Routine Optimization of Result-Effective Variable Can Bridge Gaps in Prior Art

| Raymond S. LuBrandon G. Smith


Before Lourie, Bryson, and Stark.  Appeal from the Patent Trial and Appeal Board.

Summary: Evidence that a claimed parameter is recognized as a result-effective variable can overcome the lack of explicit disclosure of the exact parameter in the prior art.

Merck and Sanofi requested inter partes review of a patent owned by Pfizer.  The patent at issue claimed a molecular weight range of a specific type of glycoconjugate.  The PTAB recognized, and Petitioners conceded, that none of the asserted prior art disclosed any molecular weight for the specifically claimed glycoconjugate.  However, the PTAB found that glycoconjugate molecular weight is a result-effective variable for improving stability and good immune response.  Thus, a person of ordinary skill in the art would have been motivated to optimize the glycoconjugate molecular weight.  Based on this finding, the PTAB invalidated the claims as obvious over the prior art.

On appeal, the Federal Circuit affirmed the Board’s decision.  Pfizer contended that the PTAB erred in applying the “result-effective variable doctrine,” arguing that the doctrine is only appropriate where an actual overlap exists between a claimed range and a range disclosed in the prior art.  The court disagreed.  The court recognized that overlap between a claimed range and a prior art range creates a presumption of obviousness that can be rebutted with evidence that a claimed parameter is not recognized as result effective.  The court then held that the contrapositive is also true—evidence that a claimed parameter is recognized as result-effective can bridge gaps in the prior art to render a claim obvious.   Here, although the prior art did not teach a molecular weight for the particular glycoconjugate claimed, it did teach molecular weight ranges for other similar glycoconjugates.  Because those ranges overlapped with the claimed range, and because glycoconjugate molecular weight is a result-effect variable, optimization of the variable was within the grasp of a person of ordinary skill in the art. 

Editor: Sean Murray