Overstated Confidence And Oversimplified Situation: Court Rejects Obviousness Argument In Favour Of Mirabegron Patent

• Published date: 07 July 2022
• Subject Matter: Intellectual Property, Patent
• Law Firm: Marks & Clerk
• Author: Ms Caitlin Ahern

Overview

In two actions that were heard together, Teva and Sandoz ('the Claimants') sought revocation of Astellas' patent EP (UK) 1 559 427 B1 ('the Patent'). The patent relates to a compound mirabegron (sold under the name Betmiga) which is used to treat overactive bladder (OAB). Mirabegron is a β3 adrenoreceptor ("β3-AR") agonist. Astellas counterclaimed for infringement, which was admitted by the Claimants if the patent was valid.

The judgment deals with the Claimants' allegation that the patent is invalid due to obviousness over a piece of cited prior art (Australian Patent Application AU 199889288 B2 ("'288")) and insufficiency run as a 'squeeze' against obviousness. These grounds involved disputes over the witnesses, the characteristics of the skilled person, and the scope of their common general knowledge ('CGK').

Witnesses

Astellas criticised the Claimants' pharmacology expert, Dr Argentieri, on several bases.

The first and second criticisms related to the approach Dr Argentieri took when deciding the characteristics of the skilled person. Astellas argued that he approached the cited prior art, '288, on the basis that the skilled person would have already been committed to pursuing β3-AR agonists for the treatment of OAB and the question was therefore whether it would have been reasonable to synthesise and test the compounds in '288 for that purpose. Astellas also alleged that Dr Argentieri had read the prior art through the eyes of a notional skilled person that was "smarter than everyone else" working in the field. Meade J considered that these were not criticisms relating to the integrity and independence of the expert but instead reflected that he had not been asking himself the right questions.

The final two criticisms related to Dr Argentieri providing an incomplete list of the therapeutic pathways under consideration at the priority date, and his assessment of the data found in the '288 prior art. Whilst Meade J acknowledged that that the list of pathways was produced from memory, and was only directed to those pathways he considered to have momentum, Dr Argentieri should have nonetheless taken more care when generating the list. The judge stated that he was left with the impression that the Claimants' lawyers had too great a hand in generating the list, as opposed to the expert's own independent decision making. Meade J also found that Dr Argentieri often overstated the persuasiveness of the content of '288, and expressed concern that the...