Samsung Biopis UK Limited v Alexion Pharmaceuticals Inc.

Patent claims are construed purposively, but the court must respect precise scientific language and deliberate claim limitations. Purpose cannot justify rewriting a claim or giving no effect to a specified sequence. A patent specification which presents an invention as old is a powerful reason to reject a construction covering that subject matter.

Reference to prosecution history remains exceptional. It requires a truly unclear claim whose meaning is unambiguously resolved by the file, or a public-interest case in which the patentee clearly disclaimed the relevant scope. A debatable construction is insufficient.

Obviousness must be assessed without hindsight. A party cannot mosaic non-common-general-knowledge documents merely because one would have been found during research from a selected starting point.

These conjoined Patents Court actions concerned European Patent (UK) No 3 167 888, relating to the antibody drug eculizumab. Alexion alleged that biosimilar products proposed by Samsung Bioepis and Amgen infringed claims to an antibody binding C5 and a pharmaceutical composition comprising it.

The patent defined the light chain by reference to SEQ ID NO: 4, which included a 22-amino-acid leader sequence absent from mature eculizumab. Alexion contended that the claims should be construed purposively as covering mature eculizumab. The defendants argued that the claims required the exact sequence stated, and challenged validity by anticipation, obviousness and other grounds.

The central issues were claim construction, the permissible use of prosecution history, anticipation, obviousness and whether the non-technical arguments required determination.

1. Claim construction. The claims required an antibody whose light chain consisted of SEQ ID NO: 4, including the 22 additional amino acids. The scientific precision of the sequence and the drafting convention that “consisting of” specifies exactly what is present were powerful considerations. The antibody could be made and might bind C5, so there was no technical basis for disregarding the sequence.
2. The specification consistently treated eculizumab as old and distinguished it from the antibody defined by the sequence identifiers. The reference to eculizumab in one embodiment did not overcome that distinction. The incorporation by reference of Evans was boilerplate and could not displace the specification’s express treatment of eculizumab.
3. The prosecution history did not alter the construction. Under Actavis v Lilly, reference is exceptional. The claims were not truly unclear, and the file did not unambiguously resolve their meaning. Alexion’s unsuccessful attempt to obtain claims literally covering mature eculizumab did not amount to a clear disclaimer of a purposive construction of the granted claims.
4. Anticipation. Bowdish, read with Evans, did not disclose the claimed antibody clearly and unambiguously. The references to “parental 5G1.1” were unclear as to whether the antibody was murine or human, full-length or a fragment, and the defendants’ case depended on assumptions about experimental controls. Claim 2 was not anticipated because disclosure of an antibody in solution did not establish a pharmaceutical composition suitable for use.
5. Obviousness. The Bowdish attack impermissibly mosaicked Thomas into a course of reasoning selected with hindsight and, alternatively, involved an illegitimate stepwise exercise. The Tacken attack succeeded. Read with Mueller and Thomas, Tacken disclosed the hybrid constant region and relevant variable regions. In light of the common general knowledge concerning immunogenicity and framework residues, it was obvious to make and test versions differing at light-chain position 38, with a strong expectation that the human residue would preserve binding and reduce immunogenicity risk.
6. Claim 2 added no independent inventive step. The insufficiency, lack of technical contribution and Agrevo obviousness arguments were unnecessary and would not succeed on the rejected construction.
7. The court declined to decide judicial estoppel, approbation and reprobation, and abuse of process. Those difficult and novel issues could not affect the result and had not been fully argued.
8. The defendants did not infringe. Alexion conceded that the patent should be revoked on that construction. Had the claims covered mature eculizumab, the patent would in any event have been invalid for obviousness over Tacken together with the documents to which it referred.

First-instance decision. No earlier judgment in the same proceedings was stated.