Since the Federal Circuit’s October 5, 2017 decision in Amgen Inc. v. Sanofi overruling the so-called “newly characterized antigen” test for written description under 35 U.S.C. 112, patent challengers in the pharmaceutical and biotechnology fields have gained powerful tools for attacking antibody claims for lack of adequate written description. More broadly, patent challengers are likely to extrapolate the court’s findings to support various types of attacks on other types of pharmaceutical and biotechnology claims.
Section 112 of 35 U.S.C. requires that the specification “contain a written description of the invention … in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains … to make and use the same….” The Federal Circuit has previously explained that this requirement seeks to ensure “that the inventor actually invented the invention claimed” and that the specification provides a “precise definition” for a claim to a genus via disclosure of “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.”
The “newly characterized antigen” test, as articulated by the U.S. Patent & Trademark Office (“PTO”) in Manual of Patent Examining Procedure (“MPEP”) § 2163 provides the following guidance:
Although structural formulas provide a convenient method of demonstrating possession of specific molecules, other identifying characteristics or combinations of characteristics may demonstrate the requisite possession. As explained by the Federal Circuit, “(1) examples are not necessary to support the adequacy of a written description; (2) the written description standard may be met … even where actual reduction to practice of an invention is absent; and (3) there is no per se rule that an adequate written description of an invention that involves a biological macromolecule must contain a recitation of known structure.” Falkner v. Inglis, 448 F.3d 1357, 1366, 79 USPQ2d 1001, 1007 (Fed. Cir. 2006); see also Capon v. Eshhar, 418 F.3d at 1358, 76 USPQ2d at 1084 (“The Board erred in holding that the specifications do not meet the written description requirement because they do not reiterate the structure or formula or chemical name for the nucleotide sequences of the claimed chimeric genes” where the genes were novel combinations of known DNA segments.). For example, disclosure of an antigen fully characterized by its structure, formula, chemical name, physical properties, or deposit in a public depository provides an adequate written description of an antibody claimed by its binding affinity to that antigen, if “generating the claimed antibody is so routine that possessing the [antigen] places the applicant in possession of an antibody.” Centocor Ortho Biotech, Inc. v. Abbott Labs.,636 F.3d 1341, 1351-52, 97 USPQ2d 1870, 1877 (Fed. Cir. 2011), distinguishing Noelle v. Lederman, 355 F.3d 1343, 1349, 69 USPQ2d 1508, 1514 (Fed. Cir. 2004) (holding there is a lack of written descriptive support for an unknown antibody defined by its binding affinity to an antigen that itself was not adequately described). Centocor concerned claims to antibodies with specific properties, including high affinity to a particular antigen, which was characterized in the prior art. The patent disclosed the antigen, but did not disclose any antibodies with the specific claimed properties. The court held that the claimed antibodies were not adequately described because the generation of such antibodies was not possible using conventional, routine or well-developed technology as of the priority date of the patent.
MPEP § 2163(II)(A)(3)(a)(emphasis added).
Reacting to the Federal Circuit’s decision, on February 22, 2018, the PTO issued a memorandum to the Patent Examining Corps that the “newly characterized antigen” test should not be used in determining whether there is adequate written description under 35 U.S.C. § 112(a) for a claim drawn to an antibody, even when preparation of such an antibody is routine and conventional.
The Federal Circuit explained that this test was contrary to the law because it allows patentees to claim antibodies by describing something that is not the invention, i.e., the antigen, and thereby contradicts the statutory “quid pro quo” of the patent system where “one describes an invention, and, if the law’s other requirements are met, one obtains a patent.” The Federal Circuit noted that Congress has not created a special written description requirement for antibodies as it has, for example, for plant patents. Further, the Federal Circuit explained that it could not conclude that the underlying science has established that a finding of routine or conventional production equates to the required description of the claimed products because the Court “would have to declare a contested scientific proposition to be so settled as to be entitled to judicial notice.” Fed. R. Evid. 201(b). As such, the Federal Circuit held that an adequate written description must contain enough information about the actual makeup of the claimed products—“a precise definition, such as by structure, formula, chemical name, physical properties, or other properties, of species falling within the genus sufficient to distinguish the genus from other materials,” which may be present in “functional” terminology only when the art has established a correlation between structure and function. This is in contrast to cases in which it has been disputed that knowledge of the chemical structure of an antigen gives the required kind of structure-identifying information about the corresponding antibodies.
Furthermore, in challenging the patent in district court, Sanofi sought to introduce post-priority date evidence to show that the patent purportedly did not disclose a representative number of species. In reversing the district court’s exclusion of that evidence, the Federal Circuit explained that the use of post-priority-date evidence to show that a patent does not disclose a representative number of species of a claimed genus is a proper means for challenging written description.
Patent challengers will likely feel emboldened to attack claims beyond those in the antibody context on various broader grounds by extrapolating the Federal Circuit’s holdings in Amgen.
Claims that specify claim elements functionally rather than structurally are subject to attack for lack of written description where the art has not established a correlation between structure and function. By reading the decision as requiring that an established correlation comply with Fed. R. Evid. 201(b), i.e., be a fact that is either “generally known” or “accurately and readily [discernible] from sources whose accuracy cannot reasonably be questioned,” patentees will have difficulty meeting this high bar when challenged. Patent challengers can attack claims for lack of written description by contesting that there is an art-established correlation between structure and function. Particularly, the decision encourages patent challengers to generate post-priority date evidence that the patent does not disclose a representative number of species, including evidence of species that fall within the claimed genus but are not disclosed by the patent. In other words, patent challengers are encouraged to attack claims for lack of written description by submitting evidence that one of skill in the art could not have “visualized or recognized” the members of the claimed genus based on the specification disclosures.
While traditionally analyzed in the context of the enablement requirement of 35 U.S.C. § 112, one may extrapolate the foregoing analysis to attack written description support of patents in which in vitro data is disclosed in the specification but the claims encompass in vivo methods, or where animal model data is disclosed in the specification but the claims are directed to human treatment methods:
- Method of treatment claims supported by in vitro data may be subject to attack for lack of written description where an argument can be made that the art has not established a correlation between in vitro activity and in vivo Thus, patent challengers can attack claims for lack of written description by contesting that there is an art-established correlation between in vitro activity and in vivo efficacy. Particularly, the decision encourages patent challengers to conduct testing to find species within the claimed genus that do not have correlative in vivo activity and to use that post-filing data against the patentee’s claims in support of an argument that persons skilled in the art could not have “visualized or recognized” the members of the claimed genus.
- Method of human treatment claims supported by animal model data are subject to attack for lack of written description where an argument can be made that the art has not established a correlation between animal model data and human Thus, patent challengers can attack claims for lack of written description by contesting that there is an art-established correlation between animal model data and human efficacy, including by submitting post-priority date evidence.
Finally, by apparently heightening the standards for meeting the written description requirement and providing challengers with new tools to generate data demonstrating a lack of written description, the decision encourages patent challengers to look to the specification of priority documents to demonstrate that the granted claims lacked written description support in the priority documents, thereby denying priority benefit claims and using intervening prior art to invalidate the claims on obviousness or anticipation grounds. Accordingly, patent challengers may find it beneficial to generate post-priority date evidence showing that the priority document did not disclose a representative number of species falling within the genus of the granted claims. By denying the priority benefit claim, an intervening disclosure of a species within the claimed genus would be available to the patent challenger as anticipatory prior art.
Pharmaceutical patent challengers will have more options and strategies available to attack patents. For example, in a petition filed on April 2, 2018, Alnylam Pharmaceuticals, Inc. (“Alnylam”) has sought post grant review of U.S. Patent No. 9,695,423 (“the ’423 patent”) assigned to Silence Therapeutics GmbH for, inter alia, lack of written description. Alnylam has sought to use post-priority dated evidence in reliance on the Amgen decision to show that the inventors did not have possession of the claimed genus, that the claims are not entitled to the priority benefit claimed, and are anticipated by intervening prior art. Even though the ’423 patent claims priority to a series of applications filed as early as 2002, Alnylam challenges the legitimacy of the priority claims based on lack of written description and alleges that it is therefore eligible for challenge in a Post Grant Review proceeding. Accordingly, the Federal Circuit’s decision in Amgen will likely further encourage challenges of pharmaceutical and biotechnology patents in various types of proceedings, including Post Grant Review challenges of patents claiming priority benefit to applications filed prior to March 16, 2013.
 Amgen Inc. v. Sanofi, 872 F.3d 1367 (Fed. Cir. 2017).
 Ariad Pharm., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1350-51 (Fed. Cir. 2010) (en banc).
 Ariad, 598 F.3d at 1345.
 Citing 35 U.S.C. § 162 (exempting plant patents from § 112 “if the description is as complete as is reasonably possible”) as an example.
 Alnylam Pharmaceuticals, Inc. v. Silence Therapeutics GmbH, Case PGR2018-00059, Paper 1 (P.T.A.B. April 2, 2018).
 Post-grant review is available for patents reciting at least one claim that is not entitled to a priority date earlier than March 16, 2013.