May 31 (Bloomberg) -- Roche Holding AG’s Herceptin, a breast cancer drug that targets the HER-2 gene, added almost three months of life to stomach cancer patients in a study that may expand use of DNA testing to that malignancy.

Giving Herceptin with chemotherapy boosted overall survival for those with stomach cancer to 13.8 months, compared with 11.1 months for patients on chemotherapy alone, said Eric Van Cutsem, the study leader and a professor at the University of Leuven, Belgium. The finding was presented today at the American Society of Clinical Oncology meeting in Orlando, Florida.

The world’s second-biggest cancer killer, stomach tumors may result in 10,620 deaths and 21,130 new cases in the U.S. this year, according to the American Cancer Society. Added use of Herceptin for stomach tumors in the one-in-five patients who test positive for the HER-2 gene could generate an extra $450 million globally yearly for the drug, said Amit Roy, an analyst with London-based Nomura International PLC, in an e-mail.

The finding “will force us to test patients for HER-2, treat patients who are HER-2 positive, and conduct research on gastric cancer that is HER-2 positive,” said Richard Schilsky, the oncology society’s president and a professor at the University of Chicago. Schilsky predicted the findings will quickly change medical practice.

Roche will seek marketing approval of Herceptin for stomach cancer in countries outside the U.S., said Corinne Wolter, a Roche spokeswoman. Kristina Becker, a spokesman for Roche’s Genentech Inc. unit that developed the drug, said the decision to seek U.S. clearance is under review.

$4.74 Billion in Sales

Herceptin had $4.74 billion in sales last year. First cleared in the U.S. in 1998 to treat aggressive breast cancer, Herceptin attacks the HER-2 protein that’s churned out in about 25% percent of breast cancer patients. The drug is a lab- designed antibody, a protein that’s usually produced by the body’s immune system to battle harmful substances.

“We were happily surprised at the strength of the survival benefit,” Van Cutsem, the researcher, said in an interview. “It’s the first time a biological has improved survival in gastrointestinal cancer, and fits the theme of this meeting which is ‘Personalizing Cancer Care.’”

The trial, called TOGA, was sponsored by Basel, Switzerland-based Roche.

Herceptin was originally developed for breast cancer by scientists at Genentech, in South San Francisco. It may become the first therapy targeting a solitary gene to battle stomach cancer, Roche said. It won’t be for all stomach cancer patients, the report found.

One in Five Patients

About one in five of 3,807 stomach cancer patients originally screened by the researchers were positive for the HER-2 gene variant. Of those, 594 patients were entered in the clinical trial and randomly assigned to get Herceptin plus a double combination chemotherapy regimen or just chemotherapy.

The drug shrank tumors and boosted survival significantly beyond the one-year mark that has been a hurdle for patients with advanced gastrointestinal tumors, Van Cutsem said.

“We broke the barrier,” he said.

Among risk factors for stomach cancer, the World Health Organization lists consumption of traditional salt-cured meats and pickles, and bacterial infection by the ulcer bug helicobacter pylori.

Even though stomach cancer incidence is higher in Asia than in the United States and Europe, Van Cutsem said certain gastric cancers that lie between the stomach and esophagus linked to acid reflux are rising in the West as rates of obesity increase. Such tumors may also be linked to HER-2, he said.

Safety profiles were similar in both groups of patients, the scientists found. Even though Herceptin can potentially cause heart damage as a side effect, Van Cutsem said he didn’t find significant rise in symptoms of congestive heart failure.

To contact the reporter on this story: Marilyn Chase in San Francisco at Or mchase6@bloomberg.net

Last Updated: May 31, 2009 10:30 EDT