A patent term extension (PTE) of up to five (5) years beyond the 20-year term is available for new pharmaceuticals under s70 of the Patents Act 1990. This benefit is to account for the lengthy regulatory approval process for medicinal products to come to market.

The decision in Pharma Mar S.A. [2020] APO 8 relates to a patent term extension for Australian Patent No. 754073 (the Patent) to 18 February 2024. The basis of the requested PTE is inclusion of APILIDIN in the Australian Register of Therapeutic Goods (ARTG). Prior to the hearing, a Commissioner’s delegate issued four deficiency notices regarding the s70 application before the matter was heard by a Hearing Officer.

Didemnin compounds have cytotoxic and antiviral activity but are typically difficult to formulate into compositions for therapeutic use. The Patent sets out that the invention solves this problem by providing a pharmaceutical composition of a didemnin compound, comprising firstly a lyophilised didemnin preparation including water-soluble material and secondly a reconstitution solution of mixed solvents. The Patent was filed on 18 February 1999 and APILIDIN was entered on the ARTG on 12 December 2018, clearly a long period of time.

Section 70 sets out the following conditions that must be met in order to qualify for a PTE:

• one or more pharmaceutical substances per se (or 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;
• goods containing, or consisting of, the substance must be included in the ARTG; and
• the period beginning on the date of the patent and ending on the first regulatory approval date for the substance must be at least 5 years.

ADIPILIN is a two-part product consisting of a vial of plitidepsin powder (formed from lyophilised didemnin and mannitol) and an ampoule of reconstitution solution comprising several solvents. The medicinal substance is formed by mixing the components and reconstitution as a solution prior to parenteral administration.

In the delegate’s view during examination of the PTE application, the combination of separate integers is not a pharmaceutical substances per se. The Hearing Officer found that Claim 1 is not an orthodox composition claim but rather is a claimed mixture of separate parts. Moreover, the goods listed on the ARTG in substance disclosed in the specification as filed and in substance falls within the scope of the claims. It is worth noting that the Patentee pressed the argument that plitidepsin per se in substance falls within the scope of the claims as well as the mixture immediately prior to, and after, reconstitution. The Hearing Officer rejected each of these propositions.

The final consideration turned on whether the claimed combination of, separately, a plitidepsin preparation and a reconstitution solvent, as claimed in the Patent is a pharmaceutical substance per se. The phrase “pharmaceutical substance per se” has been the subject of much judicial interpretation, particularly the relevance of including “per se” by the legislative draftsperson. The Hearing Officer cited an earlier Australian Patent Office decision in The Children’s Medical Center Corporation [2011] APO 80, which considered whether a combination of two drugs presented as separate dosage forms qualifies as a pharmaceutical substance per se. The delegate in this decision reviewed judicial authority to arrive at the following conclusion:

“It is clear from these decisions that the term ‘pharmaceutical substance per se’ is intended to be a pharmaceutical that is presented as a single entity, and not in the form of a kit or as separate dosage forms. As noted in Boehringer, the per se qualification was introduced by the 1998 amendments to the Patents Act, in order to limit the operation of this section to patents disclosing and claiming a pharmaceutical substance ‘by or in itself, intrinsically, essentially’ or ‘taken alone; essentially; without reference to anything else…”

The Hearing Officer noted that unlike tablets or solutions, or integrated formulations of multiple actives or actives and excipients, the presented claimed invention is not an integrated dosage form, but a plitidepsin preparation together with a separate solvent mixture which the specification indicates has been optimised for reconstitution. Or put another way, a plitidepsin preparation in combination with other elements. According to the Hearing Officer, such a “deconstructed” formulation intended for later reconstitution does not fall within the scope of a pharmaceutical substance per se under s70 of the Act. Furthermore, the subject matter defined by the claim and the goods included in the ARTG “is the antecedent to the pharmaceutical substance which is to be applied to the human physiological system but is not itself a pharmaceutical substance per se within the meaning of section 70(2)(a).”

The application for a PTE was refused.