This is written from the perspective of a European Patent Attorney.
1. An antibody will normally be defined with reference to its specificity. The specification should provide as much detail as possible for further limiting the specificity, for example to exclude cross-reacting antibodies that bind to related proteins. One possible way of doing this is to provide basis for specifying that the antibody does not bind proteins with less than a given percentage homology to the protein the antibody has been raised to.
2. It is often difficult to get claims at the EPO which simply refer to the antibody being specific for a particular protein. Therefore as much information as possible should be given for the region or epitope which the antibody binds.
3. Examiners will often raise inventive step objections against claims to antibodies, and therefore it is desirable to give as many advantages of the antibody as possible, and preferably also unexpected properties. Thought may be given to including date in the specification comparing the antibody properties to prior art antibodies.
4. This is an area where the EPO and USPTO are becoming stricter, particularly in how the antibody is defined. Therefore including the sequence of the CDR’s will reduce the risk of objections against how the antibody is defined, though in theory this should not be needed. Any form of structure-function analysis should also be provided.
5. Antibodies can be defined with reference to a hybridoma deposit. However thought should be given as to how variants of the antibody made by the hybridoma can be defined. There is a possibility the Examiner will require the claims to be restricted to the specific antibody made by the hybridoma.
6. If the antibody is defined by having a particular activity, for example blocking binding to a particular receptor, then the specification should provide an assay that can be used to screen for the activity. There is a risk the Examiner will consider it an undue burden to make antibodies with the required activity, and so the specification needs to be drafted with this in mind.
7. In general Examiners will want the claims restricted to specific antibodies and therefore thought should be given when drafting to the breadth of claims that are desirable. If broad claims are important to obtain, then data supporting broad claims will be needed.
8. In general where a novel protein is claimed an antibody specific for the protein can be claimed.
9. Where an antibody is claimed then all functional fragments and derivatives should also be claimed. The terms ‘monoclonal’ and ‘isolated’ should be included as features which could be used to limit the antibody claim. Thought should be given to other standard features that could be used to define the antibody, such as its class, species (e.g. camel or shark) and whether it is humanised.
10. For therapeutic antibodies thought may need to be given to claiming the composition that will be administered. This could include a nucleic acid which expresses the antibody in vivo, rather than the antibody itself. Clearly thought needs to be given to claiming such nuclei acids per se.