Ibrance vs Verzenio
Both are CDK4/6 inhibitors. Here is how Ibrance and Verzenio compare on class, mechanism, dosing, approval and supply.
At a glance
Key differences
- Same class. Both Ibrance and Verzenio are CDK4/6 inhibitors, so they work through the same broad mechanism. Differences between them tend to be about dosing, route, how selective they are, and side effects rather than what they target.
- Time on the market. Ibrance was first approved by the FDA in 2015, Verzenio in 2017. That gives Ibrance roughly 2 more years of real-world use and long-term safety data.
- Who markets them. Ibrance is marketed by Pfizer; Verzenio by Eli Lilly.
- Same drug, more than one brand. Abemaciclib is sold as Verzenio / Verzenios — the same active ingredient marketed under different brand names, typically for different approved uses or doses.
What each one treats
IBRANCE is a kinase inhibitor indicated: • for the treatment of adult patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced or metastatic breast cancer in combination with: o an aromatase inhibitor as initial endocrine-based therapy ( 1.1 ); or o fulvestrant in patients with disease progression following endocrine therapy. ( 1.1 ) • in combination with inavolisib and fulvestrant for the treatment of adult patients with endocrine-resistant, PIK3CA -mutated, HR-positive, HER2-negative, locally advanced or metastatic breast cancer, as detected by an FDA‑authorized test, following recurrence on or after completing adjuvant endocrine therapy. ( 1.1 ) • in combination with trastuzumab, with or without pertuzumab, and endocrine therapy for the maintenance treatment of adult patients with HR-positive, HER2‑positive locally advanced or me…
An oral targeted therapy used to treat hormone receptor-positive breast cancer.
How each one works
12.1 Mechanism of Action Palbociclib is an inhibitor of cyclin-dependent kinases (CDK) 4 and 6. Cyclin D1 and CDK4/6 are downstream of signaling pathways which lead to cellular proliferation. In vitro, palbociclib reduced cellular proliferation of estrogen receptor (ER)-positive breast cancer cell lines by blocking progression of the cell from G1 into S phase of the cell cycle. Treatment of breast cancer cell lines with the combination of palbociclib and antiestrogens leads to decreased retinoblastoma (Rb) protein phosphorylation resulting in reduced E2F expression and signaling, and increased growth arrest compared to treatment with each drug alone. In vitro treatment of ER-positive breast…
An oral targeted therapy used to treat hormone receptor-positive breast cancer.
Related comparisons
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Which medicine is right for a given person depends on their diagnosis, other conditions, other medicines, kidney and liver function, pregnancy, and cost or reimbursement — none of which this page knows. Two drugs in the same class are not automatically interchangeable. Never start, stop or switch a prescription medicine on the basis of a web page; that decision belongs to you and your clinician or pharmacist.
How this page is built
The facts on this page are pulled directly from official U.S. FDA datasets — they are not written from memory. Each field below names the dataset it came from, so you can check it yourself.
- FDA Drug Label (openFDA) ↗ Indications, mechanism of action and pharmacologic class
- Drugs@FDA ↗ First FDA approval date and the company holding the application
- FDA Drug Shortage Database ↗ Current US supply / shortage status
Plain-English summaries and drug-class explainers are written and reviewed by Sreepriya Prasannan (MSc Digital Transformation of Life Sciences (Innopharma Education / Griffith College); MSc & BSc Botany). Data is retrieved automatically from the sources above and cross-checked with AI-assisted verification (Anthropic's Claude) — brand and generic names are matched against the exact FDA product record so that a combination product or a different formulation cannot be mistaken for the drug on this page. An editor reviews the result before publication. We describe this in full in our editorial standards and corrections policy. The FDA data on this page was last retrieved on 8 Oct 2026. How every register is built: methodology · fixes we have made: corrections log.