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About IBRANCE<sup>®</sup>



You can find the answers to some common questions about IBRANCE ® here, but if you still have questions about IBRANCE ® or your condition, it is important that you talk to your doctor. The information here does not replace the advice of your doctor.


What is
IBRANCE® (palbociclib)?​​​​​​​1

IBRANCE® is a prescription medicine used to treat hormone receptor-positive (HR-positive), human epidermal growth factor receptor 2-negative (HER2-negative) breast cancer that has spread to other parts of the body (metastatic breast cancer). IBRANCE® is a targeted therapy that belongs to a group of medicines called cyclin-dependent kinase 4/6 inhibitors (CDK4/6 inhibitors).

IBRANCE® is taken in combination with another medicine known as an anti-hormonal therapy (or endocrine therapy). Your doctor will have prescribed either:1

  • an aromatase inhibitor (eg letrozole), or
  • fulvestrant.

IBRANCE® is only used to treat breast cancer that is HR-positive and HER2-negative.1


How does IBRANCE® (palbociclib) work?

IBRANCE® is a targeted therapy known as a cyclin-dependent kinase 4/6 inhibitor (CDK4/6 inhibitor)1. It works by blocking two proteins, called CDK 4 and CDK 6, which are found in the nucleus of cells.​​​​​​​1

In HR-positive breast cancer, the estrogen hormone activates the estrogen receptor which stimulates cells to grow and multiply.2 The CDK 4 and CDK 6 proteins are part of the cell machinery that is switched on by the estrogen receptor to cause cells to multiply uncontrollably.2

When IBRANCE® and an anti-hormonal therapy are used together, IBRANCE® blocks the effects of CDK 4 and CDK 6, while the anti-hormonal therapy works to reduce the action of estrogen and the estrogen receptor. Their combined action can help to control cell growth and may slow the progression of some breast cancers.​​​​​​​1


All medicines can have side effects, and IBRANCE® is no different. Because IBRANCE® acts on both healthy cells and breast cancer cells it can cause side effects, some of which can be serious.1

  • A low white blood cell count​​​​​​​1
  • A low red blood cell count and low platelet count​​​​​​​1
  • Other possible side effects1

A low white blood cell count (neutropenia) is common when taking IBRANCE® and may cause serious infections that can, rarely, lead to death. Your white blood cell count will be monitored before and during your treatment with IBRANCE®.

If you develop a low white blood cell count during treatment with IBRANCE®, your doctor may stop your treatment, decrease your dose, or tell you to wait to begin your treatment cycle.

Tell your doctor, nurse or pharmacist right away if you have signs and symptoms of a low white blood cell count or infection, such as fever and chills.

A low red blood cell count (anemia) and low platelet count are also common with IBRANCE®. Tell your doctor, nurse or pharmacist right away if you develop any of these symptoms during treatment:

  • dizziness
  • bleeding or bruising more easily than usual
  • shortness of breath
  • weakness
  • nosebleeds

Other possible side effects of IBRANCE® include:

  • Fatigue
  • Nausea or vomiting
  • Skin rash
  • Mouth sores
  • Hair thinning or loss
  • Diarrhea
  • Decreased appetite
  • Abnormalities in liver blood tests

Not all possible side effects are listed here. For more information, talk to your doctor, nurse or pharmacist.

It is also important to remember that feeling unwell may be an adverse effect of your disease or another treatment you may be receiving for your condition.

Tell your doctor if you have any side effect that bothers you, or that does not go away.



  1. IBRANCE® (palbociclib) Tablets Prescribing Information. Pfizer Corporation Hong Kong Limited. Version: January 2021.
  2. Cadoo, KA., Gucap, A. & Traina, T A. (2014) Palbociclib: an evidence-based review of its potential in the treatment of breast cancer. Breast Cancer (Dove Med Press) 6:123-133. DOI: 10.2147/BCTT.S46725


The information enclosed is for your understanding of the disease and is provided via your Healthcare Provider. The information is for patients who receive Ibrance®. It cannot replace a consultation with medical professional nor as a basis of self-diagnosis or for treatment decision. Please consult your doctor for more information.

Ibrance® is a prescription only medication. The effectiveness and side effects to medication may vary among individuals. Please consult your doctor or your pharmacist for more information.

Drug Safety

How to report adverse events of Pfizer products?

Patient safety is of paramount importance throughout the life cycle of a medicine - and pharmaceutical companies have ethical and regulatory responsibilities to monitor the safety of the products they sell for as long as they are used by consumers anywhere in the world. The Drug Safety Unit at Pfizer Corporation Hong Kong Ltd addresses product experience reports /including adverse events. If you have any experience pertinent to the above, please contact us at +852 2811 9711 as soon as possible.

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