December 9, 2023

Scientists have discovered a previously unknown type of immune cell that develops in people who successfully fight cancer. Unlike other killer T cells, they can target multiple cancer-related targets simultaneously, preventing the formation of new tumors a year later and potentially leading to more effective cancer treatments.

Our immune system is our first line of defense against pathogens or disease, including cancer, but sometimes it needs a little help. This is the basis behind an emerging therapeutic field called immunotherapy, which involves removing immune cells from patients, boosting them and then returning them to attack the cancer with renewed vigor.

In the new study, Cardiff University researchers investigated possible biological differences between successful and unsuccessful treatment rounds in different patients. For more than a decade, they have conducted phase I and II clinical trials examining so-called tumor-infiltrating lymphocyte (TIL) therapy, which focuses on white blood cells that are already at work in patients’ tumors.

The researchers focused on patients whose cancer was successfully cleared after treatment. They exposed patients’ blood samples to tumor cells previously collected from the same patients and found that the survivors’ killer T cells showed a very strong response even a year after entering remission.

They used algorithms designed to predict which targets these T cells were recognizing based on the differences between healthy and cancer cells. To their surprise, the scientists found that T cells from cancer-beating patients were able to recognize multiple protein changes in cancer cells. In contrast, each T cell is generally thought to target only one protein at a time.

“Multiple-pronged killer T cells from cancer survivors are much better at recognizing cancer than normal anti-cancer killer T cells,” said lead researcher Professor Andy Sewell on the study. “Additionally, the ability to respond to multiple cancer-associated proteins simultaneously means that these T cells can respond to most types of cancer, as cancers only need to express one abnormal target to be recognized as dangerous and killed.”

The team then found large numbers of these multitubular T cells in the blood of patients who had successfully cleared their cancer, but not in patients whose cancer had progressed.

Future work is needed to definitively demonstrate the link between these T cells and cancer clearance, the team said. Understanding what these immune cells are targeting should also help improve other cancer treatments.

“We’ve now seen multipronged T cells in multiple cancer survivors, so examining whether these cells are associated with good prognosis will be a key next step,” said Garry Dolton, Ph.D., lead author of the study. It will take several years, but we are encouraged by the findings so far.”

The study was published in the journal cell.

source: Cardiff University