Alexion Pharmaceuticals v Samsung Bioepis NL (CoA, 20 December 2024)

Dhenne Avocats · 10 October 2026

Our analysis

Summary

In an order of 20 December 2024 (UPC_CoA_402/2024), the Court of Appeal dismissed Alexion’s appeal against the Hamburg Local Division’s refusal to grant provisional measures against Samsung Bioepis’s marketing of Epysqli®, a biosimilar of Soliris® (eculizumab), under EP 3 167 888. The Court declined to correct, by way of interpretation, the sequence SEQ ID NO: 4 recited in claim 2 so as to exclude its first 22 amino acids: neither the existence of the error nor the precise way to correct it was sufficiently certain to the skilled person. Read as including those 22 amino acids, the claim is more likely than not to be revoked for insufficiency. The Court ruled the same day, in parallel terms, on Alexion’s appeal against Amgen. The order sets out the strict standard for correcting errors in claims and gives weight to the applicant’s own statements during grant.

Facts and procedure

The patent stems from a chain of divisional applications going back to an international application filed on 15 March 2007. It was granted with unitary effect in May 2024 following T 1515/20, in which the EPO Technical Board of Appeal refused to replace SEQ ID NO: 4 with residues 23 to 236 and ordered grant on auxiliary request 5 (paragraphs 5 and 11). Samsung Bioepis filed an opposition on 2 May 2024 (paragraph 5). Alexion sought from the Hamburg Local Division a cease and desist order backed by penalty payments and surrender of products. The Division dismissed the application on 26 June 2024, with reasons of 17 July 2024, finding infringement likely but validity not sufficiently certain (paragraphs 14 to 16). On appeal, Alexion withdrew at the hearing its main request for remittal to the same panel, so only its alternative request for the measures to be granted was decided (paragraphs 17 and 22).

The applicable law

Claim interpretation follows the approach laid down by the Court of Appeal in NanoString v 10x Genomics: the claim is the decisive basis for the scope of protection, read in the light of the description and drawings (paragraph 35). The ground of invalidity relied on was insufficiency under Article 83 EPC.

Question

Can claim 2 be read as excluding the first 22 amino acids of the light chain defined by SEQ ID NO: 4, on the footing that they are a signal peptide included in error, and is validity then sufficiently certain to justify provisional measures?

Decision

A linguistic error, spelling mistake or other inaccuracy in a claim can only be corrected by interpretation if the existence of the error and the precise way to correct it are sufficiently certain to the average skilled person, on the basis of the claim, description, drawings and common general knowledge. This is a strict standard, since an error as such creates legal uncertainty for third parties (paragraphs 35 and 36). The Court rejected the purposive reasoning adopted at first instance (paragraphs 33 and 34) and found that the expert statements did not show why the skilled person would analyse the sequence or regard it as wrong (paragraphs 37 to 41). Alexion’s arguments before the Board, endorsed by it, confirmed the uncertainty and indicated the skilled person’s view at the filing date (paragraphs 42 and 43). The references to eculizumab in the description did not alter this (paragraph 44), and the length of the signal peptide was itself uncertain, prediction tools giving only probabilistic results (paragraphs 45 to 47). The claim therefore includes the 22 amino acids, so read, revocation for insufficiency is more likely than not. The appeal was dismissed with costs against Alexion (paragraphs 48 and 49).

Key points for practice

• Correcting an error by interpretation requires two cumulative certainties, as to the error and as to its correction, judged by the average skilled person.
• Positions taken by the applicant during grant, especially when endorsed by a Board of Appeal, may be held against it when the claim is construed.
• Withdrawing a request for remittal at the hearing leads the Court of Appeal to rule on the measures itself, without deciding the complaints against the impugned order (paragraph 23).
• Practical point: with biological sequences, an inconsistency known at grant should be cured before the EPO, the UPC will not correct it at the provisional measures stage.

Provisions applied

Rules of Procedure

Rules 9.3, 221, 222.1, 225, 226, 236 and 238

European Patent Convention

Art. 83

Case law cited

NanoString v 10x Genomics, Court of Appeal, 26 February 2024, EPO Technical Board of Appeal, T 1515/20, 21 September 2023

Prepared by Dhenne Avocats from the official decision, consulted on 10 October 2026. The database is updated every week, on Friday. Only the official text is authoritative.