A drug used to treat advanced kidney cancer and a type of liver cancer that cannot be removed by surgery. It is also used to treat a type of advanced thyroid cancer that did not get better with radioactive iodine treatment. It is being studied in the treatment of other types of cancer. BAY 43-9006 stops cancer cells from dividing and may prevent the growth of new blood vessels that tumors need to grow. It is a type of kinase inhibitor and a type of antiangiogenesis agent. Also called Nexavar and sorafenib tosylate.