Pharmacological properties of JTE-052: a novel potent JAK inhibitor that suppresses various inflammatory responses in vitro and in vivo

Objective To evaluate the pharmacological properties of JTE-052, a novel Janus kinase (JAK) inhibitor. Methods The JAK inhibitory activity of JTE-052 was evaluated using recombinant human enzymes. The inhibitory effects on cytokine signaling pathways were evaluated using primary human inflammatory cells. The in vivo efficacy and potency of JTE-052 were examined in a mouse interleukin (IL)-2-induced interferon (IFN)-γ production model and a rat collagen-induced arthritis model. Results JTE-052 inhibited the JAK1, JAK2, JAK3, and tyrosine kinase (Tyk)2 enzymes in an adenosine triphosphate (ATP)-competitive manner and inhibited cytokine signaling evoked by IL-2, IL-6, IL-23, granulocyte/macrophage colony-stimulating factor, and IFN-α. JTE-052 inhibited the activation of inflammatory cells, such as T cells, B cells, monocytes, and mast cells, in vitro. Oral dosing of JTE-052 resulted in potent suppression of the IL-2-induced IFN-γ production in mice with an ED 50 value of 0.24 mg/kg, which was more potent than that of tofacitinib (ED 50 = 1.1 mg/kg). In the collagen-induced arthritis model, JTE-052 ameliorated articular inflammation and joint destruction even in therapeutic treatments where methotrexate was ineffective. Conclusions The present results indicate that JTE-052 is a highly potent JAK inhibitor, and represents a candidate anti-inflammatory agent for suppressing various types of inflammation.