Under Australian Patent Law, it is possible to apply for a patent term extension (PTE) of up to 5 years for a standard patent that claims a pharmaceutical substance in recognition of the exceptionally long time and regulatory requirements involved in developing and commercialising a new pharmaceutical substance.

Two recent decisions from the Australian Patent Office, ImmunoGen, Inc. [2014] APO 88 (19 December 2014) andNovartis Vaccines and Diagnostics S.r.l. [2015] APO 2 (2 February 2015) clarify the breadth of the scope of PTE provisions as they relate to pharmaceutical substances involving recombinant DNA (rDNA) technology.

Briefly stated, the decisions make clear that:

  • the relevant claims do not need to be limited to products made by rDNA technology;
  • a product-by-process claim is not required; and
  • whilst rDNA technology must be relevantly involved, the specific rDNA processes themselves need not be the novel and inventive subject matter.

Background

To be eligible for a PTE, goods containing, or consisting of, the pharmaceutical substance must be included in the Australian Register of Therapeutic Goods (ARTG) and according to Section 70(2) of the Patents Act 1990 the claims of the patent must either:

  1. Include within their scope one or more pharmaceutical substances
  2. Include within their scope one or more pharmaceutical substances when produced by a process that involves use of rDNA technology.

Section 70(2) stipulates that the one or more pharmaceutical substances “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”.

The Decisions

ImmunoGen, Inc. [2014] APO 88 (“ImmunoGen”)

ImmunoGen Inc. sought an extension of term for AU 2006283726 on the basis of Kadcyla® which is trastuzumab (a recombinantly-produced anti-HER2 antibody used in the treatment of breast cancer) conjugated to maytansinoid (a cytotoxic agent).

Claim 1 of the patent is directed to a process for preparing an antibody-maytansinoid conjugate comprising applying a linker to an antibody followed by conjugating the maytansinoid to the antibody-linker combination, and purification steps. Dependent claim 31 of the patent specifies that the antibody used in the process is trastuzumab.

The PTE application was initially rejected by a delegate of the Commissioner of Patents on the basis that “[t]he process defined in the claims for preparing this conjugate is a crosslinking process, not a process involving recombinant DNA technology” (ImmunoGen at [3]).

However, at a Hearing into matter, the Deputy Commissioner construed s 70(2)(b) more broadly than the delegate, finding that s 70(2)(b) does not require the disclosure of a new recombinant process, nor does it require that a claim is limited solely to a product produced by recombinant DNA technology (ImmunoGen at [20]). At [21], the Deputy Commissioner concluded that:

“In simply requiring a process “that involves the use of recombinant DNA technology” the legislation appears to encompass a range of scenarios including the present one where the processes described includes forming a conjugate from an antibody produced by known recombinant techniques.”

The Deputy Commissioner noted that claim 31 of the patent defined a process for preparing the pharmaceutical substance in respect of which the extension was sought but that the patent did not include a “product-by-process claim” directed to the pharmaceutical substance.

Importantly, the Delegate did not consider absence of a product-by-process claim fatal to the PTE application1 on the basis that:

“…a 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…and an infringement of one type of claim is necessarily an infring[e]ment of the other” (ImmunoGen at [24]).

It was therefore considered that the pharmaceutical substance (Kadcyla®), in substance fell within the scope of a claim to a process for preparing the antibody-maytansinoid conjugate and that it was therefore:

“[un]necessary for the claim to specifically recite recombinant process steps. It is enough for a product made by a process including such steps be “included amongst the things claimed”. (ImmunoGen at [26]).

Accordingly, the PTE was allowed.

Novartis Vaccines and Diagnostics S.r.l. [2015] APO 2

In a more recent decision Novartis Vaccines and Diagnostics S.r.l (“Novartis”) sought an extension of term for AU 2002330681 on the basis of Bexsero® which is a Meningococcal B vaccine comprising three recombinant protein antigens from N. meningitides, a bacterial extract, aluminium hydroxide and histidine.

The PTE application was initially rejected by a delegate of the Commissioner based on her construction of s 70(2)(b) as requiring a claim to be explicitly limited to a recombinantly-produced pharmaceutical substance and that the claims in question did not require the involvement of rDNA technology.

Claim 1 of the patent is directed to a process for producing a composition comprising an antigen, an aluminium salt and histidine, by specific admixture steps. Novartis relied on a product-by-process claim (claim 20), which encompassed a composition obtained according to the process of claim 1 wherein that the antigen is selected from a group which includes “a protein antigen from N. meningitides”.

Novartis’s specification was directed to the use of the amino acid histidine to improve the stability of vaccine compositions containing aluminium salt as an adjuvant. Preferred antigens were recited in the specification and one example disclosed the mixture of the three recombinant protein antigens from N. meningitides and the bacterial extract in combination.

The patent described the antigens and their preparation by reference to other documents, the contents of which were “incorporated by reference” into the specification. Reference to those documents confirmed that the antigens were produced according to rDNA technology. Indeed the protein antigen components in Bexsero® do not exist in nature.

Therefore, it was in view of the extended disclosure of the specification that it was found reasonable to conclude that there was “in substance” disclosure of a pharmaceutical substance produced by rDNA technology in the specification.

At the Hearing, the Commissioner’s Delegate agreed with the finding in ImmunoGen Inc., that it is not necessary for a claim to explicitly recite recombinant process steps, and found that a recombinantly-produced protein antigen was encompassed by claim 20. Therefore, included “amongst the things claimed” was a substance when produced by a process that involves the use of rDNA technology, even though a recombinantly-produced antigen was not required or specifically recited in the claim.

Accordingly, the requirements of s 70(2)(b) were found to be satisfied and Novartis’ PTE application was allowed.2

Implications

  • A process claim can support a PTE for a pharmaceutical substance which is, or comprises a component, made using rDNA technology, even where the claim does not explicitly recite recombinant process steps or that the product/component is recombinantly-produced and where the rDNA process per se is not novel or the subject of a separate patent.
  • A claim defining a process for producing a pharmaceutical substance is substantially indistinguishable in scope from a claim to a product made by that process. However, it remains prudent to include product-by-process claims.
  • The deadline for filing a PTE application is the later of 6 months from the date of grant of the patent or 6 months from listing on the ARTG. Accordingly, where a pharmaceutical substance involving rDNA technology is to be listed, or has been listed recently on the ARTG, it is advisable for patent holders to review their patent(s) for the possibility of an extension of term.