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Thursday, October 1, 2015

The Saga Continues, per se

by Nick Li, Lawyer

Last week, in yet another episode in the battle in the Alphapharm v Lundbeck case, the Full Court of the Federal Court of Australia unanimously upheld the decision to grant an extension to the term of Lundbeck's escitalopram patent. In ambitious arguments that sought to side step the many earlier decisions, Alphapharm (on behalf of a number of generic companies) mounted an offensive on whether the escitalopram enantiomer as claimed in the patent qualified as a pharmaceutical substance per se under section 70(2)(a) of the Patents Act 1990 (Cth). This was a brave approach, as it effectively challenged the findings of an earlier Full Court in relation to the same patent.

The crux of the case was whether escitalopram, as claimed, was a pharmaceutical substance per se – as required for Lundbeck to obtain an extension of term for its patent – or whether the claim was escitalopram with an additional requirement as to purity.

In short, and unsurprisingly, the court declined to disagree with itself but rather disagreed with Alphapharm (again).

A long, long time ago…


The litigation between these parties is prolonged and complex. Below is a very simplified summary.
  1. The compound in question is optically active, meaning that it exists in two stereochemical forms, known as enantiomers. A racemate is a mixture containing equal amounts of each enantiomer.
  2. The escitalopram patent, owned by Lundbeck, was granted with a priority date of 13 June 1989, and claimed the (+) or dextrorotatory enantiomer of citalopram. The racemate, citalopram, was claimed in an earlier Lundbeck patent which expired on 5 January 1993.
  3. Citalopram was marketed as Cipramil, and was registered on the Australian Register of Therapeutic Goods (ARTG) on 9 December 1997. Escitalopram was marketed as Lexapro, and obtained ARTG registration on 16 September 2003.
  4. In 2008, Lundbeck sought an extension of its escitalopram patent, until 13 June 2014, on the basis of its Lexapro registration. This was successfully opposed by Alphapharm. The trial decision of Justice Lindgren and the subsequent affirmative Full Court decision (collectively, the Lexapro decisions) are referred to at length by the Full Court in the present case.
  5. Following the Lexapro decisions, Lundbeck sought an extension of time in which to apply for an extension of term of the escitalopram patent based on the Cipramil registration. As reported in our previous post on the High Court decision, Lundbeck was ultimately successful in obtaining that extension of time (to apply for an extension of term).
  6. Lundbeck then applied for an extension of term based on the Cipramil registration. This was successful before the Delegate, who extended the term of the patent to 9 December 2012. On appeal, it was upheld by the primary judge. The generic parties appealed the decision to grant the extension of term to the Full Federal Court, which brings us to the present decision.

A generic case theory…


Alphapharm's main submission was that the Delegate, and the primary judge, erred in their interpretation of claim 1 of the patent in holding that the (+) enantiomer was a pharmaceutical substance per se. It argued that the claim, which expressly claimed the (+) enantiomer, was not actually a claim to the particular enantiomer, but rather a claim to a pharmaceutical substance limited by a requirement as to purity. It argued that the requirement of purity was an additional integer and therefore the claim was not to a pharmaceutical substance per se.

In doing so, Alphapharm propounded a very creative interpretation of the reasoning from the Lexapro decisions. Justice Lindgren, and the subsequent Full Court, found that the compound as expressed in claim 1, was a reference to the (+) enantiomer alone, rather than as part of the racemate. Alphapharm argued that it was therefore necessary to construe the claim as being to pure (+) only, as an alternative construction would have meant the invention was anticipated by the earlier racemate.

…rejected


The court rejected Alphapharm's submissions. While the Lexapro decisions held that the compound claimed was the (+) enantiomer alone, the Full Court explained that this did not mean the claim was subject to a limitation as to purity, citing the following points from the Lexapro decisions.
  1. Justice Lindgren and the Full Court had both held that the (+) enantiomer disclosed was a pharmaceutical substance per se
  2. The claim to the (+) enantiomer alone did not introduce a limitation to purity into the claim
  3. The Lexapro Full Court had found that the prior disclosure of the racemate did not anticipate the (+) enantiomer.
Importantly, the court emphasised the findings of Justice Bennett in the earlier Full Court decision, which drew a distinction between a notion of an enantiomer being identified separately (as opposed to being a component of the racemate) and a limitation of purity.

Here, the Full Court held that terms such as 'alone', 'isolated', 'separated' or 'pure' can be used to explain the difference between a new pharmaceutical substance and a pharmaceutical substance in combination with something else, but do not add an integer limiting the claim to enantiomerically pure mixtures of the (+) enantiomer only. The specific references to the (+) enantiomer were to distinguish it from the (-) enantiomer and the racemate. Accordingly, claim 1 is a claim to the (+) enantiomer as a separated, purified or isolated enantiomer, an independent molecule distinct from the racemate. These are simply indicia of the separate identity of the pharmaceutical substance and do not mean that the claim has an additional integer requiring a particular level of purity.

In a less than surprising outcome, the Full Court ultimately found that claim 1 claims the (+) enantiomer only. Therefore, it claims a pharmaceutical substance per se. Therefore, Lundbeck is entitled to an extension of term for its escitalopram patent.

So is this the end of the line? Can Lundbeck finally seek damages for the full period of infringement under the extended term of the patent? The generic parties still have time to apply for special leave to appeal to the High Court. Given the fortitude they have shown to date, motivated no doubt by the significant sums at stake, there might still be one final round to play.

Our prediction? The High Court will decline special leave, thereby handing victory to Lundbeck.

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