Providence researchers find immunotherapy treatment synergizes with targeted radiation eliminating tumors, destroying errant cancer cells

January 13, 2016

Providence researchers have identified an immunotherapy approach that synergizes with radiation so well it not only eliminated the tumor in most preclinical models with pancreatic cancer, it found and destroyed distant, cancer cells – which could have grown into lethal metastatic tumors.

The findings, “Radiation therapy combined with novel STING-targeting oligonucleotides results in regression of established tumors,” have been posted online and are published in the January issue of the journal Cancer Research. The study will be featured on the cover of the journal, as well.

The immune system is designed to fight infections of all kinds. However, it also constantly searches out and destroys cancer cells in the body. Cancer cells can survive this attack in two ways: some of these cells are able to hide from the immune system, while others can actually turn off or suppress the immune system. The goal of immunotherapy researchers is to find ways to reactivate the immune system so it can identify and eliminate cancer cells.

Through extensive research, a team led by Michael Gough, Ph.D., and Jason Baird, Ph.D., from the Robert W. Franz Cancer Research Center in the Earle A. Chiles Research Institute at Providence Cancer Center, found that the combination of CT-guided radiation therapy and a STING, or STimulator of Interferon Genes, ligand could work together to attack and kill local and distant tumors. The researchers call this dual approach STINGray.

“Radiation therapy is very effective at killing cancer cells, STING ligands are very effective at activating the immune response – together they are a potent combination,” Gough said. “I have never seen tumors cleared so quickly.”

The treatment in the study required radiation therapy precisely targeted to the tumor using image guidance, and two injections of the novel agent into the tumor. After that, the immune response did the rest. When immune responses were suppressed, the tumors re-grew.

Providence researchers are going on to develop methods to treat cancers that cannot be reached by injection, using the power of radiation therapy to target tumors anywhere in the body.

“There is massive potential here,” Baird said. “We need to know whether this works with other therapies, and we need to know if this can work in patients.”

“We have seen this work in models of other cancer types, including lung cancer, breast cancer and head and neck cancer, so this might be very effective.”

According to the American Cancer Society, nearly 49,000 people in the United States will be diagnosed with pancreatic cancer in 2015. More than 40,000 will die from the disease. Pancreatic cancer spreads rapidly and is seldom detected in its early stages, which is why it is a leading cause of cancer death. Often it is quite advanced at diagnosis and complete surgical removal is not possible.

The research was supported in part by funding from a National Cancer Institute grant to Gough. In addition, Baird recently was awarded a prestigious American Cancer Society postdoctoral fellowship to move this work forward.

Researchers at the Earle A. Chiles Research Institute at Providence Cancer Center have focused on immunotherapy for the past two decades, considering it the fourth modality for treating patients with cancer in addition to surgery, chemotherapy and radiation.

Providence is an international leader in immunotherapy research. Immunotherapy takes advantage of a patient’s own immune system, activating it in a way that allows it to attack and eradicate the cancer while minimizing damage to normal tissue.