The development of monoclonal antibodies has revolutionised medical science, and the use of these molecules in the development of future therapies, diagnostics and research appears assured. However, the scope of patent protection afforded to new monoclonal antibodies has varied significantly between jurisdictions, particularly as the technology has progressed and the use of such antibodies has become more common. For example, the Australian Patent Office has previously been relatively accommodating of claims directed to monoclonal antibodies; in some cases a single, unique CDR has been sufficient to define an antibody in Australian applications. This is in contrast to the often more stringent requirements demanded of US and European applicants. Recent changes to Australian patent law will likely see the support requirements for Australian applications brought into closer alignment with US and EP requirements. Moreover, a recent decision from the Australian Patent Office also points to greater hurdles for Australian applicants to demonstrate the inventiveness of claims directed to monoclonal antibodies.

In Alethia Biotherapeutics Inc. v Daiichi Sankyo Company, Limited, the claims under consideration were directed to antibodies which were a) defined according to the sequence of their binding target and b) by the functionality of the antibody. The target of the claimed antibodies, the protein Siglec-15, was a known therapeutic target (a fact acknowledged in the specification by the inventors). The prior art also suggested that inhibitory antibodies binding to Siglec-15 could be developed for use in treating disorders characterised by altered bone metabolism, even though no such antibodies were described.

The Patent Office found that the claims lacked an inventive step on the basis that the steps taken to proceed from the prior art disclosure to the claimed antibodies “are of a routine nature, which the person skilled in the art would directly be led to as a matter of course to try, in the expectation that it might well produce a useful alternative or better drug than the existing agents…”. The Patent Office commented that once a potential target had been identified, the steps for determining an appropriate targeting strategy, including the preparation of inhibitory antibodies, the screening of those antibodies and confirmation of their in vivo activity, were all routine steps that the skilled person would perform, with an expectation of arriving at a useful result.

So is there a cause for concern? No - we do not think that the recent Patent Office decision places undue burden on Australian applicants in the immediate future as in most cases, applicants define antibodies with respect to particular sequence and structural features. However, the decision does demonstrate that steps that were once considered inventive, can over time be deemed routine. In order to avoid any danger of a claim to an antibody being found to lack an inventive step, we strongly recommend that applicants emphasise any difficulties encountered during the identification and development of novel antibodies. For example, applicants should consider the inclusion of negative or conflicting data in their specifications.

Interestingly, the claims which defined specific hybridomas producing relevant antibodies were found to be inventive. It is not clear where the Patent Office drew the line between the inventiveness of the steps required to arrive at the claimed hybridomas and those steps required to arrive at any antibody binding to Siglec-15; this was not articulated in the decision. However, the decision does suggest that claims directed to monoclonal antibodies warrant careful review and consideration prior to examination.

The decision of the Patent Office has been appealed to the Federal Court of Australia.