IL23A and Crohn disease: Given the major role of the IL-23/IL-17 pathway in inflammation and autoimmunity, new drugs in development specifically aim to neutralize only the IL-23 pathway and three anti-p19 neutralizing antibodies, MK-3222, CNTO 1959, and AMG 139, respectively, developed by MERCK, Janssen Biotech, and Amgen/MedImmune are currently in clinical trials for psoriasis, as well as Crohn's disease for AMG 139 [203, 207].