Holding: In Immunex Corp. v. Sanofi-Aventis U.S. LLC, No. 2019-1749 (Fed. Cir. Oct. 13, 2020), the U.S. Court of Appeals for the Federal Circuit ("Federal Circuit") affirmed the Patent Trial and Appeal Board's ("Board") decision in an inter partes review ("IPR") IPR2017-01884 that all of the claims of U.S. Patent No. 8,678,487 ("the '487 patent") were unpatentable. Id. at Slip Op. page 2. Sanofi-Aventis U.S. LLC., Genzyme Corp. and Regeneron Pharmaceuticals. Inc. (collectively, "Sanofi") filed the IPR petition challenging the '487 patent claims owned by Immunex Corp. ("Immunex"). Id.

Background: Sanofi filed three IPRs, and the Board instituted two of them as IPR2017-01884 and IPR2017-01879. Id. at 5. In IPR2017-01884, the Board found all challenged claims unpatentable, but in the other instituted IPR (IPR2017-01879), the Board did not, for reasons of inventorship. Id. at 2. Immunex appealed the unpatentability decision, and Sanofi appealed the inventorship determination. Id. Consolidating the two cases, the Federal Circuit affirmed the unpatentability decision in IPR2017-01884 and because this left no valid claims in the second IPR, it dismissed Sanofi's inventorship appeal from IPR2017-01879. Id. at 2, 3.

The '487 patent is directed to antibodies that bind to the human interleukin-4 ("IL-4") receptor, and the antibodies could be used for treating various inflammatory disorders. Id.

Claim 1 reads:

An isolated human antibody that competes with a reference antibody for binding to human IL-4 inter-leukin-4 (IL-4) receptor, wherein the light chain of said reference antibody comprises the amino acid sequence of SEQ ID NO:10 and the heavy chain of said reference antibody comprises the amino acid sequence of SEQ ID NO:12.

Claim 1 of the '487 patent (emphasis added).

The appeal turned on the construction of the claim term "human antibody." In addressing the science, the Federal Circuit noted that antibodies are proteins that are composed of amino acid sequences. Immunex at 3. Antibodies with amino acid sequences from other organisms, such as mice, caused undesired immune reactions when administered to humans. Id. at 4. To reduce the reaction to antibodies from other species, scientists create antibodies that include both human amino acid sequences and non-human antibody sequences. Id. Such partially human antibodies include "humanized" antibodies that include predominantly human amino acid sequences. Id. Scientists also construct fully human antibodies in which only human amino acid sequences are present. Id.

In IPR2017-01884, the Board found that claims 1-17 would have been obvious over a reference that disclosed an antibody with amino acid sequences from a mouse and a reference that taught humanizing such antibodies from mice. Id. In reaching that decision, the Board construed the term "human antibody" to include humanized antibodies, which are partially human. Id. In the appeal, Immunex argued that the Board erred in its claim construction of the term "human antibody" and that it should be construed as requiring fully human antibodies. Id. at 5-6.

Standard for claim construction

As an initial matter, the Federal Circuit considered the applicable claim construction standard in view of Immunex's apparent effort to have the Federal Circuit apply a Phillips district-court claim construction rather than the Board's broadest reasonable interpretation ("BRI"). Id. at 6.

After appellate briefing was complete, Immunex filed a terminal disclaimer in the '487 patent that resulted in the '487 patent expiring two months before oral argument. Id. In view of the patent expiration, Immunex asked the Federal Circuit to change the applicable claim construction standard on appeal from the BRI standard to the Phillips standard. Id.

In the IPR below, the Board properly applied the BRI standard. Although the Board now applies the Phillips standard to proceedings based on petitions filed on or after November 13, 2018, Sanofi filed its IPRs before the new rule applied. Prior to the rule change, the Board applied the BRI standard to unexpired patents and applied the Phillips standard only to expired patents. Id. at 7.

Immunex contended that the Federal Circuit should apply the Phillips standard in this case because the Federal Circuit previously applied the Phillips standard when a patent expired during a pending appeal. Id. The Federal Circuit, however, stated that the precedent does not require applying the Phillips standard "whenever a patent expires on appeal, at anytime and for any reason." Id. In the prior case, the patent expired on its expected expiration date before briefing began. Id. Here, the patent's term was cut short by the patentee's terminal disclaimer after the parties fully briefed claim construction under the BRI standard. Id. Moreover, Immunex did not request further briefing on the implications of changing to the Phillips standard. Id.

Noting that "[o]ur predecessor court has refused to consider terminal disclaimers filed after the Board's decision," the Federal Circuit decided to review the Board's claim construction under the BRI standard. Id. at 8.

Claim construction of "human antibody"

Next, the Federal Circuit addressed the Board's claim construction. Id. Immunex contended that the Board erred by construing the term "human antibodies" to encompass not only "fully human" but also "humanized" antibodies, which are only partially human. Id. According to Immunex, "humanized" is not "human." Id. The Federal Circuit disagreed. Id.

(1) Intrinsic evidence

(a) Claims

The Federal Circuit found that "nothing in the claim's language restricts 'human antibodies' to those that are fully human." Id. at 9. And the dependent claims fail to provide further guidance.  Id. at 10.

(b) Specification

The Federal Circuit noted that the '487 patent did not have an express definition of "human antibody." Id. However, "the usage of 'human' throughout the specification confirms its breadth." Id. For example, the Court stated the following quote from the specification "makes clear that 'human antibodies' is a broad category encompassing both partially and completely human antibodies":

A method for producing an antibody comprises immunizing a non-human animal, such as a trans-genic mouse, with an IL-4R polypeptide, whereby antibodies directed against the IL-4R polypeptide are generated in said animal. Procedures have been developed for generating human antibodies in non-human animals. The antibodies may be partially human, or preferably completely human.

Id. at 11 (emphases in original).

The Court also noted the specification sometimes includes the word "fully" preceding the term "human antibodies," which indicates that the term "human antibodies" is not limited to fully human antibodies. Id. at 11-12. For example, after providing the following quote, the Court stated that "[i]f 'human antibodies' were already understood to mean 'fully human,' no clarification would be necessary:

Examples of antibodies produced by immunizing such transgenic mice are the human monoclonal antibodies designated 6-2 (described in example 6); 12B5 (described in example 8); and MAbs 63, 1B7, 5A1, and 27A1 (all described in example 9). Monoclonal antibodies 6-2, 12B5, 63, 1B7, 5A1, and 27A1 are fully human antibodies . . .

Id. (emphases in original). The Federal Circuit concluded that "the language of the specification confirms a broadest reasonable interpretation of 'human antibodies' that includes those that are partially human-including 'humanized' antibodies." Id. at 12.

(c) Prosecution history

The Federal Circuit concluded that the prosecution history further supported the Board's claim construction. Id. at 12.

The Federal Circuit noted that "Immunex used both 'fully human' and 'human' within the same claim set in another patent application in the same family." Id. at 12-13. Citing its own precedent, the Court stated such related prosecution may be relevant to the construction of claim terms. Id. at 13. "Immunex provides no convincing explanation for its simultaneous use of the two terms beyond what is apparent: they are not interchangeable." Id

The Federal Circuit also stated that "there is a strong presumption against a claim construction that excludes a disclosed embodiment." Id. at 13 (citing Nobel Biocare Servs. AG v. Instradent USA, Inc., 903 F.3d 1365, 1381 (Fed. Cir. 2018)). Here, the Federal Circuit pointed out the specification's embodiments included both "fully human" and "partially human" antibodies. Id.

During prosecution, claim 11, which recited "a human, partially human, humanized, or chimeric antibody," was canceled. Id. At the same time claim 11 was canceled, the word "human" was added to claim 1. Id. While Immunex argued that the amendment "surrender[ed]" the partially human embodiments, the Federal Circuit determined that the argument "has not overcome [the] presumption" against their exclusion. Id. at 14.

Immunex also argued that during prosecution, the examiner must have understood "human antibodies" to mean only "fully human" antibodies because the examiner repeatedly referred to fully human antibodies while describing a cited prior art document. Id. The Federal Circuit disagreed, stating that "[n]othing supports reading Immunex's claim as limited to fully human antibodies just because the particular combination of prior art used to reject it included antibodies that were fully human." Id. at 15.

The Federal Circuit, moreover, also noted that in a post-amendment office action, the examiner expressly wrote that the amended "human" antibodies encompassed "humanized" antibodies, and Immunex "made no effort to disabuse the examiner of this understanding." Id.

(2) Extrinsic evidence

Immunex additionally argued that the Board "failed to establish how a person of ordinary skill in the art would have understood the term 'human antibody'" in view of Immunex's extrinsic evidence, such as experts testimony, product catalogs, and a selection of journal articles. Id.

The Federal Circuit noted that it "seek[s] the meaning of claim terms from the perspective of the person of ordinary skill in the art," but the key is it look to how that person would have understood a term "in view of the specification." Id. at 16. (emphasis in original)

Stating that "we give the intrinsic evidence 'priority'", the Federal Circuit clarified that "[w]hile extrinsic evidence may sometimes illuminate a well-understood technical meaning . . . that does not mean that litigants can introduce ambiguity in a way that disregards language usage in the patent itself." Id. at 17.

Accordingly, the Federal Circuit concluded that the intrinsic evidence "trumped" any contrary extrinsic evidence here. Id.

Board's departure from a district court's claim construction not a problem

In the litigation that prompted the IPRs, the district court construed "human" to mean "fully human" only. Id. That claim construction order issued two months before the oral hearing in the IPR, and the parties discussed it in their briefing and at oral argument before the Board. Id. at 18. After conducting a full analysis, the Board did not adopt the district court's construction. Id. The Board concluded that "it reached a different interpretation 'based on the broader applicable case law.'" Id.

Immunex argued that the Board should have explained more fully its departure from the district court's narrower Phillips-based construction. Id. Immunex contended that "the Board must explain in detail why, under a broader legal standard, it reache[d] a broader construction than a district court does." Id.

The Federal Circuit disagreed. Id. The Federal Circuit reiterated that the Board "is not generally bound by a previous judicial construction of a claim term." Id. (quoting Power Integrations, Inc. v. Lee, 797 F.3d 1318, 1326 (Fed. Cir. 2015)). The Federal Circuit also cited Mayne Pharma Int'l Pty. Ltd. v. Merck Sharp & Dohme Corp., 927 F.3d 1232, 1242 (Fed. Cir. 2019), where the court was not persuaded that "the Board erred in discounting the district court's construction because the court construed the claims under the narrower, Phillips standard." Id. at 18-19.

In sum, the Federal Circuit agreed with the Board&rsqursquo;s claim construction of "human antibody" and affirmed the Board's unpatentability decision. Id. at 19.

Take-Away: This decision is a reminder of how drafting and prosecution may affect claim construction. This includes drafting and prosecution, which can come home to roost not only in a future dispute, but also in related applications. As the Federal Circuit stated, the intrinsic evidence "trumps" inconsistent extrinsic evidence.

Thus, prosecution practitioners should be mindful that statements made in the specification and during prosecution and even in prosecution of related applications, can affect claim construction. If possible, practitioners should strive to use terms consistently in a way that makes the desired meaning clear. The petitioner in this case could have had a harder time had the patent owner presented an independent claim to a "fully human antibody." Surely, in patent application drafting and in prosecution, acting like Nostradamus can inure to the benefit of the patent owner.

This decision also informs us that terminal disclaimers filed too late may not be effective in switching the standard of review from the BRI standard to review under the Phillips standard.  

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