Rezurock (belumosudil)
An approved treatment for Chronic Graft-versus-Host Disease.
Drug facts
The same compound appears under different names depending on the context. Here is how to identify Belumosudil wherever you encounter it, plus the key facts at a glance.
- Generic name
- Belumosudil
- Brand name
- Rezurock
- Development codes
- KD025, SLx-2119
- Drug class
- ROCK2 inhibitor
- Manufacturer
- Kadmon / Sanofi
- How it's taken
- Taken as an oral tablet, 200mg once daily with food.
The first ROCK2 inhibitor approved for chronic GVHD, for adults and children 12 years and older after failure of at least 2 prior lines of systemic therapy.
Belumosudil is designed to address both the immune dysfunction and the tissue fibrosis (scarring) that characterize late-stage cGVHD.
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Where Belumosudil fits
Third-line agent approved after two or more prior therapy lines.
- The anti-fibrotic properties make belumosudil particularly valuable for patients with sclerotic skin disease, bronchiolitis obliterans, or other fibrotic manifestations of cGVHD.
- Positioned alongside ruxolitinib (Jakafi, second-line), ibrutinib (Imbruvica, second-line), and axatilimab (Niktimvo, third-line) in a growing cGVHD treatment landscape.
How Belumosudil works
In chronic GVHD, the immune system becomes imbalanced: there are too many inflammatory Th17 cells and too few protective regulatory T cells (Tregs). A protein called ROCK2 controls this balance by regulating which direction immune cells develop. Belumosudil selectively blocks ROCK2, shifting the immune system back toward balance.
When ROCK2 is inhibited, inflammatory Th17 cells decrease, protective Treg cells expand, and the production of pro-inflammatory cytokines like IL-17 and IL-21 drops. This addresses the root immune dysfunction driving cGVHD rather than broadly suppressing the immune system.
What sets belumosudil apart is its anti-fibrotic activity. ROCK2 also controls fibrotic (scarring) pathways in tissues. Many late-stage cGVHD patients develop chronic scarring in the skin, lungs, and other organs. By blocking ROCK2, belumosudil reduces both the inflammatory attack and the progressive fibrosis, making it particularly valuable for patients with sclerotic or fibrotic disease manifestations.
Side effects and safety
Common side effects include infections (viral and bacterial), fatigue and weakness, nausea, diarrhea, shortness of breath, cough, swelling (edema), bleeding, abdominal pain, musculoskeletal pain, headache, and elevated blood pressure. Lab abnormalities can include decreased phosphate levels, elevated liver enzymes (GGT), and decreased lymphocyte counts.
About 18% of patients stopped treatment because of side effects. Rezurock can harm an unborn baby, so people who can become pregnant should use effective birth control during treatment and for at least 1 week after the last dose, and men with partners who can become pregnant should also use birth control.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Belumosudil
Taken as an oral tablet, 200mg once daily with food. If taking a proton pump inhibitor (acid reflux medication) or a strong CYP3A inducer (such as rifampin), the dose is increased to 200mg twice daily. Treatment continues until disease progression requiring new therapy.
Availability and cost
Only available as the brand-name product.
Help paying for Rezurock
With private insurance, the drugmaker's copay card can lower what you pay for Rezurock. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE, but charity funds often can. Of the 3 charity funds for Chronic Graft-versus-Host Disease, 1 was open on October 26, 2026. Without insurance, you can apply to the drugmaker's free medicine program, which sets its own eligibility rules. Pick your insurance below to see which offers fit you.
- Copay help
Commercially or privately insured patients may pay as little as $0 per month; yearly maximum. Medicare, Medicaid, TRICARE and cash-paying patients are not eligible.
For: private insurance · source - Free medicine program
Uninsured or underinsured patients meeting income criteria may get free REZUROCK for up to 12 months through Sanofi Cares North America.
For: no insurance, underinsured · source - Bridge or quick-start supply
Quick Start: free 30-day supply for new patients with drug coverage facing coverage delays over 5 business days. Bridge: 30-day supply for commercially insured patients with coverage interruptions.
The official page does not say who qualifies. Ask the program. · source - Insurance and case manager help
Case Managers verify benefits, help with prior authorizations and appeals, coordinate specialty pharmacy delivery, and refer to independent foundations.
The official page does not say who qualifies. Ask the program. · source
Good to know: Mon-Fri 8 AM-8 PM ET.
Charity funds for Chronic Graft-versus-Host Disease
- From a charity · TotalAssist (formerly PAN Foundation)Graft-vs-Host Disease (GVHD) fundOpen
Pays for: Out-of-pocket costs for approved medications, up to $9,500 per year. Requires health insurance (any kind).
- From a charity · NMDP (formerly Be The Match / National Marrow Donor Program)NMDP Patient Financial Assistance Grants fundApply directly
Pays for: Out-of-pocket costs before and after blood or marrow transplant, ongoing GVHD treatment costs, clinical-trial travel and financial-crisis grants.
The foundation says: “Status not shown on page”
Every program and charity fund for Chronic Graft-versus-Host Disease →
Belumosudil treatment timeline for Chronic Graft-Versus-Host Disease
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Stage 1 of 5 · Start to 1 mo
Starting belumosudil
You are starting belumosudil after your chronic GVHD has not responded to at least two prior therapies. You have likely already tried steroids and at least one other agent (such as ruxolitinib or ibrutinib). Belumosudil works differently from those drugs: it is a ROCK2 inhibitor that rebalances your immune system by reducing inflammatory Th17 cells while boosting protective regulatory T cells. It also has direct anti-fibrotic (anti-scarring) effects, which makes it particularly relevant if your GVHD involves skin tightening, joint contractures, or lung scarring (bronchiolitis obliterans). Belumosudil can harm an unborn baby, so the label advises effective birth control during treatment and for 1 week after, for women and for men with partners who could become pregnant. The dose is 200mg once daily, taken with a meal at about the same time each day, swallowed whole. Your team will check baseline labs including blood counts, liver enzymes, and phosphate levels. Stomach acid medicines called proton pump inhibitors, and some drugs such as rifampin, can lower belumosudil levels. In those cases, the label raises the dose to 200mg twice daily. Make sure your team reviews all your medications.
Coming up
Over the next 2-4 weeks, your team will monitor for side effects and early signs of response. Because belumosudil has anti-fibrotic properties, improvements in sclerotic skin disease and joint mobility may take longer to become noticeable compared to improvements in mucosal disease (mouth, GI). Some patients see initial improvements in skin softening and range of motion within the first month, but meaningful fibrotic improvement often takes 2-3 months or longer. Your steroid taper, if applicable, will likely wait until your team sees evidence of response. Lab checks will focus on blood counts, phosphate (which can drop on belumosudil), liver enzymes (especially GGT, which can rise), and signs of infection.
Get in touch with your transplant team if you notice
- Fever, chills, or signs of serious infection (you are heavily immunosuppressed from prior treatments, and infections are the most common serious side effect)
- Unusual bruising, bleeding, or petechiae (small red dots on skin)
- Rapid swelling in legs or shortness of breath (could indicate fluid retention)
- Severe nausea or vomiting that prevents you from taking the medication
- New or worsening GVHD symptoms (disease can progress early before the drug takes full effect)
- Given the specific organs my GVHD affects, is belumosudil a good fit for me?
- How long should I expect before seeing improvement in skin tightness or scarring?
- Should I take belumosudil with a full meal, or is a snack sufficient?
- Are there drug interactions I should know about with my other medications?
- What labs will you be monitoring, and how often?
- If my previous treatments did not work, what makes belumosudil different enough to expect a better result?
Every stage of Belumosudil treatment at a glance
Starting belumosudil Start to 1 mo
You are starting belumosudil after your chronic GVHD has not responded to at least two prior therapies. You have likely already tried steroids and at least one other agent (such as ruxolitinib or ibrutinib). Belumosudil works differently from those drugs: it is a ROCK2 inhibitor that rebalances your immune system by reducing inflammatory Th17 cells while boosting protective regulatory T cells. It also has direct anti-fibrotic (anti-scarring) effects, which makes it particularly relevant if your GVHD involves skin tightening, joint contractures, or lung scarring (bronchiolitis obliterans). Belumosudil can harm an unborn baby, so the label advises effective birth control during treatment and for 1 week after, for women and for men with partners who could become pregnant. The dose is 200mg once daily, taken with a meal at about the same time each day, swallowed whole. Your team will check baseline labs including blood counts, liver enzymes, and phosphate levels. Stomach acid medicines called proton pump inhibitors, and some drugs such as rifampin, can lower belumosudil levels. In those cases, the label raises the dose to 200mg twice daily. Make sure your team reviews all your medications.
Over the next 2-4 weeks, your team will monitor for side effects and early signs of response. Because belumosudil has anti-fibrotic properties, improvements in sclerotic skin disease and joint mobility may take longer to become noticeable compared to improvements in mucosal disease (mouth, GI). Some patients see initial improvements in skin softening and range of motion within the first month, but meaningful fibrotic improvement often takes 2-3 months or longer. Your steroid taper, if applicable, will likely wait until your team sees evidence of response. Lab checks will focus on blood counts, phosphate (which can drop on belumosudil), liver enzymes (especially GGT, which can rise), and signs of infection.
Early response evaluation 1 mo to 4 mo
You have been on belumosudil for 1-4 months. Your transplant team is evaluating whether your GVHD is responding. In the ROCKstar trial, the overall response rate was 75% at the 200mg dose, in people who had already tried two to five other treatments. Responses can appear in different ways depending on which organs are affected. Mucosal improvements (mouth, GI) tend to show up first, while skin softening and joint mobility improvements from the anti-fibrotic effect develop more gradually. If you have had pulmonary function testing, your team is also watching whether your FEV1 has stabilized or improved (for patients with bronchiolitis obliterans). Symptom improvement, measured by tools like the Lee Symptom Scale, is another important way your team tracks progress.
If your GVHD is improving, your team will continue belumosudil and may begin tapering steroids if you are still on them. In a long-term pooled analysis of 2 belumosudil studies, the median time before people started a new cGVHD treatment was about 22 months (Lee et al., 2025). If you are seeing partial improvement, your team will likely continue belumosudil for several more months before deciding whether it is enough. If you are not responding at all by 3-4 months, your team may consider switching to axatilimab or discussing clinical trial options. If side effects are a problem, dose adjustments or supportive measures may help.
Response assessment 4 mo to 8 mo
This is the window where your team makes a formal determination about your response. By 4-8 months, the trajectory of your GVHD should be clear. If skin softening has continued, joint mobility has improved, and mucosal symptoms are better, belumosudil is working. The ROCKstar paper reported a median duration of response of 54 weeks. The FDA label measures it differently and reports that 62% of people who responded had no death or new treatment for at least 12 months. Your team will keep checking whether your response holds over time. Your team is also assessing practical outcomes: can you eat more comfortably, has your range of motion improved, are you able to reduce or stop steroids, and has your overall quality of life gotten better? These functional improvements matter as much as lab numbers.
For patients with good response: belumosudil usually continues. The label advises liver tests at least monthly for as long as you take it, though other checks may become less frequent. If you are off steroids and in sustained response, your team may eventually discuss tapering belumosudil, though there is less published data on belumosudil tapering compared to other agents, so this is an individualized decision. For patients with partial response: continue belumosudil because the anti-fibrotic effects can continue to accrue over many months. Your team may consider adding another agent for uncontrolled symptoms in specific organs. For patients not responding: axatilimab is the most evidence-based next option for patients who have failed belumosudil and other prior therapies. Clinical trials may also be available.
Sustained response 8 mo to 18 mo
You have been on belumosudil for 8 months or more and are in the sustained response phase. If the drug is working, your GVHD symptoms have stabilized or continue to slowly improve. Anti-fibrotic effects in particular can continue to accrue over many months, so you may still notice gradual improvements in skin flexibility and joint range of motion. You are hopefully on a low steroid dose or off steroids entirely. Clinic visits may now be spaced further apart. The label still advises liver tests at least monthly while you take belumosudil. Your team is focused on maintaining the gains you have made while addressing any long-term side effects and overall health optimization.
If you have been in sustained response for 6 or more months and are off steroids, your team may discuss whether to try reducing or discontinuing belumosudil. Because belumosudil has anti-fibrotic properties, some clinicians prefer to continue it longer than they might continue other agents, particularly in patients with significant sclerotic disease. The rationale is that the anti-fibrotic effect may continue to improve tissue remodeling even after the active inflammatory component of GVHD has resolved. This is a judgment call that your team will make based on your specific disease history and current status. If belumosudil is tapered and a flare occurs, it can be restarted.
Long-term management 18 mo on
You are in the long-term management phase. You may still be on belumosudil, you may have tapered to a lower dose, or you may have discontinued it. Your care now encompasses both GVHD management and general survivorship. Many patients at this stage are dealing more with the chronic effects of GVHD damage (dry eyes, restricted mobility, lung function limitations, skin changes) than with active inflammation. Physical therapy, occupational therapy, and targeted rehabilitation can be very valuable at this stage for maximizing function. Your transplant team and primary care provider share long-term monitoring responsibilities.
Long-term follow-up includes visits every 3-6 months with organ assessments, labs, and age-appropriate health screening. Pulmonary function tests should continue annually or semi-annually if you had any lung involvement. Ophthalmology follow-up for GVHD-related dry eye disease is important. Dermatologic screening for skin cancer is recommended annually. Bone density screening should be done if you had prolonged steroid use. If your GVHD relapses after stopping belumosudil, restarting it or trying a different agent are both reasonable options. The cGVHD treatment landscape continues to evolve with new agents and combinations.
This timeline shows typical patterns from the prescribing information, guidelines and published studies. Your own treatment may differ, and your transplant team is the source of truth for your plan. Last checked against the FDA label on .
Clinical trial results
The Phase 2 ROCKstar trial enrolled patients with active cGVHD after two or more prior systemic therapy lines. The overall response rate was 75% at the 200mg once-daily dose. Among people who responded, 62% were alive without needing a new treatment for at least 12 months after their response.
Development history
Originally developed by Surface Logix as SLx-2119, the compound was licensed to Kadmon Corporation and became the first specific ROCK2 inhibitor described in scientific literature. Kadmon received orphan drug designation in 2017 and completed the ROCKstar Phase 2 trial. FDA approved belumosudil in July 2021. Sanofi subsequently acquired Kadmon and now markets the drug.
Explore Chronic Graft-versus-Host Disease trials
Other Chronic Graft-versus-Host Disease treatments
Common questions about Belumosudil
▸What is Belumosudil (Rezurock)?
The first ROCK2 inhibitor approved for chronic GVHD, for adults and children 12 years and older after failure of at least 2 prior lines of systemic therapy. Belumosudil is designed to address both the immune dysfunction and the tissue fibrosis (scarring) that characterize late-stage cGVHD.
▸How does Belumosudil work?
In chronic GVHD, the immune system becomes imbalanced: there are too many inflammatory Th17 cells and too few protective regulatory T cells (Tregs). A protein called ROCK2 controls this balance by regulating which direction immune cells develop. Belumosudil selectively blocks ROCK2, shifting the immune system back toward balance.
When ROCK2 is inhibited, inflammatory Th17 cells decrease, protective Treg cells expand, and the production of pro-inflammatory cytokines like IL-17 and IL-21 drops. This addresses the root immune dysfunction driving cGVHD rather than broadly suppressing the immune system.
What sets belumosudil apart is its anti-fibrotic activity. ROCK2 also controls fibrotic (scarring) pathways in tissues. Many late-stage cGVHD patients develop chronic scarring in the skin, lungs, and other organs. By blocking ROCK2, belumosudil reduces both the inflammatory attack and the progressive fibrosis, making it particularly valuable for patients with sclerotic or fibrotic disease manifestations.
▸What are the side effects of Belumosudil?
Common side effects include infections (viral and bacterial), fatigue and weakness, nausea, diarrhea, shortness of breath, cough, swelling (edema), bleeding, abdominal pain, musculoskeletal pain, headache, and elevated blood pressure. Lab abnormalities can include decreased phosphate levels, elevated liver enzymes (GGT), and decreased lymphocyte counts. About 18% of patients stopped treatment because of side effects. Rezurock can harm an unborn baby, so people who can become pregnant should use effective birth control during treatment and for at least 1 week after the last dose, and men with partners who can become pregnant should also use birth control.
▸How is Belumosudil taken?
Taken as an oral tablet, 200mg once daily with food. If taking a proton pump inhibitor (acid reflux medication) or a strong CYP3A inducer (such as rifampin), the dose is increased to 200mg twice daily. Treatment continues until disease progression requiring new therapy.
▸Is Belumosudil FDA approved?
Yes, Belumosudil (Rezurock) is FDA approved (2021) for the treatment of Chronic Graft-versus-Host Disease.
▸What is Rezurock used for?
Rezurock (belumosudil) is an FDA-approved ROCK2 inhibitor for adults and children 12 years and older with chronic graft-versus-host disease after failure of at least 2 prior lines of systemic therapy. It was approved in July 2021 and is designed to address both immune dysfunction and tissue fibrosis. [1]
▸How does belumosudil help with fibrosis in GVHD?
Belumosudil blocks ROCK2, a protein that controls both immune cell balance and fibrotic (scarring) pathways. This makes it particularly valuable for patients with sclerotic skin disease, lung scarring (bronchiolitis obliterans), or other fibrotic cGVHD manifestations. [1]
▸What are the side effects of Rezurock?
Common side effects of Rezurock (belumosudil) include infections, fatigue and weakness, nausea, diarrhea, shortness of breath, cough, swelling, bleeding, abdominal pain, musculoskeletal pain, headache, and elevated blood pressure. Lab changes can include low phosphate, elevated liver enzymes (GGT), and low lymphocyte counts, and about 18% of patients stopped treatment because of side effects. Rezurock can harm an unborn baby, so people who can become pregnant should use effective birth control during treatment and for at least 1 week after the last dose. [1]
▸What did the ROCKstar trial show for belumosudil?
The Phase 2 ROCKstar trial enrolled people with active chronic GVHD after 2 or more prior lines of systemic therapy. Belumosudil produced an overall response rate of 75% at the 200mg once-daily dose, and 62% of responders were alive without needing a new treatment for at least 12 months after their response. These results supported FDA approval in July 2021. [2][1]
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- U.S. Food and Drug Administration · July 2021. FDA approves belumosudil for chronic graft-versus-host disease. https://www.fda.gov/drugs/resources-information-approved-drugs/fda-disco-burst-edition-fda-approval-rezurok-belumosudil-adult-and-pediatric-patients-12-years-and
- Transplantation and Cellular Therapy. Belumosudil for Chronic Graft-versus-Host Disease After 2 or More Prior Lines of Therapy. https://pmc.ncbi.nlm.nih.gov/articles/PMC9197942/
- Sanofi / Kadmon. MyROCK ASSIST Program. https://www.rezurock.com/myrock-assist