Abemaciclib and Tovorafenib: 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
Tovorafenib
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.
You've been prescribed two cancer medicines, abemaciclib (Verzenio) and tovorafenib (Ojemda). Here's the concern: tovorafenib can speed up the liver enzyme that breaks down abemaciclib. When abemaciclib is cleared out faster, there may be less of it in your body, which could make it work less well against the cancer.
This warning is based on lab and modeling predictions rather than real-world patient reports, so it's a caution, not a certainty. The good news is your cancer team can manage this. Keep taking both exactly as prescribed, and let your oncologist or pharmacist know you're on both so they can watch your response closely.
Effect: Tovorafenib is a CYP3A inducer; abemaciclib is a CYP3A4 substrate. Coadministration is predicted to increase abemaciclib metabolism, lowering its exposure (AUC/Cmax) and potentially reducing antineoplastic efficacy.
- Direction: reduced abemaciclib effect (induction, not prodrug).
- Magnitude: modeling with midazolam predicts >=20% decrease in Cmax/AUC; abemaciclib-specific data not established.
- Onset: unspecified (enzyme induction typically develops over days).
- Evidence: theoretical / model-informed.
Management: Avoid coadministration where possible. If unavoidable, monitor closely for loss of oncologic efficacy; dosing may need individualization by the oncology team.
What happens
Reduced CYP3A substrate with NTI exposure and reduced efficacy of CYP3A substrate with NTI
Interaction Deep Dive
Do not give tovorafenib, a CYP3A inducer, together with certain CYP3A substrates for which even small changes in concentration can cause serious therapeutic failures. When tovorafenib is used alongside CYP3A substrates that have a narrow therapeutic index (NTI), the exposure to those NTI CYP3A substrates may fall, potentially lowering their efficacy. Should coadministration be unavoidable, watch patients for any loss of effectiveness. A model informed drug interaction study predicts that the steady-state Cmax and AUC of midazolam, a CYP3A4 substrate, will drop by at least 20% when it is given with tovorafenib1.
Why it happens (mechanism)
Induction of CYP3A-mediated metabolism by tovorafenib
How to manage this interaction
Your care team will decide the safest approach. Because tovorafenib can lower abemaciclib levels and possibly weaken its effect, they typically:
- Try to avoid using the two together when another option exists.
- If both are truly needed, monitor you more closely for signs the cancer treatment isn't working as expected.
- Adjust and individualize your plan based on how you respond.
What you should do: keep taking both exactly as prescribed, don't change or stop anything on your own, and make sure your oncologist and pharmacist know you are on both so they can watch your progress.
Management is individual — confirm any change with your pharmacist or prescriber.
Literature reports
1 report — tap to read
a) In a study using a model informed approach to assess drug interactions, midazolam (a CYP3A4 substrate) is predicted to show a decrease of at least 20% in steady-state Cmax and AUC when coadministered with tovorafenib 1.
Common questions
Can I take Abemaciclib and Tovorafenib together?
Tovorafenib may lower abemaciclib levels and make it less effective, so your oncology team will try to avoid the combination or monitor you closely if both are needed. Keep taking both as prescribed and confirm the plan with your care team. Always confirm with your pharmacist or prescriber before making any change.
How serious is the Abemaciclib and Tovorafenib 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 Tovorafenib interaction managed?
Your care team will decide the safest approach. Because tovorafenib can lower abemaciclib levels and possibly weaken its effect, they typically: Try to avoid using the two together when another option exists. If both are truly needed, monitor you more closely for signs the cancer treatment isn't working as expected. Adjust and individualize your plan based on how you respond. What you should do: k… 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 Abemaciclib or Tovorafenib 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: OJEMDA oral tablets, oral suspension, tovorafenib oral tablets, oral suspension. Day One Biopharmaceuticals, Inc.(Per FDA), Brisbane, CA, 2024. DailyMed
Keep reading about Abemaciclib
Keep reading about Tovorafenib
These medications also interact with supplements
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist