Sunitinib and Belumosudil: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 15, 2026 · Source data updated Jul 11, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Sunitinib
Belumosudil
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
These two medicines can interact. Belumosudil (Rezurock) can slow down a protein pump called BCRP that normally helps move sunitinib (Sutent) out of your body. When that pump is blocked, sunitinib can build up to higher levels in your blood.
Sunitinib is a cancer medicine with a narrow safety window, meaning even small increases can raise the risk of side effects like fatigue, mouth sores, high blood pressure, low blood counts, or diarrhea. This concern is based on how the drugs behave rather than direct testing, but it is taken seriously. The good news is your care team can manage this by adjusting your dose and watching you more closely. Do not change anything on your own. Talk with your oncologist or pharmacist.
Effect: Increased sunitinib exposure via belumosudil-mediated inhibition of BCRP efflux transport. Sunitinib is a BCRP substrate with a narrow therapeutic index, so modest exposure increases may translate to serious toxicity.
- Direction: Increased sunitinib AUC/Cmax (belumosudil is the inhibitor; sunitinib is the affected substrate).
- Magnitude: Not quantified for sunitinib; belumosudil raised rosuvastatin (BCRP/OATP1B1 substrate) Cmax 3.6-fold and AUC 4.6-fold.
- Evidence: Theoretical. Onset: Unspecified.
- Management: Avoid coadministration. If unavoidable, reduce sunitinib dose as needed and monitor closely for toxicity (hematologic, hepatic, cardiovascular, GI).
What happens
Increased SUNItinib exposure
Interaction Deep Dive
Do not give belumosudil (a BCRP inhibitor) together with SUNItinib, which is a BCRP substrate with a narrow therapeutic index (NTI), because even small shifts in concentration can produce serious toxicities. When coadministration is unavoidable, reduce the SUNItinib dose as required. A drug interaction study showed that adding belumosudil raised the Cmax and AUC of rosuvastatin (a substrate of OATP1B1 and BCRP) by 3.6-fold and 4.6-fold, respectively1.
Why it happens (mechanism)
Inhibition of BCRP-mediated efflux transport of SUNItinib
How to manage this interaction
What your care team may do:
- Where possible, avoid using these two drugs together, or consider an alternative.
- If you do need both, your sunitinib dose may need to be adjusted and individualized by your oncology team.
- Your team may monitor you more closely for side effects such as blood pressure changes, blood count drops, mouth sores, diarrhea, and fatigue.
What you should do: Keep taking both exactly as prescribed and do not stop or change a dose on your own. Tell your pharmacist and prescriber that you take both, and report any new or worsening side effects promptly.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In a study of drug interactions, giving belumosudil together with rosuvastatin (a substrate of OATP1B1 and BCRP) raised the rosuvastatin Cmax by 3.6-fold and the AUC by 4.6-fold 1.
Common questions
Can I take Sunitinib and Belumosudil together?
Belumosudil can raise sunitinib levels by blocking its BCRP transporter, and because sunitinib has a narrow safety margin this combination is best avoided or used only with a reduced, individualized sunitinib dose and close monitoring. Talk to your oncologist or pharmacist before changing anything. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Sunitinib and Belumosudil interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How is the Sunitinib and Belumosudil interaction managed?
What your care team may do: Where possible, avoid using these two drugs together, or consider an alternative. If you do need both, your sunitinib dose may need to be adjusted and individualized by your oncology team. Your team may monitor you more closely for side effects such as blood pressure changes, blood count drops, mouth sores, diarrhea, and fatigue. What you should do: Keep taking both exa… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Sunitinib or Belumosudil need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- Product Information: REZUROCK(R) oral tablets, belumosudil oral tablets. Kadmon Pharmaceuticals LLC (per FDA), Bridgewater, NJ, 2024. DailyMed
Keep reading about Sunitinib
Keep reading about Belumosudil
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