Chugai Pharmaceutical Co. Ltd v UCB Pharma SA & Ors

Under US law, patent claims are construed objectively through the eyes of the skilled person at the relevant filing date. The claims, specification and prosecution history must be considered together, without a rigid sequence. Extrinsic evidence may assist, but cannot contradict clear intrinsic evidence.

Validity is relevant as a tie-breaker only where the claim remains ambiguous after the available construction evidence has been considered. A product claim is not converted into a product-by-process claim merely because the specification describes methods of designing or producing the product.

On the proper construction of “non-human donor”, a framework residue sourced from the human acceptor remains acceptor even if it is conserved in the donor sequence. The product therefore fell outside the relevant patent claim.

The claimant licensed a portfolio of US patents from the defendants and paid royalties on sales of tocilizumab. After the other patents expired, the parties disputed whether royalties remained payable under the licence for products manufactured after 13 January 2016.

The dispute narrowed to whether tocilizumab fell within claim 2 of US patent 7,566,771. The issue concerned the meaning of “non-human donor” in relation to conserved amino-acid residues in a humanised antibody. The claimant also argued that the claim was a product-by-process claim. The court had to apply US patent law to construe the claim.

1. Applicable construction principles. The ordinary and customary meaning of claim language is assessed from the standpoint of the skilled person at the effective filing date. The claims, specification and prosecution history form the intrinsic evidence and must be read together. There is no rigid hierarchy or mandatory sequence. Extrinsic evidence may educate the court about the technical field and skilled meaning, but cannot contradict an unambiguous intrinsic meaning.
2. Validity and alternative constructions. The validity tie-breaker is available only after the intrinsic and extrinsic evidence has been considered and the claim remains ambiguous. It cannot be used to depart from the only reasonable construction. The court accepted that the preference for a narrower construction in Athletic Alternatives, Inc. v Prince Manufacturing, Inc. remained available, with the validity-preserving construction considered first where both tie-breakers applied.
3. Product-by-process argument. Claim 2 was a claim to an antibody molecule with defined structural features. References in the specification and prosecution history to designing or producing antibodies did not impose limitations based on the process by which the molecule was made.
4. Meaning of “non-human donor”. The claims alone supported both parties’ constructions. The specification and prosecution history were also mixed. However, the skilled person would understand “donor” and “acceptor” as references to source. A framework residue taken from the human acceptor sequence remained acceptor even where the corresponding donor residue was identical. Only a framework residue changed from the human acceptor to the donor sequence was donor.
5. The court therefore adopted the claimant’s construction. Tocilizumab did not infringe a valid claim of US patent 7,566,771. No royalties were due under the licence for tocilizumab manufactured after 13 January 2016.