A month after reporting promising interim results from a pivotal study of sorafenib in kidney cancer, Onyx Pharmaceuticals Inc. and Bayer Pharmaceuticals Corp. have begun a Phase III trial of the drug in melanoma.

The study will evaluate the progression-free survival rate of sorafenib (formerly BAY 43-9006) in combination with carboplatin and paclitaxel in more than 200 patients who have failed no more than one prior chemotherapy treatment with decarbazine or temozolomide. Patients will be randomized to receive either 400 mg of oral sorafenib or placebo two times per day, in addition to standard dosing of carboplatin and paclitaxel.

Onyx officials could not be reached for comment. A Bayer spokeswoman said executives there were traveling to Orlando, Fla., for the American Society of Clinical Oncology meeting. The companies are presenting data from several studies involving sorafenib, a small-molecule, multi-kinase inhibitor designed to target serine/threonine and receptor tyrosine kinases to stop tumor growth and blood flow to the tumor.

Preclinical models have shown the drug capable of targeting kinases involved in tumor cell proliferation and tumor angiogenesis, such as RAF kinase, VEGFR-2, VEGFR-3, PDGFR-beta, KIT, FLT-3 and RET.

Onyx and Bayer are investigating the drug in a number of cancer indications, both as a single-agent therapy and in combination with standard chemotherapeutics. An ongoing Phase II trial is evaluating sorafenib in combination with decarbazine in the treatment of metastatic melanoma. Trials also are under way for indications including liver cancer, breast cancer, chronic myeloid leukemia, non-small-cell lung cancer and colorectal cancer.

The FDA has granted orphan drug designation to sorafenib in kidney cancer, and a new drug application in that indication is expected to be filed this year. The companies said in April an independent data monitoring committee reviewed safety and efficacy data from the Phase III trial in advanced kidney cancer and determined that patients receiving sorafenib showed significantly longer progression-free survival rates than patients receiving placebo. Following the announcement of that data, Onyx and Bayer recommended that all patients in the trial begin receiving sorafenib. (See BioWorld Today, April 19, 2005.)

The collaboration with Bayer calls for Onyx to fund 50 percent of the development costs, in exchange for an even split of profits on U.S. sales. Outside the U.S., Onyx would receive a share less than 50 percent. The only exception is Japan, in which Bayer funds development costs and Onyx would receive royalty payments.

Shares of Onyx (NASDAQ:ONXX) lost 59 cents Friday to close at $31.85.