You may know that Toxoplasma gondii, the parasite commonly found in cat feces, is linked to a number of adverse health consequences, such as rage disorder and even schizophrenia. However, new research suggests that the parasite may actually have a use in the medical world, and could play a role in research to find the elusive cure for cancer.

Scientists from Dartmouth’s Geisel School of Medicine found that a specific protein secreted by T. gondii causes the immune system in mice to attack ovarian tumors, ultimately increasing their chances of survival. The scientists hope they can replicate these results and eventually use the protein in the immunotherapy treatments currently administered to human ovarian cancer patients.

Past research has shown that a safe vaccine strain of T. gondii could cure several types of tumors in mice; however, in this recent study, the Dartmouth team wanted to understand why. To do this, the team systematically deleted genes in the parasite and then injected these altered parasites into mice with aggressive ovarian cancer to see what would happen. Eventually, through this trial and error process, they were able to identify the specific protein excreted by the parasite that was responsible for the cancer-fighting effect.

Although the research is still in its infancy, the study shows promise in treating ovarian cancer, a serious condition that accounts for about three percent of all cancers among women. According to the American Cancer Society, about 22,280 women will receive a new diagnosis of ovarian cancer in 2016, and about 14,240 women will die from ovarian cancer — the fifth in cancer deaths among women.

Immunotherapy itself relies on utilizing the patient’s own immune system to combat cancer. Part of what makes cancer so deadly is its ability to evade the body’s immune system. This ability to hide, also called immune tolerance, makes it difficult for the immune system cells to know which cells to attack. As a result, cancer is allowed to grow and spread.

However, in mice, T. gondii helps to break the ovarian cancer cell’s immune tolerance, making it easier for the mice’s immune system to effectively detect and destroy aggressive ovarian cancer cells. There are already clinical trials underway to explore the usefulness of bacterium Listeria monocytogenes in breaking the immune tolerance of pancreatic tumors.

Source: Fox BA, Sanders KL, Rommereim LM, Guevara RB, Bzik DJ. Secretion of Rhoptry and Dense Granule Effector Proteins by Nonreplicating Toxoplasma gondii Uracil Auxotrophs Controls the Development of Antitumor Immunity. PLoS Genetics. 2016.