Drug linked to cancer treatment. (Special Report: Biotechnology/Health Industry).

Scientists at the Northeastern Cancer Centre continuing research to determine why certain breast cancer patients find themselves resistant to drugs have stumbled upon agents that may aid in cancer treatment, says Dr. Amadeo Parissenti, chair in cancer research.

"We are identifying agents that appear to work effectively to kill drug resistant breast tumour cells," Parissenti says.

"Even cells that are very, very highly resistant to a number of chemotherapy drugs seemed to be killed by this drug."

Although Parissenti did not disclose the name of the agent, he says it is a common drug that has been around a while.

"The good thing or the bad thing about it, depending on your point of view, is that it is a drug that has been around a while so it would not be a money maker. Sometimes when it is not a money maker pharmaceutical companies do not jump at it."

Parissenti says science is not always as it seems. He happened upon this drug by accident.

"We were using the drug for something else and found it was killing our cell lines. When it was killing it so strongly we thought well let's try it on the drug resistant ones. It did not differentiate between the drug resistant and the drug sensitive cells."

Parissenti has published a manuscript on the agent, which is now under revision.

"Hopefully there will be some interest in the drug. I have colleagues in Toronto and throughout Canada. I will see whether there is. some interest in pursuing this."

Parissenti says scientists know very little about the toxicity level of the drug in humans. Moreover, a possibility exists for breast cancer patients to develop a resistance to this drug, which is what occurred with other drugs used in treating breast cancer patients.

"There are often cases in breast cancer where a patient will end up resistant to a specific drug," Parissenti explains.

"So you will give a patient one drug and then the patient will then become resistant to that drug and often times they become resistant to a whole series of other drugs they have not been given."

This is a phenomenon called multi-drug resistance. In fact, after patients in breast cancer chemotherapy are given the first drug, anthracycline, only half of the patients respond to the next drug Taxol, Parissenti explains.

"So it is a 50-50 (chance), which is not great odds," he admits.

What Parissenti and his colleagues are doing is comparing normal tumour cells that are sensitive to drugs with tumour cells that are resistant to drugs.

Researchers have identified a whole series of genes that become altered as the tumour cells become resistant to drugs, Parissenti says.

"The genes may help us identify or predict whether a patient's tumour will respond to drug x or drug y," he explains.

The end of the test tube research has been complete. Now researchers will be going into a national clinical trial to asses 55 Canada-wide females diagnosed with inflammatory breast cancer.

"It is not an intervention," the doctor says. "What we will do is give them the drug they normally have. We know some will respond some will not and we will look at their genetics and see whether their genetics would have told us whether they would respond or not."

The whole idea is that if scientists can extract some clue as to the patient's chemistry system through their genetics, then doctors could perhaps tailor the treatment for breast cancer.

The study will take place over a two-year period. The genetic research will be conducted in Sudbury and the administering of the drugs will take place as standard treatment protocols in cancer treatment centres across Canada through the National Cancer Institute of Canada study.

"More and more we know that this resistance to drugs is probably the major reason why chemotherapy fails in the majority of instances."

However, to date there is no alternative, Parissenti adds. "We only have limited success in chemotherapy," Parissenti says.