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Thursday, October 14, 1999 Published at 02:06 GMT 03:06 UK


E. coli fights cancer

A toxin produced by E.coli destroys cancer cells

Bugs normally found in food poisoning cases have been used to give bone marrow transplants for cancer patients more chance of success.

E. coli bacteria can cause serious and sometimes fatal illness in some vulnerable patients, but scientists at the University of Alberta have harnessed their destructive potential.

The technique is used to make sure that bone marrow transplants are free of cancer cells before being put back into the body of people suffering from diseases such as leukaemia or Hodgkin's lymphoma, and some breast cancer patients.

It could also be used for a cancer of the immune cells in the bone marrow called multiple myeloma, for which there is presently no cure.

Last resort

Such transplants are often a last resort for patients who have not responded well enough to other treatments.

Bone marrow, vital for making red and white blood cells, can be destroyed by powerful cancer treatments.

[ image: Bone marrow is removed before powerful cancer drugs are given]
Bone marrow is removed before powerful cancer drugs are given
So the usual practice is to take some bone marrow from the body, then use radiation or chemotherapy to "cleanse" the rest of the body of cancer.

The bone marrow is then filtered to try and make sure it is free of cancer, then put back so it can start producing the blood cells again.

However, the filtration cannot guarantee that every cancer cell has been removed.

Dr Jean Gariepy of Princess Margaret Hospital's Ontario Cancer Institute used a toxin from the E.coli, called SLT-1, to attack and destroy the remaining cancer cells in the marrow.

Toxin only attacks cancer cells

She said: "Our group has seized an opportunity to use a deadly bacterial toxin responsible for hamburger disease to treat a variety of cancer patients."

The toxin can tell the difference between cancerous cells and the normal bone marrow cells, latching on and destroying them.

University of Alberta oncology professor Linda Pilarski said: "We've shown that myeloma cells are effectively purged by SLT-1, and that normal stem cells survive.

"This means it is potentially safe to use as a purging agent for the graft before reinfusing it into the patient."

She added: "There is a lot more work to be done to refine the technique, and to ensure safety, but this could prove to be an important advance."

The potential is for a much more effective system for "autologous" bone marrow transplants - in which the patient's own marrow is used - with hopefully a far lower rate of relapse for those patients.

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