The 199-patient late-stage trial showed the drug prolonged the lives of patients with metastatic gastrointestinal stromal tumors, or GIST, by almost four months on average without a worsening of their condition, Bayer said.

The median survival period without tumor growth among patients on regorafenib was 4.8 months while for the control group on placebo it was less than a month.

The trial involved only patients whose disease had progressed despite prior standard treatment with Pfizer's Sutent and Novartis drug Gleevec/Glivec.

Detailed results of the trial were presented at the annual congress of the American Society for Clinical Oncology (ASCO) in Chicago over the weekend. First results were published in April.

There was also some evidence of a better overall survival rate but the trial was not designed to show that on a statistically reliable basis.

Bayer said it plans to start filing for marketing approval for use of the drug to treat GIST in the second half of this year. Last month it filed for approval in the United States and the European union for regorafenib as a treatment of metastatic colorectal cancer (mCRC).

Onyx Pharmaceuticals is the U.S. marketing partner for regorafenib. The companies also cooperate on a compound similar to regorafenib called Nexavar.

Bayer is testing regorafenib against a number of tumor types including kidney cancer and is targeting annual peak sales from the treatment of more than 1 billion euros ($1.2 billion). ($1 = 0.8089 euros)

(Reporting by Ludwig Burger; Editing by Hugh Lawson)

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