Amgen's Phase 2 Study of GDNF for Advanced Parkinson's Disease Fails to Meet Primary Endpoint; Six Months of Treatment Showed Biological Effect But No Clinical Improvement

THOUSAND OAKS, Calif.--(BUSINESS WIRE)--June 28, 2004--Amgen (Nasdaq:AMGN), the world's largest biotechnology company, today announced that the Phase 2 study of its novel glial cell line-derived neurotrophic factor, or GDNF, for the treatment of advanced Parkinson's disease did not meet the primary study endpoint upon completion of six months of the double-blind treatment phase of the study. In the study, GDNF was safe and well-tolerated.

The Phase 2 randomized, double-blind placebo-controlled study involved 34 patients with advanced Parkinson's disease who received direct, continuous infusion of GDNF into the putamen, a region of the brain known to be affected by Parkinson's disease. The primary endpoint of the study was improvement of symptoms as defined by the Unified Parkinson's Disease Rating Scale, a measurement tool that assesses the status of patients suffering from Parkinson's disease. Initial analysis of the preliminary data showed no clinical improvement compared to placebo following six months of treatment, despite evidence of alteration in brain function. All patients in the trial are receiving GDNF in an open label extension study.

"We are currently analyzing the data to understand why this study differs from the long-term improvement of the patients, who have been treated with GDNF for close to three years in an ongoing open-label study being conducted in the United Kingdom," said Beth Seidenberg, M.D., chief medical officer and senior vice president, Amgen. "We are committed to understanding if a different approach, including evaluating a higher dose, may yield an outcome that is consistent with the open label study."

Further details about the trial will be available when all data analyses are complete. Data from the study are being submitted for presentation at the annual meeting of the American Neurological Association in October.

Amgen's recombinant GDNF protein is a duplicate of a naturally occurring GDNF found in the central nervous system that promotes the growth, regeneration and protection of specific nervous tissue.

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