Can you take Verzenio after Ibrance fails?

Although guidelines do not currently recommend it, using Verzenio after Ibrance is common in clinical practice. A recent clinical trial published in the Journal of Oncology also reported patients were more likely to live for longer without their breast cancer getting worse (also called progression-free survival) if they were given Verzenio + fulvestrant after previous CDK4/6 inhibitor treatment (such as Ibrance + endocrine therapy).

Because Verzenio and Ibrance belong to the same drug class, called CDK 4/6 inhibitors, historically there seemed to be no advantage in switching from one drug to another if one failed.

However, breast cancer cells can acquire resistance to CDK 4/6 inhibitors by producing higher amounts of CDK6 and real-world data has shown benefits for either stopping Ibrance temporarily for 4 weeks or switching from Ibrance to Verzenio after a treatment holiday. Ibrance also only targets CDK 4 and 6, whereas Verzenio targets CDK 4, 6, and 9. These factors support switching after disease progression despite previous CDK 4/6 inhibitor treatment.

Healthcare providers may consider switching to Verzenio when:

• Disease progression occurs on Ibrance
• The patient experiences intolerable side effects
• Earlier treatment fails to achieve desired results.

About Verzenio and Ibrance

Verzenio and Ibrance are targeted treatments that help 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 women with HR-positive, HER2-negative disease. They are given when cancer has progressed or spread to other parts of the body despite other treatments.
• Verzenio can also be used to treat adults with early breast cancer at high risk of recurrence in combination with endocrine treatment (tamoxifen or an aromatase inhibitor). Ibrance is not approved for early breast cancer.
• 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. Both Verzenio and Ibrance can be used in men.
• Only Verzenio can be used alone (as monotherapy) for adult patients with HR-positive, HER2-negative disease.

Research has shown that breast cancer cells can acquire resistance to CDK 4/6 inhibitors by producing higher amounts of CDK6. This will be shown by tumor growth in imaging studies.

• Laboratory studies suggest this may be reversible by having a treatment holiday of 28 days (4 weeks).
• Upon starting the CDK 4/6 inhibitor again, the tumors shrank.
• A switch from one CDK 4/6 inhibitor to another, with a treatment holiday period in between, should be considered if the breast cancer progresses.

Related questions

• How long does Ibrance extend life?
• Will insurance pay for the cost of Ibrance?
• What are 10 key Ibrance side effects to watch out for?

What is the difference between Verzenio and Ibrance?

There may also be some advantages for Verzenio over Ibrance.

• Verzenio is taken 2 times a 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.

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.