Giving hope to those affected
by secondary breast cancer

Research. Support. Education.


26th June 2022 by Claire O'Donnell Education


What is Palbociclib.

Palbociclib is a type of targeted cancer drug; It is a treatment for breast cancer that has spread to another part of the body (advanced / metastatic / secondary / stage 4)


What is a targeted cancer drug:

Targeted therapy is a type of cancer treatment that targets proteins that control how cancer cells grow, divide, and spread.


You would usually have this in combination with a hormone therapy drug

It is used for a type of breast cancer that is hormone receptor positive [HR+] and human epidermal growth factor receptor negative [HER2-].  You will have tests on your breast cancer cells to check for this. 


How does Palbociclib work.

Palbociclib is a type of cancer growth blocker that targets the proteins cyclin dependent kinase 4 and 6 (CDK4 and CDK6) on cancer cells.

CDK 4 and CDK 6 are proteins that stimulate cancer cells to grow and divide. It works by blocking these proteins. It aims to slow or stop the growth of cancer.


You have palbociclib as capsules. You take it with food and swallow the capsules whole.

Whether you have a full or empty stomach can affect how much of a drug gets into your bloodstream.

You should take the right dose, not more or less.


You have palbociclib as cycles of treatment. This means that you have the drug and then a rest to allow your body to recover. One cycle lasts 28 days (4 weeks). A normal cycle would be 3 weeks of capsules and 1 week of no capsules. 

You then start a new cycle of treatment.

You take this treatment for as long as it’s working, and the side effects aren’t too bad. 


Some side effects to be aware of:

  • Increased risk of infection
  • Bruising, bleeding gums or nose bleeds
  • Breathlessness and looking pale
  • Loss of appetite
  • Feeling or being sick
  • Diarrhoea
  • Sore mouth
  • Skin problems
  • Hair loss
  • Tiredness and weakness
  • Liver changes


Other important facts:

Grapefruit and grapefruit juice

You should not eat grapefruit or drink grapefruit juice when you are taking this drug because it may increase the side effects.

Lactose intolerance

This drug contains lactose (milk sugar). If you have an intolerance to lactose, contact your doctor before taking this medicine.