Abemaciclib and Sevabertinib: Interaction Details
AI-assisted, pharmacist-reviewed · AI content regenerated Jul 11, 2026 · Source data updated Jul 10, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Abemaciclib
Sevabertinib
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 cancer medicines can interact. Sevabertinib (Hyrnuo) slows down a liver enzyme called CYP3A4. That enzyme is one of the main ways your body breaks down abemaciclib (Verzenio). When it is slowed, abemaciclib can build up to higher levels than expected.
Higher levels can mean more side effects, such as diarrhea, low blood cell counts, tiredness, or nausea. This is worth taking seriously because abemaciclib has a fairly narrow safe range. The good news is your cancer care team can manage this. Do not stop or change either medicine on your own. Just talk with your oncologist or pharmacist so they can decide the safest plan for you.
Mechanism: Sevabertinib inhibits CYP3A-mediated metabolism. Abemaciclib is a CYP3A4 substrate with a narrow therapeutic index, so co-administration is expected to increase abemaciclib exposure (AUC/Cmax) and the risk of dose-related toxicity (diarrhea, neutropenia, hepatotoxicity, fatigue).
Magnitude: A dedicated study showed sevabertinib 20 mg BID increased midazolam AUC ~2-fold and Cmax ~1.8-fold, illustrating moderate CYP3A inhibition. Evidence: probable. Onset: unspecified.
- Avoid concomitant use with NTI CYP3A substrates such as abemaciclib.
- If unavoidable, consider abemaciclib dose reduction per labeling for strong/moderate CYP3A inhibitors and intensify monitoring for toxicity.
What happens
Increased CYP3A substrate with NTI exposure and an increased risk of CYP3A4 substrates with NTI-related adverse reactions
Interaction Deep Dive
Concurrent administration of sevabertinib with CYP3A substrates that have a narrow therapeutic index should be avoided, since this combination can raise exposure to the NTI CYP3A substrate and heighten the likelihood of adverse reactions associated with that NTI CYP3A substrate. When sevabertinib 20 mg twice daily was given together with midazolam in a drug interaction study, the AUC of midazolam (a CYP3A substrate) rose 2-fold and its Cmax increased 1.8-fold1.
Why it happens (mechanism)
Inhibition of CYP3A-substrate metabolism by sevabertinib
How to manage this interaction
Keep taking both exactly as prescribed unless your care team tells you otherwise. Because sevabertinib can raise abemaciclib levels, the documented guidance is to avoid using them together when possible.
- Your oncology team may choose an alternative, adjust and individualize your abemaciclib dose, or monitor you more closely.
- Watch for and promptly report side effects like diarrhea, fever or signs of infection, unusual bruising, severe fatigue, or nausea.
- Do not start, stop, or change either drug on your own.
Ask your pharmacist or prescriber to review both medicines together so they can set the safest plan.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In a study examining drug interactions, taking sevabertinib 20 mg twice daily together with midazolam raised the AUC of midazolam (a CYP3A substrate) by 2-fold and its Cmax by 1.8-fold 1.
Common questions
Can I take Abemaciclib and Sevabertinib together?
Sevabertinib can raise abemaciclib levels and increase its side effects, so this combination is generally avoided; let your oncology team adjust the plan and monitor you. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abemaciclib and Sevabertinib 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 Abemaciclib and Sevabertinib interaction managed?
Keep taking both exactly as prescribed unless your care team tells you otherwise. Because sevabertinib can raise abemaciclib levels, the documented guidance is to avoid using them together when possible. Your oncology team may choose an alternative, adjust and individualize your abemaciclib dose, or monitor you more closely. Watch for and promptly report side effects like diarrhea, fever or signs… Management is individual — always follow your own care team's guidance.
How strong is the evidence for this interaction?
The evidence is graded "probable". Good supporting evidence, though not definitively proven.
Questions for your pharmacist
- Does my dose of Abemaciclib or Sevabertinib 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: HYRNUO® oral tablets, sevabertinib oral tablets. Bayer HealthCare Pharmaceuticals Inc. (per FDA), Whippany, NJ, 2025. DailyMed
Keep reading about Abemaciclib
Keep reading about Sevabertinib
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