Abemaciclib and Mavorixafor: 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
Mavorixafor
Abemaciclib
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. Mavorixafor (Xolremdi) slows down a liver enzyme called CYP3A4. Your body uses that same enzyme to break down abemaciclib (Verzenio). When the enzyme is slowed, abemaciclib can build up higher than usual in your blood.
Higher levels can mean more side effects, such as diarrhea, low blood counts, tiredness, or nausea. The good news is this is very manageable. Your care team can adjust your abemaciclib dose and watch you a little more closely. Keep taking both exactly as prescribed, and let your pharmacist or doctor know if you notice new or worsening side effects.
Mechanism: Mavorixafor inhibits CYP3A4, reducing metabolism of abemaciclib (a CYP3A4 substrate), increasing its exposure and risk of dose-related toxicity. Neither drug is a prodrug, so this raises the active substrate effect.
- Direction: Increased abemaciclib AUC/Cmax and adverse-effect risk (diarrhea, neutropenia, hepatotoxicity, fatigue).
- Magnitude: With midazolam, mavorixafor 400 mg raised Cmax 1.1-fold and AUC 1.7-fold; abemaciclib treated as an NTI substrate.
- Onset: Unspecified. Evidence: Probable.
- Management: Monitor more frequently for abemaciclib toxicity; dose may need individualization per oncology labeling.
What happens
Increased CYP3A4 substrate with NTI exposure and an increased risk of CYP3A4 with NTI-related adverse events
Interaction Deep Dive
When mavorixafor, an inhibitor of CYP3A4, is given together with a CYP3A4 substrate that has a narrow therapeutic index (NTI), the exposure to that CYP3A4 substrate with NTI can rise, potentially increasing the likelihood of adverse events related to that CYP3A4 substrate with NTI. For CYP3A4 substrates in which even small shifts in substrate concentration can produce serious adverse reactions, patients should be watched more closely for substrate-related adverse reactions during concurrent mavorixafor therapy. A drug interaction study in healthy subjects found that giving mavorixafor 400 mg alongside midazolam (a CYP3A4 substrate) raised Cmax by 1.1-fold and AUC by 1.7-fold1.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism by mavorixafor
How to manage this interaction
This interaction can be managed. Your care team can tailor your abemaciclib dose and monitor you more closely while you are also taking mavorixafor.
- Keep taking both as prescribed unless your doctor tells you otherwise.
- Your abemaciclib dose may be adjusted and individualized by your oncology team.
- Expect closer monitoring for side effects such as diarrhea, low blood counts, fatigue, or liver changes.
- Report promptly: ongoing diarrhea, unusual bruising, fever, or feeling very tired.
Ask your pharmacist or prescriber before starting or stopping either medicine.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In a drug interaction study conducted in healthy subjects, the concurrent administration of mavorixafor (a CYP3A4 inhibitor) 400 mg with midazolam (a CYP3A4 substrate) raised the Cmax and AUC by 1.1-fold and 1.7-fold, respectively 1.
Common questions
Can I take Abemaciclib and Mavorixafor together?
Mavorixafor can raise abemaciclib levels by blocking its breakdown, increasing side-effect risk; keep taking both as prescribed while your care team adjusts the dose and monitors you more closely. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abemaciclib and Mavorixafor 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 Mavorixafor interaction managed?
This interaction can be managed. Your care team can tailor your abemaciclib dose and monitor you more closely while you are also taking mavorixafor. Keep taking both as prescribed unless your doctor tells you otherwise. Your abemaciclib dose may be adjusted and individualized by your oncology team. Expect closer monitoring for side effects such as diarrhea, low blood counts, fatigue, or liver chan… 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 Mavorixafor 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: XOLREMDI(TM) oral capsules, mavorixafor oral capsules. X4 Pharmaceuticals, Inc. (Per FDA), Boston, MA, 2024. DailyMed
Keep reading about Mavorixafor
Keep reading about Abemaciclib
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