Blocking the Road: Antibodies and Epitope Claims

District Court Decision: Amgen Inc. et al v. Sanofi et al., DED-1-14-cv-01317 (Mar. 16, 2016)

Background: Amgen is the owner of two patents directed to anti-PCSK9 antibodies, US 8,829,165 and US 8,859,741. PCSK9 (proprotein convertase subtilisin/kexin type 9) is an enzyme found in the liver, among other tissues, and binds to receptors for low-density lipoprotein (“LDLR”). The patents include claims to monoclonal antibodies that bind to particular residues on PCSK9 and block uptake by LDLR. The specification provides testing data on, inter alia, epitope contact residues for two antibodies that prevent LDLR uptake, as well as competitive binding (“binning”) experiments for a series of additional antibodies.

Issue: At trial, the defendants alleged the claims lacked enablement and written description because they covered a large genus of antibodies without providing sufficient examples or structural details of antibodies targeting the correct epitope. The defendants also argued the claims were obvious over prior art antibodies directed to PCSK9.

Outcome: The jury heard extensive testimony regarding the adequacy of the crystal structure data for the two antibodies in Amgen’s patents, and the binning experiments for a number of other antibodies, and concluded this was sufficient to establish enablement and written description.

Prosecution Takeaway: While the outcome of the Amgen case could still change as the result of a post-trial motion or on appeal, the initial decision highlights the potentially broad reach of epitope claims. It also demonstrates the importance of including a solid evidentiary basis for epitope and competitive binding claims when drafting an antibody application. Patent practitioners should work with their inventors to obtain as much data as possible on epitopes and competitive binding for their newly-developed antibodies, along with data showing any other functional aspects of the constructs, and consider carefully whether to include that data in the application. If presented properly, the data may be able to support broader protection for a commercial product.