Rare Immune Cells Prevent Cancer from Spreading
Cancer metastasis, the spreading of tumors to different tissues in the body, is usually what makes cancer so lethal and difficult to treat. But scientists have now identified a rare immune cell that, when injected, could prevent metastasis. A new study from the University of British Columbia shows how this is possible.
A group of killer T cells (green and red) surrounding a cancer cell (blue, center). Killer T cells use special chemicals to kill cancer cells. Credit: National Institutes of Health
The trials and tribulations of cancer immunotherapy, a treatment approach based on boosting the immune system to fight cancer, are well-known to scientists studying cancer and the immune system’s role in defeating it. Immunotherapy has been shown to be effective in blood-borne cancer types, like lymphoma, but less effective in treating solid tumors.
Why do we need immunotherapy? Why can’t the immune system naturally fight off cancer on its own? Tumors tend to “hide” from the immune system. Some can do so because they lack a protein called interleukin-33 (IL-33), allowing cancer cells to proliferate and metastasize freely, uninhibited by an immune attack.
However, a new finding may help scientists shine a light on the dark corners of the body infested with growing tumors. IL-33 normally activates cells called type-2 innate lymphoid cells (ILC2). And although some cancers lack IL-33, scientists can activate ILC2 cells manually to treat cancer.
Innate lymphoid cells were only first discovered in 2008. Scientists studying asthma identified type-2 innate lymphoid cells specifically. Uniquely, these cells do not require activation by cancer antigens, like other cells of the immune system. This means that scientists could inject ILC2 cells without needing to alter them in the lab first.
In the new study, researchers examined mice models of lung cancer, genetically altered to lack ILC2 cells. Would tumors grow faster in ILC2-deficient mice, compared to control mice with normal levels of the immune cell? They did, but even more noticeable was the rate of metastasis in the ILC2-deficient mice compared to the control mice; in mice without ILC2, tumors spread all over the body.
“These results raise the possibility that harnessing the immune system to fight cancer might be a matter of more effectively triggering ILC2 cells with IL-33, or simply having more ILC2 cells – or perhaps a combination of both,” explained study leader Wilf Jefferies.
Going forward, Jefferies and his team plan to investigate if injecting mice with ILC2 will inhibit metastasis. The study and other builds a foundation for future clinical trials with ILC2 injections for human cancer patients.
The present study was published in the journal Scientific Reports.