Belumosudil for chronic graft-versus-host disease

Chronic graft-versus-host disease (cGvHD) is a multisystem disease that is diagnosed in up to 70% of patients following allogeneic hematopoietic cell transplantation. In cGvHD, the donor immune cells attack the patient's cells, resulting in inflammation and fibrosis in multiple tissues. cGvHD can affect almost any organ and is the major cause of morbidity and mortality in transplant survivors. Rho-associated coiled-coil-containing protein kinase (ROCK) is a signaling pathway that modulates inflammatory response and fibrotic processes and is dysregulated in autoimmune disorders. Many inhibitors targeting the ROCK pathway have been studied, but most lack isoform selectivity resulting in dose-limiting effects. Belumosudil mesylate is a selective oral ROCK2 inhibitor that has demonstrated safety and efficacy for cGvHD. It has been approved by the U.S. Food and Drug Administration (FDA) for the treatment of adult and pediatric patients 12 years and older with cGvHD after failure of at least two prior lines of systemic therapy, becoming the first and only approved therapy targeting ROCK2. This review examines the preclinical and clinical studies leading to the first approval of the novel drug belumosudil for cGvHD.