• Head-to-head trials comparing Verzenio to Ibrance have not been conducted. However, one is currently underway with results expected in 2023.
• Verzenio is taken twice daily, every day. Ibrance is taken every day for 21 days followed by a 7-day break.
• Verzenio can be used as monotherapy or in combination with other treatments. Ibrance is always taken in combination with either an aromatase inhibitor or fulvestrant.
• Verzenio is more likely than Ibrance to cause severe diarrhea.
• Both Verzenio and Ibrance can be used as combination treatment to treat breast cancer in men.

It is not known if Verzenio is better than Ibrance. They are similar treatments which have not been compared in head-to-head trials, although one trial is currently underway comparing the effects of Ibrance and Verzenio with an aromatase inhibitor and other medications in the treatment of breast cancer. Results are likely to be published in 2023.

Both Verzenio and Ibrance are CDK 4/6 inhibitors, a type of targeted treatment that helps to reduce the growth and spread of cancer cells in the body. The active ingredient in Verzenio is abemaciclib and in Ibrance it is palbociclib.

Both Verzenio and Ibrance are used to treat advanced or metastatic breast cancer in adults with HR-positive, HER2-negative (HR+ HER2-) disease. They are given when cancer has progressed or spread to other parts of the body despite other treatments. Verzenio is also approved to treat adults with early breast cancer at high risk of recurrence in combination with endocrine treatment (tamoxifen or an aromatase inhibitor).

Both Verzenio and Ibrance can be used in combination with an aromatase inhibitor or, in those who have not reached menopause, with fulvestrant intramuscular injection.

What is the difference between Verzenio and Ibrance?

There may also be some advantages for Verzenio over Ibrance.

• Verzenio is taken twice daily, every day. Ibrance is taken every day for 21 days followed by a 7-day break.
• Verzenio can be used as monotherapy or in combination with other treatments. Ibrance is always taken in combination with either an aromatase inhibitor or fulvestrant.

There may be some disadvantages too. Verzenio is more likely than Ibrance to cause diarrhea; however, most patients can manage this side effect with the anti-diarrhea medication loperamide.

How do Verzenio and Ibrance work?

Verzenio and Ibrance belong to the class of medicines known as CDK4/6 inhibitors. CDK4/6 inhibitors target particular enzymes, called CDK4 and CDK6. CDK stands for cyclin-dependent kinase, and it is an enzyme that is important for cell division. CDK4/6 inhibitors interrupt signals that stimulate the growth of cancerous cells.

Certain cancers, for example, hormone-receptor-positive breast cancer, are more likely to have disturbances in CDK4/6, and CDK 4/6 inhibitors may form part of the treatment protocol. Most often, CDK4/6 inhibitors are given at the same time as hormonal therapy (such as an aromatase inhibitor or fulvestrant), although Verzenio may be used alone to treat HR+ HER2- metastatic breast cancer in pre-treated patients.

Research suggests CDK4/6 inhibitors may increase the time people have before cancer spreads. More evidence is needed to determine their impact on overall survival.

Common side effects include fatigue and gastrointestinal disturbances, such as nausea, severe diarrhea, and vomiting. Bone marrow suppression resulting in neutropenia and leukopenia may also occur, although anemia and thrombocytopenia are less common. In general, the side effects associated with CDK4/6 inhibitor therapy are less severe than those experienced with chemotherapy.