A new breast cancer 'smart bomb' drug which hunts down and kills tumour cells will offer fresh hope for women with a deadly form of breast cancer.
The potent drug, codenamed T-DM1, could give women out of all other options extra precious months of life.
Lead researcher Kimberly Blackwell called the drug a "breakthrough".
She said: "We talk a lot about delivering a cancer bomb, this is an example of delivering that bomb to the cancer, not the patient."
Experts predict the treatment will lead to a new generation of 'smart drugs' which kill cancer cells while reducing the side-effects of current methods such as chemotherapy.
A trial presented to the American Society for Clinical Oncology showed it stopped the disease for three months.
But after two years, 65% of patients were still alive compared to just 47% who received standard care.
Professor Paul Ellis of Guy's hospital in London said: "These results are remarkable because for the first time in breast cancer we have been able to significantly improve efficacy while substantially reducing many of the unpleasant side-effects associated with chemotherapy."