Cancer: Immunotherapy Could Work by Unleashing Body's Own Natural Killer Cells

Scientists have offered new insight into how immunotherapy, a revolutionary cancer treatment that harnesses the power of the immune systems, works.

By focusing on the role the white blood cells known as natural killer cells play in the body's defense against cancer, the study broadens our understanding of the drugs known as immune checkpoint inhibitors, which prompt the immune system to attack the disease.

For years, it was believed these drugs targeted T cells. T cells have a number of jobs: some instruct the immune system on how to attack intruders such as viruses, others launch attacks themselves, while some aid B cells in creating antibodies.

Dr. Michele Ardolino, assistant professor at the Department of Biochemistry, Microbiology and Immunology at Ottawa Hospital and co-senior author of the study, told Newsweek: "We discovered that another population of white blood cells, called natural killer cells, is suppressed by the same mechanisms that suppress T cells and can be activated by the same immunotherapies known to activate T cells."

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"Our work challenges the central dogma about how cancer immunotherapy works," said Ardolino. "It opens up an exciting new avenue of research that could lead to even more effective immunotherapy treatments."

T cells and natural killer cells take different approaches to finding and killing cancer cells. Natural killer cells are the body's first line of defense, and pick up on wider trends of how cancer cells change. T cells, meanwhile, recognize individual abnormal molecules in cancer cells and launch a laser-focused attack.

The team at Ottawa Hospital behind the study, published in the Journal of Clinical Investigation, looked into the effects of checkpoint inhibitors in mice with cancer. They found the drugs still reduced the size of tumors in mice who didn't have T cells, suggesting other cells must be kicked into action to attack the disease. This hypothesis appeared to be bolstered when the drugs worked less potently in mice without natural killer cells. What's more, natural killer cells were shown to produce the same checkpoint receptor molecules as T cells. That indicates both cells can be awakened by these drugs.

A stock image showing a lung cancer x-ray. Researchers believe the body's natural killer cells could be harnessed in immunotherapy treatments. Getty Images

"While I was expecting that some effect of immunotherapy was mediated by natural killer cells, I was absolutely amazed by the discovery that eliminating natural killer cells in mice made immunotherapy completely ineffective in some tumor models," said Ardolino.

These findings could help make personalized cancer treatments a reality, according to Ardolino.

"I believe that immunotherapy is the ultimate personalized therapy and my dream is that one day a patient with a tumor would walk into an hospital and, by looking at the patient's tumor and immune system, we'd be able to provide a tailored and effective immunotherapy," he said. "A lot of work has to be done and funding basic research is essential to let this happen."