Roche, the world's largest maker of cancer drugs, said on Thursday it was the first positive Phase III study of an anti-angiogenic therapy, which uses drugs to stop tumors from making new blood vessels, in advanced ovarian cancer.

It is a timely boost for the medicine after Roche said earlier this week Avastin had failed to reach its main target in a stomach cancer study, which some analysts said could cut core earnings by 1 to 4 percent.

This is a positive catalyst for Roche and further supports the Avastin franchise, especially welcome after failure of Avastin in the gastric cancer setting, said Vontobel analyst Silvia Schanz.

We estimate peak sales of 1 billion Swiss francs for the indication ovarian cancer, she said. The phase III trial of Avastin in prostate cancer is expected to read out later this year.

At 0958 GMT, Roche stock was trading down 0.22 percent at 179 Swiss francs, compared with a flat DJ Stoxx European healthcare index.

Ovarian cancer is the sixth most commonly diagnosed cancer in women and the eighth leading cause of cancer death among women worldwide, Roche said, adding each year an estimated 230,000 women are diagnosed with the disease and some 140,000 die.

The Phase III study showed women with advanced ovarian cancer who are treated with Avastin and chemotherapy and then continue to take Avastin live longer without their disease worsening than if they only have chemotherapy.

Roche will present the data at the American Society of Clinical Oncology annual meeting in June.

Avastin, which works by starving tumors of blood and is made by the recently acquired Genentech unit, is used to treat lung, colon and breast cancers, and had 2009 annual global sales of 6.2 billion Swiss francs ($5.7 billion).

Its sales are seen hitting $8.5 billion by 2013 as Roche expands its use into different types of cancer, according to consensus forecasts from Thomson Pharma.

Medicine Cancer