Pharmacia’s Dynastat patent valid, imminent patent expiry no reason to avoid injunction

Introduction

Pharmacia LLC and Pfizer Australia Pty Ltd (together, Pharmacia) have partially succeeded at first instance in their claim against Juno Pharmaceuticals Pty Ltd (Juno) in respect of Pharmacia’s patent 2002256031.  The Federal Court decided that there is no basis to depart from the usual course that an injunction follow a finding of infringement, despite the patent in question being due to expire on 2 April 2022, only six weeks after the date of judgment.

The judgment considers whether six product batches, including 40 mg products and 20 mg products (representative batches), fall within the scope of the claims.  Juno does not hold any ARTG listing for 20mg parecoxib products in Australia and, although not explicitly identified in the judgment, according to Juno only these batches were found by the Court to fall within the scope of the claims. ^[1]  The judgment records that the agreed position between the parties was that the judge’s conclusions on these representative batches, together with certain admissions made by Juno, would be sufficient for the parties to propose orders giving effect to the judgment.  Until such orders are published, the exact effect of the judgment is unknown.  However if Juno has not and does not intend to sell the 20mg product in Australia during the patent term, it appears that there may be no infringement and that, both in terms of injunction and damages, the practical effect may be negligible.

Regardless of that issue, Justice Burley’s judgment is a useful guide on aspects of evidence preparation in patent cases, particularly as regards inventive step under the pre-Raising the Bar test (that is, prior to the IP Laws Amendment (Raising the Bar) Act 2012 (Cth) coming into effect).  His Honour also addresses (and rejects) an interesting argument by Pharmacia on inventive step: that the skilled addressee had insufficient time from the date the prior art was ascertainable until the patent priority date to carry out the steps that Juno argued would have led to the claimed invention.

The patent

Pharmacia’s patent relates to lyophilised formulations of parecoxib, a prodrug of the selective COX-2 inhibitor valdecoxib used to treat pain.  Parecoxib is water-soluble but converts to valdecoxib, which is less soluble, on exposure to water.  There was no dispute that it was common general knowledge before the priority date to formulate active pharmaceutical ingredients in lyophilised (or freeze-dried) form if they were unstable in aqueous solutions, for reconstitution in water immediately prior to administration.  The patent is directed to certain features of such lyophilised formulations, for example minimised amounts of bulking agents like mannitol in order to enhance stability during storage, and the use of the sodium salt of parecoxib to reduce reconstitution times.

Infringement

The key issues determined by the judge in this respect were issues of claim construction, focussed on technical matters.  Ultimately Justice Burley found that three of the batches fell within the scope of at least some of the claims of the patent, whereas the other three batches did not.

Invalidity

His Honour’s invalidity analysis navigates many practical aspects of preparing evidence on inventive step.  Firstly, his Honour found that a pain expert was an appropriate member of the team, even though the invention is directed to pharmaceutical formulations rather than methods of treatment. Relevantly, the specification addresses the clinical advantages of injectable formulations and selective COX-2 inhibitors and has dependent claims to treatment of patients with the claimed formulations.

The status of this team member was critical because Pharmacia’s formulation experts and Juno’s clinician expert took different approaches to literature searching.  Under the Patents Act 1990 (Cth) (Act) as it stood pre-Raising the Bar, prior art can only be relied upon for inventive step purposes if the skilled person could be reasonably expected to have ascertained the document, understood it and regarded it as relevant.  (This requirement has now been removed for post-Raising the Bar patents.)  Typically this requirement is proven by expert evidence outlining the document searching strategy that the expert would employ to carry out a hypothetical task to solve the problem which led to the invention.  In this case, the appropriate search strategy (and in turn, the relevance of the clinician in the team) gained prominence, since that used by Juno’s experts located the key prior art documents, whereas that of Pharmacia’s experts did not.  Ultimately Justice Burley applied a practical approach, finding that there was a “logical connection” between the task and the searches proposed by Juno’s expert, grounded in the common general knowledge.  Further, the use by Juno’s expert of ‘MeSH terms’ (a searching mechanism provided within the PubMed database) rather than keyword searches was “conventional and appropriate”, having been available for decades at the relevant date.

Justice Burley then considered Pharmacia’s ‘timing argument’.  Juno’s inventive step case was that the skilled addressee would have followed a ‘development pathway’ comprising eight steps, including ascertaining two pieces of prior art, obtaining the active ingredient parecoxib sodium, and formulating the lyophilised composition (as opposed to a solution formulation).  The MeSH terms which identified the first prior art document were only added to PubMed about a week before the priority date, and Pharmacia argued that the skilled addressee would not have had time to follow this development pathway and reach the invention by the priority date, particularly if that person had to synthesise parecoxib sodium.  Justice Burley rejected this argument, noting that ‘the person skilled in the art is not an avatar for expert witnesses’, but rather ‘a tool for analysis’, and that the obviousness test under the Act involves no temporal element.

Nevertheless, ultimately Burley J found that Juno had failed to establish that the notional research group would have taken several of the steps in the development pathway necessary to arrive at the invention, illustrating the high burden in Australia on a patent challenger relying on obviousness.

Injunction granted

Juno argued that it would be appropriate for the judge to exercise his discretion not to award an injunction in this case given the short time until patent expiry.  Justice Burley declined, finding that this timing consideration did not diminish the patentee’s prima facie entitlement to an injunction.

However given that Juno does not sell, and has not sold, the 20mg product found to fall within the scope of the claims in Australia, it appears unlikely that there will in fact be an infringement finding.  In practical terms the finding that Juno’s 40mg products do not fall within the claims may be the commercially significant aspect of the decision, rather than the findings in respect of the 20mg product.

^[1] https://www.junopharm.com.au/business-development