Checkpoint inhibitors

Checkpoint inhibitors are drugs which ‘take the brakes off’ the immune system, allowing tumour cells to be destroyed.

There are currently no checkpoint inhibitor treatments approved for treating brain tumours within the NHS.

There is, however, growing interest in combining checkpoint inhibitors with chemotherapy, radiotherapy, and other treatments to boost their effectiveness. Different drugs and approaches are still being tested in clinical trials across the world. For example, some checkpoint inhibitors currently in research include:

• Ipilimumab 
• Pembrolizumab 
• Nivolumab 
• Pidilizumab 

You can learn more about finding clinical trials here.

How Checkpoint inhibitors work

Normal cells in your body have particular proteins on their surface that the immune system recognises as friendly, so your body’s immune system doesn’t attack them. As these proteins effectively hold the immune system in check, they are called ‘checkpoint proteins’.

However, tumour cells can sometimes fool the immune system by also producing these checkpoint proteins, preventing the immune system from recognising them as unfriendly and from attacking them.

‘Checkpoint inhibitors’ are drugs that block these checkpoint proteins, so the tumour cells now become visible to the immune system and the ‘brakes’ are taken off the immune system, allowing the tumour cells to be destroyed.

The down-side of this, however, is that it also takes the brakes off the immune system attacking your normal cells. This can lead to various side-effects, which can occur at any time and can affect many different organs.

Taking the Brakes Off the Immune System

Narrated by Jill O’Donnell-Tormey, Ph.D. from the Cancer Research Institute, this 1-minute animated video provides a quick overview of checkpoint inhibitors.

Side Effects

The most common side-effects are a rash, diarrhoea, reduced levels of thyroid hormone, and fatigue. More severe side-effects can be due to inflammation of the lung, intestines or liver, hormonal abnormalities, and kidney, heart, or neurologic problems.

If the side-effects are mild, it may be possible to continue using the checkpoint inhibitors, but you will need to be closely monitored.

Some people may have to take corticosteroids to reduce the inflammation. Your medical team will then modify your treatment plan depending on what is best for you.

Make the right choices for you

Our Step by Step interactive guide outlines what happens following a diagnosis, to answer your questions and help you to understand what to expect.

Read our guide