Background
Pfizer’s U.S. Patent No. 9,492,559 concerns immunogenic compositions used in pneumococcal vaccines. After Sanofi Vaccines US Inc. and SK Bioscience Co., Ltd. challenged the patent’s claims through inter partes review, Pfizer sought to substitute claims covering compositions containing multiple known pneumococcal serotypes conjugated to the CRM197 carrier protein. The proposed claims also required more than a 2-log increase above baseline serum IgG levels across all included serotypes after two equal doses were administered to New Zealand White Rabbits.
The Patent Trial and Appeal Board initially found proposed substitute claims 46, 48, and 49 obvious over prior-art publications. In an earlier appeal, the Federal Circuit affirmed as to claim 46 but remanded claims 48 and 49 because the Board had not adequately explained why a skilled artisan would have expected the additional serotypes in those claims to achieve the required immune response. On remand, the Board supplied further analysis, again found claims 48 and 49 obvious, and denied Pfizer’s motion to amend.
The Court’s Holding
The Federal Circuit affirmed in a nonprecedential opinion. It held that substantial evidence supported the Board’s finding that a person of ordinary skill would have had a reasonable expectation of achieving the claimed 2-log increase for every serotype in proposed substitute claims 48 and 49.
The evidence included Hausdorff’s data showing a greater-than-2-log increase for all serotypes included in its tested vaccine, expert testimony that increasing IgG levels was a recognized indicator of immunogenicity, and expert testimony that CRM197 conjugates allowed new serotypes to be added without harming the vaccine’s existing components. Although the prior art lacked immunogenicity data for several specific serotypes added by claims 48 and 49, the court emphasized that obviousness requires only a reasonable expectation of success, not a guarantee. The Board therefore did not abuse its discretion by denying Pfizer’s motion to amend.
Key Takeaways
- A reasonable expectation of success may be supported without prior-art data for every claimed vaccine serotype.
- Experimental results for related serotypes, combined with expert testimony about immunogenicity and carrier-protein performance, constituted substantial evidence here.
- Because the Board adequately addressed the issue identified in the earlier remand, the Federal Circuit upheld its obviousness determination and denial of Pfizer’s proposed amendments.
Why It Matters
The decision illustrates that patent claims adding known vaccine components and a performance limitation may still be obvious when the record supports a reasonable expectation that the combined composition would achieve the claimed result. Patent owners cannot necessarily defeat obviousness merely by showing that the prior art lacks test data for each individual claimed component.
It also demonstrates the importance of reasoned PTAB findings. The Federal Circuit previously remanded because the Board had not explained its treatment of claims 48 and 49, but affirmed after the Board connected the prior-art evidence and expert testimony to the disputed immune-response limitation.