Carotegrast methyl (Carogra((R))) is a small-molecule alpha4 integrin antagonist being developed by EA Pharma (formerly Ajinomoto Pharmaceuticals) and Kissei Pharmaceutical for the treatment of ulcerative colitis. The active metabolite of carotegrast methyl exerts an anti-inflammatory effect by blocking the interaction of alpha4beta1 or alpha4beta7 integrins and their ligands, VCAM-1 and MAd-CAM-1, thereby inhibiting the adhesion of inflammatory cells, including T cells, to vascular endothelial cells and extravasation into inflammatory sites. In March 2022, carotegrast methyl received its first approval in Japan for the treatment of moderate ulcerative colitis in patients who had inadequate response to 5-aminosalicylic acid. This article summarizes the milestones in the development of carotegrast methyl leading to this first approval for the treatment of moderate ulcerative colitis.