17 May 2006

John Gutheil, M.D., Joins Proacta as Chief Medical Officer and Senior Vice President of Clinical Affairs

San Diego, CA, May 17, 2006– Proacta Inc, a privately held, clinical stage biotechnology company, announced today that John Gutheil, M.D. has joined the organization as its Chief Medical Officer and Senior Vice President of Clinical Affairs. Dr. Gutheil will play a central role in the development of Proacta's lead program, PR-104, a hypoxia targeted small molecule prodrug designed to improve the outcomes of current treatment regimens that can include chemotherapy. PR-104 is designed to be activated in the low oxygen environment of hypoxic tumors, and a three center Phase I study of cancer patient treatment is currently underway.

Dr. Gutheil is the former Vice-President of Medical Affairs for Favrille, Inc. and former Executive Director of Clinical Research and Development at Vical, Inc. Dr. Gutheil also served as the Director of Clinical Research at the Sidney Kimmel Cancer Center in San Diego. Prior to this, Dr. Gutheil was a faculty member at the University of Maryland Cancer Center, where he was Co-director of the Neuro-oncology Program, Director of the Fellowship Program and Director of the Community Physician Outreach Program.

Dr. Gutheil received his bachelor's degree from the University of California, San Diego in 1979 and his M.D. from the Medical College of Wisconsin in 1983. He completed his internship and residency at the Johns Hopkins University and his Medical Oncology and Hematology training at the University of Maryland Cancer Center. Dr. Gutheil holds board certifications in both internal medicine and medical oncology. Dr. Gutheil's outstanding scientific credentials and accomplishments complement the strong development team we have built at Proacta, said Paul Cossum Ph.D., President and CEO of Proacta Inc. Dr. Gutheil will serve as a key member of our management team, and will be responsible for designing and leading Proacta's clinical development programs. His extensive experience in clinical oncology and translational laboratory research will be invaluable as we further develop PR-104 and our pipeline of clinical candidates.

I am pleased to be joining such a seasoned team at Proacta, and to take part in the development of this important science,” said Dr. Gutheil. Proacta's efforts to better understand and treat hypoxic tumors have the potential to help large patient groups achieve better outcomes in fighting cancer.

Founded by leading cancer researchers Professors Bill Denny and Bill Wilson of the University of Auckland, and Professors Martin Brown and Amato Giaccia of Stanford University, Proacta has already developed a strong IP portfolio using tumor hypoxia as a target for innovative cancer therapies. The company's current pipeline spans nine chemical classes and over twenty patents. The Phase I trial currently in process is a dose-escalating safety evaluation in patients with a range of tumor types. The company expects to launch a second Phase I study in 2006, followed by Phase II studies and a second compound entering the clinic in 2007.

About Proacta
Proacta Inc is a privately held, clinical stage biotechnology company that discovers and develops innovative small molecule prodrugs that address critical, unmet needs in oncology. Proacta's initial programs are focused on developing prodrugs to be selectively activated under hypoxic conditions within a solid tumor. The company's exceptional pipeline spans nine chemical classes and over twenty patents. Its scientific founders are at the University of Auckland, New Zealand, and Stanford University, Palo Alto. The company has scientific collaborations with Genentech Inc, Onyx, Manchester University in the UK, Stanford University and the University of Auckland. Proacta, Inc has its headquarters in San Diego, CA and has a wholly-owned subsidiary, Proacta Therapeutics Ltd, in Auckland where drug discovery efforts are located. www.proacta.com