Shares of Onyx Pharmaceuticals Inc. soared more than 95 percent on news that its kidney cancer drug, Nexavar, yielded positive survival data in a Phase III trial in liver cancer patients.

Following an interim analysis, the trial's data monitoring committee reported that efficacy data showed that the study met its primary endpoint earlier than expected, demonstrating superior overall survival in patients receiving Nexavar (sorafenib) tablets over placebo.

The committee recommended that Onyx and partner Bayer Pharmaceuticals Corp. conclude the study "quite a bit earlier than planned," said Hank Fuchs, executive vice president and chief medical officer of Emeryville, Calif.-based Onyx. The trial wasn't expected to conclude until the second half of this year.

The company has not yet provided a revised timetable for a new drug application, but Fuchs said the goal is to "get a filing put together quickly." If the drug follows a similar regulatory path as the previous kidney cancer approval - which came in December 2005, just 10 months after the companies reported positive Phase III data - Nexavar could be launched in liver cancer early next year, Fuchs told BioWorld Today.

Investors jumped on the news, sending shares of Onyx (NASDAQ:ONXX) up 97 percent, or $11.89, Monday to close at $24.15.

"[They're] great data," said analyst Phil Nadeau, of New York-based Cowen & Co., particularly since "nothing has ever really shown a survival benefit in liver cancer before. I would guess that Nexavar would get a label in live cancer in both the U.S. and Europe based on these data."

Wall Street's reaction also seemed to revive rumors that West Haven, Conn.-based Bayer might be considering a takeover bid for Onyx. "Investors have wondered," Nadeau said, though no acquisition discussions have been reported. The two companies have a 50/50 profit-sharing arrangement for Nexavar in the U.S., with Onyx receiving less than 50-percent share in the rest of the world, except for Japan, where Bayer agreed to fund all development in exchange for a royalty payment to Onyx.

Outside of Nexavar, Onyx has only one product in development, a cell-cycle kinase inhibitor partnered with New York-based Pfizer Inc. That product entered clinical testing in late 2004.

Full results from the Phase III Nexavar trial in liver cancer are expected to be presented at the American Society of Clinical Oncology meeting in June, and Fuchs only could say that the DMC cited "compelling data" evidenced by both survival and clinical benefit. In its recommendations, the DMC also suggested that patients in the trial receiving placebo be allowed access to Nexavar.

The trial was initiated in March 2005 and was expected to enroll about 500 previously untreated patients with advanced unresectable liver cancer to receive either Nexavar, an oral multi-kinase inhibitor designed to target both the tumor cell and tumor vasculature, or placebo. Endpoints were set to measure differences in survival, time to symptom progression and time to tumor progression. (See BioWorld Today, March 9, 2005.)

At this time, liver cancer, also known as hepatocellular carcinoma, has no real therapeutic standard of care. The disease, which generally results from viruses such as hepatitis C or hepatitis B or from alcoholic cirrhosis, is a "devastating condition," Fuchs said, in which "median survival is measurable by months."

If approved, Nexavar could reach peak sales between $150 million and $300 million in liver cancer.

The drug already is approved for kidney cancer - pulling in U.S. and European revenues totaling about $45 million for the third quarter of 2006 - though it quickly gained competition from Pfizer's Sutent (sunitinib). The two products also are vying for places in the non-small-cell lung cancer and breast cancer markets. Nexavar is being evaluated in NSCLC patients in three randomized trials, and Onyx is getting ready to start a "number of randomized trials in breast cancer this year," Fuchs said.

"We want to try to extend the benefit of Nexavar to an ever-enlarging circle of patients," he added.

Onyx and Bayer reported disappointing results from a Phase III study of the drug in melanoma late last year, though Fuchs said they were awaiting further survival data before deciding whether or how to move forward. Those data are expected sometime in the middle of the year. (See BioWorld Today, Dec. 5, 2006.)