Medications
Abemaciclib (Verzenio)
A CDK4/6-blocker tablet taken twice a day for certain hormone-receptor-positive, HER2-negative breast cancers, alone or with hormone therapy.
How Medicare covers it
Part D (forms used at home). Part A during a covered inpatient stay. No Part B clinician-administered form in the CMS Part B spending file.
| Coverage details | |
|---|---|
| Part B status | No abemaciclib row in the CMS Part B Spending by Drug HCPCS file (RY26, data through 2024) — no J-code basis; coverage path is Part D. |
| Medicare Advantage | Most Medicare Advantage plans that include drug coverage (MAPD plans) use the same formulary-and-tier system; the plan's own drug list decides coverage and copay — check the plan's formulary. |
| Medicare Supplement (Medigap) | Medicare Supplement (Medigap) plans sold today do not include prescription drug coverage; drug coverage comes from Part D or an MAPD plan. |
What it treats
Abemaciclib (brand name Verzenio) treats hormone receptor-positive, HER2-negative breast cancer, including early breast cancer at high risk of coming back and advanced or metastatic breast cancer. It is used alone or with hormone therapy drugs.
What it is for, in depth
Abemaciclib, sold as Verzenio, treats hormone receptor-positive, HER2-negative breast cancer. It is used for early breast cancer at high risk of coming back and for advanced or metastatic breast cancer that has spread. It is used alone or together with hormone therapy drugs. It works by blocking CDK4 and CDK6 proteins that cancer cells need to grow and divide, which slows or stops the cancer cells. It comes as a tablet taken by mouth twice a day, with or without food. The tablets come in four strengths: 50 MG, 100 MG, 150 MG, and 200 MG.
How it works
It is a kinase inhibitor that blocks CDK4 and CDK6 proteins cancer cells need to grow and divide, which slows or stops the cancer cells.
How it is taken
It comes as a tablet taken by mouth twice a day, with or without food.
Common side effects
The most common side effects were diarrhea, infections, low white blood cell counts (neutropenia and leukopenia), tiredness, belly pain, nausea, anemia, and vomiting.
Serious warnings
It can cause severe diarrhea with dehydration and infection, low white blood cell counts, serious and sometimes fatal lung inflammation (ILD/pneumonitis), liver damage, and blood clots in the veins or lungs. It can also harm an unborn baby.
Who should be careful
Blood counts and liver tests must be checked before and during treatment, and people with severe liver problems take it only once a day. People who can become pregnant should use effective birth control during treatment.
Major interactions
Ketoconazole must be avoided, other strong and moderate CYP3A inhibitors require a lower dose or close monitoring, and grapefruit products should be avoided. Strong and moderate CYP3A inducers must also be avoided because they can make it work less well.
Why it is in its tier
Abemaciclib is listed by 100.0% of Part D plans, and 96.91% of those listing plans place it on Tier 5. Tier 5 is the specialty tier, where you usually pay the highest percentage coinsurance instead of a flat copay, so cost share is at the high end. Abemaciclib is a brand-name cancer drug sold as Verzenio, with no generic name shown in this data, which fits specialty placement. CMS dashboard data show average spending per beneficiary of $94025.92 — that is a CMS program average for program spending, not a copay you pay. Individual plans vary, so check your own plan.
Sources
- VERZENIO (ABEMACICLIB) TABLET [ELI LILLY AND COMPANY] — DailyMed
- MedlinePlus — National Library of Medicine
- MedlinePlus — Abemaciclib
What official patient guides say
Abemaciclib is a tablet taken by mouth twice a day, with or without food, at around the same times every day. Swallow the tablets whole; do not split, chew, or crush them, and do not take a tablet that is broken, cracked, or damaged. Take it exactly as directed. If you vomit after a dose, do not take another dose — continue your regular schedule. If you forget a dose, skip the missed dose and continue your regular schedule; do not take a double dose. Your doctor may lower your dose or pause treatment depending on how you feel, so tell your doctor how you are feeling during treatment. Keep the tablets in the container they came in, tightly closed, at room temperature away from excess heat and moisture, not in the bathroom, and out of sight and reach of children with safety caps locked. Dispose of unneeded tablets through a medicine take-back program; do not flush them.
Source: MedlinePlus — Abemaciclib
Part D formulary coverage
| Formulary summary | |
|---|---|
| Most common tier | 5 |
| Plans listing this drug | 5495 |
| Total Part D plans | 5495 |
| Share of plans listing it | 100 |
| Formularies listing it | 286 |
| Tier | Plans |
|---|---|
| Tier 1 | 123 plans |
| Tier 2 | 1 plans |
| Tier 4 | 46 plans |
| Tier 5 | 5325 plans |
Source: CMS Prescription Drug Plan Formulary, Pharmacy Network, and Pricing Information Files — Monthly file 2026-10-15 (plan year 2027), file 2027_20261008.zip (data.cms.gov dataset ed1496ea-23e7-41f1-9292-172fa842ccfb): basic drugs formulary file + plan information file, both dated 20261031 inside the zip; downloaded and aggregated 2026-10-30. Medication RxCUI sets resolved through the NLM RxNav (RxNorm) API.
What you pay
| With Medicare Part D | |
|---|---|
| Most common tier | Tier 5 |
| Typical copay | $0 — half of plans charge between $0 and $0 |
| Typical coinsurance | 26.0% of the price |
| Based on | 5237 plans that cover this drug · 2027 plan year |
A tier is not a price; what you pay depends on your plan, pharmacy, and benefit stage; Extra Help or Medicaid can lower it further.
Sources: CMS Plan Benefit Package + formulary data; CMS NADAC · Checked 2026-11-07
Similar medications
Other medications in the same FDA pharmacologic class (Kinase Inhibitor):
Read next
Part D spending averages (2024)
| Brand name | Generic name | Total claims 2024 | Total spending 2024 | Total beneficiaries 2024 | Rank by beneficiaries 2024 |
|---|---|---|---|---|---|
| Verzenio | Abemaciclib | 71933 | 1.05676e+09 | 11239 | 969 |
Source: CMS Medicare Part D Spending by Drug (Drug Spending Dashboard), release RY26 P04 V10, data through 2024 (DSD_PTD_RY26_P04_V10_DY24_BGM.csv), downloaded 2026-10-30
Companies covering this drug
5,495 plans from 509 companies list this drug on a formulary for 2027. Search by company or plan name, or filter by tier. Cost sharing is the plan's published amount for this drug's tier in the initial coverage stage (1-month retail supply), where the plan publishes it; a blank means the plan does not publish it.
| Company | Plan | Tier | Copay | Coinsurance |
|---|
A tier is not a price; what you pay depends on your plan, pharmacy, and benefit stage; Extra Help or Medicaid can lower it further.
Coverage and costs change. Drug lists (formularies), tiers, and copays can change during the year and differ by plan. Always check with your insurance company or plan directly to confirm what is covered and what you will pay.
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