Pembrolizumab: New hope for women with aggressive types of breast cancer

New evidence presented at the European Society for Medical Oncology Congress 2024 shows that a drug which encourages the body’s own immunity to kill cancer cells could save at least 800 women with breast cancer a year, in the UK.

The drug, called pembrolizumab, which is already used for many other cancers, was introduced for breast cancer (given alongside chemotherapy) in a trial called KEYNOTE-522. It has already shown that in women with an aggressive form called triple-negative breast cancer it increased the response rate to chemotherapy, when given before surgery (neoadjuvant).

Although this suggested a benefit for women it was not known for sure until this new data was published last week.

The researchers from Queen Mary University, London, showed that women given this drug had a 10% increased chance of long-term cure than those just given chemotherapy (70% v 80% survival). Pembrolizumab, although expensive, has already been approved for use in these women in the UK via designated funding stream which oncologists have to apply for individually. This data will secure its long-term availability and make it routinely available.

What is triple-negative breast cancer? 

This refers to the fact that the cancer cells don’t have oestrogen or progesterone receptors (ER or PR) or overexpress a protein called HER2. This tends to be a more aggressive type of breast cancer, which can present at any age, but more likely in younger women with a family history and are carriers of the breast cancer susceptibility genes BRCA 1 and 2.

These breast cancers grow and spread faster, women often present with more advanced disease and hence have a worse prognosis. It represents one in five of the breast cancers so that’s about 8,000 women each year in the UK.

What is Pembrolizumab?

Pembrolizumab is a type of immunotherapy called a PDL-1 inhibitor. It is made by the pharmaceutical company, Merck with a trade name of Keytruda. It stimulates the body’s immune system helping it recognise cancer cells and foreign bodies so it can kill them. It costs the NHS about £3,000 a month per patient.

What should women do to help themselves whist taking pembrolizumab

Pembro, as it is now nicknamed, does have side effects from fatigue, skin rashes, lung inflammation, thyroid and steroid disorders. The risk of these can be reduced by being physically active, getting enough sleep, avoiding too much processed sugar and eating a healthy plant-based diet. It is also important to adopt strategies to enhance gut health as this will enhance immunity and help the pembro work. It has been shown that people with a good gut health whilst taking pembro have a 40% greater chance of it working and are less likely to suffer adverse side effects.

Strategies to improve gut health include eating more prebiotic rich foods such as mushrooms and beans as well as foods which contain healthy bacteria such as kimchi and for those who don’t eat these, a good quality probiotic capsule could help.

For further advice on lifestyle whilst on cancer treatments and afterwards, the book How to Live provides more in-depth explanations and practical advice.