Scientists at King’s College in London have come up with a new treatment researchers say could be a “game changer” for the thousands of men who have advanced prostate cancer. It’s a cancer fighting protein that’s injected directly into the tumor to boost the immune system to kill malignant cells.

The injections consist of a man-made version of a naturally occurring protein called interleukin or IL-15 which increases the number and vigor of cancer-fighting cells to shrink tumors.

The hope is that in upcoming clinical trials, the protein will not only shrink tumors but also provide lasting protection again the disease. According to the Daily Mail, our cells naturally contain minute amounts of IL-15 but injecting it into the tumor boosts the levels of protein, which helps the immune system attack the cancer.

Nearly three-quarters of men diagnosed with advanced prostate cancer die within four years. One of the reasons for that alarming statistic is that there are minimal treatment options once the cancer has spread to other organs of the body. The British researchers hope that the new immunotherapy protocol will change that.

So far, early lab trials have shown that IL-15 managed to shrink tumors by more than half, notes senior research fellow Dr. Christine Galustian.

“This has the potential to be a real game changer for men with prostate cancer,” she says.

The American Cancer Society estimates that there will be about 164,690 new cases of prostate cancer in the United States in 2018 and about 29,430 men will die. It’s the most common cancer in American men, other than skin cancer, and about 1 in 9 will be diagnosed in his lifetime.