Treating cancers with immunotherapy and radiotherapy at the same time could stop them from becoming resistant to treatment, according to a new study. Combining the two modalities helped the immune system hunt down and destroy cancer cells that were not killed by the initial radiotherapy in mice with breast, skin, and bowel cancers.  The approach was found to improve survival and protect the mice against the return of the disease.

Radiotherapy is a very successful treatment for many forms of cancer. However, in cancer cells that it does not kill, it can switch on a flag on their surface called programmed death ligand 1 (PD-L1). PD-L1 tricks the body’s defenses into thinking that cancerous cells pose no threat.

The immunotherapy works by blocking these flags to reveal the true identity of cancer cells, allowing the immune system to see them for what they are and destroy them.

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This research was based at The University of Manchester in the United Kingdom and funded both by MedImmune, the global biologics research and development arm of AstraZeneca, and by Cancer Research UK.  It was published in Cancer Research (2014; doi:10.1158/0008-5472.CAN-14-1258).

“Using the body’s own defenses to treat cancers has huge potential. Early phase clinical trials have demonstrated 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 trial to see just how much of a difference it could make,” said Simon Dovedi, PhD, the lead researcher based at The University of Manchester and member of the Manchester Cancer Research Centre.

Approximately 50% of all cancer patients undergo radiotherapy, which has been at the heart of improved survival rates so that 1 in 2 patients with cancer 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,” said Professor Nic Jones, PhD, Cancer Research UK’s chief scientist.