Pfizer Limited v GlaxoSmithKline Biological SA & Anor

For obviousness and sufficiency in biotechnology cases, the skilled team must be identified realistically. Where the technology concerns protein structure, the team may include a specialist structural biologist, and its members must be treated as a collaborative team. Common general knowledge may include relevant developments in structurally related viruses and fusion proteins.

Secondary evidence is admissible but normally carries weight according to its completeness and testability. A party relying on it should plead the case and support it with evidence from relevant real-world workers. A patent claim directed to a defined stabilisation mechanism is not construed at the broader level of any product achieving the same ultimate result. Applying those principles, the patents were obvious, but not insufficient, and the accused product did not infringe either patent.

Pfizer sought revocation of two UK patents owned by GSK concerning recombinant RSV F-protein antigens stabilised in the prefusion conformation. GSK counterclaimed for infringement by normal interpretation and under the doctrine of equivalents. Pfizer also sought an Arrow declaration.

The principal issues were the composition of the skilled team, common general knowledge, construction of “stabilizes” and “polypeptide”, infringement, priority, novelty, obviousness, secondary evidence, insufficiency, plausibility and the grant of declaratory relief. EP490 was removed from the proceedings. The central questions were whether the patents were valid and whether Pfizer’s RSVPreF product infringed them.

Outcome. EP258 and EP710 were held invalid for obviousness over each relied-on piece of prior art. They were not insufficient and were not invalid on AgrEvo or plausibility grounds. Pfizer’s product did not infringe either patent, including by equivalents. An Arrow declaration was granted.

1. The skilled team comprised a skilled vaccinologist and a structural biologist with advanced structural-biology expertise. The team operated collaboratively. That conclusion applied both to obviousness and sufficiency. The skilled team would consider relevant developments in PIV and other class I fusion proteins, not RSV in isolation.
2. “Stabilizes” was deliberately broad and context-dependent. In the claims, however, the relevant stabilising mechanism was the addition of a C-terminal heterologous trimerisation domain. “Polypeptide” had the precise definition supplied by the patents: a polymer whose amino-acid residues are joined through amide bonds. Pfizer’s product comprised two polypeptides joined by disulphide bonds and therefore fell outside the claims.
3. For equivalents, the inventive concept had to be considered at the level of the particular claims. The Pfizer construct did not achieve substantially the same result in substantially the same way. The different chemistry and the express definition of “polypeptide” also showed that strict compliance was intended to be essential.
4. The Jardetzky disclosures, Yin and the ASV abstract supplied sufficient motivation to stabilise RSV F in its prefusion form using a trimerisation domain. Deletion of furin cleavage sites was an obvious further stabilisation step. The evidence of secondary evidence was incomplete, largely unpleaded and insufficient to displace the primary obviousness case.
5. The claims were sufficiently disclosed. The skilled team could test the prefusion conformation by crystallography, electron microscopy, liposome-association assays or conformation-specific antibodies. The claims were plausible across their scope, including with or without an adjuvant.