Immunotherapy Combined with Radiation Amplifies Effects of Treatment

Researchers at the University of Chicago completed a recent cancer study with mice as subjects. The mice were given a combination of radiation therapy with anti-tumor vaccines, and this improved the response of the cells in the immune system that fight cancer. It led to tumor regression in the mice.

The blocking of immune checkpoints, which are molecules that stop immune cells from being able to fight cancer in our bodies, is serving as a promising new treatment for various cancers. Most patients do not benefit from only blocking the checkpoints though because that does not help the tumor-fighting T-cells infiltrate the tumor. Rather, they require some sort of combination therapy to see any actual results.

Radiation has often been used as part of a combination therapy because it causes damage to tumor DNA, thereby killing some tumor cells. Additionally, it radiation also helps the immune system recognize the cancer cells that need to be destroyed.

The researchers in this study wanted to see if the radiation therapy could help in mice with pancreatic cancer. The mice in the study had PD-L1, which is a gland on a tumor that makes it highly resistant to just one kind of therapy. It has the ability to turn immune cells off.

The director of the study was pleased with the results. He said that they now had a “step by step strategy” to get past the normal barriers associated with cancer treatment and get more cancer-fighting T-cells to turn “on” and join the fight. By increasing the amount of T-cells that are infiltrating the tumor, the combination treatment became more effective.

The researchers then studied 183 human pancreatic cancer cells and found that the ones with the worst outcomes were the ones that had a low amount of T-cells fighting the tumor and a high expression of the PD-L1 gland.

They then recreated these conditions in the mice and found that the checkpoint inhibitors by themselves or in combination with a vaccine did not stop tumor growth. However, when radiation was introduced, the tumor growth was halted which suggests that radiation breaks down some barriers for these other treatments to make them more effective. This means it further promotes a healthy and responsive immune system as well.This new strategy could be used to fight many cancer types because it makes radiation treatment multi-purpose.