Immunotherapy for Breast Cancer

Who may be offered pembrolizumab?

For certain early breast cancers at high risk of recurrence or locally advanced triple-negative cancers, NICE TA851 recommends pembrolizumab with chemotherapy before surgery, then pembrolizumab alone afterwards. Your specialist checks whether your diagnosis fits the recommendation and discusses the possible benefit and harms.

For some triple-negative cancers that have spread, or have returned locally and cannot be removed surgically, immunotherapy may also be considered. These decisions have different criteria from treatment before surgery. Do not assume that a recommendation for early cancer applies to secondary cancer.

What does PD-L1 testing mean?

PD-L1 is a protein that can help guide some immunotherapy decisions. The laboratory uses specific tests and scoring systems. For example, NICE TA801 covers pembrolizumab with paclitaxel or nab-paclitaxel for certain adults with no previous chemotherapy for metastatic disease, a combined positive score (CPS) of at least 10 and immune-cell staining (IC) below 1%, under its funding arrangement. A generic “PD-L1 positive” result alone does not establish eligibility.

Ask your oncologist which test, score and treatment criteria apply. NHS access decisions and implementation can differ across the UK; Scotland has its own Scottish Medicines Consortium assessments. Your local specialist can explain the current position for you.

How is treatment given?

Pembrolizumab can be given into a vein or, where suitable and available, as an injection under the skin. NHS England announced the injection rollout in 2026. Your team will confirm the formulation, treatment schedule, monitoring and planned duration. Having a quicker injection does not remove the need to report side effects.

Which side effects should I report?

Checkpoint immunotherapy can cause the immune system to inflame healthy tissues, including the bowel, lungs, liver and hormone glands. Some effects can be serious, and they may start after treatment has ended. Keep the patient alert card with you and show it to any healthcare professional treating you.

• Contact your hospital’s 24-hour treatment line straight away about new or worsening diarrhoea, abdominal pain, a new cough or breathlessness.
• Also report yellowing of the eyes or skin, a significant rash, severe headache, dizziness or unusual extreme tiredness. Follow all the other instructions on your alert card.
• Do not wait for the next infusion or try to manage possible immune side effects on your own. The team may need to assess you and adjust treatment.
• Call 999 for a life-threatening emergency, such as severe breathing difficulty, collapse or new confusion.

Is immunotherapy the same as a targeted medicine?

No. Different medicines act in different ways. Antibody–drug conjugates carry a chemotherapy drug attached to an antibody and are usually described as targeted treatments. They should not be confused with checkpoint immunotherapy. Your team can explain the medicines in your own plan.

What questions can I ask my oncologist?

• What is the aim of immunotherapy in my situation?
• Which result shows that it is an option for me?
• How much additional benefit is expected, and what are the uncertainties?
• Could my other illnesses or medicines affect treatment?
• Who should I contact about symptoms during treatment and after it ends?