The Manual of Patent Office Practice designates antibodies as a 'special topic' – no other molecule is set apart this way. The Commissioner's Decision (CD) on monoclonal antibodies (CD 1302) and the recent Commissioner's Decision on humanised antibodies (CD 1398) indicate that the Canadian Intellectual Property Office (CIPO) is becoming more amenable to treating antibody inventions according to the same rules that apply to other molecules.

When an application contains a claim for humanised antibodies, CIPO practice has been to reject the claim for insufficient disclosure unless a humanised antibody was made before the filing date, or the complementarity determining region (CDR) sequences defining the antibody binding site have been disclosed in the application. In a development favourable to applicants, this practice is set to change with re Chugai Seiyaku Kabushiki Kaisha (CD 1398).

The application in CD 1398 was for a pharmaceutical preparation comprising an anti-glypican 3 antibody for inhibiting abnormal proliferation of hepatic and lung cancer cells. The application disclosed two anti-glypican 3 mouse monoclonal antibodies and showed in vitro that they displayed activities relevant to cancer therapy. The application disclosed known methods for making humanised antibodies, but did not disclose the CDR sequences, and there was no evidence that a humanised antibody was made before the filing date.

The examiner allowed the independent claims which recite an anti-glypican 3 antibody, but rejected the dependent claims that specify a humanised anti-glypican 3 antibody. The examiner's rejection rested largely on re Sloan-Kettering Institute for Cancer Research (CD 1296), which concluded that, based on the absence of CDR sequence information and other factual considerations, the specification in that case did not adequately describe or enable a humanised antibody. CD 1398 reversed the examiner's rejection.

The commissioner framed the issue thus:

"Would the recited humanized antibodies be correctly and fully described; and would the specification enable the POSITA to practice the invention as claimed without displaying inventive ingenuity or undertaking undue experimentation in circumstances where there is no evidence that a humanized antibody had been made and sequence information regarding the variable regions of an anti-glypican-3 antibody is not disclosed?" (Emphasis added.)

On enablement, the commissioner distinguished the present case from CD 1296, stating that the evolution of common general knowledge is an important factor and that CD 1296 cannot impose a rigid rule requiring sequence information. The commissioner noted that the application at issue in CD 1296 was filed in 1990, while the subject application was filed in 2002. In the intervening 12 years common general knowledge has evolved such that antibody humanisation has become routine.

On written description, the commissioner also distinguished the present case from CD 1296, stating that the specification does not need to disclose the CDRs if the humanised antibodies are adequately described in other terms. The commissioner referred to re Immunex Corporation (CD 1302), where it was decided that a monoclonal antibody is adequately described by disclosure of the corresponding antigen because there is a direct structural relationship and functional identity between the antigen and the monoclonal antibody. The commissioner considered that the rationale in CD 1302 also applies to humanised antibodies and since the glypican 3 antigen is well characterised (in contrast to the antigen in CD 1296), the humanised antibodies are adequately described.

Until recently, CIPO required that a claim for a monoclonal antibody must be supported by a demonstration that such an antibody was made before the filing date. CIPO changed its practice on monoclonal antibodies only in 2010 when the commissioner reconsidered the issue in CD 1302.

CD 1398 and CD 1302 signal a welcome change to CIPO's practice of treating antibody inventions as special compared with other inventions.

For further information on this topic please contact Thuy Nguyen at Smart & Biggar/Fetherstonhaugh by telephone (+1 613 232 2486) or email ([email protected]). The Smart & Biggar/Fetherstonhaugh website can be accessed at