The scientists said they were excited by their findings (Photo: ERIC PIERMONT/AFP/Getty)

A team of British and American scientists have discovered a way to slow the growth of breast cancer stem cells in the lab, which could eventually lead to combination drug therapies on previously untreatable forms of the disease.

Around three quarters of women who have breast cancer have what are known as oestrogen receptor positive tumours. Some breast cancer cells have receptors that bind to the hormone oestrogen and depend on it to grow. Though anti-oestrogen drugs such as tamoxifen and fulvestrant are able to prevent reoccurrence in most of these breast cancers, tumours reoccur in 1 out of 4 cases.

Many of the women relapse after several years, because some of the cancer cells remain after treatment. The cells, called cancer stem cells, lay dormant in the body and cannot be targeted by anti-oestrogen therapies.

Scientists have now found that cancer stem cells resistant to anti-oestrogen drugs express an immune system-related receptor, called interleukin 1 receptor. They also found that Anakinra, a drug used to treat rheumatoid arthritis, was able to reduce the ability of the cancer stem cells to grow.

However, the team said further research in animals and humans is needed before they can confirm if drugs targeting interleukin 1 receptor could be used as an effective treatment.

Scientists from the Universities of Michigan, Liverpool and Edinburgh were closely involved in the study led by Dr Bruno Simes and Professor Rob Clarke from The University of Manchester

Dr Simes said: Resistance to anti-oestrogen therapies in breast cancer patients is a major problem and one which cancer scientists have been trying to address for many years. Many drugs have been investigated by scientists as a possible combination therapy taken with anti-oestrogen therapies and we are still searching for a solution for these patients.

However, most of these drugs target actively dividing cells whereas we are trying to also target cells that are in a dormant state. So we hope that these women who have increased numbers of cancer stem cells and do not respond to currents treatment could one day benefit from combination therapy.

Theres a very long way to go before we can say if this approach will help these women but we are excited by our findings.

The study is published in the journal Stem Cell Reports.

Justin Stebbing, professor of cancer medicine and medical oncology at Imperial College London, said: Stem cells represent a very important target to understand better and eradicate, because they are responsible for some of the most worrying aspects of cancer, such as its ability to regrow, or be resistant to treatment. They are also a rare population but this laboratory research shows that cancer stem cells have on their surface a protein that we have a drug for interestingly one that is being trialled in Covid-19 too.

Hopefully, we can in the future link this laboratory work to research in women in the clinic, helping to reduce recurrence rates by eradicating rare stem cell populations that contribute to recurrence.

Baroness Delyth Morgan, chief executive at Breast Cancer Now, which helped fund the study, said: Its promising that targeting this protein [interleukin-1 receptor] may help reduce the growth of breast cancer stem cells, which are thought to be central to the disease spreading around the body, where it becomes incurable.

The development of resistance to hormone therapies remains a major challenge in the clinic. With around 11,500 women still dying from breast cancer each year in the UK, we urgently need to find new ways to prevent the disease spreading and to treat it more effectively when it does.

This exciting discovery highlights the importance of research to understand the molecular detail of how breast cancer spreads, and of investigating the potential of existing drugs to try to stop it. In particular, these findings offer further evidence that arthritis drugs such as Anakinra may be useful additions in treating breast cancer, and we hope further research can now help us fully understand their potential and whether and how they might work as a cancer treatment.

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Drug target for aggressive breast cancer found by team of UK and US scientists - iNews