Using the immune system to put cancerous cells to sleep

Researchers at the University of Fribourg have shown that chemotherapy used in the treatment of breast cancer can activate the immune system in such a way as to put tumour cells to sleep, thus reducing the risk of relapses. These are important results which open new therapeutic perspectives.

Breast cancer is one of the most common cancers in Switzerland. Post-operative supplemental therapies, such as radiotherapy or chemotherapy, substantially improve recovery rates. It is generally thought that the benefits which accrue from adjuvant chemotherapy are due to their ability to kill remaining tumour cells directly. Professor Curzio Rüegg’s team have recently identified a new mechanism which enables chemotherapy to activate the immune system so that it induces a state of dormancy, or prolonged sleep, in tumour cells.

A mechanism similar to viral infections
To better understand the effects of adjuvant chemotherapy, the principal authors of the study, Sanam Peyvandi et Qiang Lan, began by treating breast cancer cells with chemotherapy drugs commonly used on patients. They then tested the behaviour of the surviving cells. Their results showed that these cells formed only very few tumours and, what is more, that these had a very long period of latency. They subsequently demonstrated that the previously treated tumour cells had acquired the ability to activate the immune system by way of interferons, a means normally activated following a viral infection. They also established that the T-cells, as well as the molecular mechanisms associated with them, are essential to this protective effect. And finally, the researchers of the University of Fribourg, in collaboration with Dr Christine Desmedt of the Jules Bordet Institute in Brussels, established that patients treated with chemotherapy for breast cancer who developed an interferon immune response had an increased level of therapeutic benefit.

These new and significant studies show that, in certain patients, chemotherapy induces an interferon immune response normally only observed during responses to viruses and that this is able to induce a prolonged dormant state in surviving tumour cells. The research results lead the way to improving the effectiveness of adjuvant treatments for breast cancer.