Result-Effective-Ugh…a Bridge Too Far?

| April 25, 2024

Pfizer Inc. v. Sanofi Pasteur Inc.

Decided: March 5, 2024

Result-Effective Variable; Obviousness

Before LOURIE, BRYSON, and STARK, Circuit Judge. Opinion drafted by LOURIE.


Pfizer appealed to the Federal Circuit following rulings from five inter partes review proceedings petitioned by Sanofi challenging all claims of Pfizer’s U.S. Patent No. 9492559 (‘559 Patent). The ‘559 Patent claims immunogenic compositions comprising glycoconjugates of various Streptococcus pneumoniae serotypes for use in pneumococcal vaccines. Independent claim 1 is as follows (emphasize added):

  1. An immunogenic composition comprising a Streptococcus pneumoniae serotype 22F glycoconjugate, wherein the glycoconjugate has a molecular weight of between 1000 kDa and 12,500 kDa and comprises an isolated capsular polysaccharide from S. pneumoniae serotype 22F and a carrier protein, and wherein a ratio (w/w) of the polysaccharide to the carrier protein is between 0.4 and 2.

The Board instituted review based on each petition and issued final written decisions which, taken together, found all claims unpatentable. Pfizer raised four challenges on appeal. The first, which will be the only challenge discussed herein, alleged that the Board erred in determining that the ‘559 Patent was obvious based on prior art references PCT Patent Application Publication 2007/071711 (“GSK-711”) and U.S. Patent Application Publication 2011/0195086 (“Merck-086”).

The Board recognized that neither GSK-711 nor Merck-086 disclosed any molecular weight for a S. pneumoniae serotype 22F glycoconjugate, as required by claim 1 of the ’559 Patent, but nevertheless concluded that, based on the evidence of record, glycoconjugate molecular weight is a result-effective variable that a person of ordinary skill in the art would have been motivated to optimize to provide a conjugate having improved stability and good immune response. It is here that Pfizer argued the Board erred, because it is undisputed that the prior art does not disclose any molecular weight for the claimed serotype 22F glycoconjugate, there could be no presumption of obviousness. The CAFC disagreed.

The CAFC begin by stating that “the determination whether or not a claimed parameter is a result-effective variable is merely one aspect of a broader routine optimization analysis.”

The CAFC followed that “an overlap between a claimed range and a prior art range creates a presumption of obviousness that can be rebutted with evidence that the given parameter was not recognized as result-effective. See Genentech, Inc. v. Hospira, Inc., 946 F.3d 1333, 1341 (Fed. Cir. 2020) (citing E.I. DuPont, 904 F.3d at 1006); In re Applied Materials, Inc., 692 F.3d 1289, 1295 (Fed. Cir. 2012).” However, they emphasized that this “does not mean that the determination whether or not a variable is result-effective is only appropriate when there is such an overlap.” Rather that “a routine optimization analysis generally requires consideration whether a person of ordinary skill in the art would have been motivated, with a reasonable expectation of success, to bridge any gaps in the prior art to arrive at a claimed invention. Where that gap includes a parameter not necessarily disclosed in the prior art, it is not improper to consider whether or not it would have been recognized as result-effective. If so, then the optimization of that parameter is “normally obvious.” In re Antonie, 559 F.2d 618, 620 (CCPA 1977).”

Thus, the CAFC concluded that the Board did not err in considering, as part of its obviousness analysis, whether or not the claimed molecular weight of a S. pneumoniae serotype 22F glycoconjugate was a result-effective variable, dispute the cited references being silent thereon.

It was ultimately concluded that “substantial evidence supports the Board’s conclusion that the molecular weight recited in claim 1 would have been obvious over the references.” Such evidence included the fact that  GSK-711 gave the molecular weights for fourteen other S. pneumoniae serotype glycoconjugates, and that Expert Testimony showed that, at the time of the invention, conjugation techniques and conditions were routine such that a person of ordinary skill in the art would have understood the claimed molecular weight to be “typical of immunogenic conjugates.”


An argument against a Result-Effective Variable assertion may be weakened, even when the prior art is silent on said variable, if a PHOSITA can bridge the gaps in the teaching with a reasonable success based on the evidence overall. Thus, it may be necessary to demonstrate more than simply the variable not being recognized by the reference. That is, one may also have to show there is no reasonable expectation of success in said variable

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