Abemaciclib and Lazertinib: 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
Lazertinib
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.
Here's what's going on. Your cancer medicine abemaciclib (Verzenio) is broken down by a liver enzyme called CYP3A4. Lazertinib (Lazcluze) slows that enzyme down a bit. When the enzyme works slower, abemaciclib can build up in your body a little more than usual.
The practical worry is that higher levels can mean more of abemaciclib's side effects, like diarrhea, tiredness, low blood counts, or nausea. The good news is this is very manageable. Your care team can watch you more closely and adjust your abemaciclib dose if needed. Please keep taking both exactly as prescribed and let your pharmacist or doctor know about any new or worsening symptoms.
Mechanism: Lazertinib is a moderate CYP3A4 inhibitor; abemaciclib is a CYP3A4 substrate. Neither is a prodrug, so inhibition raises active abemaciclib exposure.
Direction/magnitude: Increased abemaciclib exposure (AUC/Cmax) with heightened risk of dose-related toxicity. Probe substrate midazolam showed Cmax up 1.4-fold and AUC up 1.5-fold with lazertinib.
- Evidence: Probable; onset unspecified.
- Monitor: Diarrhea, neutropenia/CBC, hepatotoxicity (LFTs), fatigue, ILD signs.
- Manage: Consider closer monitoring; abemaciclib dose may be individualized/reduced per tolerability and label guidance.
What happens
Increased CYP3A4 substrate with NTI exposure and an increased risk of CYP3A4 substrates with NTI-related adverse reactions
Interaction Deep Dive
When lazertinib is taken together with CYP3A4 substrates that have a narrow therapeutic index, exposure to those NTI substrates can rise, along with a heightened likelihood of adverse reactions linked to the NTI CYP3A4 substrate. In the case of midazolam (a CYP3A4 substrate), co-administration with lazertinib raised the Cmax by 1.4-fold and the AUC by 1.5-fold. For any CYP3A4 substrate in which even small shifts in concentration could produce serious adverse reactions, watch for such reactions1.
Why it happens (mechanism)
Inhibition of CYP3A4-substrate metabolism by lazertinib
How to manage this interaction
What your care team may do:
- Watch you more closely for abemaciclib side effects, such as diarrhea, fatigue, or low blood counts.
- Order routine bloodwork to keep an eye on your counts and liver.
- Adjust and individualize your abemaciclib dose if side effects appear.
What you should do:
- Keep taking both medicines exactly as prescribed unless your team tells you otherwise.
- Report new or worsening diarrhea, unusual tiredness, fever, or signs of infection promptly.
- Ask your pharmacist or prescriber before starting any new medicine or supplement.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) Coadministration of lazertinib raised the Cmax of midazolam (a CYP3A4 substrate) by 1.4-fold and its AUC by 1.5-fold 1.
Common questions
Can I take Abemaciclib and Lazertinib together?
Lazertinib can raise abemaciclib levels and increase its side effects, so your team may monitor you more closely and adjust your abemaciclib dose. Keep taking both as prescribed and report new symptoms. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abemaciclib and Lazertinib 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 Lazertinib interaction managed?
What your care team may do: Watch you more closely for abemaciclib side effects, such as diarrhea, fatigue, or low blood counts. Order routine bloodwork to keep an eye on your counts and liver. Adjust and individualize your abemaciclib dose if side effects appear. What you should do: Keep taking both medicines exactly as prescribed unless your team tells you otherwise. Report new or worsening diar… 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 Lazertinib 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: LAZCLUZE™ oral tablets, lazertinib oral tablets. Janssen Biotech, Inc. (Per FDA), Horsham, PA, 2025. DailyMed
Keep reading about Abemaciclib
Keep reading about Lazertinib
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Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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