Parecoxib Judgement

Pharmacia LLC v Juno Pharmaceuticals Pty Ltd

The decision in the Pharmacia v Juno matter relating to a lyophilized powder form of Parecoxib has just been published by the Federal Court.  The full reasons can be found here.  In summary, Burley J. found that Australian patent AU 2002256031 (the ‘031 patent) was valid, but only partially infringed. The case is interesting as infringement was tested against a series of six samples, three of which were found to infringe.  

By way of background, Pharmacia initiated proceedings against Juno in August 2019, with allegations that the Juno Parecoxib products infringes the ‘031 patent.  This patent is currently in force, but set to expire in April 2022.  Juno cross-claimed, challenging validity of certain claims.  Pharmacia did not seek to enjoin Juno from selling its Parecoxib product pending full trial, thus Juno has been selling its Parecoxib products in Australia for around 4 years.

The decision raises interesting questions of claim construction including the scope of the term “about” in pharmaceutical composition claims in Australia, as well as how any “residual water” in the composition should be treated in analyzing percentage ranges of the chemical components in the composition. A further key issue in the case, was what constituted the ‘therapeutic agent’ in the composition. Specifically, the question was whether it was the active component, Parecoxib, or the agent included in the composition, the salt form Parecoxib sodium.

Burley J. applied a relatively narrow construction of the term “about”, ‘in relation to weight percentage ranges of components in the composition, allowing for rounding to the nearest whole percentage, such that ‘about 90%’ extends to 90.49% at its upper bound’ [216].  In doing so, Burley J. rejected Pharmacia’s argument that the term should be interpreted on what range would be acceptable for pharmaceutical regulatory authorities such as the TGA or FDA.

On the identity of the ‘therapeutic agent’, Burley J. decided that the salt form, Parecoxib sodium, which was the component introduced into the composition, was the therapeutic agent referred to in the relevant claims.

The question of ‘residual water’ presented the Court with some difficulty. Residual water is not mentioned in any claim, but it was agreed by the experts for both parties that some residual water would inevitably be present.  Further,  if residual water was to be included in the calculation of the percentage proportions of the components of the composition, it  would alter the outcome of those calculations, potentially sufficiently enough to turn a potentially non-infringing formulation into an infringing one.  The difficulty arises however, as the amount of residual water is variable from batch to batch, and indeed from vial to vial.

Burley J. held that, despite the difficulty in calculating the percentage of residual water present in the Parecoxib vials, the presence of residual water cannot be ignored, and accordingly residual water must be included in the formulation calculations

On invalidity, Juno had argued that the relevant claims were invalid as obvious over the prior art, in particular a journal article by Jain. Burley J. agreed that the Jain article was relevant in that Parecoxib was a known therapeutic agent and its formulation as a lyophilizate utilizing a known buffering agent was an option that would readily present itself to a skilled formulator. However, whilst Burley J. accepted that such a lyophilized formulation was well known in the field, he was not convinced that parecoxib itself could have been obtained or synthesized before the priority date. Accordingly, the invalidity attack was rejected.

This article was written by Paul Jones