R343

R343 is a syk kinase inhibitor. Syk kinase is a protein tyrosine kinase that plays a pivotal role in high affinity IgE receptor signaling in mast cells. Syk kinase inhibitors bind to syk in mast cells interrupting the signal from the Immunoglobulin E (IgE receptor), thus preventing cellular activation and subsequent chemical mediator release, and potentially blocking an allergic response in allergic asthma. Allergic asthma is a chronic inflammatory disorder of the airways whereby persistent inflammation of the airway passages results in airway obstruction. In some patients, allergens, such as pollen, trigger the production of immunoglobulin E antibodies (IgE antibodies) which then bind to mast cells and cause an intracellular signal that results in the release of various chemical mediators. [Rigel Pharmaceuticals Press Release]