Researchers are hard at work trying to find a cure for cancer, and the investigators from one recent study think the key to a vaccine may lie in a parasite commonly found in cat feces. Toxoplasma gondii, or T. gondii for short, is a single-celled parasite that resides in the intestines of warm-blooded animals, but its ideal environment is a cat’s intestines. It can be contracted by eating undercooked or contaminated meat, drinking contaminated water, and of course, through contact with cat feces. T. gondii can cause a disease called toxoplasmosis with flu-like symptoms and muscle aches and pains, but the majority of people infected do not experience any symptoms. The researchers explain that when the t. gondii parasite enters the human body, cells that fight cancer are produced in response. In essence, T. gondii can help boost the body’s immune system that would otherwise be shut down by cancer.
Because T. gondii replicates inside the body in order to spread, the study authors note that it is unsafe to inject live strains of the parasite into cancer patients. In response, they created a mutant T. gondii parasite, called “cps”, which is unable to replicate and would make a safe cancer vaccination. During the study, the cps vaccine was tested on mouse models with aggressive melanoma and ovarian cancer. The mice showed significantly high survival rates. The researchers believe the vaccine could also be tailored to each patient’s needs. While further investigation into the mechanisms behind the T. gondii parasite and the mutant version (cps) is needed before human testing can begin, the study authors say that the vaccine appears to hold promise for new cancer treatments.
Source: Baird J, Byrne K, Lizotte P, et al. Immune-mediated regression of established B16F10 melanoma by intratumoral injection of attenuated toxoplasma gondii protects against rechallenge. The Journal of Immunology, 2013; 190 (1): 469-478.