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Drugs commonly used to treat arthritis may help to prevent breast cancer spreading to the bone, where it is incurable, new research suggests. 

In a new study published in Nature Communications, scientists from the University of 91̽�� and The University of Manchester propose that NHS arthritis drugs anakinra, canakinumab and sulfasalazine could in future be repurposed to help treat breast cancer, following the discovery of the role of bone marrow in the spread of the disease to the bone. 

The new study - that was largely funded by research and care charity Breast Cancer Now - found that bone marrow releases a protein called interleukin 1-beta (IL-1β) which encourages breast cancer cells to form secondary tumours once they reach the bone. 

The study established that the process started by this molecule can be blocked by drugs already used in treating arthritis, with anakinra found to be able to prevent breast cancer forming secondary tumours in the bone. 

Dr Penelope D Ottewell, Senior Lecturer in Bone Biology at the University of 91̽��’s Department of Oncology and Metabolism, said: “Discovering that a molecule, known as IL-1β, is responsible for growth of breast cancer in the skeleton is very exciting. 

“Drugs currently available on the NHS to treat rheumatoid arthritis, including anakinra and canakinumab inhibit activity of IL-1β. Our findings indicate that these drugs could be rapidly repurposed to provide benefit to late stage breast cancer patients whose tumours are likely to spread to the bone.” 

Breast cancer is the UK’s most common cancer and around 11,500 women still lose their lives each year. Almost all of these deaths are attributable to secondary breast cancer, where breast cancer has spread to form tumours in other parts of the body, which can be controlled, but not cured. 

One of the most common parts of the body for breast cancer to spread to is the bone, which can cause debilitating symptoms such as joint pain or fractures that often require surgery. 

The growth of breast cancer cells was investigated in the lab and in mice to establish what helps the disease settle and grow in a new location. They discovered that the molecule IL-1β (which is released by bone marrow) was responsible for helping breast cancer stem cells grow into tumours and these findings were supported using data from patients with secondary breast cancer¹. 

Drugs that can inhibit the action of IL-1β already exist and are used in treating other conditions on the NHS. Research is now ongoing to understand how blocking the action of IL-1β to stop breast cancer spreading may affect the immune system, and whether the drugs currently available could work with existing therapies - including bisphosphonates - to prevent the spread of the disease to the bone. 

Lead author Dr Rachel Eyre, from The University of Manchester, said: “We are very excited by our results in the lab showing that breast cancer in bone can be prevented using drugs that are already approved for other diseases. We hope it can soon be established whether these drugs can be used for breast cancer patients following successful testing in clinical trials. 

“We will now look to see if similar processes are also involved in breast cancer growing in other organs, such as the liver and lungs. We hope that by continuing this work, we could in future identify those at high risk of their breast cancer spreading, and where possible use drugs already available to prevent this from happening.” 

Baroness Delyth Morgan, Chief Executive at Breast Cancer Now, said: "These major findings offer another promising step forward in repurposing existing drugs to prevent the spread of breast cancer.

"While more research is needed, it’s really exciting that these well-tolerated and widely-available arthritis drugs may help prevent secondary breast cancer in the bone. 

“If further research can now help us fully understand how these arthritis drugs would work as a cancer treatment, we hope these drugs can be quickly advanced into clinical trials for breast cancer patients.”