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Immunex v. Sanofi-Aventis – The “Mystery Dance” of Claim Construction

In “Mystery Dance”, Elvis Costello  moans that he’s “tried and I’ve tried, and I’m still mystified” about the “Mystery Dance”, which probably has something to do about romance, but could easily describe the state of the relationship between appeals from the district courts to the Fed. Cir. and appeals to the Fed. Cir. from PTAB decisions. I let Immunex v. Sanofi, Appeal no. 2019-1749, 2019-1777 (Fed. Cir., October 13, 2020) sit on my desk for the last month because it looked to be a simple claim construction decision. Well, it is that, but quite a lot more.

To try to simplify the facts, Sanofi challenged Immunex’s patent no. 8,679,487. Claim 1 reads:

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

So the claim covered isolated human antibodies that bind the human interleukin -4 receptor. The Board invalidated the claims as obvious in view of three references. As the Fed. Cir. wrote: “This appeal concerns what “human antibody’ means in this patent.” The panel discussed the differences between chimeric antibodies, humanized antibodies and “fully human antibodies [that] can be made in which even the CDRs are human in origin…The claim construction dispute is this; in the context of this patent, must a ‘human antibody,’ be entirely human? Or may it also be ‘partially human’, including ‘humanized.’ Immunex wanted “entirely human” while Sanofi wanted the term to encompass “humanized” antibodies, since it was arguing the obviousness, inter alia, over two references that taught a wholly murine antibody and how to humanize it. The Board agreed with Sanofi.

Things get more interesting now. Immunex wanted the Fed. Cir. panel to use the Philips standard, in which the precise meaning of a claim term is determined by looking at the entirety of the prosecution historythe intrinsic evidence—and, if necessary—extrinsic evidence such as expert testimony and treatises. Sanofi wanted the panel to apply the broadest reasonable interpretation (BRI) standard that the PTAB had used. This standard essentially applies a presumption of broadness to claims terms vs., possibly, a narrower, more technically defined claim scope that a Philips analysis might providesince the claims are to be interpreted by the hypothetical POSA.

After appellate briefing was complete, Immunex filed a terminal disclaimer of its patent, causing the patent to expire two months before oral argument. Immunex then filed a “citation of supplemental authority” asking the Fed. Cir. to change the BRI claim standard to the Philips standard (Phillips v AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005)). This is the standard that is used by the Fed. Cir. and the PTAB today, but it only applied to petitions filed at the PTAB after November 13, 2018. When Sanofi filed its IPR petition, the Board applied the Philips standard only to expired patents which of course, had been prosecuted under that standard. In all its proceedings in this IPR, the PTAB had applied the BRI standard.

Immunex’s attempt to have its appeal decided under the Philips standard failed. Immunex cited two recent Fed. Cir. decisions in which the Fed. Cir. had applied the Philips standard but, in those cases the patents had expired before the Board’s decision. The panel also discussed Apple v Andrea Electronics, 949 F.3d 697 (Fed. Cir. 2020), but distinguished it on the basis that, in that case, the expiration of the patent in question occurred before the appellate briefing and, “[n]ot so here, where the patentee shortened the term abruptly  after the parties had already fully briefly claim construction under the BRI standard.”

The panel then went on to find that the Board correctly used intrinsic evidence a la Cuozzo Speed Techs. v. Lee, to construe the term “human antibody” to include not only “fully human” but also “partially human” antibodies—”The usage of ‘human’ throughout the specification confirms its breadth.”(Check out the brown dog footnote (4) on page 11 of the slip opinion.) The panel also found that the prosecution history supported a broad definition of human antibodies and that in the case of the weight to be given to intrinsic vs. extrinsic evidence “the intrinsic evidence trumps”. And the panel ended by noting that the PTAB is not bound by a previous judicial construction of a claim term. Maybe I should have written that the panel noted that PTAB claim construction can “trump” a contrary judicial claim interpretation but I am more than tired of hearing that word.

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