The first randomised, international and multicentre phase III study of trastuzumab (Herceptin) in patients with gastric cancer has found that patients who received trastuzumab plus standard chemotherapy lived significantly longer than patients who received standard chemotherapy alone, with a 26 per cent reduction in the risk of death. This is the first time trastuzumab – used to treat HER2-positive breast cancer – has been proven effective in another cancer, according to the results presented at American Society of Clinical Oncology 2009 Meeting in Orlando.

'This is the first phase III study to report improved overall survival with a personalised, targeted treatment for gastric cancer," said Dr. Eric Van Cutsem, professor at the University Hospital Gasthuisberg in Leuven, Belgium, and lead author of the study. "These data indicate that trastuzumab has the potential to have a place in the treatment of a cancer other than breast cancer, and to become a common treatment for gastric cancer patients who are candidates for this drug."

Trastuzumab is a targeted cancer therapy that works by blocking a receptor called HER2. This receptor, which can fuel cancer growth, is present in high amounts in up to 25 per cent of breast cancers. High amounts of HER2 have been found in a similar percentage of patients with gastric cancer.

Among 3,807 gastric cancer patients in the study, 22.1 per cent had high amounts of HER2 in their tumours. Of these patients, 594 with locally advanced, recurrent or metastatic HER2-positive gastric cancer were randomised to receive either standard chemotherapy (5-fluorouracil or capecitabine and cisplatin) plus trastuzumab or standard chemotherapy alone.

Median overall survival was 13.8 months in the trastuzumab group versus 11.1 months in the standard chemotherapy group. The treatment was generally well tolerated, and there were no unexpected side effects in the trastuzumab group: the rate of symptomatic congestive heart failure was similar between the two groups. The incidence of decreased ventricular ejection fraction (a measure of the heart’s pumping ability) was generally low (5.9 per cent in the trastuzumab group compared with 1.1 per cent in the standard therapy group) and the mean ventricular ejection fraction remained above 60 per cent throughout the study.