New breast cancer drug combo shrinks aggressive tumours

Jun 2 2008

An international trial of a new breast cancer drug has shown the drug is able to shrink tumours caused by one of the most aggressive forms of the disease.

The new drug pertuzumab was given to women with with an advanced and aggressive HER2-positive form of breast cancer.

The drug trastuzumab (Herceptin) had already been tried with the women without success but when they were treated with a combination of Herceptin and Pertuzumab, some of the growths began to reduce in size.

The trial involved 66 women from the UK, France, Italy, Spain and Canada who had advanced breast cancer which had already spread to other organs.

The Phase II trial revealed that one in four given the drug saw a reduction in the size of their tumours and another one in four found that their tumours had not grown larger.

The success of the combo of trastuzumab and pertuzumab offers new hope to the thousands of women diagnosed each year with aggressive HER2-positive breast cancer.

HER2-positive breast cancer accounts for 20 to 30 per cent of all breast cancer cases and is harder to treat as it does not respond well to chemotherapy.

HER2-positive breast cancer means a protein known as HER2 is found on the surface of the tumour cells and pertuzumab works by preventing the HER2 protein from binding with other cells, which is thought to encourage the growth and spread of the cancer.

This is the first time a drug has been found which acts in this manner.

Experts are optimistic that hope they will eventually prevent breast cancer from initially forming by giving the drug to high-risk women who test positive for the HER2 protein.

The drug could also remove the need for radical chemotherapy.

Dr. David Miles, a cancer specialist hospital at Mount Vernon Hospital, Middlesex, who is one of the study authors says the use of the combination therapy in one quarter of the women, shrunk their tumours and in another quarter, stabilised their growth.

Dr. Miles says the study results are impressive considering that this was a treatment regimen containing two antibodies only and did not involve any chemotherapy.

He says the drug has the potential to target and block a highly relevant pathway for tumour growth and the combination of trastuzumab and pertuzumab used with chemotherapy will be even more effective if used to treat women newly diagnosed with advanced cancer.

The clinical trial results were presented at the American Society of Clinical Oncology conference in Chicago last week.