A new edition of the EPO examination guidelines will come into force on 1 March 2021. The EPO has just released an unofficial preview version. It includes a new section on the examination of claims to antibodies (section G-II, 5.6 on pages G-II-43 to -46).
A section dedicated to this important area of life sciences practice is very welcome and, appropriately for examination guidelines, it does not contain any major surprises compared to our typical experiences of handling antibody patent applications at the EPO.
The new section affirms some well-established aspects of EPO practice:
- An antibody is not inventive solely because its sequence could not have been predicted in advance. That is, the EPO does not follow the approach of “structural non-obviousness”.
- If an antibody is defined only by sequence, then it is usually necessary to define at least the 6 CDRs, unless there is evidence that one or more CDRs do not interact with the target, or the antibody is of a specific format that permits antigen recognition with fewer CDRs (e.g. heavy-chain only antibodies).
- Furthermore, when arguing inventive step for such an antibody on the basis of binding affinity, then it is also necessary to define the framework regions (i.e. the whole variable domains), because framework mutations can influence affinity (even though many do not).
- However, it is possible to define an antibody by partial sequences, in combination with functional features.
- It is also possible, in principle, to define antibodies purely in terms of functional features, though there are warnings about enablement and clarity, and hence also novelty.
- The need for clarity when an antibody is defined in terms of its epitope; and the different implications of this for linear and discontinuous epitopes
While examination guidelines clearly cannot deal with all aspects of practice, there are some instances where the new section is disappointingly superficial:
- Surprisingly, there is no mention of the issues surrounding antibodies that are defined by competition with a reference antibody. While examiners will often object that such antibodies do not necessarily share the inventive properties of the reference antibody, this is far from universal and it would have been useful to have some guidance to ensure consistency of examination of such claims.
- Part of the guidance on functional features, often one of the most hotly contested areas in examination of antibody cases, is very unclear:
If an antibody is claimed exclusively by functional features and the prior art discloses in an enabling manner an antibody directed to the same antigen using an immunisation and screening protocol that arrives at antibodies having the claimed properties, it has to be assumed that the prior-art antibody inherently displays the same functional properties as the claimed antibody, which thus lacks novelty (cf. G-VI, 6). … In both these cases the burden of proof of novelty resides with the applicant.
This seems to be a poorly paraphrased version of G-VI, 6 to which it refers, but that section uses the standard of “no reasonable doubt”, rather than an assumption of inherency and reversal of the burden of proof.
This highly unclear guideline may further encourage the practice of some examiners to demand proof that all possibly relevant prior art antibodies are outside the scope of the claim, so emphasises the importance of including good fallback positions to combine with claims defined in terms of functional features, such as human/humanised to avoid many research antibodies, additional functional features, and partial sequence definitions as mentioned previously.
- The section on inventive step states, “Examples of surprising technical effects when compared to known and enabled antibodies are, for example, an improved affinity …”. This suggests that any improvement in affinity can support inventive step, which is not our typical experience of EPO examination and could result in inconsistent practice among examiners or unrealistic expectations. Similar comments apply to reduced immunogenicity.
We appreciate the introduction of this new section of the examination guidelines, and are confident that the limitations can be addressed in future editions.
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The Mewburn Ellis Life sciences team has unparalleled experience in handling antibody applications at the EPO and other jurisdictions, having handled numerous blockbuster pharmaceutical antibodies, as well as several platform technologies.
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