Although the current provisions for extending the term of a pharmaceutical patent have been in force since 1999, the several hundred extensions granted since then have all been made under only one of the two available criteria, that is, on the basis of claiming a “pharmaceutical substance per se”. 

Here we look at two recent decisions in which the Patent Office has, for the first time, granted extensions on the alternative basis of a “pharmaceutical substance when produced by a process that involves the use of recombinant DNA technology”.

Criteria for an extension of a pharmaceutical patent term

Subsection 70(2) sets out that in order to be granted an extension of patent term one or both of the following criteria must be satisfied:

  1. one or more pharmaceutical substances per se must in substance be disclosed in the complete specification of the patent and in substance fall within the scope of the claim or claims of that specification:
  2. one or more pharmaceutical substances when produced by a process that involves the use of recombinant DNA technology, must in substance be disclosed in the complete specification of the patent and in substance fall within the scope of the claim or claims of that specification.

ImmunoGen Inc.

On the basis of a strategy developed by Davies Collison Cave, ImmunoGen requested an extension of term for AU 2006283726 based on the inclusion of KADCYLA®, which contains the antibody conjugate trastuzumab emtansine as the active ingredient, in the Australian Register of Therapeutic Goods (ARTG).

The claimed invention was directed to processes for preparing conjugates of high purity, which involved coupling an antibody to a cytotoxic molecule via a crosslinking agent, and purification steps. The well known techniques for producing trastuzumab and other humanized monoclonal antibodies were referred to in the specification.  

The Examiner concluded that the process defined by the claims related to a process for preparing a conjugate by a crosslinking process, and not a process involving recombinant DNA technology, and rejected the application.

A process that “involves” the use of recombinant DNA technology

On appeal, the Delegate for the Commissioner was asked to consider the Explanatory Memorandum to the Bill which introduced the patent term extension provisions, as well as the decision of the Federal Court in Boehringer Ingelheim International v Commissioner of Patents [2000] FCA 1918.  

From a consideration of these materials, the Delegate determined that it was clear that the general intent of Parliament was to provide patent term extensions for pharmaceutical substances per se, rather than old or known substances used in a new mode of treatment, or prepared by a new process.  The sole exception to this general rule was in respect of pharmaceutical substances when produced by a process that involves the use of recombinant DNA technology.   

Importantly, however, whilst acknowledging that the likely intent of this exception was to support the development of improved recombinant techniques, the Delegate concluded that this nevertheless fell short of qualifying the term “involves” in subsection 70(2)(b) to require a claimed product to be made by new recombinant DNA technology, or that the process claimed be limited entirely to a recombinant process.  Instead, the Delegate held that the legislation appeared to encompass a range of scenarios, including the present one where the processes included forming a conjugate from an antibody produced by known recombinant techniques.

Is a product-by-process claim necessary?

Having concluded that the first leg of the test was satisfied, the Delegate also needed to determine whether one or more pharmaceutical substances when produced by a process that involves the use of recombinant DNA technology, in substance fell within the scope of the claim or claims of the specification, that is to say, whether such a substance was “included amongst the things claimed”.  The claims as granted were directed to processes and did not include a claim specifically to a product when produced by a process.

To address this, the patentee had proposed further voluntary amendments to include product-by-process claims. However, the Delegate found that these were not  necessary to satisfy the requirements of subsection 70(2)(b).  In particular, the Delegate held that, in effect, the claim to a product made by a particular process is substantially indistinguishable in scope from a claim to the particular process used to make the product, such that infringement of one type of claim was necessarily an infringement of the other, and that therefore, a product made by a process including recombinant process step was included amongst the things claimed.  

Following on from these findings, the Delegate held that the application for an extension of term must be accepted.  

Novartis Vaccines and Diagnostics

The request for a patent term extension was made by Novartis on the basis of the inclusion in the ARTG of the meningococcal B vaccine Bexsero®, which contained four antigenic ingredients derived from N. meningtides serogroup B, as well as several other components, including aluminium hydroxide and histidine.

Three of the antigens are produced using recombinant technology.  The specification and claims related to processes for the production of vaccine compositions, by admixture of the antigen with an aluminium salt/histidine mixture.  A product-by-process claim was also included.   Again, the application for extension was initially rejected on the basis that the claims were not specifically restricted to a recombinantly produced pharmaceutical substance.

In considering the appeal, the Delegate was guided by the earlier ImmunoGen decision and agreed with the previous Delegate’s broad interpretation of subsection 70(2)(b).  

The Delegate then went on to find that the pharmaceutical substance (the composition of aluminium hydroxide, histidine and four antigens) was included within the scope of the product-by-process claim, and, as the antigen was recombinantly produced, subsection 70(2)(b) was therefore satisfied.  

While the decision was ultimately made with consideration to the product-by-process claim, the Delegate did note that, consistent with the finding in ImmunoGen, Novartis could have equally relied on the process claim to support the application.   

Clear guidance for inventions involving recombinant DNA technology

These decisions provide welcome guidance for patent holders seeking to extend the term of pharmaceutical patents for inventions “involving” recombinant DNA technology:

  • It is now clear that there is no need for the pharmaceutical substance in question to be directly produced by new recombinant techniques or that a claim specifically recite recombinant technology process steps.  Furthermore, while these decisions are in respect of specific circumstances,  the “involvement” of recombinant DNA technology in producing the pharmaceutical substance is potentially not limited to analogous circumstances and may encompass a range of scenarios. 
  • The scope of a product-by-process claim, being a claim to a product made by a particular process, is substantially indistinguishable from a claim to that process used to make a product, and therefore, the presence of an actual product-by-process claim is not required.

Practical advice for pharmaceutical patentees in light of these decisions

In light of the Patent Office’s expanded interpretation of subsection 70(2)(b), there could be value in pharmaceutical patent holders reviewing their portfolios with a view to possible extension of patents relating to processes which might be considered to  “involve” recombinant DNA technology.  In this regard, the deadline for filing an application for extension is the later of six months from the date of grant of the patent, or six months from the first listing date in the ARTG.

Furthermore, even where these deadlines have now passed, the effective change in position taken by the Office in these decisions, may now, under certain circumstances, raise the possibility of belatedly seeking a patent term extension request.