University of Cambridge researchers have discovered the reason for the failure of anti-cancer vaccines, in a step that could pave the way for the development of effective cancer vaccines in the future.

A normal cell type found in tumours may be preventing the immune system from killing cancer cells. This has important consequences for vaccines, as they act to boost this immune response.

The findings have generated a lot of interest within the scientific community. Dr Claire Knight, from Cancer Research UK, described the findings as providing “exciting clues” as to how tumour cells evade the immune system by coercing health cells.

Vaccines developed to kill tumours by attacking cancerous cells have heretofore not affected the growth of tumours.

The new research, published last week, suggests that this is due to a subset of normal connective tissue cells called stromal cells, scattered throughout tumours, which help provide support to tissues and cells.

These stromal cells express a protein normally involved in wound healing called fibroblast activation protein alpha (FAP) that is thought to cause immune suppression in and around the tumour.

Cambridge scientists engineered a mouse in which cells expressing FAP could be destroyed. When this was carried out in animals with lung cancer, the cancer ‘died’ rapidly.

However Professor Douglas Fearon from the Cambridge University Department of Medicine emphasised that although the identification of these cells was an “important step,” these findings are based on mouse models and “although there is much overlap between the mouse and human immune systems, we will not know the relevance of these findings in humans until we are able to interrupt the function of the tumour stromal cells expressing FAP in patients with cancer.”

Consequently, the Fearon lab is hoping to collaborate with the Cancer Research UK Cambridge Research Institute to repeat the findings in a model that more closely resembles human cancer and to examine the FAP-expressing stromal cells in human tumours.

Fearon explained that “further studying of how these cells exert their effects may contribute to improved immunological therapies by allowing us to remove a barrier that the cancer has constructed.”

Although still at an early stage, manipulation and selective destruction of these cells could result in a cancer vaccine being a realistic prospect.