First published in EPLAW
Lord Justice Arnold returned to the High Court in March to hear a trial involving the validity and threatened infringement of six patents concerning the use of inhibitors (referred to as HIF-PHIs) of an enzyme called hypoxia inducible factor-prolyl hydroxylase (HIF-PH) for treating various types of anaemia and related conditions.
In a very technical and necessarily detailed judgment running to 132 pages, Lord Justice Arnold found that of all the claims in issue across all six patents, only one claim survived in an amended form and even then, that claim was not infringed.
Akebia and Otsuka sought to revoke six patents belonging to FibroGen to clear the way for their product vadadustat. Astellas, as the exclusive licensee under the six patents, brought a cross-claim for threatened infringement. Astellas had obtained a marketing authorisation for its own product, the first oral HIF-PHI product, roxadustat, in Japan in September 2019, and intends to launch the product more widely, including in the UK. (There were parallel proceedings due to be heard in the same trial involving two GSK companies and their product daprodustat, these were settled shortly before trial.) Daprodustat and vadadustat were undergoing Phase III trials at the time of the trial.
I cannot do the decision justice in a brief headnote. It covers interesting questions of excessive claim breadth, insufficiency, claim amendment, infringement of medical use claims, quia timet infringement, infringement by equivalence and the relevance of the prosecution history. In relation to the latter two subjects, Lord Justice Arnold allowed reference to the prosecution history, commenting that this was “one of those cases referred to by Lord Neuberger in Actavis v Lilly at  where it would be contrary to the public interest for the contents of the prosecution file to be ignored”.
Of particular note to UK practitioners are Lord Justice Arnold’s comments on expert witnesses in patent cases and his guidance on primers:
- He gave a stark warning to patent practitioners over how experts should be instructed and cross-examined. He referred to guidance he gave in MedImmune Ltd v Novartis Pharmaceuticals UK Ltd and a comment he made in Merck Sharp and Dome Ltd v Shionogi that “too much time is spent by cross-examiners in patent cases on ad hominem attacks that are unfair to the witness, unhelpful to the court and waste expensive time”. He went on to re-iterate the “sequential unmasking” process that should be followed when introducing an expert witness to the prior art and the patent.
- Lord Justice Arnold was clearly frustrated with the lack of any primer in this case involving two moderately complex areas of science. He commented that in future, “the preparation of a technical primer should be regarded as mandatory in Category 4 and 5 cases unless there are good reasons to the contrary”.
The full judgment can be seen here.