Federal Circuit Adds More Clarity (or Confusion) in Amgen v. Sanofi

We are pleased to bring to you a guest post by Adarsh Ramanujan. Adarsh is an Advocate with Lakshmikumaran & Sridharan, New Delhi, primarily assisting clients as a litigation attorney. He obtained his B.Sc. LL.B. (Hons.) degree (Gold Medalist) from National Law University, Jodhpur  and LL.M. degree from University of California, Berkeley. A major portion of his time is spent, practicing in the areas of IP & Technology Laws as well as in International Trade Law. His expertise also extends to regulatory laws such as environmental laws, biodiversity laws and cyber laws. Adarsh is also a visiting lecturer at the National Law Universities in Jodhpur and New Delhi as well as at the CEIPI Institute (University of Strasbourg). He has authored or coauthored close to 30 publications on diverse topics, including on IP, WTO, constitutional law and international tax. Adarsh has guest blogged for us in the past as well (see here).

Federal Circuit Adds More Clarity (or Confusion) in Amgen v. Sanofi

Adarsh Ramanujan

In its decision dated October 5, 2017 the Federal Circuit in Amgen v. Sanofi, vacated the permanent injunction granted in favour of Amgen, enjoining sales of Sanofi’s Praluent ® alirocumab (Praluent). The Federal Circuit has remanded the matter back to the District Court, effectively to re-assess the validity of Amgen’s U.S. Patent Nos. 8,829,165 and 8,859,741, from a written description and enablement perspective. The Federal Circuit opinion has brought out fundamental, but potentially controversial clarifications on three points: (i) the relevance of post–priority documents in assessing written description and enablement, (ii) the principle to be followed in assessing written description (iii) the scope of public interest in determining whether to grant an injunction.


In the District Court proceeding, Amgen sued Sanofi claiming that Sanofi’s Praluent infringed the two patents of Amgen. Sanofi stipulated to infringement, but challenged the validity of the patents in question on written description, enablement and obviousness grounds. The challenge on written description and enablement grounds were based on certain post-priority date evidence, which were entirely excluded by the District Court. This was under challenge before the Federal Circuit.  Also under challenge was the District Court’s instructions to the jury concerning the principle to be applied to assess fulfillment of the written description requirement, in relation to “Newly Characterised Antigen”. Further, Sanofi also challenged the summary judgment in favour of Amgen on non – obviousness, in relation to priority references cited by Sanofi.

While the Federal Circuit agreed that written description is to be judged based on the state of art as on the priority date, the relevance of post-priority date documents cannot be entirely excluded. The law requires that a patent claiming a genus must disclose “a representative number of species”. In the Court’s opinion, relevant to this analysis is evidence that some of the species covered within the claimed genus are not disclosed by the patent. In this respect, the Court also believed that as a logical matter, post-priority date evidence could disclose such species that purportedly fall within the scope of the claimed genus but are not really disclosed in the specification. Further with respect to enablement, the court once again believed that post-priority date evidence showing the extent of undue experimentation engaged by Sanofi, would also be relevant to show or to assess whether Amgen’s patents fulfils the enablement requirement. Accordingly, the Federal Circuit reversed the District Court decision to exclude post-priority date evidence for the assessment of written description and enablement, and remanded the matter back to the District Court for a new trial on these issues. In the course of this reasoning the Federal Circuit also clarified the scope of its decision in the cases of Centocor Ortho Biotech, Inc. v. Abbott Labs., 636 F.3d 1341 (Fed. Cir. 2011) and In re Hogan, 559 F.2d 595, 605 (CCPA 1977)).

The District Court had among others, instructed the jury that “…In 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…”

The Federal Circuit concluded that this instruction was improper. Citing prior jurisprudence, the Federal Circuit noted that it had already questioned the correctness of the “newly characterised antigen” test. In the Court’s opinion, the jury instruction issued by the District Court allowed the jury to return a finding of adequate written description merely from a finding of the ability to make and use any antibody. On the other hand, the en banc ruling in Ariad Pharm., Inc. v. Eli Lilly & Co., 598 F.3d 1336, 1351 (Fed.Cir. 2010) (en banc) (Ariad), was that the statutory requirement of written description cannot be fulfilled merely by showing how to make and use the invention; instead, the specification 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 “when the art has established a correlation between structure and function.”

The Federal Circuit held that as per the evidence on record, there was a serious factual dispute that knowledge of the chemical structure of an antigen gives the required kind of structure-identifying information about the corresponding antibodies. Under the circumstances, the Federal Circuit was of the opinion that the scientific premise behind the jury instruction was not accurate and the instruction under challenge displaced the required fact-finding exercise, which is impermissible in law. Moreover, the Court noted that the statutory mandate requires a “written description of invention” under 35 U.S.C. § 112. Since the so-called “newly characterised antigen” test allowed patentees to claim antibodies by describing something that is not the invention, i.e. the antigen, in the Court’s view, the so called “newly characterised antigen” test is not in line with the statutory requirement.

On the issue of permanent injunction, the Federal Circuit first concluded that the District Court’s decision on the issue of permanent injunction in this case was not in accordance with the Supreme Court’s decision in eBay, Inc. v. MercExchange, L.L.C., 547 U.S. 388 (2006).  This was because the District Court issued a permanent injunction despite finding that grant of injunction in this case would dis-serve the public interest. Nevertheless, the Court further opined that the District Court’s analysis of the public interest factor was incorrect. In the underlying decision, the District Court weighed “being a patent holder and a verdict winner” on the one hand and “taking an independently developed, helpful drug off the market” on the other. The Federal Circuit held that eliminating a choice of drug, is not, by itself, sufficient to disserve public interest. If that were the case, courts could never injunct the sale of an infringing drug because doing so would always reduce a choice of drugs. The Court held that just as much as a patentee does not automatically receive an injunction by merely proving infringement, similarly, an infringer cannot escape an injunction merely by producing infringing drugs. It was held that a mere reduction in choice of drugs cannot be sole reason to deny an injunction.


The Federal Circuit’s decision to allow post – priority evidence through a limited window is definitely a shift in the approach to assess written description and enablement.

The court has also effectively chastised the “Newly Characterised Antigen Test”. However, this ruling may not be welcomed by all in the industry, especially those who are involved at the break through level of identifying antigens. Ultimately, the identification of the antigen is what results in the development of antibodies. Where one innovator takes the effort to identify the antigen (and consequently develop, say, one or more antibodies), competitors can piggy-back on that effort to identify other antibodies that bind to that antigen. Under the current patent law standards, the identification of the antigen is not, by itself, patentable. From that innovator’s perspective, their breakthrough in identifying the antigen should not become a stepping stone for competitors to develop and commercialise competing products. On the other hand, given the uncertainties involved in developing antibody to a newly characterised antigen, there may be questions raised on the ability of that innovator to cover every possible antibody that binds to an antigen. Equally important is the policy consideration in terms of the extent of disclosure required and the concept that patents should also ultimately contribute to downstream research. This a very important issue, where legal policy may have serious implications on research and development in the future. There is certainly no easy answer to this conundrum.

As sophisticated as these issues may be, one must realize that the decision of the Federal Circuit certainly carries a lot of weight across the globe, especially in jurisdictions such as India where patent law is not yet fully developed. Therefore, subject to any potential clarifications from the Supreme Court on this matter, the reverberation of this decision will certainly be felt in the other jurisdictions as well. The clarification provided by the Federal Circuit on the public interest factor in assessing injunctions is also a very important development since, in India also public interest is a factor in the grant or denial of interim injunctions.

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