What Does It Mean To Be Human?
| November 26, 2020
Immunex Corp v. Sanofi-Aventis U.S. LLC
Prost, Reyna and Taranto.Opinion by Prost
October 13, 2020
Summary
This is a consolidated appeal from two Patent and Trademark Appeal Board (“Board”) decisions in Inter partes reviews (IPR) of US Patent No. 8,679,487 (‘487 patent) owned by Immunex. In the first IPR the Board invalidated all challenged claims. Immunex appealed the construction of the claim term “human antibodies.” In the other IPR, involving a subset of the same claims, the Board did not invalidate the patent for reason of inventorship. Sanofi appealed the Boards inventorship determination.
Briefly, the CAFC agreed with the Board’s claim construction and affirmed the invalidity decision. Since this left no claims valid, the CAFC dismissed Sanofi’s inventorship appeal.
The ’487 patent is directed to antibodies that bind to human interleukin-4 (IL-4) receptor. This appeal concerned what “human antibody” means in this patent. That is, in the context of this patent, must a human antibody be entirely human, or does it include partially human, for example humanized?
Amid infringement litigation, Sanofi filed three IPR’s against the ‘487 patent, two if which were instituted. In one final decision the Board concluded that the claims were unpatentable as obvious over two references, Hart and Schering-Plough. Hart describes a murine antibody that meet all the limitations of claim 1 except that it is fully murine, so not human at all. The Schering-Plough reference teaches humanizing murine antibodies.
In response, Immunex insisted that the Board had erred in construction of “human antibody” to include humanized antibodies.
After Appellate briefing was complete, Immunex filed with the PTO a terminal disclaimer of its patent. The PTO accepted it, and the patent expired May 26, 2020, just over two months prior to oral arguments. Immunex then filed a citation apprising the CAFC of (but not explaining the reason for) its terminal disclaimer and asking the court to change the applicable construction standard.
Specifically, in all newly filed IPRs, the Board now applies the Phillips district-court claim construction standard. However, when Sanofi filed its IPR, the Board applied this standard to expired patents only. To unexpired patents, it applied the Broadest Reasonable Interpretation (BRI) standard.
Immunex urged the CAFC to apply Phillips citing Wasica Finance GmbH v., Continental Automotive Systems, Inc., 853 F.3d 1272, 1279 (Fed. Cir. 2017) and In re CSB-System International 832 F. 3d 1335, as support. However, unlike here, the patents at issues in these cases had expired before the Board’s decision. The CAFC noted that it had applied the Phillips standard when a patent expired on appeal. Nonetheless, the CAFC clarified that in these cases the patent terms had expired as expected and not cut short by a litigant’s terminal disclaimer.
Accordingly, the CAFC affirmed it will review the Board’s claim construction under the BRI standard.
Initially, the CAFC turned to the intrinsic record, specifically, the claims, the specification, and the prosecution history.
The CAFC noted that the claims themselves were not helpful as the dependent claims provided no further guidance.
Next, the CAFC noted that while the specification gave no actually definition, the usage of “human” throughout the specification confirmed its breadth. Specifically, the specification contrasts “partially human’ with “fully human.” For instance, the specification states that “an antibody…include, but are not limited to, partially human…. fully human.” Thus, the specification makes it clear that “human antibody” is a broad category encompassing both “fully” and “partially.”
Immunex insisted that the Board undervalued the prosecution history. While the CAFC agreed, it concluded the prosecution history supported the Board’ construction.
First, they noted that Immunex had used the term “fully human” and “human” in the same claim of another of its patents in the same family. Next, claim 1 as originally presented merely stated “an isolated antibody” and “human” were added during prosecution.
As a result, a dependent claim which recited ‘a human, partially human, humanized or chimeric antibody’ was cancelled. Immunex suggested that the amendment “surrendered” the partially human embodiment. The CAFC disagreed.
The Board noted that “human” was not added to overcome an anticipating reference that disclosed ‘nonhuman.’ The CAFC also noted that the claim language does not require the exclusion of partially human embodiments. Thus, the CAFC held that nothing indicates that “human” was added to limit the scope to fully human.
The CAFC noted that in a post-amendment office action, the Examiner expressly wrote that the amended “human” antibodies encompassed “humanized” antibodies and that Immunex had made no effort to correct this understanding.
Next, the CAFC addressed the role of extrinsic evidence. Immunex argued that the Board had failed to establish how a person of ordinary skill in the art would have understood the term. Immunex had provided expert testimony to argue that “human antibody” would have been limited to “fully human.”
The CAFC held that while it is true that they seek the meaning of a claim term from the perspective of a person of ordinary skill in the art, the key is how that person would have understood the term in view of the specification. That, while extrinsic evidence may illuminate a well-understood technical meaning, that does not mean that litigants can introduce ambiguity in a way that disregards usage in the patent itself.
Here, the extrinsic evidence provided conflicts the intrinsic evidence. Priority is given to the intrinsic evidence.
Lastly, the CAFC discussed the Boards’ departure from an earlier court’s claim construction. That is, in the litigation that prompted this IPR, a district court construed “human” to mean “fully human” only, under the narrower Phillips-based construction. However, the CAFC reiterated that the Board “is not generally bound by a previous judicial construction of a claim term.”
Thus, to conclude, the CAFC affirmed the Board’s claim construction under the BRI standard, and thus its invalidity judgment based thereon.
Take-away
- Claim drafting – words matter
- The importance of dependent claims
- Be mindful of amendments made during prosecution that are not done for the purpose of overcoming prior art.
- In claim construction, intrinsic evidence has priority over extrinsic evidence when they conflict.
- Be mindful of comments made by the Examiner during prosecution in an action (office action, notice of allowance, etc.,) regarding interpretation of the claims.
