AC410 is a potent, selective, orally-administered, small molecule inhibitor of Janus kinase 2 (JAK2, Kd = 0.18 nM) and has potential utility in autoimmune and inflammatory indications. Activity data: the specificity of AC410 for JAK2 vis-a-vis JAK1 (Kd = 2.5 nM) and JAK3 (Kd = 5 nM).