A trial looking at pembrolizumab (MK3475) for advanced melanoma

Cancer type:

Skin cancer




Phase 3

This trial looked at a drug called pembrolizumab for melanoma that couldn’t be removed with surgery or that had spread to another part of the body. The trial was open to people with advanced melanoma who hadn’t had a drug called ipilimumab.

More about this trial

Ipilimumab is a type of biological therapy called a monoclonal antibody. Doctors use ipilimumab to treat advanced melanoma. In this trial, researchers compared ipilimumab with pembrolizumab.

Pembrolizumab works by helping the immune system to recognise cancer cells. Researchers compared 2 different doses of pembrolizumab with ipilimumab.

The aims of this trial were to find out

  • How well pembrolizumab works for people with advanced melanoma
  • Which dose of pembrolizumab works best
  • How safe pembrolizumab is
  • How pembrolizumab affects quality of life Open a glossary item

Summary of results

The researchers found that people who had pembrolizumab had a longer time before their advanced melanoma got worse and overall they lived longer than the people who had ipilumumab. They also had fewer side effects from their treatment.

 In total 834 people took part in the trial in 16 countries.

  • 279 had pembrolizumab every 2 weeks
  • 277 had pembrolizumab every 3 weeks
  • 278 had ipilumumab

Treatment was stopped in all groups if the melanoma started to grow again (disease progression).

The numbers of people whose melanoma had not grown (progression free survival) after 6 months were

  • 132 out of the 279 people (47.3%) having pembrolizumab every 2 weeks
  • 128 out of the 277 people (46.4%) having pembrolizumab every 3 weeks
  • 74 out of the 278 people (26.5 %) having ipilimumab

And after 12 months of the trial the number of people who were alive were

  • Just over 7 out of 10 people (74.1%) having pembrolizumab every 2 weeks
  • Just under 7 out of 10 people (68.4%) having pembrolizumab every 3 weeks
  • Just under 6 out of 10 people (58.2%) having ipilimumab

Because the numbers of people alive at 12 months was better for the groups having pembrolizumab the trial was stopped early to allow people having ipilimumab the chance of having pembrolizumab.

A number of people taking part in the trial had a complete response. To a researcher this means the disappearance of all signs of cancer for at least four weeks. This happened in

  • 5 out of 100 people (5%) having pembrolizumab every 2 weeks
  • About 6 out of 100 people (6.1 %) having pembrolizumab every 3 weeks
  • About 1 out of 100 people (1.4%) having ipilimumab

The researchers also looked at the side effects of the two drugs.

The most common side effects of pembrolizumab were

  • Tiredness (fatigue)
  • Diarrhoea
  • Skin rash
  • Itching

The most common side effects of ipilimumab were

  • Itching
  • Diarrhoea
  • Tiredness (fatigue)
  • Skin rash

Less people having pembrolizumab stopped treatment because of side effects  than those having ipilimumab.

And the side effects were more likely to be rated as severe in those who had  ipilimumab. 1 person having ipilimumab died and this was directly linked to having the drug.

When the researchers compared the 2 groups having pembrolizumab they didn’t find any significant difference in the side effects or how long it controlled their melanoma.

So, the results of this trial have shown that pembrolizumab compared with ipilimumab is a better treatment for people with advanced melanoma.

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

Dr James Larkin

Supported by

Experimental Cancer Medicine Centre (ECMC)​
Merck, Sharp & Dohme

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.

Charlie took part in a trial to try new treatments

A picture of Charlie

“I think it’s really important that people keep signing up to these type of trials to push research forward.”

Last reviewed:

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