Onyx Pharmaceuticals, Inc. announced that it has received a $15 million creditable milestone-based payment from Bayer Pharmaceuticals Corporation related to the development of BAY 43-9006, a novel anti-cancer compound, which the two companies are co-developing. The milestone was achieved upon the previously announced initiation of the first Phase III clinical trial for BAY 43-9006.

This is the second milestone payment Onyx has received from Bayer. The first payment of $5 million was paid when the two companies began the first Phase II trial of BAY 43-9006 in 2002. In addition, Onyx can achieve two more milestones, each triggering a creditable milestone-based payment from Bayer of $10 million. The first of these milestones is the filing of a New Drug Application (NDA), and the second is the approval of BAY 43-9006 in the United States, Germany, Italy, Spain or the United Kingdom. All milestone payments are repayable to Bayer from a portion of Onyx's future profits and royalties.

BAY 43-9006 is an orally active small molecule in Phase III clinical testing for patients with advanced renal cancer. The compound is also being studied in two ongoing Phase II trials, as well as eight Phase Ib studies evaluating its use in combination with standard chemotherapeutics. This novel signal transduction inhibitor has a dual mechanism of action, targeting both cell proliferation and angiogenesis (formation of blood vessels). By inhibiting RAF kinase, BAY 43-9006 blocks the RAS/MEK/ERK signaling pathway in cells, an important mediator of tumor cell proliferation. BAY 43-9006 also exerts an anti-angiogenic effect, which could come from both direct effects on the VEGFR-2 and PDGFR-ß receptors, as well as from downstream effects on RAF kinase.

Under the co-development agreement between Bayer and Onyx, Onyx funds 50 per cent of the development costs for BAY 43-9006. In return, Onyx will have a 50/50 profit share in the United States, if it elects to co-promote the product and continues to fund development costs. Everywhere else in the world, except Japan, Bayer has exclusive marketing rights, and Onyx's share of any profits will be less than 50 per cent. In Japan, Bayer will fund all product development, and Onyx will receive a royalty on any product sales.

Onyx Pharmaceuticals is engaged in the development of novel cancer therapies that target the molecular basis of cancer. With its partners, the company is developing small molecule drugs, including BAY 43 9006 with Bayer Pharmaceuticals Corporation.