%0 Journal Article %A Noriyuki Yamamoto %A Keisuke Takeshita %A Michitaka Shichijo %A Toshio Kokubo %A Masako Sato %A Kosuke Nakashima %A Mina Ishimori %A Hiroichi Nagai %A Ying-Fu Li %A Takeshi Yura %A Kevin B. Bacon %T The Orally Available Spleen Tyrosine Kinase Inhibitor 2-[7-(3,4-Dimethoxyphenyl)-imidazo[1,2-c]pyrimidin-5-ylamino]nicotinamide Dihydrochloride (BAY 61-3606) Blocks Antigen-Induced Airway Inflammation in Rodents %D 2003 %R 10.1124/jpet.103.052316 %J Journal of Pharmacology and Experimental Therapeutics %P 1174-1181 %V 306 %N 3 %X Spleen tyrosine kinase (Syk) tyrosine kinase plays essential roles in receptors for Fc portion of immunoglobulins and B cell receptor complex signaling in various inflammatory cells; therefore, inhibitors of Syk kinase may show potential as antiasthmatic/allergic therapeutics. We identified 2-[7-(3,4-dimethoxyphenyl)-imidazo[1,2-c]pyrimidin-5-ylamino]-nicotinamide dihydrochloride (BAY 61-3606), a potent (Ki = 7.5 nM) and selective inhibitor of Syk kinase. BAY 61-3606 inhibited not only degranulation (IC50 values between 5 and 46 nM) but also lipid mediator and cytokine synthesis in mast cells. BAY 61-3606 was highly efficacious in basophils obtained from healthy human subjects (IC50 = 10 nM) and seems to be at least as potent in basophils obtained from atopic (high serum IgE) subjects (IC50 = 8.1 nM). B cell receptor activation and receptors for Fc portion of IgG signaling in eosinophils and monocytes were also potently suppressed by BAY 61-3606. Oral administration of BAY 61-3606 to rats significantly suppressed antigen-induced passive cutaneous anaphylactic reaction, bronchoconstriction, and bronchial edema at 3 mg/kg. Furthermore, BAY 61-3606 attenuated antigen-induced airway inflammation in rats. Based on these anti-inflammatory effects of BAY 61-3606 both in vitro and in vivo, it was demonstrated that Syk may play a very critical role in the pathogenesis of allergic reactions. The American Society for Pharmacology and Experimental Therapeutics %U https://jpet.aspetjournals.org/content/jpet/306/3/1174.full.pdf