PTO to Reexamine Plavix® Patent

Scott Daniels | August 17, 2009

The PTO granted today an ex parte request by Apotex Corp. to reexamine Sanofi-Aventis’ U.S. Patent No. 4,847,265. The ‘265 patent claims an enantiomer which prevents blood platelets from clotting, thereby reducing the chances for heart attack or stroke.

The request is the latest development in an on-going dispute between Sanofi-Aventis and Apotex regarding the latter’s generic pharmaceutical Plavix®. After Apotex filed an ANDA for Plavix® in 2001, Sanofi-Aventis sued Apotex for infringement of the ‘265 patent. The trial judge ruled in 2007 that the ‘265 patent was valid and enforceable, and this past December the CAFC affirmed those validity and enforceability rulings in favor of the patentee Sanofi-Aventis.

The PTO has now found, however, that each of three prior art references or combinations of prior art references “raise a substantial new question of patentability” for the ‘265 claims. None of the references cited was before the PTO during the initial prosecution of the ‘265 patent application.

The primary references relied upon Apotex in its request – U.S. Patent No. 4,529,596 and Canadian Patent No. 1,194,875 – were raised in the earlier litigation with Sanofi-Aventis and found by the CAFC not to invalidate the ‘265 claims. Nevertheless, Apotex’s request successfully invoked In re Swanson (No. 07-1534, 2008 WL 4068691 (Fed. Cir. 2008)) for the principle that a reexamination raises different issues with different standards of proof from those in District Court litigation. Accordingly, the PTO will reexamine the ‘265 claims despite the fact that the CAFC has already affirmed a District Court judgment that the ‘265 claims are valid over the same prior art references.

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