PARP inhibitors

PARP inhibitors are a type of targeted cancer drug. They are a treatment for some women with ovarian cancer. They are also in trials as a treatment for other types of cancer.

Olaparib, niraparib and rucaparib are all examples of PARP inhibitors. 

How do PARP inhibitors work?

PARP is a protein (enzyme) found in our cells, it stands for poly-ADP ribose polymerase. It helps damaged cells to repair themselves.

As a cancer treatment, PARP inhibitors stop the PARP from doing its repair work in cancer cells and the cell dies.

Researchers first looked at these drugs in cancers that already had problems repairing cell damage. They focused on cancers with a change (or fault) in genes called BRCA.

Normally, BRCA1 and BRCA2 genes play a part in cell repair in the body. Cells are less likely to repair themselves if there is a fault in one or both of these genes. People who have faulty BRCA genes have an increased risk of certain cancers including:

• breast cancer
• ovarian cancer
• prostate cancer

Cancer cells with BRCA gene faults already have a poor repair system. So blocking PARP with a PARP inhibitor drug means that the cells are not able to repair themselves and they die.

When do you have PARP inhibitors?

PARP inhibitors are a treatment for the following types of cancer:

• ovarian cancer
• fallopian tube cancer
• peritoneal cancer

Researchers think that they might work in cancers that have weaknesses in the cell similar to the BRCA gene fault. There are trials to find whether they are useful in other types of cancer including:

• lung cancer
• pancreatic cancer
• head and neck cancer
• a type of brain tumour called glioblastoma multiforme
• prostate cancer
• cancer of the stomach and foodpipe (oesophagus)
• womb and cervical cancer
• kidney and bladder cancer

In some of these trials you have a PARP inhibitor on its own. Or you might have it in combination with other treatments, such as chemotherapy, radiotherapy or another targeted drug.   

How you have them

You usually take PARP inhibitors as tablets or capsules once or twice a day. How often you have them and how long you have treatment will depend on:

• which drug you have
• the type of cancer you have

Types of PARP inhibitors

There are different types of PARP inhibitors including:

• olaparib (Lynparza)
• rucaparib (Rubraca)
• niraparib (Zejula)

These PARP inhibitors are for some women with one of the following types of cancer:

• ovarian cancer
• fallopian tube cancer
• peritoneal cancer

Researchers are also looking at these PARP inhibitors for other types of cancer. And they are looking at a type of PARP inhibitor called veliparib in trials for other types of cancer.

Side effects

All treatments can cause side effects. While there are general side effects for a type of treatment, they vary for each individual drug.

Tell your doctor or nurse if you have any of these side effects. You might be able to have medicines to help control them.

Common side effects of PARP inhibitors include:

• an increased risk of infection, bleeding problems, tiredness and breathlessness due to a drop in the number of blood cells
• feeling or being sick
• tiredness
• diarrhoea
• indigestion and taste changes
• headaches and dizziness
• changes to the way your liver and kidneys works – you have regular blood tests to check for this

For more information about the side effects of your treatment, go to the individual drug pages.