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Update on the patentability of antibodies at the European Patent Office

Update on the patentability of antibodies at the European Patent Office

European News 14/03/2024

An update on the patentability of antibodies at the European Patent Office

In a series of articles relating to the patentability of antibodies, we have previously provided an outline of the requirements associated with patenting antibodies and related biologics at the European Patent Office (EPO). In particular, we focused on the different ways an antibody can be claimed at the EPO and also the information often required in a patent application to support the presence of an inventive step. Previous articles can be found below:

- Patentability of antibodies at the European Patent Office

- Assessing-inventive-step-of-antibodies-at-the-european-patent-office

The EPO has recently issued updated Guidelines for Examination, which entered into force on 1 March 2024. Some of the most significant modifications have been made to the guidance surrounding antibody inventions.

Notably, the new Guidelines have been updated to remove the separate section relating to “definition by the epitope”, which is now briefly discussed at section G, II - 6.1.3 - “definition by target antigen and further functional features”. This appears to confirm the current EPO practice of examining this format of claim analogously to other functional claim language. In this respect, it is particularly important to note that for any antibody exclusively defined by functional features - such as an ability to bind a specific epitope - the skilled person must not be faced with an undue burden to identify further antibodies falling within the scope of the claim. Indeed, ideally, an application directed to functionally defined antibodies should not only provide examples of antibodies exhibiting the claimed functional property, but should also describe suitable methods for generating and identifying further antibodies falling within the scope of the claims, particularly if broad protection is to be obtained.

The updated Guidelines also point out that any functional definition must allow the skilled person to verify whether they are working inside or outside the scope of the claim. On this point, the updated guidance now indicates that the claim itself should typically recite the method used to determine and define the claimed functional property. It may be possible to avoid this requirement if (i) the measurement method to be employed belongs to the skilled person's common general knowledge and/or (ii) all the relevant measurement methodologies would provide the same result (GL F, IV – 4.11).

In addition, the guidance regarding specification of “linear” and “discontinuous” epitopes has been removed from the 2024 Guidelines altogether. Previously, if a claim was directed to a linear epitope (i.e., a continuous portion of amino acids of an antigen) and defined by a protein sequence, it could not be defined with open language; instead the claimed antibody required definition by a clearly limited fragment with closed wording. Alternatively, if the epitope was a non-linear epitope (i.e., a discontinuous portion of amino acids with multiple distinct segments of an antigen) and defined by a protein sequence, the specific amino acid residues making up the epitope needed to be clearly identified and the method by which the epitope was determined indicated in the claim. Whether removal of this guidance will dramatically impact the interpretation of such claims remains to be seen. However, its removal appears to at least afford applicants a greater degree of freedom when choosing the terminology by which to define a target epitope.

The updated Guidelines also now address the possibility of defining antibodies by their ability to compete with a reference antibody disclosed in an application for the first time. Such terminology allows the antibody target to be defined without specifying an exact epitope structure in the claims, offering a broader claim coverage in many instances. However it is important to note that defining an antibody solely via such means may not enable antibodies in the state of the art to be identified. This runs the risk a complete search cannot be carried out and the EPO will be required to issue an invitation to indicate the subject matter to be searched. It therefore remains important to include in the application as filed disclosure of further features associated with the reference antibody and/or its antigen in order to provide sufficient information for a complete search to be conducted. As mentioned above, the application must also provide sufficient disclosure to enable the skilled person to identify further antibodies falling within the scope of the claim.

Regarding the novelty of functionally defined antibodies, the updated Guidelines now clarify that, unless there is any indication to the contrary, any functionally defined antibody will be deemed to lack novelty in view of any prior art antibody known to target the same antigen. Thus, the onus is placed on the applicant to provide data and/or other evidence showing the functionally claimed antibody is indeed distinguished from antibodies of the prior art which target the same antigen. It therefore appears increasingly important to consider the inclusion of comparative data in an application if an antibody binding to a known target antigen is to be defined by functional language. If this is not possible at the filing stage and instead post-filed data is to be relied upon, it is vital the application provides sufficient information that allows the skilled person to at least derive the claimed functional property from the technical teaching of the application.

Finally, on the matter of inventive step, applicants will be pleased to note the updated Guidelines no longer mention the need to specify the antibody framework regions (in addition to any essential CDRs) when relying on a technical effect associated with binding affinity.

The attorneys at Secerna LLP are highly experienced in drafting and prosecuting patent applications relating to antibodies at the EPO. If you would like any further information on this topic, please contact Secerna LLP at or +441904 202900.