2007 Press Releases

Onyx Pharmaceuticals Announces An Analyst Briefing

Teleconference Scheduled for June 5, 2007

EMERYVILLE, CALIF. — May 25, 2007

Onyx Pharmaceuticals, Inc. (Nasdaq: ONXX) today announced today that it will webcast a post-ASCO teleconference on Tuesday, June 5, 2007, beginning at 8:00 a.m. Central Time. Clinical investigators and management will participate in the event.

The physicians will review recently reported liver cancer data for Nexavar® (sorafenib) tablets, being developed in collaboration with Bayer Pharmaceuticals Corporation. Interested parties may access a live webcast of the presentation by clicking on the link below:
http://events.streamlogics.net/conferenceplus/onyx/event001/index.asp

or by dialing 847-413-3362 and using the passcode 17973020. The accompanying slides will be posted on the Onyx website at http://www.onyx-pharm.com/view.cfm/32/Event-Calendar approximately 15 minutes before the teleconference is scheduled to begin. A replay of the presentation will be available on the Onyx website through July 5, 2007.

Onyx Pharmaceuticals, Inc. is a biopharmaceutical company developing innovative therapies that target the molecular mechanisms that cause cancer. The company is developing Nexavar®, a small molecule drug, with Bayer Pharmaceuticals Corporation. Nexavar is approved for the treatment of advanced kidney cancer in approximately 50 countries. For more information about Onyx's pipeline and activities, visit the company's web site at: www.onyx-pharm.com.

Nexavar® (sorafenib) tablets is a registered trademark of Bayer Pharmaceuticals Corporation.