Updated 09 September 2014

Cat poo parasite could cure cancer

The tiny toxoplasmosis parasite found in cat faeces shows great promise as a cancer fighter.

Researchers at the Norris Cotton Cancer Center and the Geisel Scool of Medicine, Dartmouth, USA, are using a mutated form of the Toxoplasmosis cat parasite to stimulate the immune system to kill tumour cells.

Toxoplasma gondii (T. gondii) is a microscopic parasite found most often in cats' intestines, although it can live in any warm-blooded animal - including humans. A third of the world's population is infected with T. gondii.

Read: Cat faeces a danger to unborn children

It is acquired by swallowing the parasite from contaminated food or cat faeces. (For example, if hands aren't adequately washed after cleaning the litter box, and then used for preparing or eating food.)

Most people have no symptoms, but some experience a flu-like illness. In people with suppressed immune systems, however, for example patients with HIV/Aids or those undergoing chemotherapy, T.gondii can can develop into a serious illness, toxoplasmosis.

Toxoplasmosis typically causes infection of the brain, which, unless treated in time, may progress to coma and death.

Toxoplasmosis and HIV

From lab to litter-box

T.gondii triggers a healthy immune system to respond in a very similar way to how it would tackle a tumour. In response to T. gondii, the body produces defender cells of the same type that it generates to fight cancer.

Cancer often weakens the body's defensive mechanisms, but introducing T. gondii into a tumour environment can give the immune system a "jump start".

As it wouldn't be safe to inject a cancer patient with live strains of T. gondii, the researchers created "cps," a genetically engineered, mutant parasite that can be grown in the laboratory but can't reproduce in animals or people. Nonetheless, cps still retains its unique biological makeup that stimulates the ideal vaccine responses.

David J. Bzik, Professor of Microbiology and Immunology at the Geisel School of Medicine, compares the action of cps on "train wreck" aggressive cancers to a microscopic superhero that catches the wayward train, halts its progression, and shrinks it to nothing.

Lab victories over melanoma and ovarian cancers

Laboratory studies from the Geisel School of Medicine have tested the cps vaccine in extremely aggressive mouse models of melanoma and ovarian cancer, and found unprecedented high rates of survival.

Bzik said that cps stimulated amazingly effective immunotherapy against cancers, superior to anything seen before.

Promising future for personalised cancer vaccine

Much more work is needed before cps can leave the laboratory for the clinic, but the researchers hope it can be tailored to treat individual patients in future.

Bzik explained that his team envisages introducing cps into cells isolated from the patient. Then these "Trojan Horse" cells would be returned to the patient as an immunotherapeutic cancer vaccine, to stimulate the immune response for eradicating the cancer cells, and also providing life-long immunity against future recurrence of that cancer.

Read more:
The real crazy cat people
Toxoplasmosis: know this about your kitty
Toxoplasmosis linked to schizophrenia

- Adapted for Health24 from a press release by the Norris Cotton Cancer Center

Image of kitten in litterbox: Shutterstock

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