In AbbVie Deutschland GmbH & Co. v. Janssen Biotech, Inc., the US Federal Circuit reminded patent applicants of the importance of providing a suitable selection of representative examples to support broad claims, particularly claims which define a class of products (a genus) in terms of function rather than structure.

The patents described the sequences of approximately 300 antibodies having a Koff rate falling within the claimed range. Since all of these species were derived from a single antibody, they all had the same VH3 heavy chains and λ light chains, and shared at least 90% sequence similarity in the variable region.

AbbVie alleged infringement by Janssen’s (previously Centocor) anti-IL-12 antibody, Stelera®. Unlike AbbVie’s antibodies, Stelera has VH5 heavy chains and κ light chains, and shares only about 50% sequence similarly in the variable regions with AbbVie’s antibodies. Despite these structural differences, the Koff rate of Stelera® caused it to fall within the scope of AbbVie’s claims.

Janssen challenged the validity of AbbVie’s patents, arguing that the group of structurally similar antibodies disclosed by AbbVie was not representative of the broad claims. The Federal Circuit agreed, noting that although AbbVie described a large number of antibodies, these were all so structurally similar that they did not represent other types of structures encompassed by the claimed genus. AbbVie’s patents were therefore held to be invalid for lack of written description. In other words, AbbVie had failed to demonstrate that their broad claims were justified in view of what they had actually invented.

The Judgment noted that functionally-defined claims can be vulnerable to invalidity, especially where it is difficult to establish a correlation between structure and function. This message is particularly relevant to molecules for which, like antibodies, small structural differences can radically alter function. Applicants are therefore advised to identify structural features which are common to all members of a claimed genus and which are linked to the relevant function. Although this case was decided under US law, similar provisions apply in Europe. It is therefore recommended to include as much structural information as possible on filing a patent application, preferably including complete structural or sequence data for the most important molecules.