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January 25, 2001
Abstracted from PR Newswire

FDA Grants Expedited Review to Abarelix

Cambridge, Mass., January 25, 2001 -- Praecis Pharmaceuticals Incorporated (Nasdaq: PRCS) today announced that the United States Food and Drug Administration (FDA) has informed the company that the FDA has accepted and filed the company's New Drug Application (NDA) for abarelix depot for the hormonal treatment of prostate cancer. In addition, the FDA advised the company that the agency has granted abarelix depot priority review, a classification applied to a product that, if approved, would in the FDA's judgment represent a significant improvement compared to marketed products. The FDA's classification of this NDA as a priority review means that the agency is committed to complete its review of the NDA within six months of the submission, which would be June 12, 2001. During the review period, the agency may ask for additional information that could extend its review beyond June 12, 2001. Following completion of its review, the FDA will inform the company whether or not the drug is approved for marketing, and if not, what additional steps are necessary for its approval.

Additional Information
Graphic taken from T. Cook and W.P. Sheridan. Development of GnRH Antagonists for Prostate Cancer: New Approaches to Treatment. Oncologist; 5 (2): 162-168, April 2000. Full text article available here in PDF format.

Abarelix is the latest drug for suppression of testosterone production in men with prostate cancer. Abarelix, a peptide analog of GnRH (gonadotropin releasing hormone), acts to block receptors in the anterior pituitary gland. Abarelix offers a theoretical advantage over existing GnRH analogs (Lupron, Zoladex), which are agonists, ie they stimulate production of testosterone before suppressing it. Abarelix is a pure antagonist, and no preliminary surge of testosterone is seen in men receiving it.

Abarelix is the product of Praecis Pharmaceuticals. After FDA approval, the product will be marketed by Amgen. Phase III trial data of Abarelix, which were presented at ASCO 2000, are summarized here. The major abstract by John Trachtenberg et al is available here.



Graphic taken from ASCO 2000 Poster of M. Garnick et al.
Garnick's stylized chart shows differences in testosterone response following administration of agonist (Lupron / Zoladex) or antagonist (Abarelix) types of GnRH analogs. While a brief, mild "surge" in testosterone levels is initially seen when a GnRH agonist (Lupron or Zoladex) is administerered, a castrate level is seen after 2 - 3 weeks in approximately 95% of men treated with either an agonist or antagonist. In former times, when most men receiving GnRH analogs had overt metastatic disease, the testosterone surge wasassociated with a clinical disease "flare" in approximately 10% of patients (I. Thompson et al, J. Urol. 144:1479-80, December 1990). However, most men in contemporary series do not have overt metastases; disease flare nowadays appears to be less common than in former times; and any long-term effect of testosterone surge is unknown.
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