In the recent case AstraZeneca AB v Apotex Pty Ltd & Ors  HCA 30, the High Court unanimously found that AstraZeneca’s patent for its cholesterol lowering drug rosuvastatin lacked inventive step and was therefore invalid.
AstraZeneca’s patent was directed at low dosage levels of rosuvastatin, a commercially successful product marketed under the brand Crestor®. Generic pharmaceutical suppliers Apotex, Watson Pharma (now Actavis Pharma) and Ascent Pharma challenged the validity of the patent.
Subsections 7(2) and 7(3) of the Patents Act 1990 (Cth) were central to the High Court’s decision. These subsections provide that an invention does not involve an inventive step if it would have been obvious to a person skilled in the art in light of the following before the priority date of the patent:
(a) the common general knowledge considered alone; or
(b) the common general knowledge considered together with prior art information publicly available in a single document. The single document is to contain prior art information which could reasonably be expected to have been “ascertained, understood and regarded as relevant” by the skilled person.
It was not disputed that rosuvastatin did not form part of the common general knowledge. However, its existence was disclosed in two documents, a European patent which claimed the invention of the compound rosuvastatin and methods of preparing it, and a journal article referred to as the ‘Watanabe Article’.
Both the primary judge and the Full Federal Court considered that the invention lacked inventive step by reference to the common general knowledge considered with either of the two prior publications.
AstraZeneca raised two primary contentions on the inventiveness test, each of which was rejected by the High Court.
- AstraZeneca argued that the two prior art documents had not been shown to satisfy the requirement of relevance. AstraZeneca said that the test for assessing relevance required that each of the documents must be considered separately. The evidence of the expert witnesses regarding identification of the European patent and the Watanabe Article involved a comparison of those documents with a number of other documents in a prior art search which AstraZeneca said was not permissible.
The High Court rejected this argument, and found that in assessing whether any particular document satisfied the test as to relevance, it was permissible to consider a number of sources of information to determine whether any one of those documents satisfied the test.
- AstraZeneca also argued that even if the documents were considered relevant, obviousness was not made out as there existed additional documents which identified other compounds as being of interest. AstraZeneca’s contention was that a person skilled in the art was confronted with a choice between compounds and the experts did not explain what they would do in this situation.
The High Court rejected this approach, and found that the question is not whether it would have been obvious to the skilled addressee to choose rosuvastatin over other compounds. Rather, it is whether a person skilled in the art would, in light of the common general knowledge plus either the European patent or the Watanabe article, have been directly led as a matter of course to try rosuvastatin in the expectation that it might produce a solution.
Notably, Chief Justice French also stated that there was a tendency in AstraZeneca’s arguments to confer upon the person skilled in the art “more human characteristics of volitional and purposive action than are necessary”.
The High Court decision clarifies that in assessing whether a particular piece of prior art information would be “regarded as relevant”, there is no requirement that the information be considered in isolation. The decision also establishes that the inventive step test does not involve a question of whether it was obvious to choose one piece of prior art information over another.