Onyx Pharmaceuticals Inc.'s oral, multi-kinase inhibitor Nexavar (sorafenib), partnered with Bayer HealthCare Pharmaceuticals, received the FDA's blessing in advanced liver cancer, only a few weeks after winning European approval in that indication.

The agency's decision came as no surprise, owing to the drug's positive Phase III data - among those were impressive overall survival results showing a 44 percent increase in patients receiving Nexavar vs. placebo - and to the fact that few treatment options are available for patients with unresectable hepatocellular carcinoma (HCC).

In fact, Nexavar is the first systemic therapy approved for HCC, the most common form of liver cancer that generally results from viruses such as hepatitis C or hepatitis B or from alcoholic cirrhosis.

"It's wonderful news for patients and their families," said Julie Wood, Onyx's vice president of corporate communications and investor relations. "They finally have a treatment, where before, they had nothing."

The approval also marks Nexavar's second under the FDA's priority review process, she said. The drug got the nod in advanced kidney cancer in late 2005.

The latest approval, however, wasn't reflected in the company's stock movement Monday, as shares of Emeryville, Calif.-based Onyx (NASDAQ:ONXX) fell $3.09. or 5.3 percent, to close at $55.23.

The reason for that drop wasn't clear, and Wood said the company does not comment on stock price.

What is clear, though, is that Onyx's share price has doubled since mid-summer, its most recent jump coming on its third-quarter earnings earlier this month, in which the company posted a net income of $555,000 instead of the net loss most analysts were predicting.

And its latest closing price is a far cry from the $10-$12 range the stock was trading at in January, before a 100 percent increase took the stock to $24.25 after a data monitoring committee recommended an early halt to the Phase III SHARP (Sorafenib HCC Assessment Randomized Protocol) trial following an interim review yielding promising efficacy results. (See BioWorld Today, Feb. 13, 2007.)

Onyx and partner Bayer filed a new drug application based on those data, which demonstrated a median overall survival in the Nexavar-treated group of 10.7 months vs. 7.9 months in the placebo group.

While "it's difficult to know what the total market potential is," Wood told BioWorld Today, liver cancer is the sixth most common cancer in the world, believed to affect 15,000 people in the U.S. and 60,000 in Europe annually.

But the biggest markets for Nexavar in liver cancer will be the Asia-Pacific region. More than 300,000 patients are diagnosed each year in China, Japan and Korea. Onyx and Bayer have regulatory applications pending for Nexavar in both China and Japan, and earlier this year, reported that an independent data monitoring committee for an Asia-Pacific Phase III trial - conducted at the behest of Asian health authorities - found that Nexavar significantly improved overall survival, progression-free survival and time to progression in advanced HCC patients. As with the SHARP study, that trial was stopped early due to positive results.

Under the terms of the companies' collaboration, Onyx is funding 50 percent of Nexavar's development costs, in exchange for a 50/50 profit share in the U.S. and a lesser share in the rest of the world, except for Japan. In Japan, Wayne, N.J.-based Bayer is shouldering all product development costs, with royalties to be paid to Onyx.

Nexavar, a kinase inhibitor designed to target RAF kinase, VEGFR-1, VEGFR-2, VEGFR-3, PDGFR-B, KIT and FLT-3, continues to be investigated in melanoma, despite disappointing results from a 2006 Phase III study, as well as in combination with chemotherapy in non-small-cell lung cancer.

Nexavar sales revenue totaled $104.6 million in the third-quarter, a 29 percent increase over second-quarter revenue. The drug has continued to hold onto its market share in kidney cancer despite the approval of competing Sutent (sunitinib malate), a multi-kinase inhibitor from New York-based Pfizer Inc.

Third-quarter sales of Sutent, which is approved in gastrointestinal stromal tumors in addition to kidney cancer, totaled about $151 million.

While Sutent also is in development for liver cancer, it trails Nexavar by at least a couple of years, only now moving into Phase III testing.

Beyond Nexavar, Onyx's only other clinical candidate is an early stage cell-cycle kinase inhibitor partnered with Pfizer.