Upcoming Mallesons seminarsOriginator and generic pharmaceutical companies who have, or intend to have, racemic or enantiomer compounds as part of their suite of products. The implications should also be considered in relation to the extension of pharmaceutical patents.
What do you need to do?Consider the implications of this decision and watch for the outcome of the special leave application.
Christina Taylor
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Partner
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Melbourne
Robert Cooper
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Brisbane
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The Full Federal Court recently handed down its decision in H. Lundbeck A/S and anor v Alphapharm Pty Ltd (and 2 other appeals).
The appeals related to a patent for escitalopram, the S-enantiomer (in this case the (+)-enantiomer) of citalopram, a selective serotonin reuptake inhibitor used in the treatment of major depressive disorder. The patent is owned by a Dutch company, H. Lundbeck A/S, and licensed to its Australian subsidiary Lundbeck Australia Pty Ltd. Citalopram was previously patented (including in Australia) by Lundbeck, and the term of that patent has expired.
In these proceedings, and in parallel proceedings involving the Commissioner of Patents, the Lundbeck parties appealed against Justice Lindgren’s decision that Lundbeck was not entitled to an extension of the term of its patent. The Lundbeck parties also appealed against his Honour’s decision that claim 5 of the patent was invalid for want of utility.
In its cross claim, Alphapharm appealed against his Honour’s finding that the claims (other than claim 5) of the patent were valid and that Alphapharm had infringed claim 6 (which protects the process of manufacturing escitalopram). Alphapharm did not challenge his Honour’s finding that claim 6 of the patent was valid.
The third appeal related to Arrow Pharmaceuticals (another generic).
Enantiomers may be patentable as a separate invention to the racemate
By a majority judgment of Bennett and Middleton JJ (Emmett J dissenting on this point) the Full Federal Court has rejected Alphapharm’s argument that the S-enantiomer of citalopram is not new in light of the existence of the racemic mixture, citalopram. Bennett and Middleton JJ agreed with Justice Lindgren’s analysis that the claim of the patent was to the pure or isolated or separated (+)-enantiomer of citalopram.
Bennett J found that the “disclosure of a racemate does not necessarily amount to a disclosure of the individual enantiomer. It depends upon the disclosure in the context of the prior art document” Her Honour found that the citalopram patent did not provide clear and unmistakable directions to obtain the enantiomers and therefore did not anticipate the escitalopram patent. This decision leaves open the ability for companies to patent enantiomers as a separate invention to the racemate.
Bennett J found that his Honour had erred in construing the claim “(+)-citalopram” to mean 95% pure (+)-citalopram. Her Honour found that in the “absence of a qualification of purity expressed in the claim or made clear in the specification, none should be imported”.
To claim below the minimum and above the maximum dose for a drug may leave the claim open to invalidity for lack of utility
At first instance, Justice Lindgren considered whether a claim for a pharmaceutical composition wherein the active ingredient is present in an amount from 0.1 to 100 milligrams was invalid for lack of utility.
His Honour accepted the evidence of one of the expert witnesses that the minimum useful dose of the drug was 5 mg and the maximum useful does was 40 mg. His Honour also accepted evidence that doses up to 100mg would not be harmful. Consequently, his Honour found that the claim was invalid for inutility as it claimed below the lowest useful dose. Bennett J (with whom Middleton J agreed; Emmett J not having to decide as he found the patent invalid for want of novelty) upheld his Honour’s decision. Consequently, patentees should be careful to claim only the useful dose for pharmaceutical patents.
For the purposes of certain sections of the Patents Act a racemate will consist of or contain its enantiomers
A critical question in relation to whether a pharmaceutical patent will be granted an extension of term is whether there is a product registered on the Australian Register of Therapeutic Goods that “consists of or contains” the substance which is claimed in the relevant patent.
Bennett J (with whom Middleton J agreed; Emmett J not needing to decide as he found the patent invalid for want of novelty) upheld Justice Lindgren’s finding that, for the purposes of Part 3 of the Patents Act, the racemate, citalopram, consisted of or contained, the enantiomer, (+)-citalopram. Bennett J reserved her decision in respect of whether it was sufficient for the purposes of Part 3 of the Act to have a de minimis amount of the substance in question (such an argument was irrelevant in this matter as racemic citalopram consists of 50% (+)-citalopram and 50% (-)-citalopram).
The Full Court has ordered that the extension of the term of the escitalopram patent be removed, however Lundbeck have successfully applied for a stay of that order, pending an application for special leave to appeal to the High Court.
A “work around”, replacing essential integers, may be sufficient to avoid infringement of a method claim
Justice Lindgren found at first instance that the only difference between the method used by Alphapharm and the patented process is that the cyano-diol used in the patented process is replaced by the bromo-diol in Alphapharm’s process, and that the 5-cyano substituent is later replaced in the compound by a cyanation process accepted as well known and routine. His Honour found that by merely creating an additional step, the product of which is later removed in the Alphapharm process is not sufficient to avoid infringement.
Emmett J (with whom Bennett and Middleton JJ agreed) found that cyano-diol was an essential integer of the process, therefore substitution of the bromo-diol did not infringe. Emmett J held that the claim used the convention “R” to indicate where substitution was permissible. The cyano-diol was expressly required, and the convention to indicate that substitution was permissible was not used.
This aspect of the case confirms that to infringe a method claim, all essential aspects of the method must be incorporated into the method used.