Definition

The mesylate salt form of belumosudil, an orally bioavailable inhibitor of Rho-associated coiled-coil kinase 2 (ROCK2; ROCK-II), with potential immunomodulating activity. Upon oral administration, belumosudil binds to and inhibits the serine/threonine kinase activity of ROCK2. This inhibits ROCK2-mediated signal transduction pathways and modulates various pro- and anti-inflammatory immune cell responses through the regulation of signal transducer and activator of transcription 3 and 5 (STAT3/STAT5) phosphorylation. This downregulates pro-inflammatory Th17 cells and increases regulatory T (Treg) cells. Belumosudil also inhibits ROCK2-mediated fibrotic processes, including stress fiber formation, myofibroblast activation and pro-fibrotic gene transcription. ROCK2 is upregulated in various diseases, including various fibrotic, neurodegenerative and autoimmune diseases.