New breast cancer drug shown to prolong life

A DRUG that delivers a powerful poison to tumours without some of the side effects of traditional treatments can delay the worsening of breast cancer and also appears to prolong lives, according to a new study.

Besides representing an advance in treating breast cancer, the success in the clinical trial validates an idea that is being pursued by pharmaceutical companies to treat various types of cancer in a way that delivers drugs to cancerous cells while sparing healthy ones.

''We've envisioned a world where cancer treatment would kill the cancer and not hurt the patient,'' said Kimberly Blackwell, professor of medicine at the Duke Cancer Institute and the lead investigator in the trial. ''And this drug does that.''

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The drug, known as T-DM1, was developed by Genentech. The company plans to file for approval later this year. That could mean the drug will reach the market next year.

T-DM1 and similar drugs under development consist of powerful toxins linked to proteins called antibodies. The antibodies latch on to cancer cells and deliver the toxic payload directly into those cells. Since the toxin is not active until it reaches the tumour, side effects are reduced.

Such treatments, known as antibody-drug conjugates, have been pursued for decades, but only now is success being achieved. One such drug, Adcetris, was approved last year to treat two rare types of lymphoma. T-DM1 could be the first approved for a common cancer.

Results of the trial were formally presented yesterday at the American Society of Clinical Oncology meeting in Chicago.

The late-stage clinical trial involved 991 women with metastatic breast cancer whose cancer was worsening despite previous treatment with the drug Herceptin and a chemotherapy drug called taxane. Half the women got T-DM1 and the other half received two drugs that are now commonly used for such patients - Tykerb, also known as lapatinib, and Xeloda, also known as capecitabine.

About 84.7 per cent of patients getting T-DM1 were alive after one year, compared with 77 per cent of those in the control group. By another commonly used measure called the hazard ratio, T-DM1 reduced the risk of death by 38 per cent.

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New breast cancer drug shown to prolong life