Pfizer v. Sanofi Vaccines — Federal Circuit Upholds Obviousness of Pneumococcal Vaccine Substitute Claims

Background

Pfizer’s U.S. Patent No. 9,492,559 covers pneumococcal vaccine compositions containing glycoconjugates for multiple serotypes of Streptococcus pneumoniae. In earlier inter partes reviews, Pfizer proposed substitute claims 48 and 49, which added known serotypes and required more than a two-log increase above baseline in serum IgG levels in rabbits. After an earlier Federal Circuit remand for a fuller explanation, the Patent Trial and Appeal Board again found the proposed claims obvious and denied Pfizer’s motion to amend.

The Court’s Holding

The Federal Circuit affirmed. The Board had substantial evidence that a skilled artisan would have reasonably expected the claimed immune response across the added serotypes. Prior-art data showed the required increase for thirteen serotypes in a multivalent vaccine. Expert testimony supplied both a reason to seek increased IgG levels and evidence that additional serotypes could be incorporated without impairing the vaccine’s other components.

Pfizer emphasized that the references did not report immunogenicity data for every added serotype. The court answered that obviousness requires a reasonable expectation of success, not certainty or a guarantee. Because the added serotypes were known and the Board’s prediction rested on data and expert testimony, its conclusion survived substantial-evidence review.

Key Takeaways

• A patent owner seeking substitute claims in an IPR must establish patentability over the record developed for those claims.
• Reasonable expectation of success can extend beyond experiments reporting every claimed species when related data and expert evidence support the prediction.
• An agency cures a prior explanation defect when its remand decision connects the evidence to the disputed limitation with enough detail for judicial review.

Why It Matters

The ruling shows the practical difficulty of using an IPR motion to amend to preserve pharmaceutical claims. Adding measurable performance limitations will not necessarily avoid obviousness when the record supports a reasonable expectation that known components would achieve that performance.