Scientists discover immune cells that 'hunt down' cancer in the body

Scientists have made a discovery that could help bring about new treatments for advanced breast cancer.

A new study has uncovered a group of immune cells, called immune B cells, that hunt down cancer in the body, making them successful at targeting the disease when it spreads through the body, including tumours.

Findings, published in Nature Immunology, show that when a receptor on the B cell identifies a cancer cell and binds to it, the B cell changes to be even more effective at targeting those cancer cells. Researchers have developed a tool aimed at spotting these anti-cancer cells, which they say could lead to better, personalised immunotherapies for patients.

Immunotherapy uses someone’s own immune system to fight cancer, and works by helping it recognise and attack cancer cells.

Breast cancer is the most common cancer in women in Scotland, accounting for 28 per cent of all diagnoses, excluding non-melanoma skin cancer, according to The Scottish Public Health Observatory. In 2022 there were 4,644 patients diagnosed with breast cancer, Public Health Scotland figures report.

Dr Stephen-John Sammut, first author on the study and leader of the Cancer Dynamics Group at The Institute of Cancer Research, London, (ICR) said: “Once cancer spreads to other parts of the body, it’s often much more difficult to treat.

“Our research has revealed that the immune response to cancer isn’t limited to the site where a tumour initially appears – if an immune B cell is successful at detecting cancer in one part of the body, it will search for similar cancer cells elsewhere in the body.”

The consultant medical oncologist at The Royal Marsden NHS Foundation Trust, added: “Currently there are very few immunotherapies that can be used to treat breast cancer. The computational tool we have developed will allow us to zoom in and identify the B cells that have recognised cancer cells, as well as the antibodies they are producing.

“This will allow us to develop anti-cancer antibody treatments similar to the ones the B cells produce, which can then be given as a personalised treatment to boost the immune system’s response against breast cancer that has spread.”

Scientists at the ICR, the University of Oxford and University of Cambridge, took biopsies from patients with breast cancer and identified genetic variations in the B cells. B cells are part of the immune system and produce proteins called antibodies which stick to harmful substances such as viruses and cancer, and recruit other parts of the immune system to destroy them.

The team studied the B cells of people with advanced breast cancer who had died, after their cancer had spread to other parts of the body. They also looked at a group of patients with early breast cancer, as they were treated with chemotherapy over time.

Some unique B cells which had changed – after identifying and targeting cancer cells – were present at multiple tumour sites the cancer had spread to, the researchers found. This means that recognising cancer in one area of the body, B cells hunt down cancer at different sites around the body.

Other B cells which were found only in one tumour site were less likely to have changed and did not perform effective cancer surveillance. The researchers used this information to develop a tool to predict which B cells were most likely to successfully detect and target cancer cells.

Professor Kristian Helin, chief executive of the ICR, said: “Immunotherapies have transformed the outlook for a range of different cancers but, unfortunately, they still only work for a minority of patients.

“We need a greater understanding of how the immune system defends the body against cancer and most research has, until now, focused on the role of T cells – with CAR-T cell therapy being the best-known treatment to come from that research.

“This study provides a fascinating insight into the role of B cells over the course of a cancer’s growth and spread, and I look forward to seeing this tool used to focus efforts for the development of personalised cancer immunotherapies which could work in far more people than most existing immunotherapies.”

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