A study looking at pembrolizumab with chemotherapy before and after surgery for breast cancer (KEYNOTE 522)

Please note - this trial is no longer recruiting patients. We hope to add results when they are available.

Cancer type:

Breast cancer




Phase 3

This study is for people with triple negative breast cancer. Triple negative breast cancer does not have receptors Open a glossary item for oestrogen, progesterone and HER2. 

More about this trial

Surgery is the usual treatment for people with triple negative breast cancer. Chemotherapy can be given before surgery (neo adjuvant treatment) and after treatment (adjuvant treatment).

Giving treatment before surgery can help to shrink the size of the cancer and make surgery easier. Having treatment after surgery helps to reduce the chances of the cancer coming back.

Pembrolizumab (Keytruda) is a type of targeted cancer drug (biological therapy) called a monoclonal antibody. It can seek out cancer cells by looking for particular proteins. Pembrolizumab is already being used to treat some cancers such as advanced melanoma and non small cell lung cancer.          

In this study doctors want to see if adding pembrolizumab improves treatment for people with triple negative breast cancer.

There will be 2 treatment groups, one group has pembrolizumab and the other has a dummy drug (placebo Open a glossary item)

  • alongside usual chemotherapy drugs before surgery
  • on its own after surgery

Comparing these 2 groups helps the doctors to know which treatment is best.

The doctors also want to see how safe it is to give pembrolizumab with chemotherapy before surgery. And on its own after surgery.

Who can enter

The following bullet points list the entry conditions for this study. Talk to your doctor or the study team if you are unsure about any of these. They will be able to advise you.

You may be able to join this study if you have one of the following stages of triple negative breast cancer:

  •  T1 with cancer in the lymph nodes (N1 to N2)
  •  T2, T3 or T4 with or without cancer in the lymph nodes

This is also called locally advanced triple negative breast cancer.

As well as the above you may be able to join this study if all of the following apply. You

  • Haven’t had any treatment for your triple negative breast cancer
  • Are willing to have a sample of your cancer taken (a biopsy)
  • Are well enough to carry out all your normal activities, apart from heavy physical work (performance status 0 or 1)
  • Have satisfactory blood test results
  • Have satisfactory results from a heart scan (MUGA or ECHO)
  • Are 18 or older

You cannot join this study if any of these apply. You

Cancer related

  • Have breast cancer that has spread elsewhere in the body (metastatic breast cancer)
  • Have had chemotherapy, targeted therapy or radiotherapy within the last 12 months
  • Have already taken part in a clinical trial for pembrolizumab or have had treatment with similar drugs (anti PD1, anti PD-L1 or anti PD-L2, CTLA-4, or OX-40, CD137)
  • Have had treatment with an experimental drug or device within the last 4 weeks
  • Have had treatment with an experimental anti cancer drug in the last 12 months
  • Have had another cancer in the last 5 years, unless it was a basal cell or squamous cell skin cancer or cancer in situ (CIS) of the cervix that has been successfully treated

Medical conditions

  • Have an active autoimmune disease Open a glossary item that has needed treatment that affects you whole body (systemic treatment) in the last 2 years. You might still be able to take part if the treatment you needed was replacing something usually produced by the body such as thyroxine or insulin
  • Have problems with your immune system or have taken drugs to suppress your immune system in the last 7 days such as steroids
  • Have Human Immunodeficiency Virus (HIV)
  • Have active Hepatitis B or Hepatitis C
  • Have inflammation of the lungs (pneumonitis) or  you have had it in the past and it needed treatment with steroids
  • Have an infection needing treatment that affects your whole body (systemic treatment)
  • Have congestive heart failure or have had a heart attack or heart surgery within the last 6 months
  • Have or have had TB (tuberculosis)
  • Have any other serious medical condition or mental health problem the study team think might affect you taking part


  • Are pregnant or breastfeeding
  • Have a known allergy to any of the drugs being used in this study

Trial design

This is an international phase 3 study. Researchers need about 600 people to take part and would like 36 people in the UK to join.

It is a randomised study. The people taking part are put into 2 groups by a computer. Neither you nor your doctor can decide which group you are in.

  • One group have chemotherapy and pembrolizumab before surgery and pembrolizumab after surgery
  • The other group have chemotherapy and a dummy drug before surgery and a dummy drug after surgery

You have a 2 in 3 chance of being in the group having pembrolizumab. 

Study Diagram

Neither you nor your doctor will know if you are having pembrolizumab or the dummy drug. This is a double blind study.

Before surgery
Both groups have the following chemotherapy drugs:

  • paclitaxel every week
  • carboplatin every week or 3 weeks (your doctor will discuss with you how often you have this drug)

and either pembrolizumab or a dummy drug once every 3 weeks.

You have all these drugs as a drip into a vein. Each 3 week period is called a cycle of treatment. You have 4 cycles of this treatment.

You then have:

and either pembrolizumab or a dummy drug once every 3 weeks.

You also have all these drugs as a drip into a vein and have 4 cycles of treatment.

Around 3 to 6 weeks after you finish your treatment you have your surgery.

After surgery
You have either pembrolizumab or the dummy drug once every 3 weeks. Each 3 week period is a cycle of treatment. You have 9 cycles of this treatment.

Blood and tissue samples
The researchers may also ask to take biopsies Open a glossary item of your cancer at the beginning and during treatment. They will use these to look for biomarkers Open a glossary item and they may use it for other tests in the future. If you don’t want to give these samples for research, you don’t have to. You can still take part in the trial.

The researchers also ask your permission to use one blood sample (taken at the beginning of treatment) to look at the genetic information in your cells.

You complete some questionnaires before and during treatment and at some follow up appointments. They ask about side effects and how you are feeling. These are called quality of life questionnaires.

Hospital visits

You will see the doctors and have some tests before your start treatment. The tests might include:

  • blood tests
  • urine tests
  • physical examination
  • heart trace (ECG Open a glossary item)
  • heart scan (ECHO) Open a glossary item or MUGA scan Open a glossary item
  • CT scan, MRI scan Open a glossary item, or x-ray

You go to the hospital for your treatment, you should not need to stay overnight.

You see doctors and have blood tests during the time you have treatment. This is to see how you are. You have urine tests at some visits.

You have heart tests (an electrocardiogram and echocardiogram) after you have had 4 cycles of chemotherapy, 30 days before surgery and during follow up.

You might have CT scan, MRI scan, x-ray or bone scan during the time you have treatment to check the cancer. Your doctor will tell you if you need one of these scans.

After treatment you see the doctor every:

  • 3 months for 2 years
  • 6 months for 2 years
  • 12 months afterwards

The trial team will telephone you about 6 months after finishing treatment if you are not able to attend for a follow up visit.

Side effects

Side effects of pembrolizumab include:

We have information about the side effects of:

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 Peter Schmidt 

Supported by

Merck,Sharp & Dohme 

Questions about cancer? Contact our 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.

Deborah wanted to help other breast cancer patients in the future

A picture of Deborah

“Deborah agreed to take part in a trial as she was keen to help other cancer patients in the future. "If taking part in a trial means others might be helped then I’m very happy with that."

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