Cat Poop Parasite Might help in the Fight Against Cancer

Researchers say that Toxoplasma gondii (T. gondii), a parasite found in cat feces, can be used to attack cancer tumors.

About a third of the world's population carries T. gondii. Most people don't show any symptoms, but a few do develop serious infection. The parasite had made headlines recently after a Danish study reported that women who are exposed to the parasite are more likely to commit suicide compared to other women.

Researchers at Geisel School of Medicine at Dartmouth say that the way a healthy immune system reacts to T. gondii infection is similar its attack on a tumor.

"We know biologically this parasite has figured out how to stimulate the exact immune responses you want to fight cancer," said David J. Bzik, PhD, professor of Microbiology and Immunology, Geisel School of Medicine at Dartmouth.

According to researchers, the human body, when exposed to T. gondii, produces natural killer cells and cytotoxic T cells - immune system cells also known to attack cancer. Most tumors shut down the body's immune system, but researchers speculate that by introducing T. gondii into the tumor environment, it might be able to restart the immune system.

"The biology of this organism is inherently different from other microbe-based immunotherapeutic strategies that typically just tickle immune cells from the outside," Barbara Fox, senior research associate of Microbiology and Immunology, said in a news release. "By gaining preferential access to the inside of powerful innate immune cell types, our mutated strain of T. gondii reprograms the natural power of the immune system to clear tumor cells and cancer.

Obviously, injecting a live, growing parasite in the human body - especially one that is suffering from cancer - isn't safe. So researchers have created "cps," an immunotherapeutic vaccine. The team has removed a key part of the parasitic genome, making it a mutant parasite that is capable of enhancing the immune response, but with being able to grow and replicate.

The team says that the cps vaccine can be customized to suit a cancer patient's need, thereby opening doors for new kinds of personalized cancer treatment.