Verzenios: Uses, Dosage & Side Effects
CDK4/6 inhibitor for HR-positive, HER2-negative breast cancer treatment
Verzenios (abemaciclib) is a targeted oral cancer medication belonging to the class of cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors. It is used in the treatment of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) breast cancer, which is the most common subtype of breast cancer. Verzenios works by blocking CDK4 and CDK6, two key enzymes that drive cancer cell proliferation, thereby halting tumor growth. It is approved for use in both early-stage (adjuvant) and advanced or metastatic breast cancer, always in combination with endocrine (hormonal) therapy. Verzenios is taken as a tablet by mouth twice daily and requires a prescription from a specialist physician.
Quick Facts: Verzenios
Key Takeaways
- Verzenios (abemaciclib) is a CDK4/6 inhibitor that blocks cancer cell division by preventing the cell cycle from progressing past the G1 phase, specifically targeting the molecular pathway that drives HR-positive breast cancer growth.
- It is approved for two major treatment settings: as adjuvant therapy for early-stage HR+/HER2- breast cancer at high risk of recurrence (for up to 2 years), and for advanced or metastatic HR+/HER2- breast cancer in combination with endocrine therapy.
- Diarrhea is the most characteristic side effect of Verzenios and often occurs early in treatment; proactive management with antidiarrheal medication (such as loperamide) at the first sign of loose stools is essential to maintain quality of life.
- Verzenios must not be taken during pregnancy due to potential harm to the unborn baby; effective contraception is required during treatment and for at least 3 weeks after the last dose.
- Strong CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin) and CYP3A4 inducers (e.g., rifampicin, St. John’s Wort) must be avoided or carefully managed, as they significantly alter abemaciclib blood levels and can affect both safety and efficacy.
What Is Verzenios and What Is It Used For?
Verzenios contains the active substance abemaciclib, a potent and selective inhibitor of cyclin-dependent kinases 4 and 6 (CDK4 and CDK6). These kinases are critical components of the cell cycle machinery that controls how cells divide and multiply. In hormone receptor-positive breast cancer, the estrogen receptor signaling pathway activates D-type cyclins, which in turn bind to and activate CDK4 and CDK6. This activation leads to phosphorylation of the retinoblastoma protein (Rb), releasing the cell from the G1 checkpoint and allowing it to proceed through the cell cycle and divide. By blocking CDK4 and CDK6, Verzenios prevents this phosphorylation, trapping cancer cells in the G1 phase and ultimately inducing cell cycle arrest, senescence, and apoptosis.
Unlike some other CDK4/6 inhibitors that require intermittent dosing schedules (such as 3 weeks on and 1 week off), Verzenios is designed for continuous twice-daily dosing. This continuous dosing approach reflects abemaciclib’s pharmacological profile: it has a relatively short half-life of approximately 18.3 hours, and its sustained CDK4/6 inhibition requires consistent drug exposure. Abemaciclib also demonstrates the ability to cross the blood-brain barrier to some extent, which may have clinical relevance given that the brain is a potential site of metastasis in breast cancer.
Hormone receptor-positive, HER2-negative breast cancer accounts for approximately 70% of all breast cancers. In this subtype, the cancer cells express estrogen receptors (ER) and/or progesterone receptors (PR), meaning they rely on hormonal signals for growth. The HER2-negative designation means the cancer cells do not overexpress the HER2 protein, distinguishing this subtype from HER2-positive breast cancers that benefit from different targeted therapies. Endocrine (hormonal) therapy is the backbone of treatment for HR+/HER2- breast cancer, and adding a CDK4/6 inhibitor like Verzenios has been shown to significantly improve outcomes.
Verzenios is approved by the European Medicines Agency (EMA), the U.S. Food and Drug Administration (FDA), and regulatory authorities in numerous other countries for the following indications:
- Adjuvant treatment of early breast cancer: Verzenios is used in combination with endocrine therapy (tamoxifen or an aromatase inhibitor) for the adjuvant treatment of adult patients with HR+/HER2- node-positive early breast cancer who are at high risk of disease recurrence. The landmark monarchE trial demonstrated that adding Verzenios to endocrine therapy significantly reduced the risk of recurrence compared with endocrine therapy alone, with benefits persisting after treatment completion. Adjuvant treatment with Verzenios is given for up to 2 years.
- Advanced or metastatic breast cancer – first-line therapy: Verzenios is used in combination with an aromatase inhibitor (such as letrozole or anastrozole) as initial endocrine-based therapy for postmenopausal women and men with HR+/HER2- advanced or metastatic breast cancer. The MONARCH 3 trial showed significant improvements in progression-free survival with Verzenios plus an aromatase inhibitor compared with an aromatase inhibitor plus placebo.
- Advanced or metastatic breast cancer – after prior endocrine therapy: Verzenios is used in combination with fulvestrant for the treatment of women with HR+/HER2- locally advanced or metastatic breast cancer whose disease has progressed on or after prior endocrine therapy. The MONARCH 2 trial demonstrated significant improvements in both progression-free survival and overall survival with Verzenios plus fulvestrant compared with fulvestrant alone.
CDK4 and CDK6 are enzymes that act as “on switches” for cell division. In healthy cells, these kinases are carefully regulated, but in HR-positive breast cancer, the estrogen receptor pathway causes overactivation of CDK4/6, leading to uncontrolled cell proliferation. By specifically blocking these kinases, Verzenios restores control over cell division in cancer cells while generally having a more limited effect on normal cells. This targeted mechanism is why CDK4/6 inhibitors are considered a breakthrough in breast cancer treatment, complementing and enhancing the effectiveness of traditional endocrine therapy.
What Should You Know Before Taking Verzenios?
Contraindications
Verzenios must not be used in certain situations. Understanding these contraindications is essential for safe treatment.
- Hypersensitivity: Do not take Verzenios if you are allergic to abemaciclib or any of the other ingredients in the tablets (such as lactose monohydrate, microcrystalline cellulose, croscarmellose sodium, sodium stearyl fumarate, silica colloidal anhydrous, or the film coating components).
- Pregnancy: Verzenios should not be used during pregnancy. Based on findings from animal studies, abemaciclib can cause harm to the developing fetus. A pregnancy test should be performed before starting treatment.
Warnings and Precautions
Before and during treatment with Verzenios, your doctor will monitor you for several important potential complications. Discuss the following with your doctor:
- Diarrhea: Diarrhea is the most common side effect of Verzenios and can be severe. It typically occurs during the first month of treatment. Your doctor will advise you on how to manage diarrhea, including having antidiarrheal medication (such as loperamide) available at home before your first dose. Increase your fluid intake at the first sign of loose stools. If diarrhea becomes severe or is accompanied by dehydration, your doctor may reduce your dose or temporarily stop treatment.
- Neutropenia: Verzenios can cause a significant decrease in white blood cells (neutropenia), increasing the risk of infections. Your doctor will perform regular blood tests (complete blood counts) before and during treatment. If your white blood cell count drops too low, treatment may be interrupted, the dose reduced, or supportive measures initiated.
- Venous thromboembolic events (VTE): Blood clots in the veins (deep vein thrombosis) and lungs (pulmonary embolism) have been reported in patients taking Verzenios. Symptoms of deep vein thrombosis include leg swelling, pain, redness, or warmth. Signs of pulmonary embolism include sudden shortness of breath, chest pain (especially with breathing), rapid heartbeat, or coughing up blood. Seek immediate medical attention if you experience any of these symptoms.
- Interstitial lung disease (ILD) / Pneumonitis: Serious lung inflammation has been reported with Verzenios. Symptoms include new or worsening shortness of breath, cough, chest pain, or fever. Contact your doctor immediately if you develop respiratory symptoms during treatment.
- Hepatotoxicity: Verzenios can cause elevated liver enzymes and, in rare cases, serious liver injury. Your doctor will monitor your liver function with blood tests before starting treatment and at regular intervals during treatment. Report symptoms such as dark urine, fatigue, loss of appetite, nausea, upper abdominal pain, or jaundice (yellowing of skin or eyes).
- Arterial thromboembolism: Events such as stroke and heart attack have been reported uncommonly in patients receiving Verzenios. Seek immediate emergency care if you experience symptoms suggestive of a stroke (sudden weakness or numbness, confusion, difficulty speaking, severe headache) or heart attack (chest pain or pressure, shortness of breath, cold sweat).
At the first sign of loose stools, begin taking loperamide (an over-the-counter antidiarrheal). Increase your oral fluid intake to prevent dehydration. Do not wait for diarrhea to become severe before acting. If you develop Grade 3 diarrhea (7 or more stools per day above baseline, incontinence, or hospitalization required) or any signs of dehydration (dizziness, reduced urination, dry mouth), contact your doctor immediately. Dose reduction or treatment interruption may be necessary.
Pregnancy and Breastfeeding
Verzenios must not be taken during pregnancy. Animal studies have demonstrated that abemaciclib can cause fetal abnormalities and embryo-fetal toxicity. Women of childbearing potential must use effective contraception during treatment with Verzenios and for at least 3 weeks after the last dose. A pregnancy test is recommended before starting treatment. If you become pregnant while taking Verzenios, inform your doctor immediately.
It is not known whether abemaciclib or its metabolites are excreted in human breast milk. Because of the potential risk to a nursing infant, breastfeeding should be discontinued during treatment with Verzenios and for at least 3 weeks after the last dose. Discuss the benefits and risks with your doctor if you wish to breastfeed.
Based on animal data, Verzenios may impair male fertility. Men taking Verzenios should discuss fertility preservation options with their doctor before starting treatment.
Driving and Operating Machinery
Verzenios may cause fatigue and dizziness, which could affect your ability to drive or operate machinery safely. If you experience these side effects, do not drive or use machines until symptoms resolve. Discuss with your healthcare provider if you have concerns about performing these activities during treatment.
How Does Verzenios Interact with Other Drugs?
Drug interactions with Verzenios are clinically significant because the active substance abemaciclib is extensively metabolized by cytochrome P450 3A4 (CYP3A4) in the liver. Medications that inhibit CYP3A4 slow the breakdown of abemaciclib, leading to higher blood levels and an increased risk of side effects. Conversely, medications that induce (speed up) CYP3A4 activity can lower abemaciclib levels, potentially reducing the drug’s anticancer effectiveness. Additionally, abemaciclib itself is an inhibitor of P-glycoprotein (P-gp), a transporter protein, which can increase blood levels of certain other medications.
It is essential to inform your doctor and pharmacist about all medications you are currently taking, including prescription drugs, over-the-counter medicines, vitamins, and herbal supplements. Your doctor may need to adjust your Verzenios dose, switch to alternative medications, or monitor you more closely if interactions cannot be avoided.
| Drug | Type | Effect | Recommendation |
|---|---|---|---|
| Clarithromycin | CYP3A4 inhibitor | Increased abemaciclib levels | Avoid or dose reduce |
| Itraconazole | CYP3A4 inhibitor | Increased abemaciclib levels | Avoid or dose reduce |
| Ketoconazole | CYP3A4 inhibitor | Increased abemaciclib levels | Avoid or dose reduce |
| Posaconazole | CYP3A4 inhibitor | Increased abemaciclib levels | Avoid or dose reduce |
| Voriconazole | CYP3A4 inhibitor | Increased abemaciclib levels | Avoid or dose reduce |
| Lopinavir/ritonavir | CYP3A4 inhibitor | Increased abemaciclib levels | Avoid or dose reduce |
| Rifampicin | CYP3A4 inducer | Decreased abemaciclib levels | Avoid |
| Carbamazepine | CYP3A4 inducer | Decreased abemaciclib levels | Avoid |
| Phenytoin | CYP3A4 inducer | Decreased abemaciclib levels | Avoid |
| St. John’s Wort | CYP3A4 inducer | Decreased abemaciclib levels | Avoid |
| Digoxin | P-gp substrate | Increased digoxin levels | Monitor |
| Dabigatran | P-gp substrate | Increased dabigatran levels | Monitor |
Avoid grapefruit and grapefruit juice while taking Verzenios. Grapefruit contains compounds that inhibit CYP3A4, which can increase abemaciclib blood levels and raise the risk of side effects. Similarly, Seville oranges (bitter oranges), pomelos, and starfruit may also affect CYP3A4 and should be avoided.
In clinical pharmacokinetic studies, co-administration of Verzenios with the strong CYP3A4 inhibitor clarithromycin increased the combined exposure (AUC) of abemaciclib and its active metabolites by approximately 2.5-fold. When a strong CYP3A4 inhibitor cannot be avoided, the Verzenios dose should be reduced. For example, if the current dose is 150 mg twice daily, it should be reduced to 100 mg twice daily. If the strong CYP3A4 inhibitor is later discontinued, the Verzenios dose should be increased (after a washout period of 3 to 5 half-lives of the inhibitor) back to the dose used before starting the inhibitor.
Conversely, the strong CYP3A4 inducer rifampicin decreased the combined AUC of abemaciclib and its active metabolites by approximately 77%. This dramatic reduction could render Verzenios ineffective. Therefore, co-administration with strong CYP3A4 inducers should be avoided entirely. Alternative medications that do not induce CYP3A4 should be selected whenever possible.
What Is the Correct Dosage of Verzenios?
Verzenios is an oral medication taken at home by the patient. Unlike intravenous cancer therapies that require hospital visits, Verzenios allows patients to manage their treatment independently while maintaining regular follow-up with their oncologist. Your doctor will determine the most appropriate dose based on your specific treatment indication and any concomitant medications.
Recommended Dose
Standard Dosing
Dose: 150 mg orally twice daily
Combination: Always given with endocrine therapy (aromatase inhibitor, fulvestrant, or tamoxifen depending on indication)
Schedule: Continuous dosing (no treatment breaks in the cycle)
Verzenios is taken approximately every 12 hours, preferably at the same times each day, to maintain consistent drug levels in the body.
How to Take
Administration Instructions
Route: Oral (by mouth)
Food: Can be taken with or without food
Swallowing: Swallow tablets whole – do not chew, crush, or split them
Timing: Take at approximately the same times each day (e.g., morning and evening)
If you vomit after taking a dose, or if a tablet is broken, crumbled, or otherwise not intact, do not take an additional dose. Simply take the next dose at your regularly scheduled time.
Adjuvant Treatment Duration
Early Breast Cancer (Adjuvant Setting)
Duration: Up to 2 years (in combination with endocrine therapy, which typically continues for 5–10 years)
The monarchE trial demonstrated that 2 years of adjuvant Verzenios treatment provided a significant and sustained reduction in the risk of disease recurrence. It is important to complete the full 2-year treatment course unless your doctor advises otherwise due to side effects or other medical reasons.
Missed Dose
What to Do If You Miss a Dose
If you miss a dose of Verzenios or vomit after taking it, do not take a make-up dose. Simply skip the missed dose and take the next dose at your regular scheduled time. Do not take a double dose to make up for a missed one.
Overdose
Overdose Information
If you take more Verzenios than you should, contact your doctor, pharmacist, or nearest hospital emergency department immediately. There is no specific antidote for abemaciclib overdose. Treatment is supportive and based on symptoms. Take the medicine packaging with you so the healthcare team knows what you have taken.
Your doctor may reduce your dose, temporarily stop treatment, or permanently discontinue Verzenios based on the type and severity of side effects you experience. Common reasons for dose reduction include persistent diarrhea (Grade 2 or higher), neutropenia (low white blood cell count), elevated liver enzymes, or interstitial lung disease. The dose reduction sequence is typically: 150 mg → 100 mg → 50 mg, all given twice daily. If you cannot tolerate the 50 mg twice daily dose, treatment may need to be permanently discontinued.
For patients who require co-administration with a strong CYP3A4 inhibitor, the starting dose should be reduced to 100 mg twice daily. If the CYP3A4 inhibitor is subsequently discontinued, the Verzenios dose should be increased back to the dose used before the inhibitor was started, after allowing adequate washout time.
No dose adjustment is required for patients with mild or moderate renal impairment. Verzenios has not been studied in patients with severe renal impairment or end-stage renal disease. For patients with mild hepatic impairment, no dose adjustment is needed. For patients with severe hepatic impairment (Child-Pugh C), the recommended starting dose is reduced to 100 mg twice daily, and careful monitoring is required.
What Are the Side Effects of Verzenios?
Like all medicines, Verzenios can cause side effects, although not everybody gets them. Most side effects are manageable with dose adjustments and supportive care. It is important to report any new or worsening symptoms to your doctor promptly, as early intervention can prevent side effects from becoming severe. The side effects listed below are categorized by how frequently they occur.
Very Common (affects more than 1 in 10 patients)
- Infections (upper respiratory tract infections, urinary tract infections, lung infections)
- Decreased white blood cells (neutropenia, leukopenia, lymphopenia)
- Decreased red blood cells (anemia)
- Decreased platelets (thrombocytopenia)
- Diarrhea (very frequent – up to 80–90% of patients)
- Nausea
- Vomiting
- Stomatitis (mouth sores, inflammation of the mouth)
- Decreased appetite
- Headache
- Dysgeusia (altered taste, metallic taste)
- Hair loss (alopecia)
- Fatigue and asthenia (tiredness, weakness)
- Dizziness
- Pruritus (itching)
- Rash
- Abnormal liver values (elevated ALT, AST)
Common (affects 1 to 10 in 100 patients)
- Lacrimation increased (watery eyes, tearing)
- Muscle weakness
- Dry skin
- Interstitial lung disease / pneumonitis
- Dyspepsia (indigestion)
- Nail disorders (nail changes, brittle nails)
Uncommon (affects 1 to 10 in 1,000 patients)
- Febrile neutropenia (fever with very low white blood cells)
- Visual disturbances (photopsia – flashes of light)
- Keratitis (inflammation of the cornea)
Rare (affects fewer than 1 in 1,000 patients)
- Erythema multiforme (a type of skin reaction with target-shaped lesions)
Seek immediate medical attention if you experience any of the following during Verzenios treatment: severe or persistent diarrhea with signs of dehydration (dizziness, decreased urination, dry mouth); fever with low white blood cell count (chills, sore throat, or other signs of infection); sudden shortness of breath, cough, or chest pain (possible interstitial lung disease or pulmonary embolism); leg swelling, pain, or redness (possible deep vein thrombosis); yellowing of the skin or eyes (jaundice), dark urine, or severe abdominal pain (possible liver injury); or any signs of stroke or heart attack.
Diarrhea deserves special attention as the most characteristic side effect of Verzenios. In clinical trials, diarrhea occurred in approximately 82–90% of patients, with Grade 3 diarrhea (severe, requiring hospitalization or medical intervention) occurring in approximately 10–13% of patients. The median time to onset of the first diarrhea episode is approximately 6–8 days after starting treatment. In most patients, diarrhea improves with antidiarrheal medications and, when necessary, dose adjustments. The incidence and severity of diarrhea generally decrease over time with continued treatment.
Hematological side effects, particularly neutropenia, are also common with Verzenios. Grade 3 or 4 neutropenia occurred in approximately 19–28% of patients in clinical trials. However, febrile neutropenia (neutropenia with fever) is uncommon, occurring in approximately 1% of patients. Your doctor will monitor your blood counts regularly, typically before each treatment cycle or at least monthly during the first few months of treatment.
Venous thromboembolic events (blood clots) have been observed in approximately 2–5% of patients treated with Verzenios in combination with endocrine therapy. The risk may be higher in patients with additional risk factors for blood clots. Your doctor will assess your individual risk and may recommend preventive measures in some cases.
How Should You Store Verzenios?
Store Verzenios tablets in their original blister packaging to protect them from moisture and light. The tablets should be stored at a temperature not exceeding 30°C (86°F). Do not store in the bathroom or in areas with high humidity. Keep the medicine out of the sight and reach of children at all times.
Do not use Verzenios after the expiry date stated on the blister and carton. The expiry date refers to the last day of that month. Do not dispose of medicines via wastewater or household waste. Ask your pharmacist how to dispose of medicines you no longer use. These measures help to protect the environment and ensure medication safety.
What Does Verzenios Contain?
Active Ingredient
Each Verzenios film-coated tablet contains abemaciclib as the active substance. The tablets are available in three strengths: 50 mg, 100 mg, and 150 mg. The dose prescribed will depend on your treatment indication and tolerability.
Inactive Ingredients (Excipients)
- Lactose monohydrate
- Microcrystalline cellulose
- Croscarmellose sodium
- Sodium stearyl fumarate
- Silica, colloidal anhydrous
- Film coating: polyvinyl alcohol, titanium dioxide (E171), macrogol 3350, talc, iron oxide yellow (E172), iron oxide red (E172)
Appearance
The appearance of Verzenios tablets varies by strength. The 50 mg tablet is a beige, oval-shaped film-coated tablet debossed with “Lilly” on one side and “50” on the other. The 100 mg tablet is a beige, capsule-shaped film-coated tablet debossed with “Lilly” on one side and “100” on the other. The 150 mg tablet is a beige, capsule-shaped film-coated tablet debossed with “Lilly” on one side and “150” on the other. All tablets are supplied in PVC/PE/PCTFE aluminium blister packs.
Manufacturer
Verzenios is manufactured by Eli Lilly and Company. The marketing authorization holder in the EU is Eli Lilly Nederland B.V., Utrecht, Netherlands. The product is marketed globally under the brand name Verzenios (known as Verzenio in the United States).
Frequently Asked Questions About Verzenios
Verzenios (abemaciclib) is a CDK4/6 inhibitor used to treat hormone receptor-positive (HR+), HER2-negative (HER2-) breast cancer. It has two main approved indications: first, as adjuvant treatment for early-stage HR+/HER2- breast cancer with high risk of recurrence, given in combination with endocrine therapy for up to 2 years; and second, for advanced or metastatic HR+/HER2- breast cancer, either as first-line treatment with an aromatase inhibitor or after prior endocrine therapy in combination with fulvestrant. In both settings, Verzenios has demonstrated significant improvements in patient outcomes in large clinical trials.
Verzenios works by selectively blocking two enzymes called cyclin-dependent kinase 4 (CDK4) and cyclin-dependent kinase 6 (CDK6). In HR-positive breast cancer, these enzymes are overactivated by the estrogen receptor signaling pathway, driving uncontrolled cancer cell division. By inhibiting CDK4 and CDK6, Verzenios prevents the phosphorylation of the retinoblastoma protein (Rb), which stops the cell cycle from progressing past the G1 checkpoint. This causes the cancer cells to stop dividing, undergo senescence (aging), or die. Verzenios is taken continuously twice daily, reflecting its pharmacological profile of sustained CDK4/6 inhibition.
The most common side effect of Verzenios is diarrhea, which affects up to 80–90% of patients. Other very common side effects include infections, low white blood cell count (neutropenia), low red blood cell count (anemia), nausea, vomiting, fatigue, decreased appetite, headache, taste changes, hair loss, dizziness, mouth sores, rash, itching, and abnormal liver tests. Most side effects are manageable with supportive care and dose adjustments. Diarrhea typically occurs within the first month and improves over time with appropriate management including antidiarrheal medication.
No, Verzenios should not be taken during pregnancy. Animal studies have shown that abemaciclib can cause harm to a developing fetus, including birth defects and embryo-fetal death. Women of childbearing potential must use effective contraception during treatment with Verzenios and for at least 3 weeks after the last dose. A pregnancy test should be performed before starting treatment. If you become pregnant or suspect pregnancy while taking Verzenios, contact your doctor immediately. Breastfeeding should also be avoided during treatment and for at least 3 weeks after the last dose.
Proactive diarrhea management is essential when taking Verzenios. Have loperamide (an over-the-counter antidiarrheal) available at home before starting treatment. At the very first sign of loose stools, begin taking loperamide as directed and increase your fluid intake significantly to prevent dehydration. Avoid foods that may worsen diarrhea, such as spicy or high-fiber foods. If diarrhea persists at Grade 2 or becomes Grade 3 (7 or more stools per day above baseline), contact your doctor, as a dose reduction or temporary treatment pause may be necessary. Most patients find that diarrhea improves over the first few months of treatment.
Verzenios has significant drug interactions because it is metabolized by the CYP3A4 enzyme. Strong CYP3A4 inhibitors (such as ketoconazole, clarithromycin, itraconazole, posaconazole, voriconazole, and lopinavir/ritonavir) can increase abemaciclib blood levels and should be avoided or require dose reduction. Strong CYP3A4 inducers (such as rifampicin, carbamazepine, phenytoin, and St. John’s Wort) can dramatically decrease abemaciclib levels and should be avoided entirely. Grapefruit and grapefruit juice should also be avoided. Additionally, Verzenios can increase levels of P-glycoprotein substrates like digoxin and dabigatran, requiring monitoring.
References
- European Medicines Agency (EMA). Verzenios (abemaciclib) – Summary of Product Characteristics. Last updated 2025. Available from: EMA EPAR.
- U.S. Food and Drug Administration (FDA). Verzenio (abemaciclib) Prescribing Information. Revised 2025. Available from: FDA Drug Label.
- Johnston SRD, Harbeck N, Hegg R, et al. Abemaciclib Combined With Endocrine Therapy for the Adjuvant Treatment of HR+, HER2−, Node-Positive, High-Risk, Early Breast Cancer (monarchE). J Clin Oncol. 2020;38(34):3987–3998. doi:10.1200/JCO.20.02514.
- Johnston SRD, Toi M, O’Shaughnessy J, et al. Abemaciclib plus endocrine therapy for hormone receptor-positive, HER2-negative, node-positive, high-risk early breast cancer (monarchE): results from a preplanned interim analysis of a randomised, open-label, phase 3 trial. Lancet Oncol. 2023;24(1):77–90. doi:10.1016/S1470-2045(22)00694-5.
- Goetz MP, Toi M, Campone M, et al. MONARCH 3: Abemaciclib As Initial Therapy for Advanced Breast Cancer. J Clin Oncol. 2017;35(32):3638–3646. doi:10.1200/JCO.2017.75.6155.
- Sledge GW Jr, Toi M, Neven P, et al. The Effect of Abemaciclib Plus Fulvestrant on Overall Survival in Hormone Receptor–Positive, ERBB2-Negative Breast Cancer That Progressed on Endocrine Therapy – MONARCH 2. JAMA Oncol. 2020;6(1):116–124. doi:10.1001/jamaoncol.2019.4782.
- National Comprehensive Cancer Network (NCCN). NCCN Clinical Practice Guidelines in Oncology: Breast Cancer. Version 2.2025.
- Cardoso F, Paluch-Shimon S, Senkus E, et al. 5th ESO-ESMO international consensus guidelines for advanced breast cancer (ABC 5). Ann Oncol. 2020;31(12):1623–1649. doi:10.1016/j.annonc.2020.09.010.
Editorial Team
This article was written and reviewed by the iMedic Medical Editorial Team, comprising licensed specialist physicians with expertise in oncology, breast cancer treatment, and clinical pharmacology.
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