With an estimated 1.6 million new cases of cancer to be diagnosed this year, finding a cure for the disease remains a top priority for many researchers. Now, investigators have looked to a parasite commonly found in cat feces – Toxoplasma gondii – to create a cancer vaccine.
T. gondii is a single-celled parasite that resides in the intestines of any warm-blooded animal, although its ideal environment is a cat’s intestines.
The parasite can be contracted through eating undercooked, contaminated meat, drinking contaminated water and ingesting it by coming into contact with cat feces that contain T. gondii. This can happen when cleaning a cat litter tray, for example.
T. gondii can cause a disease called toxoplasmosis, which can trigger flu-like symptoms and muscle aches and pains. Severe forms of the disease – most common among those with a weak immune system – can cause brain, eye or organ damage. However, the majority of people infected with T. gondii do not experience any symptoms.
According to the researchers of this latest study – including David J. Bzik, PhD, and Barbara Fox of the Geisel School of Medicine at Dartmouth College in Hanover, NH – they already knew that T. gondii has anti-cancer properties.
They explain that when the parasite enters the human body, cells that effectively fight cancer – such as cytotoxic T cells – are produced as a response. The team says that although cancer can shut down the body’s immune system, T. gondii can help restart it.
Since T. gondii replicates inside the body in order to spread, the researchers note that it is unsafe to inject live strains of the parasite into cancer patients, who will already have weakened immune systems.
As such, they created a mutant T. gondii parasite – named “cps” – that is unable to replicate, which they say makes it a safe cancer vaccination. According to Bzik:
“Aggressive cancers too often seem like fast moving train wrecks. Cps is the microscopic, but super strong, hero that catches the wayward trains, halts their progression and shrinks them until they disappear.”
On testing the cps vaccine on mouse models with aggressive melanoma and ovarian cancer, the mice showed significantly high survival rates. Bzik says the cps vaccine stimulates “amazingly effective immunotherapy against cancers, superior to anything seen before.”
The researchers say the vaccine could even be tailored to each patient. “In translating cps therapy to the clinic, we imagine cps will be introduced into cells isolated from the patient,” Bzik explains.
“Then, Trojan Horse cells harboring cps will be given back to the patient as an immunotherapeutic cancer vaccine to generate the ideal immune responses necessary to eradicate their cancer cells and to also provide life-long immunity against any future recurrence of that cancer.”
The researchers note that before cps can be tested in humans, they need to better understand the mechanisms behind it. However, they say that so far, it appears to hold “incredible promise” for new cancer treatments.
Medical News Today recently reported on a study published in The Journal of Leukocyte Biology that suggested antihistamines may be effective against cancer.