What Is Abemaciclib (Yulareb)? FDA Approval History
In this article
What is abemaciclib (Yulareb)?
Last updated: October 2026
Abemaciclib is an oral CDK4/6 inhibitor used with hormone therapy in hormone receptor (HR)-positive, HER2-negative breast cancer. It is used in metastatic disease and after surgery in early breast cancer with a high recurrence risk. It is licensed in Türkiye as Yulareb, but SGK does not reimburse it.
- Uses: HR-positive, HER2-negative breast cancer; with an aromatase inhibitor or fulvestrant in metastatic disease, and with hormone therapy for 2 years in high-risk early disease. Unlike other CDK4/6 inhibitors, it is taken twice daily without scheduled breaks.
- Evidence: In the 7-year monarchE results in early disease, disease-free survival increased from 70.9% to 77.4% and survival from 85.0% to 86.8% (HR 0.84).
- Türkiye: Licensed since 26 February 2019 (formerly branded Verzenios). No SGK reimbursement; a pack of 42 tablets costs 62,529.69 TL at each strength (April 2026).
- Most common adverse effect: Diarrhea, in 81-90% of patients, usually beginning in the first week. Loperamide should be started with the first loose stool.
Why does this matter?
Most breast cancers are hormone receptor-positive and HER2-negative. CDK4/6 inhibitors have transformed treatment in this group over the past decade: they substantially prolong hormone therapy’s effects in metastatic disease and reduce recurrence risk in early disease. We discuss their development separately in our article on CDK4/6 inhibitors. That article covers this development.
Of the three CDK4/6 inhibitors, palbociclib and ribociclib are reimbursed by SGK for metastatic disease in Türkiye, while abemaciclib is not. As abemaciclib is the first CDK4/6 inhibitor shown to extend life in high-risk early breast cancer, this difference is even more important for patients.
What is abemaciclib?
Abemaciclib is an oral targeted cancer drug that inhibits CDK4 and CDK6, enzymes controlling cell division. Developed by Eli Lilly, it is sold as Verzenio in the United States, Verzenios in Europe, and Yulareb in Türkiye. It is used with hormone therapy, or sometimes alone, in HR-positive, HER2-negative breast cancer.
How does abemaciclib work?
For a cell to divide, it must move from the G1 phase to the S phase, where DNA is copied. During this transition, CDK4 and CDK6 phosphorylate and inactivate the “brake” protein pRB (retinoblastoma protein). Releasing the brake frees E2F, which activates the genes needed for division. Abemaciclib inhibits these enzymes, keeping the brake engaged.
Figure 1 · How does abemaciclib stop the cell cycle?
Normal cell cycle above; abemaciclib’s effect below.
Abemaciclib inhibits CDK4 more strongly than CDK6. Its effects on bone marrow are therefore milder; it can be taken daily without breaks and causes less neutropenia but more diarrhea than palbociclib and ribociclib. It is the only CDK4/6 inhibitor approved for use alone.
Which patients receive abemaciclib?
Metastatic breast cancer
| Use | Study | Result |
|---|---|---|
| First-line with an aromatase inhibitor (postmenopausal) | MONARCH 3 (493 patients) | Median progression-free survival: 28.2 versus 14.8 months (HR 0.54). Median overall survival: 66.8 versus 53.7 months; the 13.1-month difference is not statistically significant (HR 0.80). |
| After hormone therapy, with fulvestrant | MONARCH 2 (669 patients) | Progression-free survival: 16.4 versus 9.3 months (HR 0.55). Median overall survival: 46.7 versus 37.3 months; an extension of 9.4 months (HR 0.76). |
| Alone after hormone therapy and chemotherapy | MONARCH 1 | Tumor shrinkage rate: 19.7%. |
| After another CDK4/6 inhibitor, with fulvestrant | postMONARCH (368 patients) | Progression-free survival: 6.0 versus 5.3 months (HR 0.73); 11.1 versus 5.6 months in those without visceral metastases. |
| ESR1-mutated disease, with imlunestrant | EMBER-3 | Progression-free survival: 11.1 versus 5.5 months with imlunestrant alone (HR 0.53). |
We discuss options after progression on a CDK4/6 inhibitor in this article,and imlunestrant plus abemaciclib in our FDA approval article. Both topics are covered there.
Early breast cancer: the monarchE study
monarchE included 5,637 patients who had undergone surgery, had tumor in axillary lymph nodes, and were at high risk of recurrence. Patients received standard hormone therapy alone or with abemaciclib for 2 years. At a median follow-up of 6.3 years, abemaciclib reduced recurrence risk by 27% and mortality risk by 16%.
We discuss these results in detail in our article on the 7-year monarchE results. The definition of “high risk” varies somewhat by country: the United States has not required Ki-67 since 2023, whereas the Turkish prescribing information lists Ki-67 ≥20% among its criteria.
Figure 2 · Who receives abemaciclib in early disease?
High recurrence risk criteria defined in the Turkish prescribing information (SmPC).
Abemaciclib’s FDA approval history
Licensing and reimbursement in Türkiye
- License: First licensed on 26 February 2019 (license no. 2019/117), held by Lilly İlaç Ticaret Ltd. Şti. Initially sold as Verzenios, it became Yulareb under the same license. Yulareb is available in packs of 42 tablets at strengths of 50, 100, and 150 mg.
- Early disease indication: With hormone therapy in early breast cancer at high recurrence risk, for 2 years or until recurrence or unacceptable adverse effects (Figure 2).
- Metastatic indications: In postmenopausal patients with at least 10% estrogen receptor positivity and HER2-negative disease: (1) with letrozole or anastrozole in those who have not received hormone therapy or relapse 12 months after completing adjuvant treatment; (2) with fulvestrant in those without prior fulvestrant, after progression following at least 6 months of an aromatase inhibitor in metastatic disease, or after recurrence once at least 12 months of an adjuvant aromatase inhibitor have been completed or within 12 months of its completion.
- Situations in which it is not used: Patients relapsing within the first 12 months of an adjuvant aromatase inhibitor and those who have received more than one line of an aromatase inhibitor for metastatic disease.
- SGK: Not reimbursed. Palbociclib and ribociclib have been covered for metastatic disease under SUT conditions since 2020; abemaciclib has not been included.
- Price: Since 31 March 2026, a pack of 42 tablets at any strength costs 62,529.69 TL. At two tablets daily, one pack lasts 3 weeks.
We explain the reimbursement conditions for CDK4/6 inhibitors in this article,and discuss ribociclib in our Valamor article in detail.
How is abemaciclib taken?
- Dose: 150 mg twice daily with hormone therapy; 200 mg twice daily when used alone. It may be taken with or without food, without scheduled breaks.
- Duration: For 2 years in early disease; in metastatic disease, while benefit continues or until unacceptable adverse effects develop.
- Missed or vomited dose: Do not take an extra dose; take the next dose at the scheduled time.
- Liver and kidneys: No dose change for mild-to-moderate liver impairment; in severe liver impairment (Child-Pugh C), dosing is reduced to once daily. No dose change for mild-to-moderate kidney impairment; no data are available for severe kidney impairment.
- Drug interactions: Avoid ketoconazole; with other strong CYP3A inhibitors, reduce the dose to 100 mg twice daily. Avoid strong and moderate CYP3A inducers (e.g., rifampicin, carbamazepine, and St. John’s wort). Do not consume grapefruit or grapefruit juice.
| Dose level | Combination therapy | Monotherapy |
|---|---|---|
| Starting dose | 150 mg twice daily | 200 mg twice daily |
| First reduction | 100 mg twice daily | 150 mg twice daily |
| Second reduction | 50 mg twice daily | 100 mg twice daily |
| Third reduction | — | 50 mg twice daily |
What are abemaciclib’s adverse effects?
- Diarrhea: Occurs in 81-90% of patients and is severe in 8-20%. Median onset is 6-8 days. At the first loose stool, loperamide should be started, plenty of fluids taken, and the team notified.
- Neutropenia: Occurs in 37-46%, severe in 19-32%; febrile neutropenia is below 1%.
- Lung inflammation (interstitial lung disease): Occurs in approximately 3%; rarely fatal. Report any new cough or shortness of breath immediately.
- Liver: Severe ALT elevation occurs in 2-6%.
- Blood clots (venous thromboembolism): Occurs in 2-5%; in MONARCH 2 and 3, 5% versus below 1%. Leg swelling, pain, or sudden shortness of breath requires urgent assessment.
- Increased creatinine: Occurs within the first month, because the drug inhibits creatinine excretion rather than because kidney function has deteriorated.
- Pregnancy: May harm the baby; effective contraception is required during treatment and for 3 weeks after the last dose.
Monitoring: Complete blood count and liver tests before treatment, every two weeks for the first 2 months, monthly for the next 2 months, and thereafter as needed.
Resistance: Some tumors develop drug resistance over time. Known mechanisms include loss of RB1, increased cyclin E and CDK6, activation of CDK2, changes in the PI3K/AKT pathway, and loss of FAT1.
Frequently asked questions
- Is Yulareb covered by SGK?
- No. As of October 2026, abemaciclib (Yulareb) is not reimbursed by SGK. Palbociclib and ribociclib in the same class are covered for metastatic breast cancer under SUT conditions.
- Are Yulareb and Verzenios the same drug?
- Yes. Both contain abemaciclib and have the same license number. In Türkiye, the drug was previously sold as Verzenios and is now sold as Yulareb.
- How long is abemaciclib used?
- For 2 years after surgery in early breast cancer; in metastatic disease, for as long as benefit continues and adverse effects are tolerated. Hormone therapy continues beyond 2 years in early disease.
- What should I do if I develop diarrhea while taking abemaciclib?
- Start loperamide with the first loose stool, drink plenty of fluids, and notify your oncology team. Diarrhea usually begins in the first weeks; if severe, the dose may be reduced or treatment paused.
Glossary
- CDK4/6
- Enzymes enabling the transition from G1 to S phase in the cell division cycle.
- Ki-67
- A marker showing the proportion of tumor cells that are dividing.
- Adjuvant treatment
- Treatment given after surgery to reduce recurrence risk.
- ESR1 mutation
- A change in the estrogen receptor gene that develops during hormone therapy and causes resistance to aromatase inhibitors.
DROZDOGAN Academy Commentary
Abemaciclib is the first CDK4/6 inhibitor shown to contribute to survival in early breast cancer.
⚡ Why it matters
In high-risk early disease, 2 years of treatment produces a 6.5-point absolute reduction in recurrence at 7 years.
✅ Strengths
Consistent benefit supported by large phase 3 studies; continuous dosing and penetration into brain tissue.
⚠️ Limitations
The absolute survival gain is 1.8 points; diarrhea can affect quality of life. The survival difference in MONARCH 3 was not significant. Lack of reimbursement limits access in Türkiye.
🩺 What to do in practice
- In early disease, assess recurrence risk using lymph node count, tumor size, grade, and Ki-67.
- At treatment initiation, prescribe loperamide and explain the diarrhea management plan.
- Check all medications for CYP3A interactions. Review them with this in mind.
❓ Open questions
There is no direct comparison of abemaciclib and ribociclib in early disease; which patients benefit more from either remains uncertain.
Our brief assessment: A drug with established effectiveness in high-risk early and metastatic HR-positive breast cancer; the main barrier in Türkiye is lack of reimbursement.
- This article was prepared in October 2026. Approval information came from FDA and European Medicines Agency sources, study results from original publications, dose and safety information from the US prescribing information (July 2026), and Turkish information from the Yulareb SmPC and drug price databases.
- Not verified: The complete current SGK List of Reimbursable Drugs could not be reviewed; reimbursement information relies on secondary sources. The date Verzenios became Yulareb and the exact date of European approval for early disease could not be verified.
- The diagrams and Academy commentary are our own; the diagrams were derived from verified statements in the text. This article is not personal medical advice.
References
- FDA. VERZENIO (abemaciclib) prescribing information, July 2026. accessdata.fda.gov
- Lilly. FDA approval of Verzenio (abemaciclib), 28 September 2017. lilly.com
- FDA approves abemaciclib with endocrine therapy for early breast cancer, 2021. fda.gov
- FDA expands abemaciclib indication in HR+ node-positive high-risk early breast cancer, 2023. onclive.com
- FDA approves imlunestrant in combination with abemaciclib, 2026. fda.gov
- EMA. Verzenios EPAR. ema.europa.eu
- Sledge GW et al. MONARCH 2. J Clin Oncol. 2017;35:2875-84. doi:10.1200/JCO.2017.73.7585
- Sledge GW et al. MONARCH 2 survival. JAMA Oncol. 2020. doi:10.1001/jamaoncol.2019.4782
- Goetz MP et al. MONARCH 3 final survival analysis. Ann Oncol. 2024. annalsofoncology.org
- Rastogi P et al. monarchE 5-year results. J Clin Oncol. 2024. doi:10.1200/JCO.23.01994
- Overall survival with abemaciclib in early breast cancer (monarchE). Ann Oncol. 2025. PubMed 41110697
- Kalinsky K et al. postMONARCH. J Clin Oncol. 2025. doi:10.1200/JCO-24-02086
- Shanabag A et al. Resistance to CDK4/6 inhibitors. Exp Mol Med. 2025. nature.com
- Yulareb 150 mg film-coated tablet SmPC. ilacprospektusu.com
- Yulareb 150 mg price and SGK information. ilacrehberi.com · ilacfiyati.com
- SUT amendment (palbociclib and ribociclib), Resmî Gazete 09.05.2020, issue 31122. lexpera.com.tr
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