Toxoplasma gondii can stop cancer in its tracks as a vaccine

July 18, 2014

Toxoplasma gondii (T. gondii) is a single-celled parasite that is happiest in a cat's intestines, but it can live in any warm blooded animal. Found worldwide, T. gondii affects about one-third of the world's population, 60 million of which are Americans. Most people have no symptoms, but some experience a flu-like illness. Those with suppressed immune systems, however, can develop a serious infection if they are unable to fend off T. gondii.

An Anti-Cancer Agent in Nature?

A healthy responds vigorously to T. gondii in a manner that parallels how the immune system attacks 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.

In response to T. gondii, the body produces and cytotoxic T cells. These cell types wage war against . Cancer can shut down the body's defensive mechanisms, but introducing T. gondii into a tumor environment can jump start the immune system.

"The biology of this organism is inherently different from other microbe-based immunotherapeutic strategies that typically just tickle from the outside," said Barbara Fox, senior research associate of Microbiology and Immunology. "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."

Engineering T. gondii as a Cancer Vaccine

Since it isn't safe to inject a cancer patient with live replicating strains of T. gondii, Bzik and Fox created "cps," an immunotherapeutic vaccine. Based on the parasite's biochemical pathways, they delete a Toxoplasma gene needed to make a building block of its genome and create a mutant parasite that can be grown in the laboratory but is unable to reproduce in animals or people. Cps is both nonreplicating and safe. Even when the host is immune deficient, cps still retains that unique biology that stimulates the ideal vaccine responses.

"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," said Bzik.

Laboratory Success in Melanoma and Ovarian Cancers

Published laboratory studies from the Geisel School of Medicine at Dartmouth labs have tested the cps vaccine in extremely aggressive lethal mouse models of melanoma or ovarian cancer and found unprecedented high rates of cancer survival.

"Cps stimulates amazingly effective immunotherapy against cancers, superior to anything seen before," said Bzik. "The ability of cps to communicate in different and unique ways with the cancer and special cells of the immune system breaks the control that cancer has leveraged over the immune system."

A Promising Future for a Personalized Cancer Vaccine

This new weapon against cancer could even be tailored to the individual patient. "In translating cps therapy to the clinic, we imagine cps will be introduced into cells isolated from the patient. Then Trojan Horse cells harboring cps will be given back to the patient as an immunotherapeutic to generate the ideal immune responses necessary to eradicate their cancer and to also provide life-long immunity against any future recurrence of that cancer," said Bzik.

Fox and Bzik say a lot more study is needed before cps leaves the laboratory. They are trying to understand how and why it works so well by examining its molecular targets and mechanisms.

"Cancer immunotherapy using cps holds incredible promise for creating beneficial new cancer treatments and vaccines," said Bzik.

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18 comments

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EyeNStein
4 / 5 (4) Jul 18, 2014
Quick..How can we patent and suppress this cheap natural treatment, behind a wall of cancelled clinical trials..? Its going to play havoc with our expensive lucrative cancer drug sales..
Then how do we create a scare to stop people buying cats?
Gigel
not rated yet Jul 18, 2014
I wonder whether this is connected to: http://medicalxpr...hiv.html
bearly
5 / 5 (2) Jul 18, 2014
We can only hope that this will soon be used to save peoples lives and is not buried to save corporate profits.
TheGhostofOtto1923
1 / 5 (3) Jul 18, 2014
" can develop a serious infection if they are unable to fend off T. gondii."

-Well that and the mass psychosis.
http://wwwnc.cdc...._article

Who knows what this bug has done to society? We need a way of getting rid of it.
mrdingdong
5 / 5 (2) Jul 18, 2014
Hopefully they start human trials and it don't take ten years. Also hope it does not cost $100000 per vaccine. Being a patient myself I will be waiting for this.
halloweenhouseparty
1.5 / 5 (8) Jul 18, 2014
Seriously? Is this article a joke?
Toxoplasma gondii is an obligate, intracellular, parasitic protozoan that causes the disease toxoplasmosis (essentially it's fatal, AKA: you can die from it).

Who writes this slop?
Who did this research and are these researchers even legit?
How extensive was this research study?

I smell a load of BS.
Reading this nonsense just gives cancer patients false hope.
Egleton
5 / 5 (6) Jul 19, 2014
Seriously? Is this article a joke?
Toxoplasma gondii is an obligate, intracellular, parasitic protozoan that causes the disease toxoplasmosis (essentially it's fatal, AKA: you can die from it).

Who writes this slop?
Who did this research and are these researchers even legit?
How extensive was this research study?

I smell a load of BS.
Reading this nonsense just gives cancer patients false hope.

Please read the article.
EyeNStein
not rated yet Jul 19, 2014
"A healthy immune system responds vigorously to T. gondii in a manner that parallels how the immune system attacks a tumor."

Basically our immune systems have adapted to deal with this type of cyst forming parasite in a way that is similar to our healthy anti-tumour response. If a weakened TG can be administered as a post-tumour (and pre-tumour?) vaccine then it could have wide medical applications. Especially as TG can be treated with anti-malarial drugs.
EyeNStein
5 / 5 (1) Jul 19, 2014
They may still have to develop "cps" as a vaccine for TG disease to get FDA approval. Then use it 'off label' against cancer; to get past the accountants protecting their $120,000 per course "Ipilimumab" like drug alternatives
CMDS
5 / 5 (1) Jul 19, 2014
Any study relating cat pet owners and incidence of cancer?
EyeNStein
5 / 5 (1) Jul 19, 2014
If there are 60 Million Americans with TG then any reduction in the cancer types incidences could be analysed after blood tests for TG.
Having a cat should reduce cancer incidence anyway as they reduce stress levels and so boost healthy immune responses.
tekram
3 / 5 (2) Jul 20, 2014
The standard of care for treating superficial bladder cancer is instilling Bacillus Calmette-Guerin into the bladder. Bacillus C-G is the same attenuated Bacillus used for inoculation and protection against wild type virulent TB causing bacteria.
Scroofinator
1 / 5 (1) Jul 20, 2014
Who knows what this bug has done to society? We need a way of getting rid of it.

It looks like this bug is working it's way to everyone now, even non cat people. Maybe that was it's master plan all along. I mean, in nature this parasite infects mice and makes them not afraid of cats, which isn't really the best thing for them. Closest thing to body snatchers I've heard of.
4R0NU1
5 / 5 (1) Jul 21, 2014
...
ziphead
not rated yet Jul 21, 2014
Rosser
1.5 / 5 (2) Jul 21, 2014
An exciting article. Hopefully the researchers will work with the FDA to get this to market on the fast track. The cynics in the crowd need to kiss off. One nit pick to the author of the story - "unable to reproduce in animals or people". In case you hadn't noticed, people are animals as well. It might have been more accurate to say, "unable to reproduce in mammals".
Jonseer
1 / 5 (2) Jul 21, 2014
An exciting article. Hopefully the researchers will work with the FDA to get this to market on the fast track. The cynics in the crowd need to kiss off. One nit pick to the author of the story - "unable to reproduce in animals or people". In case you hadn't noticed, people are animals as well. It might have been more accurate to say, "unable to reproduce in mammals".


I'm glad to see I'm not the only one catching the subtle efforts to support the religiously rooted notions regarding humans as something different than animals due to an intrinsic faith based belief that our superior intelligence makes us not animals.

The pathetic irony of such an effort is should it catch on, researchers who do this will be able to thank the most religious people for accepting their redefinition of what it means to be an animal and why humans aren't animals strictly based on faith.
cjn
5 / 5 (1) Jul 22, 2014
I'm glad to see I'm not the only one catching the subtle efforts to support the religiously rooted notions regarding humans as something different than animals due to an intrinsic faith based belief that our superior intelligence makes us not animals.

The pathetic irony of such an effort is should it catch on, researchers who do this will be able to thank the most religious people for accepting their redefinition of what it means to be an animal and why humans aren't animals strictly based on faith.


Not to interrupt your tirade against religion, but I think the problem is that people don't understand that the inherently toxic genes of the protozoa are removed from the genome, the cps introduced into sampled, isolated host cells, then re-introduced into the body -the cps isn't just injected into the patient's bloodstream. This isn't exactly straightforward, and can be confusing to people regardless of religious affiliation.

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