Radiation therapy not only kills cancer cells, but also helps to activate the immune system against their future proliferation. However, this immune response is often not strong enough to be able to cure tumours, and even when it is, its effect is limited to the area that has been irradiated. Now, however, research to be presented to the ESTRO 35 conference has shown that the addition of an immune system-strengthening compound can extend the radiation therapy-induced immune response against the tumour sites and that this response even has an effect on tumours outside the radiation field.
Ms Nicolle Rekers, MSc, from the Department of Radiation Oncology, Maastricht University Medical Centre, Maastricht, The Netherlands, will describe to the conference how a combination of radiation therapy and L19-IL2, an immunotherapy agent, can increase significantly the immune response when given to mice with primary colorectal tumours. L19-IL2 is a combination of an antibody that targets the tumour blood vessels and a cytokine, a small protein important in cell signalling in the immune system.
The researchers found not only that the mice were tumour-free following treatment, but also that when re-injected with cancer cells 150 days after cure, they did not form new tumours. There was also an increase in the number of cells with an immunological memory.