Tumours produce ‘anti-immune cells’ capable of inhibiting the immune response, according to new research. 

Researchers at the Princess Margaret Cancer Centre in Toronto, Canada discovered the cell sub-population by analysing more than 100 patient samples from ovarian and other cancer types whilst investigating the role of innate lymphoid cells (ILCs) in the context of each cancer.

Recent research has shown ILCs – a set of immune cells involved in non-specific immune responses – regulate the activity of adaptive T cells. T cells make up the backbone of the adaptive immune response, helping create immunity to infections.

T cells are also one set of immune cells that frequently migrate into tumours as they identify cancer cells and attempt to destroy them. These immune cells are called tumour-infiltrating lymphocytes (TILs).

The team discovered a unique ILC cell population in tumour samples which they then added to TIL lab cultures to investigate their effect. The ILCs were found to inhibit expansion of TILs through the production of a molecule called NKp46 as well as alter their expression of a key set of signalling molecules called cytokines. The presence of ILCs in TIL cultures also led to a much shorter time until disease recurrence.

“We’ve uncovered a potential new approach to modulate the immune response to cancer,” said Dr Pamela Ohashi, principal investigator for the study. “By looking at tumour 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 these barriers.”

For future drug development, Ohashi’s team’s discovery could lead to combined therapies aimed at suppressing these anti-immune cell populations in tumour whilst enhancing the immune response against cancer. If the supposed role of these ILCs is accurate, their suppression could lead to far more effective treatments for cancer patients, particularly as a method of improving those existing treatments designed to amplify the immune system to fight off the disease.

The team will now move on to identifying a molecule specific to these ILCs to potentially act a predictive test to determine how well a patient will respond to treatment.

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