On March 12, a Pfizer Inc. reissue patent was held invalid by the United States District Court for the Eastern District of Virginia, allowing for generic pharmaceutical competition to possibly enter the marketplace.

The reissue patent (U.S. Patent Number RE44048) claimed methods of treating conditions including arthritis by administering the company’s arthritis drug Celebrex (celecoxib). In a case of first impression, the court on summary judgment held the patent invalid for failure to file a divisional application because the reissue process does not allow an applicant to correct an application filed as a continuation-in-part (CIP) application to redesignate it as a divisional application. The court also held that the intentional act of filing a CIP application is not correctable via reissue, and further that the reissue patent was invalid under the judicial doctrine of obviousness-type double patenting.

Pfizer sued generic pharmaceuticals companies Apotex Inc. and Apotex Corp., Teva Pharmaceuticals USA Inc., Mylan Pharmaceuticals Inc., Watson Laboratories, and Lupin Pharmaceuticals USA Inc. last year in Virginia federal court for infringing the patent. Read more about the ruling here.

Taft partners Richard T. Ruzich and Ian Scott represented Apotex in the case (G.D. Searle LLC, et al. v. Lupin Pharmaceuticals Inc. et al.). Learn more about Taft’s Pharmaceutical and Life Sciences Litigation practice group here.