Monoclonal antibodies (mAbs) are big business with a market that continues to experience significant growth as new therapeutic mAbs are created and indications for therapeutic mAbs expand. With biosimilars also entering the market, adequate patent protection for mAbs is of critical importance to our clients.

Prior to this recent decision of the Canadian Patent Appeal Board,1 the Canadian Patent Office refused to allow patents for mAbs against a novel antigen, unless the application included a working example with evidence of actual production of a mAb. This position of the Canadian Patent Office has been a challenge for our clients, as Canada was out of line with other major jurisdictions, such as the U.S. and Europe.

We advise that the Canadian Patent Office has now changed its position. For the first time, the Board has decided that a working example is not required to support claims to a monoclonal antibody. The Board instead determined that, while the actual physical possession of a hybridoma producing a monoclonal antibody is a consideration that should not be overlooked, in cases where the antigen is novel, not overly complex and fully characterised in the specification, claims to a monoclonal antibody immunoreactive with the antigen are allowable without the applicant having actually made or deposited a specific example of the antibody or corresponding hybridoma.

This is an important decision for our clients who patent in this area, and puts Canada in line with the U.S. and Europe. Clients have continued to file Canadian patent applications with claims directed to monoclonal antibodies, with hopes that the law might change during the pendency of their applications. Now it has. On behalf of our clients, Osler will be taking steps for all pending applications to advance these claims based on this recent decision. We also encourage any applicants avoiding Canada as a jurisdiction within which to pursue patent protection for this subject matter, to proactively file and prosecute claims for monoclonal antibodies in Canada.