory cytokine that controls the initiation and progression of inflammatory diseases such as rheumatoid arthritis. Tpl2 is a MAPKKK in the MAPK (i.e. ERK) pathway, and the Tpl2-MEK-ERK signaling pathway is activated by the pro-inflammatory mediators TNFα, interleukin (IL)-1β, and bacterial endotoxin (lipopolysaccharide (LPS)). Moreover, Tpl2 is required for TNFα expression. Thus, pharmacologic inhibition of Tpl2 should be a valid approach to therapeutic intervention in the pathogenesis of rheumatoid arthritis and other inflammatory diseases in humans. We have developed a series of highly selective and potent Tpl2 inhibitors, and in the present study we have used these inhibitors to demonstrate that the catalytic activity of Tpl2 is required for the LPS-induced activation of MEK and ERK in primary human monocytes. These inhibitors selectively target Tpl2 in these cells, and they block LPS- and IL-1β-induced TNFα production in both primary human monocytes and human blood. In rheumatoid arthritis fibroblast-like synoviocytes these inhibitors block ERK activation, cyclooxygenase-2 expression, and the production of IL-6, IL-8, and prostaglandin E2, and the matrix metalloproteinases MMP-1 and MMP-3. Taken together, our results show that inhibition of Tpl2 in primary human cell types can decrease the production of TNFα and other pro-inflammatory mediators during inflammatory events, and they further support the notion that Tpl2 is an appropriate therapeutic target for rheumatoid arthritis and other human inflammatory diseases.

Selective inhibitors of tumor progression loci-2 (Tpl2) kinase with potent inhibition of TNF-α production in human whole blood

Tpl2 (cot/MAP3K8) is an upstream kinase of MEK in the ERK pathway. It plays an important role in Tumor Necrosis Factor-alpha (TNF-alpha) production and signaling. We have discovered that 8-halo-4-(3-chloro-4-fluoro-phenylamino)-6-[(1H-[1,2,3]triazol-4-ylmethyl)-amino]-quinoline-3-carbonitriles (4) are potent inhibitors of this enzyme. In order to improve the inhibition of TNF-alpha production in LPS-stimulated human blood, a series of analogs with a variety of substitutions around the triazole moiety were studied. We found that a cyclic amine group appended to the triazole ring could considerably enhance potency, aqueous solubility, and cell membrane permeability. Optimization of these cyclic amine groups led to the identification of 8-chloro-4-(3-chloro-4-fluorophenylamino)-6-((1-(1-ethylpiperidin-4-yl)-1H-1,2,3-triazol-4-yl)methylamino)quinoline-3-carbonitrile (34). In a LPS-stimulated rat inflammation model, compound 34 showed good efficacy in inhibiting TNF-alpha production.

Identification and SAR of a new series of thieno[3,2-d]pyrimidines as Tpl2 kinase inhibitors.

We report here the synthesis and SAR of a new series of thieno[3,2-d]pyrimidines as potent Tpl2 kinase inhibitors. The proposed binding mode suggests the potential flipped binding mode depending on the substitution. Biacore studies show evidence of binding of these molecules to the protein kinase. The kinome inhibition profile of these molecules suggests good selectivity.

Discovery of indazoles as inhibitors of Tpl2 kinase.

Synthesis, modeling and structure-activity relationship of indazoles as inhibitors of Tpl2 kinase are described. From a high throughput screening effort, we identified an indazole hit compound 5 that has a single digit micromolar Tpl2 activity. Through SAR modifications at the C3 and C5 positions of the indazole, we discovered compound 31 with good potency in LANCE assay and cell-based p-Erk assay.

Synthesis and biological evaluation of ((4-keto)-phenoxy)methyl biphenyl-4-sulfonamides: a class of potent aggrecanase-1 inhibitors.

The prevention of aggrecan (a key component of cartilage) cleavage via the inhibition of aggrecanase-1 may provide a unique opportunity to stop the progression of cartilage degradation in osteoarthritis. The evaluation of a series of biphenylsulfonamides resulted in the identification of the ((4-keto)-phenoxy)methyl biphenyl-4-sulfonamides analogs (19-21 and 24) with improved Agg-1 inhibition and MMP-2, MMP-13 activity.

Continued exploration of biphenylsulfonamide scaffold as a platform for aggrecanase-1 inhibition.

Design, synthesis and structure-activity relationship of a series of biphenylsulfonamido-3-methylbutanoic acid based aggrecanase-1 inhibitors are described. In addition to robust aggrecanase-1 inhibition, these compounds also exhibit potent MMP-13 activity. In cell-based cartilage explants assay compound 48 produced 87% inhibition of proteoglycan degradation at 10 μg/mL. Good pharmacokinetic properties were demonstrated by 46 with a half-life of 6h and bioavailability of 23%.