In the end it all came down to product over process. Transkaryotic Therapies Inc. lost its patent litigation with Amgen Inc. over erythropoietin after Judge William Young ruled late Friday that despite their differing production technologies, TKTX did not show that its EPO invention was different from AMGN's.

If it is upheld on appeal, the ruling could have wider implications, as it suggests that attempts to produce biologic generics via new processes, or by incorporating minor amino acid changes that have no effect on function, might not evade patent protections held by existing biologic therapeutics.

In his decision, Judge Young of the U.S. District Court for the District of Massachusetts stuck unswervingly to the distinction between product and process patents. According to the judge, TKTX did not show that its EPO invention was different from AMGN's. Thus it did not ultimately matter that TKTX's Gene Activation process was different from that used by AMGN to produce EPO.

The same product-process distinction also served to prevent TKTX from demonstrating convincingly to the court that AMGN's patents were not valid, even though AMGN's patents don't cover the Gene Activation production method, which involves genetically engineering human cells to product EPO (see BioCentury, April 3, 2000). AMGN only needed to show that the patents adequately described one method of producing EPO in order to be valid, despite TKTX's arguments that the patents did not show enough evidence that AMGN could make EPO using all the cells it claimed, particularly the human cells in which GA-EPO is produced.

In summarizing his final rulings, Judge Young commended both sides for performing "an extraordinary job in teaching the court many of the nuances of both this challenging area of law and this rather complicated realm of science. Litigation, however, is a rather rough-edged zero-sum enterprise."

Thus Young found that TKTX literally infringed AMGN's U.S. Patent No. 5,756,349 and infringed its 5,621,080 patent under the doctrine of equivalents, an alternative infringement standard.

Under a prior summary judgement motion, the judge had determined that TKTX already infringed U.S. Patent No. 5,955,422. In his final ruling, he confirmed that the '422 patent, as well as the other two infringed patents, withstood several legal challenges to their validity.

The judge found TKTX did not infringe AMGN's process patent, 5,618,698. Also, he determined that AMGN's 5,547,933 patent was not infringed because one of its terms was too vague. He noted that if another court finds his non-infringement decision erroneous for '933, he still would find that the patent is not valid on the same grounds of vagueness.