T 0835/21 - A valid functional antibody claim

Key points

• This case seems to illustrate that there is no Amgen v. Sanofi rule at the EPO. 
• Claim 1 is directed to an antibody defined purely in functional terms, i.e. in terms of what it binds to, without any restriction on the sequence/composition of the antibody itself.
• " A monoclonal antibody or an antigen-binding fragment thereof that specifically binds to human low-density-lipoprotein receptor-related protein 6 polypeptide (LRP6) having the amino acid sequence of SEQ ID NO:1, is capable of antagonizing the Wnt signaling pathway, and inhibits Wnt3- and Wnt3a-specific signaling activity, wherein the antigen binding portion binds to an epitope of human LRP6 within amino acids 631-932 of SEQ ID NO:1 as shown in Table 1." 
• On Art.83: " The preparation of a monoclonal antibody that binds to an epitope within a defined amino acid sequence, i.e. a known target, for example by immunisation of an animal with a protein or peptide consisting of or contained within the defined amino acid sequence, or by phage display using such a peptide, is a routine task for the skilled person and does not require any inventive activity. " 
• " The scant number of exemplary Fabs disclosed in the application, the lack of disclosure of the sequences of these exemplary Fabs, the lack of a direct link between Tables II and III of the application and the missing figures are hence not in themselves sufficient to call into question the general teaching in the application that the Wnt ligands fall into two groups which are preferentially antagonised by LRP6 antibodies binding to different propeller regions of LRP6, a teaching which is incidentally supported by post-published documents D2 and D5. Therefore, this argument does not persuade the board either." 
• On inventive step: " Document D8 discloses a monoclonal antibody that binds to the propeller 2 domain of LRP6 and inhibits Wnt3a-induced signalling activity (see point 52. above). The claimed antibody differs from this in that it binds to an epitope within amino acids 631 to 932 of SEQ ID NO:1, i.e. to an epitope within the propeller 3 domain of LRP6. Moreover, document D8 is silent on whether or not the inhibition of Wnt3a-induced signalling that it discloses is Wnt3- and Wnt3a-specific, as required for the claimed antibody. " 
• " The objective technical problem can therefore be formulated as the provision of an antagonistic LRP6 antibody that preferentially inhibits Wnt3 and Wnt3a signalling activity over signalling activity induced by other Wnt ligands "
• "  Nothing in the prior art pointed the skilled person towards an antibody that bound to an epitope within the propeller 3 domain of LRP6 as a solution to this technical problem. Indeed, it was not known in the art that different Wnt ligands bound to different propeller domains of LRP6, and that therefore antibodies that preferentially inhibited the signalling activity induced by particular Wnt ligands could be prepared by targeting different LRP6 propeller domains. The link between binding to the propeller 3 domain of LRP6 and preferential inhibition of Wnt3 and Wnt3a signalling activity was therefore not suggested in the prior art and hence was not obvious to the skilled person." 
• " it was not obvious to the skilled person, solely from the fact that Dkk1 binds to the LRP6 propeller 3 domain, that an LRP6 antibody that bound to the propeller 3 domain would inhibit Wnt3- and Wnt3a-specific signalling activity. This line of argument is therefore not persuasive. No other arguments that took the preferential inhibition of the Wnt3- and Wnt3a-induced signalling activity by the claimed antibodies into account were submitted by the appellant. Hence, the claimed subject-matter involves an inventive step over the antibody disclosed in document D8."
  

The link to the decision is provided after the jump.

https://www.epo.org/en/boards-of-appeal/decisions/t210835eu1