To compensate patent owners for the time it takes to obtain regulatory and marketing approval for new drugs, the Australian Patents Act provides for patent term extensions of up to five years. However, in order to have an extension of term granted, a number of requirements need to be satisfied. One of these requirements is that a patent discloses and claims a pharmaceutical substance per se or a pharmaceutical substance produced by a process that involves the use of recombinant DNA technology.

In ImmunoGen, Inc [2014] APO 88 (December 19 2014), the Patent Office considered whether a claim directed to a process for preparing an antibody conjugate encompassed within its scope a pharmaceutical substance produced by a process involving the use of recombinant DNA technology in order to determine the patent’s eligibility for extension of term.

The pertinent claim made no mention of a step involving the preparation of an antibody by recombinant DNA technology but rather defined steps of contacting the antibody to a cross-linking agent and chemically conjugating the antibody to a cytotoxic agent, maytansinoid.

Relevantly, the Patent Office accepted that the antibody-maytansinoid conjugate when produced by a process involving the use of recombinant DNA technology fell within the scope of the claim defining a process for preparing the antibody-maytansinoid conjugate. Also significantly, the Patent Office found that it is not necessary for a claim to specifically recite recombinant methodology process steps provided a recombinant product made by the defined process be included among the things claimed. Accordingly, the application for an extension of term was accepted.

Notably, the patentee filed post-acceptance amendments to include a new process claim that recited a step of humanising a mouse monoclonal antibody by recombinant DNA methodology as well as a product-by-process claim. While the delegate indicated that the proposed amendments were allowable, interestingly he also noted that they were not necessary in order for the application to comply with the requirements for an extension of term.

The salient points of this decision for those responsible for securing extensions of term on pharmaceutical patents are that:

  1. a claim defining a process of producing a pharmaceutical substance encompasses the substance made by the defined method; and
  2. it is not necessary for a relevant claim to specifically recite recombinant methodology process steps.

This article by Shelston IP Partner, Dr Grant Shoebridge, first appeared in Managing Intellectual Property magazine February 2015 issue.