Combining radiotherapy with immunotherapy could prevent therapy resistance

A recent study published in Cancer Research has found that treating cancer with both radiotherapy and immunotherapy at the same time could stop the disease from becoming resistant to treatment.

The study was carried out at The University of Manchester (Manchester, UK) with support from Cancer Research UK and MedImmune (part of AstraZeneca), where researchers demonstrated that a combination of the two treatments helped the immune system to identify and destroy cancer cells that were not killed by the initial radiotherapy in mice with breast, skin and bowel cancers.

Radiotherapy has been a successful treatment for many forms of cancer but in cancer cells that are not killed by this treatment it can switch on a ‘flag’ on the surface of the cancer cell, termed PD-L1. PD-L1 tricks the immune system into thinking that these cancerous cells do not pose a threat. Immunotherapy works by blocking these ‘flags’ to allow the immune system to identify these cancer cells and subsequently destroy them. In mouse models, this treatment improved survival and prevented the disease from returning.

Lead researcher Simon Dovedi (The University of Manchester), explained: “Using the body’s own defences to treat cancers has huge potential with early phase clinical trials demonstrating exciting patient benefit but we are still at the early stages of understanding how best to use these types of treatments. Combining certain immunotherapies with radiotherapy could make them even more effective and we’re now looking to test this in clinical trials to see just how much of a difference it could make.”

Nic Jones, chief clinician at Cancer Research UK, commented: “Around half of all cancer patients are given radiotherapy and it has been at the heart of helping improve survival rates so that today one in two cancer patients will survive for at least 10 years. Doctors and researchers are constantly looking for ways to improve treatments and this approach could open the door to a whole new way of giving radiotherapy.”

Sources: Dovedi SJ, Adlard AL, Lipowska-Bhalla G et al. Acquired resistance to fractionated radiotherapy can be overcome by concurrent PD-L1 blockade. Cancer Res. 74(19), 5458–5468 (2014); Cancer Research UK press release