A trial looking at pembrolizumab for people with non small cell lung cancer (PePS2)

Cancer type:

Lung cancer
Non small cell lung cancer




Phase 2

This trial was for people whose general health and activity wasn’t very good because of their cancer. 

Doctors measure your general health and activity using an internationally recognised scale called performance status. This trial is for people with a  performance status of 2.

This trial was open for people to join between November 2016 and December 2017 and allowed 2 years for treatment and patient follow up. The team published the results in March 2020.

More about this trial

People with non small cell lung cancer (NSCLC) can have symptoms and sometimes other conditions that can make them less active. This is classed as a lower performance status (or PS) and often means that they are not allowed to take part in clinical trials.

We know from research that pembrolizumab (also called Keytruda) can help people with some types of lung cancer. But most people who took part in the original trials for this treatment had a good performance status (performance status of 0 or 1) in terms of their activity levels.

Pembrolizumab is a type of targeted drug called an immunotherapy. It helps your immune system attack the cancer and stops it from growing.

In this trial doctors wanted to find out if pembrolizumab could also help people who had a performance status of 2. They looked for people who:

  • were up and about for more than half of the day
  • could look after themselves
  • but couldn’t work

The main aims of this trial were to:

  • find out if pembrolizumab helped people with a performance status of 2
  • learn more about how well pembrolizumab worked as a treatment for these people
  • learn what side effects this particular group of people experienced and how well they coped with them

Summary of results

The team found that it is safe for people with non small cell lung cancer who have a performance status of 2 to take pembrolizumab.   

About this trial
This was a phase 2 trial. 60 people took part. Everyone had pembrolizumab. 

They had a CT scan before treatment then every 9 weeks to see how well treatment was working.

For 24 of the 60 people pembrolizumab was the first treatment they had for their cancer. And the remaining 36 people had already had another treatment before having pembrolizumab. 

The team looked at how well pembrolizumab worked for these 2 groups. 

At 18 weeks the team looked at the CT scans to find out whether the treatment was still working. They found that it was for 22 people (37%).  Of these: 

  • 9 out of 24 people (38%) had pembrolizumab as a first treatment 
  • 13 out of 36 people (39%) had other treatment before pembrolizumab

The team also looked at how many people stopped or delayed their treatment due to the side effects of pembrolizumab. Side effects in this group of people were previously unknown as it had not previously been given to people with this performance status. 

Of the 60 people, 17 people (28%) had to stop or delay treatment. Of these:

  • 7 out of 24 people (29%) had pembrolizumab as their first treatment
  • 10 out of 36 people (28%) had another treatment before having pembrolizumab

These side effects included:

  • cough
  • shortness of breath
  • a low level of oxygen in the blood
  • fluid on the lung
  • inflammation of the lung
  • changes to how well the liver worked
  • sore, inflamed mouth
  • constipation or diarrhoea 
  • being sick

The median Open a glossary item length of time the 60 people lived after this treatment with no sign of their lung cancer was just under 4½ months (4.4 months).  This is known as progression free survival rate. 

The median length of time the 60 people lived after this treatment was just under 10 months (9.8 months). This is known as overall survival rate. 

Quality of life
These were questionnaires completed by people about their experiences on the treatment. For those who stayed on pembrolizumab they reported their health related quality of life was better than when they started this treatment.

The trial team concluded that for people with NSCLC with a performance status of 2 pembrolizumab is a possible treatment either as a first treatment or after other treatments.  It works as well as it does for people who have a higher performance status. 

Where this information comes from    
We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed Open a glossary item) and published in a medical journal. The figures we quote above were provided by the trial team who did the research. We have not analysed the data ourselves.

Recruitment start:

Recruitment end:

How to join a clinical trial

Please note: In order to join a trial you will need to discuss it with your doctor, unless otherwise specified.

Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Chief Investigator

Professor Gary Middleton

Supported by

University of Birmingham 
Merck, Sharp & Dohme 
Cancer Research UK Clinical Trials Unit

If you have questions about the trial please contact our cancer information nurses

Freephone 0808 800 4040

Last review date

CRUK internal database number:


Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

Around 1 in 5 people take part in clinical trials

3 phases of trials

Around 1 in 5 people diagnosed with cancer in the UK take part in a clinical trial.

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