SYK and rheumatoid arthritis: By targeting Syk, fostamatinib has been used to treat a wide range of diseases, such as graft-versus-host disease (Flynn et al., 2015), follicular lymphoma (Fruchon et al., 2012), chronic lymphocytic leukemia (Quiroga et al., 2009), Waldenström macroglobulinemia (Kuiatse et al., 2015), ulcerative colitis (Can et al., 2015), and idiopathic thrombocytopenic purpura (Bajpai, 2009), in addition to treating RA.