Toxoplasma gondii + cancer cure

Cat poop doesn't cure cancer


Let's begin with saying that  headlines like "Cat poop curing cancer" are of course only sensationalists. The form of toxoplasma a cat poops out, will give you toxoplasmosis, unless you have it already. What is used in laboratory is called the asexual form, that in addition was genetically modified.



Toxoplasma parasite to fight cancer?


Scientists from the Geisel School of Medicine's Department of Microbiology and Immunology of Dartmouth Medical School, may have found a way to cure cancer with a modified Toxoplasma gondii strain, that reprograms the natural power of the immune system to clear tumor cells and cancer.



A new approach to cancer therapy


Historically, there have been three main approaches to treating cancer: radiation, surgery, and chemotherapy. Immunotherapy is becoming the fourth leg. And the approach taken by Steven Fiering and other Dartmouth scientists maybe quite revolutionary:


The idea is that instead of surgically removing the tumor, to inject an immunostimulatory set of agents, one of which could be the T. gondii strain, thus stimulating the immune system to attack the tumor.


In aggressive cancers like melanomas and ovarian cancer, the classical treatment is to surgically debulk the tumor, and then use chemotherapy, but if the tumor recurrs after remission, it can be very difficult to treat.


The researchers are working for this types of cancer on an highly personalized approach, tailored to the individual patient: Introducing cps (an attenuated strain of Toxoplasma gondii) into cells isolated from the patient to fight the cancer and provide immunity against recurrence.


Since it isn't safe to inject a cancer patient with live replicating strains of T. gondii, the scientists created what they called "cps". A safe version that can trigger the desired immune response without posing any threat of its own, obtained  by removing a gene that is critical to the parasite’s ability to self-replicate in animals or people, but can be grown in laboratory.


When T. gondii can't reproduce, it's a it's a great vaccine for toxoplasmosis, for AIDS and cancer patients and may help cure cancer in quite a innovative way.


Like normal T. gondii, this strain enters host cells, stimulates a strong immune response, and, after about a week, the nonreplicating parasites are eliminated by the immune system.


In response to T. gondii, the body produces natural killer cells and cytotoxic T cells which wage war against cancer cells.


"We know biologically this parasite has figured out how to stimulate the exact immune responses you want to fight cancer," said David J. Bzik in a press release.


It's a promising possibility because it can work very powerfully against tumors and may be effective in the clinic. In laboratory tests this Toxoplasma treatment has the ability to completely cure established tumors and to then prevent their recurrence, providing life-long immunity against that cancer.

So far, tested in mice, cps needs a great deal more research before it leaves the laboratory.

David J. Bzik, PhD, of Dartmouth's Geisel Medical School, has been experimenting with toxoplasma for at least a decade and he opines that toxoplasma is a weird and wonderful microbe that still has surprises in store for humanity...



Dartmouth-Hitchcock Norris Cotton Cancer Center

The Journal of Immunology, January 1, 2013, vol. 190 no. 1 469-478