Vion Pharmaceuticals Inc announced that U.S. Patent No. 6,458,816 was issued from the U.S. Patent and Trademark Office. This patent, entitled "Modified Prodrug Forms of AP/AMP" provides composition-of-matter coverage for additional analogs of the ribonucleotide reductase inhibitor Triapine, which the Company has been studying in clinical trials in solid tumors and leukemia. Ribonucleotide reductase, an enzyme important to DNA synthesis and repair, is a clinically validated target for anticancer therapy.

Alan Kessman, Vion''s Chief Executive Officer, stated, "This new patent supplements our patent portfolio of ribonucleotide reductase inhibitors. Triapine, our lead product in this area, continues to make progress in clinical trials."

The patent was awarded to Vion Pharmaceuticals Inc and the inventors are Drs. Doyle, Karra, Li, Lin, Mao, Qiao, and Xu. Vion licenses Triapine from Yale University.