Article: January 2018: Federal Circuit Issues Important Decision On Written Description And Enablement In Amgen Inc. v. Sanof

In Amgen Inc. v. Sanofi, 872 F.3d 1367 (Fed. Cir. 2017), the Federal Circuit acknowledged the relevance of post-priority date evidence in determining whether claims satisfy the written description and enablement requirements, rejected the “newly characterized antigen” test as a means of proving written description of monoclonal antibodies, and commented on the proper application of the standards for considering permanent injunctions in the medical context. This decision provides crucial clarity on important issues in the ever growing area of biologic drugs, but also offers valuable guidance for all patent litigation.

The Patent
Amgen brought suit against Sanofi for infringement of two patents through its Praluent® alirocumab product. Id. at 1372. The two asserted patents (U.S. Patent Nos. 8,829,165 and 8,859,741) generally relate to monoclonal antibodies that help reduce lowdensity lipoprotein (“LDL”) cholesterol by inhibiting PCSK9—a naturally occurring protein that causes the destruction of LDL receptors responsible for extracting LDL from the bloodstream. Id. at 1371. The relevant claims of those patents are directed to the entire genus of monoclonal antibodies that bind to specific amino acid residues on PCSK9 and block PCSK9 from binding to LDL receptors. Id. at 1372.

The Dispute
Sanofi appealed from a final judgment of the district court holding the two patents asserted against it not invalid. Id. at 1371. Sanofi argued, inter alia, that the district court erred in at least the following respects: (1) the district court improperly excluded postpriority date evidence regarding written description and enablement; (2) it improperly instructed the jury on written description that a claim to antibodies can be adequately described by the disclosure of a newly characterized antigen; and (3) it improperly issued the permanent injunction. Id.

With respect to post-priority date evidence, the district court had concluded that the evidence “did not illuminate[] the state of the art at the time of filing,” and therefore was not relevant “to determine whether there is sufficient disclosure of the claimed invention.” Id. at 1373 (emphasis in original). Sanofi argued that excluding such evidence was improper because the “written description requirement protects against attempts to preempt the future before it has arrived” and it “would make [no] sense if future innovators were barred from introducing evidence of their own innovations in written description challenges.” Id. Amgen responded that “post-priority-date evidence may be relevant [to written description and enablement] only if it illuminates the state of the art at the filing date” and that antibodies not in existence as of the priority date are not “part of the state of the art” and “therefore cannot ‘illuminate’ it.” Id.

With respect to the challenged jury instruction, the district court had instructed the jury that “[i] n the case of a claim to antibodies, the correlation between structure and function may also be satisfied by the disclosure of a newly characterized antigen by its structure, formula, chemical name, or physical properties if you find that the level of skill and knowledge in the art of antibodies at the time of filing was such that production of antibodies against such an antigen was conventional or routine.” Id. at 1376. Sanofi argued that this instruction was improper because “disclosing an antigen does not satisfy the written description requirement for a claim to an antibody.” Id. Amgen responded that the district court’s instruction was consistent with the “newly characterized antigen” test allegedly supported by Federal Circuit precedent. Id.

With respect to the permanent injunction, the district court entered the injunction despite having concluded that doing so would “disserve the public interest” by eliminating “a choice of drugs.” Id. at 1381.

The Federal Circuit’s Opinion
The Federal Circuit panel (Chief Judge Prost, Judge Taranto, and Judge Hughes) reversed both the district court’s exclusion of post-priority date evidence and its jury instruction on written description. In reaching its decision on post-priority date evidence, the Federal Circuit confirmed that “evidence illuminating the state of the art subsequent to the priority date is not relevant to written description.” Id. at 1373- 74. However, the Federal Circuit held that “postpriority-date evidence of a particular species can reasonably bear on whether a patent fails to disclose a representative number of species falling within the scope of the genus or structural features common to the members of the genus so that one of skill in the art can ‘visualize or recognize’ the members of the genus.” Id. at 1374 (internal quotations omitted). The Federal Circuit also held that post-priority date evidence “could have been relevant to determining if the claims were enabled as of the priority date and should not have been excluded simply because it postdated the claims’ priority date.” Id. at 1375. In reversing the district court’s jury instruction on written description, the Federal Circuit stated that the instruction’s recitation of the newly characterized antigen test “effectively permitted the jury to dispense with the required finding of a written description of the invention.” Id. at 1377 (internal quotations omitted). The Federal Circuit emphasized that “to satisfy the statutory requirement of a description of the invention, it is not enough for the specification to show how to make and use the invention, i.e., to enable it.” Id. The district court’s instruction— which allowed the jury to deem any claimed antibody adequately described merely because antibodies to the antigen could be easily produced and used—was therefore erroneous. Id. The Federal Circuit further noted that the instruction was improper for the additional reason that it would allow “patentees to claim antibodies by describing something that is not the invention, i.e., the antigen.” Id. at 1378.

In light of these reversals, the Federal Circuit remanded the case to the district court for a new trial on written description and enablement and accordingly vacated the permanent injunction. Although not necessary to its decision, the Federal Circuit noted in dicta that “the district court’s permanent injunction analysis in this case was improper for two distinct reasons.” Id. at 1381. First, the district court should not have issued an injunction it found not to be in the public interest. As stated by the Federal Circuit, “[i]f a plaintiff fails to show that the public interest would not be disserved by a permanent injunction, then the district court may not issue an injunction.” Id. (internal quotations omitted). Second, the district court should not have based its finding that the injunction would disserve the public interest solely on a reduction in choice of drugs. The Federal Circuit reasoned that “[u]nder such an approach, courts could never enjoin a drug because doing so would always reduce a choice of drugs,” which “of course, is not the law.” Id.