Key Points

• You will normally take Ibrance for 21 days in a row along with other medications, such as an aromatase inhibitor or fulvestrant. This cycle is repeated every 28 days as long as you are having a benefit and tolerate the side effects from the medicine.
• Ibrance is used in women and men to treat advanced or metastatic hormone-receptor-positive (HR+), human epidermal growth factor receptor 2 negative (HER2-) breast cancer.
• Side effects due to Ibrance may include increased infections, low red blood cell counts, tiredness, feeling sick to your stomach, hair loss, diarrhea and mouth sores, among others. Always discuss side effects with your doctor.

Ibrance (generic name: palbociclib) comes as a capsule or tablet taken by mouth to treat certain types of breast cancer. Ibrance is taken once a day for 21 days, with a 7 day break before starting again. You will repeat this 28-day cycle, based on effectiveness and tolerability, as long as your doctor prescribes it. Your doctor will prescribe other medications for you to use with Ibrance, such as an aromatase inhibitor or fulvestrant.

What is Ibrance used for?

Ibrance, from Pfizer, is used in adults to treat hormone-receptor-positive, HER2-negative breast cancer that is advanced or has spread in the body (metastatic).

• It is used in combination with a hormonal therapy called an aromatase inhibitor for postmenopausal women or men who have not been treated with hormonal therapy before.
• It is also approved for use in combination with fulvestrant for those whose disease worsens after using an aromatase inhibitor.

Aromatase inhibitors include medicines such as anastrozole (Arimidex), exemestane (Aromasin), and letrozole (Femara). In clinical studies, Ibrance was studied with letrozole in postmenopausal women but is approved by the FDA to be used with any aromatase inhibitor as first-line treatment. Fulvestrant (Faslodex) is considered an estrogen receptor antagonist.

What side effects can I expect with Ibrance?

Common side effects include:

• fatigue (tiredness) and weakness
• low red blood cell (anemia) or platelet counts
• low white blood cell counts (neutropenia)
• nausea
• hair loss
• abnormal liver tests
• diarrhea
• fever
• loss of appetite
• mouth sores

Ibrance may lower the ability of your body to fight off infections due to low white blood cell counts or cause lung problems such as inflammation (pneumonitis).

If you should vomit or miss a dose for any reason, do not take an additional dose of Ibrance. Take your next dose at the normal time.

Avoid consuming grapefruit juice and grapefruit products during your treatment with Ibrance. Grapefruit may cause your blood levels of Ibrance to rise and lead to worsened side effects.

In studies in patients taking Ibrance plus letrozole, 36% of patients (36 out of every 100) needed to have a dose reduction due to a side effect. About 9.7% (43 of 444) of patients permanently stopped therapy due to a side effect, such as low while blood cell count (neutropenia, 1.1%) and elevation of liver enzymes (alanine aminotransferase, 0.7%).

In studies looking at patients taking Ibrance plus fulvestrant, 36% of patients (36 out of every 100) needed to have a dose reduction due to a side effect. About 6% (19 of 345) of patients permanently stopped therapy due to a side effect such as fatigue (0.6%), infections (0.6%), and thrombocytopenia (0.6%).