In 1989, Bayer Cropsciences filed the application that matured into US Patent #6,153,401, covering “[A] polypeptide having the biological activity of 2,4-D monooxygenase.” The enzyme they had discovered was capable of cleaving the popular herbicide 2,4-D into harmless chemical byproducts, potentially enhancing the resistance of crop plants containing the gene to herbicide application. Based on widespread scientific assumptions at the time (but in the absence of actual data) they described their enzyme as a 2,4-D monooxygenase, an enzyme that removes a key part of the 2,4-D molecule in part by utilizing an oxygen molecule, O2. The monooxygenase reaction incorporates one oxygen atom into the breakdown products of the 2,4-D cleavage, releasing the other oxygen to become part of a water molecule. Shortly after the filing of the patent application (and seven years before the issuance of the patent), it was discovered that the enzyme was in fact a dioxygenase, acting by a chemically different mechanism than the monooxygenase activity claimed (dioxygenase activity involves, unsurprisingly, the incorporation of both oxygen atoms into the reaction products, instead of just one). Despite this knowledge, Bayer did not amend their claims to remove the term monoxygenase, relying instead on their interpretation of “2,4-D monooxygenase” as simply being an enzyme that cleaves the sidechain of 2,4-D, rendering it nontoxic to plants.
Recently, in affirming a decision of the Delaware District Court (finding noninfringement by a competing Dow Agrosciences product), the Federal Circuit described the flaws in Bayer’s method. It found that, although the inventor is entitled to act as his own lexicographer, he is not entitled to change the meanings of terms that have well established, well known, and precise meanings within the art. Specifically, in the world of biochemistry, the term “monooxygenase” refers to an enzyme with an explicit monooxygenase activity, with specific requirements as to the disposition of oxygen atoms during the chemical reaction. Where Bayer had argued that they could define the language to cover any enzyme that cleaved 2,4-D, by whatever mechanism, the court ruled that their use of a highly specific and well defined chemical term precluded this stretch of terminology. The fact that the asserted chemical terminology was incorrect was found to be sufficient to preclude patenting of Bayer’s enzyme. Perhaps adding insult to injury, the court further discussed of the likelihood that by simply claiming 2,4-D-cleaving enzymes that were discovered by the disclosed method of screening soil bacteria would run afoul of the disclosure requirements of 35 U.S.C §112. Though they did not close the door entirely, the court did leave the strong impression that, had the claims been amended to remove the reference to the monooxygenase activity, the remaining disclosure would likely have been overbroad and thus still unenforceable.
So what could Bayer have done? A savvy claims drafter could, no doubt, have written claims that would support the broad genus that Bayer wanted to control. By the same token, careful amendment after the discovery of the biochemical truth may have brought some protection (though the court listed some of the pitfalls in this approach). Ultimately, though, the best thing they could have done is to draft claims that didn’t get ahead of their actual knowledge. In biotech, there is no substitute for having your science straight.