Delgocitinib, also known as LEO-124249 and JTE052, is a potent and selective JAK inhibitor. JTE-052 reduces skin inflammation and ameliorates chronic dermatitis in rodent models: Comparison with conventional therapeutic agents. JTE-052 regulates contact hypersensitivity by downmodulating T cell activation and differentiation. Delgocitinib has been shown to be effective and well-tolerated in human clinical trials and has recently been approved in Japan for the treatment of atopic dermatitis as the first drug among Janus kinase inhibitors.