Breast cancer treatment targets tumours with few side effects

CTVNews.ca Staff Published Monday, Oct. 1, 2012 3:09PM EDT Last Updated Monday, Oct. 1, 2012 11:50PM EDT

An experimental breast cancer treatment that directly targets disease cells appears to shrink tumours and improve survival rates, according to new Canadian research, and could one day lead to more effective treatment of other types of cancer with far fewer side effects.

The treatment is a three-drug combination called T-DM1, which is formulated to attack cancer cells and leave healthy cells untouched.

The cocktail is designed to treat women who are in the latter stages of HER2-positive breast cancer, a type of cancer in which the protein HER2 plays a role in tumour growth. Nearly 20 per cent of women with breast cancer have tumours with high levels of HER2.

The new drug combines Herceptin, a drug already used to treat HER2-positive cancer, with a powerful chemotherapy drug called DM1. The third drug is a chemical that prevents the chemotherapy from becoming active until it reaches the targeted cancer cells.

In a study of 991 women with HER2-positive breast cancer, patients were randomly assigned to receive either the new treatment, or standard therapy in the form of the drugs Tykerb and Xeloda.

All of the patients had previously been treated with Herceptin and taxane, a type of drug that stymies the proliferation of cancer cells by stopping cell division.

The study found that tumours shrunk in 43.6 per cent of subjects who received T-DM1, compared to 30.8 per cent of subjects who received the other drugs. In the group that received T-DM1, mean survival without disease progression was 9.6 months, compared to 6.4 months among the other group.

Study author Dr. Sunil Verma, a medical oncologist at the Odette Cancer Centre at Torontos Sunnybrook Health Sciences Centre, called the improvement in survival rates without the usual drug side effects such as hair loss and nausea a game changer.

If we can start combining our potent chemotherapy and use a delivery vehicle and get this chemotherapy right to the cancer cell, that may allow for normal healthy cells to not be exposed to chemotherapy, reducing the side effects and reducing the damage from chemotherapy, Verma told CTV News.

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Breast cancer treatment targets tumours with few side effects