The first randomized, international and multicenter phase III study of trastuzumab 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 percent 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.

"This is the first phase III study to report improved overall survival with a personalized, targeted treatment for gastric cancer," said Eric Van Cutsem, M.D., Ph.D., 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 the HER2 receptor. This receptor, which can fuel cancer growth, is present in high amounts in up to 25 percent 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 percent had high amounts of HER2 in their tumors. Of these patients, 594 with locally advanced, recurrent or metastatic HER2-positive gastric cancer were randomized 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 was generally low (5.9 percent in the trastuzumab group compared with 1.1 percent in the standard therapy group) and the mean ventricular ejection fraction remained above 60 percent throughout the study.