Articles
The Antibody Series #3 | Antibody code names in claims: why “ACZ885” is not sufficient to define the antibody
January 2026
The Boards of Appeal of the EPO (BoA) are the appeal body that reviews EPO decisions. In this case, they examined a claim that identified an antibody by an internal code name.
The real case: Your team is working with a clinical antibody known internally by a code name. You draft claims for a new indication and put this code name in the claim because, internally, there is no doubt about the molecule being targeted.
Claim 1 : (alternative claim)
“1. A medicament for use in the treatment of an auto-inflammatory syndrome in a patient in need thereof, the medicament comprising the human IL-1beta binding antibody ACZ885 and wherein said auto-inflammatory syndrome is Tumor Necrosis Factor Receptor Associated Periodic Syndrome (TRAPS), and wherein said antibody is parenterally administered at a dose between 0.1-50 mg of said antibody per kg body weight of the patient.”
Beginning of the story: Lack of clarity under Article 84 EPC. This was not the main issue in the first instance. On appeal, the question became simple and decisive: can a third party know, from reading the patent, what exactly “ACZ885” is?
The BoA’s teaching: An internal code name is not sufficient to define a claim, unless the file gives it a precise and unambiguous technical meaning. In this case, partial elements, such as sequence fragments and a reference to another document, were not sufficient to clearly identify the antibody covered by the claim.
Practical drafting tip: if you use an antibody code name in a claim, explicitly link it to a verifiable definition in the application, e.g., complete VH and VL or complete heavy and light chains with SEQ IDs, or a clearly identified combination of CDRs, or an epitope and an objective test with a quantified threshold, otherwise avoid the code name in the claim and only claim what a third party can verify.
Disclaimer : This is not legal advice; it is merely practical guidance to be incorporated early on in the filing strategy.
Source : ECLI:EP:BA:2021:T094116.20210216.
