How Do Some Cancer Cells Evade Immune System?

The loss of interleukin-33 allows tumors to hide from the immune system.

Researchers have identified how cancer cells become invisible to the body’s own immune system, according to a new study published in Scientific Reports.

“The immune system is efficient at identifying and halting the emergence and spread of primary tumors but when metastatic tumors appear, the immune system is no longer able to recognize the cancer cells and stop them,” said senior study author Wilfred Jefferies.

In the current study, researchers discovered how these tumors were able to avoid the immune system.

“We discovered a new mechanism that explains how metastatic tumors can outsmart the immune system and we have begun to reverse this process so tumors are revealed to the immune system once again,” Jefferies said.

It is known that over time, cancer cells genetically change and evolve, however, the results of the new study showed that as cancer cells evolve, they may lose the ability to create the protein interleukin-33 (IL-33). When the IL-33 proteins begin to disappear from the tumor, the immune system can no longer recognize the cancer cells, which allows them to metastasize.

The loss of IL-33 was found to occur in epithelial carcinomas, which includes breast, cervical, kidney, lung, pancreatic, prostate, and uterine cancers.

For the study, researchers examined several hundred patients. They found that prostate or renal cancer patients with tumors that lost IL-33 had more rapid recurrence of their cancer over a 5-year period.

“IL-33 could be among the first immune biomarkers for prostate cancer and, in the near future, we are planning to examine this in a larger sample size of patients,” said first study author Iryna Saranchova.

The research team found that putting IL-33 back into metastatic cancers helped revive the immune system’s ability to recognize tumors. Although researchers have long tried to use the immune system to fight off cancer, it’s only been in the last couple of years that treatments have been identified that show potential.

Next, researchers will begin to study whether testing for IL-33 is an effective way to monitor the progression of certain cancers. Furthermore, additional research will examine whether putting IL-33 back into metastatic cancers could be an effective treatment option in humans.