Federal Circuit Upholds PTAB Finding of Obviousness in Pfizer vs. Sanofi

March 18, 2024

In Pfizer Inc. vs. Sanofi Pasteur Inc., the Federal Circuit upheld the Patent Trial and Appeal Board (PTAB) decision to invalidate portions of Pfizer’s pneumococcal vaccine patent on the grounds of obviousness. My colleague’s post discusses the Federal Circuit’s decision to vacate and remand to the PTAB to further consider Pfizer’s motions to amend with regards to proposed claims 48 and 49, holding that the PTAB has not actually addressed the additional limitations for these claims. This post will focus on the patentability of Claims 1-45, and specifically how the Federal Circuit affirmed the PTAB’s application of the result-effective variable doctrine and reasonable expectation of success in order to arrive at a finding of obviousness of Claims 1-45 of U.S. Patent No. 9,492,599 (“the ‘559 patent”).

Claim 1 of the ‘559 patent recites an immunogenic composition comprising a serotype 22F glycoconjugate having a molecular weight between 1000 kDa – 12500 kDa. The PTAB determined, based on the evidence provided, that molecular weight of a glycoconjugate is a result-effective variable that has a predictable effect on conjugate stability and immune response. The Board relied on this determination to conclude that the claimed molecular weight range of the ‘559 patent would have been obvious in light of disclosed molecular weights of other serotype glycoconjugates despite the fact that the prior art of record does not expressly recite any molecular weights for a serotype 22F glycoconjugate.

The Federal Circuit agreed with the Board’s assessment of molecular weight as a result-effective variable and asserted that an overlap between a claimed range and a prior art range for a parameter is not required for the parameter to be considered a result-effective variable. Furthermore, in response to Pfizer’s argument that the prior art was silent regarding a range for the claimed limitation, the Federal Circuit held that “it is not improper to consider whether or not [a parameter not disclosed in the prior art] would have been recognized as result-effective.” The Court stated that optimization of such a result-effective parameter would therefore be obvious to one of ordinary skill in the art, even if the art does not provide disclosure of the parameter.

In the appeal, Pfizer argued that the prior art of record does not suggest a reasonable expectation of success in formulating the ‘559 patent’s immunogenic conjugates because there is high unpredictability in the art. The Federal Circuit disagreed and referenced a previous decision’s explanation that “the expectation of success need only be reasonable, not absolute.” The Court further found that although the art of pneumococcal glycoconjugate vaccines as a whole may be unpredictable, expert testimony demonstrated that the molecular weight of a glycoconjugate was not itself unpredictable because its effect was stable across similar serotypes. According to the Federal Circuit, unpredictability does not preclude a reasonable expectation of success in this case.

The references cited in the PTAB decision provided teachings on a variety of named serotype glycoconjugates. The Federal Circuit’s affirmation of the PTAB ruling highlights that the disclosure of similar compounds can be sufficient for an obviousness rejection, even if the claimed compound is not expressly taught in the prior art. The Court indicated that a reasonable expectation of success of a claimed element may be determined according to unpredictability of the element itself rather than unpredictability in the art as a whole. Thus, the conclusions set forth by the Federal Circuit highlight again that arguments related to result-effective variables and reasonable expectation of success may require a stronger showing of non-obviousness and unexpected results to overcome prior art.