on February 25, 2008 (local time) a Not approvable letter from the U.S. Food and Drug Administration (FDA) for istradefylline (KW-6002), its investigational drug for the treatment of Parkinson's disease.
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In the not approvable letter FDA expressed concern if the efficacy findings support clinical utility of istradefylline (KW-6002). FDA requested an overall summary of nonclinical mineralization findings. Additionally, FDA asked for clinical pharmacology follow-up information as a Phase 4 commitment.

After closely examining the FDA's response, Kyowa Hakko will work closely with FDA and conduct a comprehensive discussion to determine a path forward for istradefylline (KW-6002).