In Pfizer Inc. v. Sanofi Pasteur Inc., [2019-1871, 2019-1873, 2019-1875, 2019-1876, 2019-2224] (Fed. Cir. 2024), the Federal Circuit affirmed the Board’s conclusions
that claims 1–45 of U.S. Patent 9,492,559 are unpatentable, and the Board’s denial of Pfizer’s motions add certain claims, and vacated the denial as to certain other claims.

The ‘559 patent is directed to immunogenic compositions comprising conjugated Streptococcus pneumoniae capsular saccharide antigens (i.e., glycoconjugates)
for use in pneumococcal vaccines. Across five IPR’s the validity of all the claims was challenged.

Pfizer first contends that the Board erred in applying the “result-effective variable doctrine,” arguing that it is only appropriate in circumstances where there is actual overlap between a range in the prior art and a claimed range. Since the asserted prior art did not disclose a particular molecular weight range, there could be no presumption of obviousness, and it was
error for the Board to consider whether that variable was result-effective.

The Federal Circuit disagreed, saying that the determination whether or not a claimed parameter is a result-effective variable is merely one aspect of a broader routine optimization analysis. That analysis is rooted in the decades-old legal principle that “where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation.”

The Federal Circuit said 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.” The Federal Circuit found substantial evidence supported the Board’s conclusion that the varlaibe (molecular weight) would have been obvious over the references.

The Federal Circuit rejected the suggestion that unpredictability of the art affected its analysis, nothing that it has previously explained that “a rule of law equating unpredictability to patentability . . . . cannot be the proper standard since the expectation of success need
only be reasonable, not absolute.” Pfizer, Inc. v. Apotex, Inc., 480 F.3d 1348, 1364 (Fed. Cir. 2007)(“[O] bviousness cannot be avoided simply by a showing of some degree of unpredictability in the art so long as there was a reasonable probability of success”).