The US Food and Drug Administration on Tuesday approved the drug Nexavar (sorafenib tosylate) for the treatment of advanced kidney cancer.

The drug targets proteins that control tumor growth and blood vessel formation. In a randomized clinical trial of more than 900 patients, it significantly slowed tumor growth, manufacturers Bayer and Onyx pharmaceuticals said. It took an average of about 24 weeks for tumors to begin growing again in patients given Nexavar, compared to about 12 weeks in people given a dummy pill (placebo). The patients in the study all had renal cell carcinoma that had spread, and most had already been treated with interleukin-2 or interferon.

"The approval of Nexavar to treat advanced kidney cancer brings a much needed option for this group of cancer patients," said Steven Galson, MD, MPH, director of the FDA's Center for Drug Evaluation and Research.

Advanced kidney cancer is very difficult to treat. Traditional chemotherapy and radiation are not very effective against this disease. Interleukin-2 and interferon can shrink the tumors, but only 10%-20% of patients respond to these drugs and they can have severe side effects. More than 36,000 cases of kidney cancer and some 12,660 deaths are expected in the US in 2005.

Nexavar is a pill taken twice a day. In the study, the most common side effects were rash, diarrhea, blood pressure increases, and redness, pain, swelling or blistering on the palms of the hands or soles of the feet. The drug may also increase the risk of bleeding.

It's not yet known if Nexavar actually helps people with advanced kidney cancer live longer. Longer follow-up of the patients in the study will be needed to answer that question. The drug is also being tested in people with advanced liver cancer and people with metastatic melanoma.

Bayer and Onyx have set up a hotline for patients and doctors interested in Nexavar available at 1-866-NEXAVAR (1-866-639-2827).