Researchers at the Princess Margaret Cancer Centre in Toronto have discovered that innate lymphoid cells inhibit the body's immune response to fight cancer. This is important because it may lead to a better understanding of why patients do or do not respond to immune therapies.

“We've uncovered a potential new approach to modulate immune response to cancer,” said Dr. Pamela Ohashi, Director, Tumour Immunotherapy Program at the cancer center. “By looking at tumor biology from this different perspective we'll have a better understanding of the barriers that prevent a strong immune response. This can help advance drug development to target the bad cells.”

The research team analyzed more than 100 patient samples from ovarian and other cancer types to discover a distinct population of cells found in some tumors. This population of cells suppresses the growth of cancer-fighting immune cells, thereby limiting the ability of the immune system to fight cancer.

Dr. Ohashi's team has been studying tumor-infiltrating lymphocytes (TIL), which are the cell type known to kill cancer cells. Patients with TILs do much better because they already have cancer-fighting cells in their tumors.

The team's next avenue of research will be focused on identifying a biomarker that can identify this distinct suppressive cell elsewhere in the body — for example, in blood or other samples — as a potential predictive clinical tool to determine when these cells are present in patients, which currently cannot be done.

“That knowledge will guide clinical decisions to personalize cancer treatment to unleash an individual's immune response,” Dr. Ohashi said. “We need to identify ways to track these cells and find another source and ways to grow these cells for further study.”

Dr. Ohashi envisions an era of combined therapies to simultaneously target and kill these suppressive cells while augmenting the immune response against cancer. “This would really strengthen the way clinicians can treat cancer using immune therapy, which holds so much promise for patients,” she said.

The findings were published online in Nature Medicine. [1]