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 tumors, 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 today (Sunday) has shown that the addition of an immune system-strengthening compound can extend the radiation therapy-induced immune response against the tumor sites and that this response even has an effect on tumours outside the radiation field.
A combination of radiation therapy and L19-IL2, an immunotherapy agent, can increase significantly the immune response when given to mice with primary colorectal tumors. L19-IL2 is a combination of an antibody that targets the tumor blood vessels and a cytokine, a small protein important in cell signaling in the immune system.
The researchers found not only that the mice were tumor-free following treatment, but also that when re-injected with cancer cells 150 days after cure, they did not form new tumors. There was also an increase in the number of cells with an immunological memory.