The British High Court's rejection last week of a biotech company's patent on the genetic sequence coding for a therapeutically important protein may be a warning for other biotechs who hold patents on portions of the human genome.

The court ruled last week that a patent held by Human Genome Sciences since the mid 1990s was invalid because at the time the company applied for the patent they hadn't demonstrated a practical use. The patent in question covers the genetic sequence for a protein in the tumor necrosis factor family, called neutrokine-alpha. The pharmaceutical company Eli Lilly filed a suit against Human Genome Sciences, stating that the company's patent did not have sufficient evidence of function or therapeutic potential to warrant granting. The court's rejection will allow Eli Lilly to continue in the development of its own neutrokine-alpha antibody.

"What [the ruling] says to bench scientists is 'when you do get a sequence, you've got to make sure you have some specific practical use,'" Ronald Lundquist, patent attorney at Fish and Richardson, told The Scientist. "Educated guesses aren't going to be enough."

He added that this case is a follow-on from a US patent court ruling in 2004, which was later upheld by the Federal Circuit Court of Appeals. In that case, the agricultural biotech Monsanto sought to patent expressed sequence tags -- short nucleotide sequences that are fragments of a cDNA clone -- in maize plants. Both courts ruled that the practical application or use had not been sufficiently established to warrant a patent.

Although the current ruling was made in Britain, patents with a similar lack of early evidence of their therapeutic value may suffer the same fate. "It goes to show in general that Europe and the US are going to look at these sorts of patent applications in a very similar way," Lundquist said.

But the original filing was made so long ago, that it may not have much effect on companies today, Joseph Lucci, patent attorney at Woodcock Washburn told The Scientist. "A lot has occurred over the years, and early on people filed [patent applications] maybe when they didn't have a handle on what the ultimate utility would be, let alone experimental data" demonstrating therapeutic potential, he added. Over the years there has been "more of an effort to develop the utility of the sequences before filing," he said, "not just to rely upon the fact that you have a sequence."