In short
Belumosudil is a kinase inhibitor used to treat chronic graft-versus-host disease (cGVHD) in adults and adolescents aged 12 years and older. It is marketed as Rezurock 200 mg film-coated tablets and is given by mouth. One authorised Phase 3 trial is comparing belumosudil against best available therapy in 464 participants with cGVHD, measuring overall response rate at 24 weeks.
Key points
- Belumosudil is a kinase inhibitor that blocks ROCK2 and ROCK1.
- It is authorised for chronic graft-versus-host disease after failure of at least two prior systemic therapies.
- The ongoing Phase 3 trial compares belumosudil with best available therapy.
- The trial plans to enrol 464 participants aged 12 years or older.
- The main measure is overall response rate at 24 weeks.
- Belumosudil is taken as 200 mg once daily with a meal.
What is belumosudil?
Belumosudil is a kinase inhibitor, a type of medicine that blocks enzymes called kinases which are involved in cell signalling. It is also known by the brand name Rezurock and the development code KD025. Belumosudil is authorised as a medicine in the United Kingdom, where it is available as Rezurock 200 mg tablets supplied by Sanofi. It is approved for the treatment of chronic graft-versus-host disease (cGVHD), a condition that can occur after a stem cell or bone marrow transplant when the donated cells attack the recipient's body. The US Food and Drug Administration (FDA) has designated belumosudil as an orphan drug for this use, meaning it is intended to treat a rare disease.
How does belumosudil work?
Belumosudil is an inhibitor of rho-associated, coiled-coil containing protein kinase, also called ROCK. It blocks two forms of this enzyme, ROCK2 and ROCK1, with IC50 values of approximately 100 nanomolar. ROCK proteins play a role in inflammation and fibrosis, the formation of scar-like tissue. By blocking ROCK, belumosudil may reduce the abnormal immune response and tissue damage that occur in chronic graft-versus-host disease. In cGVHD, immune cells from the donor attack the patient's tissues, and belumosudil helps to dampen this response.
Which conditions is belumosudil used or studied for?
- Chronic graft-versus-host disease (cGVHD) — a long-term complication after a stem cell transplant where donor immune cells damage the patient's organs and tissues. Belumosudil is authorised for adults and adolescents aged 12 years and older whose cGVHD has not responded to at least two prior lines of systemic therapy.
How is belumosudil given?
Belumosudil is given as 200 mg film-coated tablets that are swallowed whole with a meal. The tablets should not be cut, crushed, or chewed. The recommended dose is 200 mg once daily, taken at the same time every day, and treatment continues until the chronic GVHD worsens and requires a new systemic treatment.
What do the clinical trials show?
One authorised Phase 3 trial is investigating belumosudil in participants aged 12 years or older with chronic graft-versus-host disease. The trial, recorded in the EU Clinical Trials Information System, plans to enrol 464 participants and is comparing belumosudil with best available therapy. The main measure, or primary outcome, is the overall response rate at 24 weeks, which assesses how many participants respond to treatment. The study aims to show that belumosudil is superior to best available therapy in achieving a response at 24 weeks. The comparison arm includes several other medicines used for cGVHD, such as ibrutinib, imatinib, rituximab, and methotrexate.
What side effects are known?
Belumosudil can affect the liver. Monitoring of total bilirubin, AST, and ALT — markers of liver function — is recommended at least once monthly during treatment. If liver enzyme levels rise significantly, the dose may be held until they recover, and in severe cases treatment may be permanently discontinued. Other adverse reactions of grade 3 severity may also require holding the dose until recovery, while grade 4 reactions lead to permanent discontinuation. The sources provided do not list further side effects in detail.