The UPC Court of Appeal has confirmed a strict approach to correcting erroneous patent claims by way of interpretation. The existence of the error and the precise way to correct the error both need to be sufficiently certain to the average skilled person. Statements made by the applicant during patent grant proceedings can also be indicative of the skilled person’s view at the priority date.
Background
The preliminary injunction proceedings concerned the enforcement of EP 3 167 888 B1, a divisional patent, owned by Alexion Pharmaceuticals, Inc. (Alexion). The patent claims a specific antibody and a pharmaceutical composition comprising that antibody. Alexion markets a product named Soliris®, whose active pharmaceutical ingredient eculizumab is a monoclonal antibody as protected by the patent. It is indicated for the treatment of rare blood diseases. Specifically, eculizumab binds to and thereby inhibits a specific component of the immune system called C5 that would otherwise attack the affected patient’s own red blood cells.
The enforced claim 2 reads:
An antibody that binds C5 comprising a heavy chain consisting of SEQ ID NO:2 and a light chain consisting of SEQ ID NO:4.
In the description, SEQ ID NO:4 is set out to consist of a sequence of 236 amino acids including 22 amino acids at the start of the sequence which renders the antibody non-functional. When removing this portion, however, the antibody has the intended effect in the patient. Upon discovery, the sequence was corrected in the Chemical Abstract Service (CAS) database by removing the 22 amino acids. Alexion also tried to change the patent claims accordingly. However, the Technical Board of Appeal (TBA) at the European Patent Office (EPO) rejected the request to amend the patent to exclude these 22 amino acids on the basis that this was only allowed to do so if the error was obvious, and it was immediately evident that the invention would not work as per Rule 130 of the Implementing Regulations to the Convention on the Grant of European Patents (T 1515/20). Nevertheless, the TBA thought the full antibody sequence, including the signal peptide, was sufficiently disclosed as retaining functionality so that the patent could be granted.
Hamburg local division
Alexion applied to the Hamburg Local Division of the UPC for separate preliminary injunctions against biosimilar products launched by several Amgen companies as well as Samsung Bioepis NL B.V. (Samsung) after those had been launched in 2023.
These defendants’ products did not have a signal peptide, so they were not within the literal scope of the patent claim. However, the Local Division interpreted the claim as excluding the 22 extra amino acids. This was because the skilled person would recognize them as a signal peptide and disregard them for making the antibody non-functional. In addition, the skilled person would compare the sequence with the CAS database entry and consider the technical and functional aspects of the antibody and conclude that the signal peptide would be non-functional.
Whilst the patent was therefore likely to be infringed, its validity was not sufficiently certain to the Court of First Instance to grant any provisional measures. The Court thought it was relevant that the EPO was likely to find the patent invalid for insufficiency because Alexion had admitted that the antibody with the signal peptide was non-functional. It therefore dismissed Alexion's application for a preliminary injunction and Alexion appealed that decision.
Court of Appeal decision
The Court of Appeal also held that the patent was not sufficiently certain to be valid but disagreed with the Local Division’s construction of the relevant claim.
Its key ruling was that a linguistic error, spelling mistake or other inaccuracy in a patent claim can only be corrected by way of interpretation if both the existence of the error and the precise way to correct the error are sufficiently certain to the average skilled person at the time of filing, on the basis of the patent claim, taking into account the description and drawings and using common general knowledge. This is a strict standard, because disregarding erroneous parts of claims leads to legal uncertainty for third parties.
In its view, Alexion’s experts did not give any evidence that the skilled person would be alerted to check for a signal peptide or analyze it in the first place. It was therefore not an obvious error, and the skilled person would interpret the claims as needing the complete sequence, including the 22 amino acids comprising the signal peptide. Furthermore, there were alternative production methods not reliant on signal peptides at all and the patent did not make it clear which approach to pursue. It was also not sufficiently certain to the average skilled person that the error should be corrected by deleting exactly 22 amino acids.
Accordingly, the existence of an error and the precise way to correct it were not sufficiently certain to the average skilled person at the priority date. The applicant’s assertions during the grant proceedings, and the TBA’s endorsement thereof, were an indication of the view of the person skilled in the art at the filing date.
Based on this claim interpretation, the Court of Appeal found the subject matter of the claim to likely be insufficiently disclosed pursuant to Art. 83 EPC. The Court of Appeal therefore dismissed Alexion's appeal, agreeing with the Local Division that the patent's validity was not sufficiently certain to justify provisional measures. Alexion was ordered to pay the costs of the appeal.
Main Takeaways from the decisions
- The standard for correcting errors in the patent claim by way of claim interpretation is strict to reduce legal uncertainty.
- There needs to be an “obvious” error and a sufficient degree of certainty for the skilled person to both recognize and correct the error.
- Statements made during patent grant proceedings can be relevant to the view of the skilled person when assessing the claim errors during infringement proceedings.
- This is another reason why precision in patent drafting and prosecution matters because errors may have consequences for patent enforcement.
