Discovery and Characterization of Triaminotriazine Aniline Amides as Highly Selective p38 Kinase Inhibitors

• Published in: The Journal of pharmacology and experimental therapeutics 2006-08, Vol.318 (2), p.495-502
• Main Authors: Lin, Tsung H, Metzger, Axel, Diller, David J, Desai, Madhuri, Henderson, Ian, Ahmed, Gulzar, Kimble, Earl F, Quadros, Elizabeth, Webb, Maria L
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - antagonists & inhibitors; Aniline Compounds - chemical synthesis; Aniline Compounds - pharmacology; Animals; Antigen-Antibody Complex - metabolism; Binding, Competitive - drug effects; Blotting, Western; Cell Line; Cell Survival - drug effects; Drug Design; Enzyme Inhibitors - chemical synthesis; Enzyme Inhibitors - pharmacology; Humans; Lipopolysaccharides - pharmacology; Mice; Mice, Inbred BALB C; p38 Mitogen-Activated Protein Kinases - antagonists & inhibitors; Triazines - chemical synthesis; Triazines - pharmacology; Tumor Necrosis Factor-alpha - biosynthesis
• ISSN: 0022-3565; 1521-0103
• DOI: 10.1124/jpet.105.097568

The p38 mitogen-activated protein (MAP) kinases are a family of serine/threonine protein kinases that play important roles in cellular responses to inflammation and external stress. Inhibitors of the p38 MAP kinase have shown promise for potential treatment of inflammatory disorders such as rheumatoid arthritis, acute coronary syndrome, psoriasis, and Crohn's disease. We identified a novel class of p38 inhibitors via high-throughput screening. PS200981 [3-(4-(1,4-diazepan-1-yl)-6-(((1 S ,2 R ,5 S )-6,6-dimethylbicyclo[3.1.1]heptan-2-yl)methylamino)-1,3,5-triazin-2-ylamino)-4-methylbenzamide], a representative compound identified from screening a collection of combinatorial libraries, amounting to 2.1 million compounds, inhibits p38α kinase and the lipopolysaccharide (LPS)-induced increase in tumor necrosis factor (TNF) α levels in cell media of human monocytes with IC 50 values of 1 μM. The screening data revealed a preferred synthon, 3-amino-4-methyl benzamide, which is critical for the activity against p38. This synthon appeared almost exclusively in screening hits including PS200981, and slight variations of this synthon including 3-amino benzamide and 2-amino-4-methyl benzamide also contained in the library were inactive. PS200981 is equally potent against the α and β forms of p38 but did not inhibit p38γ and is >25-fold selective versus a panel of other kinases. PS200981 inhibited the LPS-induced increase in TNFα levels when administered at 30 mg/kg to mice. Selectivity and in vivo activity of this class of p38 inhibitors was further demonstrated by PS166276 [( R )-3-(4-(isobutyl(methyl)-amino)-6-(pyrrolidin-3-ylamino)-1,3,5-triazin-2-ylamino)-4-methylbenzamide], a highly structurally related but more potent and less cytotoxic inhibitor, in several intracellular signaling assays, and in LPS-challenged mice. Overall, this novel class of p38 inhibitors is potent, active in vitro and in vivo, and is highly selective.