The power of a product patent

How far should a product patent reach? Is it sound public policy for a court to find that such a patent covers products made in ways not known when the patent was originally filed? That was the question before the Court of Appeals for the Federal Circuit (CAFC) in the recent case of Amgen v. Hoechst and Transkaryotic Therapies. The case involved Amgenʹs high successful antianemia drug EPOGEN whose sales are currently around US $2 billion per year. The story of this successful drug begins in the early 1980s, when Amgenʹs scientists applied the still relatively new technology of genetic engineering to the problem of chronic anemia in patients undergoing kidney dialysis. Amgen filed its first patent application on its work in 1983. Over the years, seven U.S. patents have issued claiming priority from this original application, six of which have been the subject of lawsuits brought by Amgen to keep potential competitors out of the lucrative market for erythropoietin.