[Pharmacological and clinical profiles of belumosudil mesylate (REZUROCK_® Tablets), a selective inhibitor of ROCK2]

Belumosudil mesylate (REZUROCK_® Tablets hereafter belumosudil) is a novel selective rho-associated, coiled-coil containing protein kinase 2 (ROCK2) inhibitor. ROCK2 is a kinase involved in immune cell differentiation and tissue fibrosis. Belumosudil exerts its effect by decreasing the inflammation and fibrosis in various organs which are the two key features of cGVHD. In the phase III clinical study in Japan, the primary endpoint was met, best overall response rate (best ORR), defined as the percentage of patients who achieved complete response (CR) or partial response (PR), was 85.7%. Belumosudil received manufacturing and marketing approval for the treatment of chronic graft-versus-host disease (cGVHD) in patients who have insufficient response to steroid therapy in March 2024 and launched in May 2024. The Japanese MHLW has also granted orphan drug designation in May 2023 for the treatment of cGVHD.