Holman

May 06, 2023

by Chris Holman

As reported in posts by Dennis and Jason, the Supreme Court recently granted certiorari in Amgen v. Sanofi, marking the first time that the Court has taken up patent law's enablement requirement since enactment of the Patent Act of 1952. The claims at issue are directed to a genus of functionally-defined molecules having therapeutic utility, i.e., monoclonal antibodies defined in terms of binding specificity. For the sake of brevity, I will refer to claims of this type as "chemical genus claims."

A few days later, on November 7, the Supreme Court denied certiorari in Juno v. Kite, a case challenging the Federal Circuit's interpretation of the written description requirement. The claims struck down for lack of adequate written description in Juno are strikingly similar to the claims that were invalidated under the enablement requirement in Amgen, being directed towards nucleic acids encoding chimeric T cell receptors (for use in Car T-cell therapy), comprising, inter alia, a functionally defined "binding element," as exemplified by a single-chain antibody variable fragment (‘‘scFv’’).

The scope afforded to chemical genus claims under 35 USC § 112(a)'s enablement and written description requirements has been hot topic recently (at least in certain quarters). Professors Lemley, Seymore, and Karshtedt (it is so sad that he is no longer with us) published an article in 2020 entitled The Death of the Genus Claim, which asserts that "the law has changed dramatically in the last thirty years, to the point where it is nearly impossible to maintain a valid genus claim." Amgen's successful petition for certiorari relies heavily on Death, and its authors filed an amici curiae brief in support of Amgen's petition.

While Death clearly raises some valid concerns regarding the challenges inventors face in trying to secure effective patent scope for inventions of this type, in my view it is an overstatement to say that chemical genus claims are "dead." I responded to Death in a two-part article arguing, for example, that the case law identified in Death provides scant support for its assertion that the standard for compliance with the enablement and written description requirements has become significantly more stringent in recent years. Christopher M. Holman, Is the Chemical Genus Claim Really "Dead" at the Federal Circuit?: Part II, 41 Biotechnology Law Report 58 (2022); Christopher M. Holman, Is the Chemical Genus Claim Really "Dead" at the Federal Circuit?: Part I, 41 Biotechnology Law Report 4 (2022).

I also point out that relatively broad chemical genus claims continue to survive § 112(a) challenges in the district courts and at the Federal Circuit. See, for example, Ajinomoto Co. v. Int’l Trade Comm’n, 932 F.3d 1342 (Fed. Cir. 2019); Bayer Healthcare LLC v. Baxalta Inc., 989 F.3d 964 (Fed. Cir. 2021); Plexxikon Inc. v. Novartis Pharmaceuticals Corp., Case No. 17-cv-04405-HSG, Document 565, July 22,2021 (N.D. Cal.).

Section 112(a)'s enablement and written description requirements, sometimes referred to as the "adequate disclosure requirements," constitute U. S. patent law's primary non-prior art-based limitations on claim scope. Although Supreme Court has in the past indicated that it views the patent eligibility doctrine as playing an important role in preventing patent claims from broadly "preempting" abstract ideas and natural phenomena, more recently the Court's patent eligibility decisions have focused on the sufficiency of "inventive concept," as opposed to claim breadth per se. Absent such limitations, under a regime in which claim scope would only be limited by the prior art, an inventor could potentially secure patent claims encompassing huge swaths of yet-to-be invented technologies.

Hypothetically, for example, the inventor of the first practical method for communicating at a distance using electricity, e.g., the telegraph, might have ended up with a patent claim encompassing all means of communicating at a distance using electricity, e.g., the internet. The inventor of a rudimentary, barely functional electric light bulb could, assuming it was the first lightbulb, potentially have obtained a patent claim encompassing all lightbulbs, including far superior lightbulbs produced by subsequent inventors. While I have simplified the facts quite a bit, the gist of these examples have been the subject of actual Supreme Court decisions. O’Reilly v. Morse and Consol. Elec. Light Co. v. McKeesport Light Co.. Not surprisingly, in both cases the Supreme Court struck down the patent claims as overly broad, invoking what we would today refer to as the enablement requirement.

More pertinent to the facts of Amgen v. Sanofi, the inventor of the first antibody capable of recognizing a particular antigen could potentially obtain a patent encompassing all antibodies capable of recognizing that antigen. For example, an inventor who has succeeded in producing a mouse monoclonal antibody that binds to a particular human protein (useless as a human therapeutic) could in principle obtain a patent claim encompassing all monoclonal antibodies that bind to that particular human protein, even a fully humanized antibody that functions as a safe and effective biologic drug, e.g., AbbVie's blockbuster Humira, or the accused product in Amgen, Praluent. Again, the gist of this example comes from an actual Federal Circuit decision, Noelle v. Lederman, wherein the claims at issue were struck down under the written description requirement.

The Federal Circuit has invoked both the written description and enablement requirements as doctrinal tools for policing claim scope. Although as a formal matter the written description requirement focuses on whether the inventor has demonstrated "possession" of the full scope of the claim, while the enablement requirement asks whether the scope of the claim is "commensurate" with the scope of disclosure, as a practical matter the two requirements have been applied in a manner that is largely redundant, albeit with a few distinctions of arguable significance discussed later in this post. In my article responding to Death, for example, I point out that the Ariad factors that the Federal Circuit has identified as relevant to assessing compliance with the written description requirement are, in substance, virtually identical to the Wands factors used in the enablement inquiry. If anything, the written description requirement has been seen as the more stringent of the two, particularly in the context of biotechnology – the written description requirement has often been referred to as a "super-enablement" requirement.

And in fact, prior to Amgen, the Federal Circuit has tended to invoke the written description requirement, rather than the enablement requirement, in striking down monoclonal antibody genus claims. See, for example, Noelle v. Lederman, 355 F.3d 1343, 1349 (Fed. Cir. 2004)(disclosure of mouse monoclonal antibody specific for mouse antigen (CD40CR) did not provide adequate written description for claim encompassing any monoclonal antibody capable of binding the human analog of the CD40CR antigen); Centocor Ortho Biotech v. Abbott Laboratories, 636 F.3d 1341(Fed. Cir. 2011)(disclosure of previously characterized antigen (human TNF-alpha) and mouse antibodies to the antigen did not provide adequate written description for claim encompassing fully human monoclonal antibodies capable of binding to a specific neutralizing epitope of the antigen); AbbVie Deutschland GmbH & Co., KG v. Janssen Biotech, Inc., 759 F.3d 1285 (Fed. Cir. 2014)(disclosure of about 300 antibodies falling within the scope of the claim did not provide adequate written description for a claim reciting neutralizing human antibodies capable of specifically binding human interleukin-12 (IL-12)).

Of course, given the redundancy of the doctrines, a claim struck down as overly broad for lack of enablement is highly likely to be invalid for lack of adequate written description, and vice versa. In Amgen, for example, the jury found Amgen's claims not invalid under the enablement and written description requirements, but on a motion for JMOL the district court overruled the jury and found that, as a matter of law, the claims are invalid under both the enablement and written description requirements. In Amgen, the Federal Circuit decided the issue based on a failure to comply with the written description requirement, rendering the enablement issue moot, but in the past the Federal Circuit has been more inclined to find claims of this type invalid for failure to comply with the written description requirement. See the examples provided above, as well as the Juno decision.

Thus, one of the big elephants in the room with respect to the grant of certiorari in Amgen is that the question for review appears to focus solely on the enablement requirement. Even if the Supreme Court lowers the bar for compliance with the enablement requirement, the ruling would presumably have no direct impact on the written description requirement, which has conventionally been thought of as imposing an even higher bar for the sort of claim at issue in the case, e.g., functionally defined chemical genus claims.

Sanofi raised this point in its Opposition brief, arguing that any ruling by the Supreme Court would not be dispositive of the case because, if the Supreme Court overturns the enablement verdict, the Federal Circuit would likely still find the claims invalid for lack of adequate written description. Sanofi points out that Amgen's own amici, i.e., Professors Lemley, Seymore and Karstedt, concluded in Death that the Federal Circuit had "strongly suggested" that the claims were not only invalid under the enablement requirement, but also the written description requirement.

Indeed, the Federal Circuit has on occasion explicitly noted that a claim's compliance with the written description and enablement requirements generally rise and fall together. For example, in Idenix v. Gilead, a recent case involving claims analogous to those at issue in Amgen, the jury also found the claims to be not invalid under the enablement and written description requirements. The district court overturned the jury verdict with respect to enablement, but denied a motion for JMOL with respect to written description. On appeal, the Federal Circuit affirmed the district court's holding that the claims were invalid for lack of enablement, but reversed its denial of JMOL for failure to meet the written description requirement, finding the claims invalid under both doctrines.

Under the Federal Circuit's current interpretation of the written description and enablement requirements, I think it would be highly unusual for the court to find claims of the type at issue in Amgen invalid for lack of enablement but not for lack of adequate written description. In fact, when the district court decision in Idenix v. Gilead initially came out, finding the claims invalid under the enablement requirement but not under the written description requirement, I thought it was so striking that I wrote an article about it. Christopher M. Holman, Enablement Invoked as a ‘‘Super-Written Description Requirement’’ to Overturn $2.5 Billion Jury Verdict, 37 Biotechnology Law Report 63 (2018). So I was not at all surprised when the Federal Circuit reversed and explicitly found the claims invalid under both the enablement and written description requirements, even though the Federal Circuit could have chosen not to address the written description issue as moot in light of the enablement ruling, as it did in Amgen.

In retrospect, I wonder if it might have been better for the Supreme Court to take up the issue of adequate disclosure in a case like Idenix, where the Federal Circuit explicitly addressed both the enablement and written description requirements in the context of the same chemical genus claims. As Jason intimated in his blog post, while it is relatively easy to point out the shortcomings in the Federal Circuit's current § 112(a) jurisprudence, it is much harder to come up with an effective alternative. I have to think that it will be particularly difficult for the Supreme Court to make a positive contribution to the law of adequate disclosure without also taking into account the written description requirement.

Although the written description requirement has long been used to police the claiming of new matter, it only took on the role of policing claim scope as what is in essence an alternate enablement requirement in 1997 when the Federal Circuit decided UC Regents v. Eli Lily, creating what I refer to as the "Lilly written description requirement" (so as to distinguish it from the "traditional written description requirement" used prevent the claiming of new matter). Early on, the Lilly written description requirement seemed to impose a much higher threshold than enablement, particular for biotechnology inventions, hence its characterization as a "super-enablement requirement." But it seems to me that at this point in time the standards for compliance with the written description and enablement requirements have become for the most part indistinguishable, as illustrated by the redundancy of the Ariad and Wands factors, and the paucity (or, to my knowledge, the absence) of any judicial decisions (upheld on appeal) explicitly finding a claim invalid under the Lilly written description requirement but not invalid for lack of enablement, or vice versa.

Nonetheless, Federal Circuit precedent has carved out some clear differences between the written description requirement and enablement, although as a practical matter it is not clear to me how significant those differences are. For example, the Federal Circuit treats the written description requirement as a question of fact, and the enablement requirement as a question of law based on underlying factual findings. In its petition for certiorari, Amgen also asked the Court to rule that enablement, like written description, is a question of fact, but the Court declined to take up that question. In principle, a decision by a jury (or judge in a bench trial) should be afforded more deference with respect to a question of fact, which might explain why in Amgen and Idenix the district courts overturned the juries’ enablement decisions, but not their written description decisions. However, it seems to me that when case reaches the Federal Circuit the formal distinction between question of fact and "question of law based on underlying factual findings" has little practical effect. See, for example, Centocor Ortho Biotech v. Abbott Laboratories, 636 F.3d 1341(Fed. Cir. 2011)(overturning jury decision finding claim encompassing fully human monoclonal antibodies not invalid for failure to comply with the written description requirement).

Another difference between the two doctrines has to do with the admissibility of evidence. In the Federal Circuit's first decision in Amgen v. Sanofi (the grant of certiorari is with respect to the Federal Circuit second decision in the case), the court held that the district court had committed legal error by improperly excluding post-priority date evidence of antibodies falling within the scope of the claim, including the accused product (Praluent). The district court based its decision to exclude the evidence on a 1977 decision of the Court of Customs and Patent Appeals, In re Hogan, which the Federal Circuit has interpreted as prohibiting, in the context of the enablement inquiry, admission of "post-priority-date evidence proffered to illuminate the post-priority-date state of the art." Without questioning the continuing vitality of Hogan, the Federal Circuit held that, in the context of the written description inquiry, post-priority-date evidence is admissible to show that a patent fails to disclose a representative number of species, explaining that Hogan is silent with respect to evidence of this type. Thus, it seems that under some circumstances post-priority-date evidence illustrating the structural and functional breadth of a chemical genus claim could be admissible for purposes of a written description challenge but not a challenge for lack of enablement.