On 29 September 2009, the Full Federal Court handed down its decision in Apotex v Sanofi-Aventis.1 The Full Court held that the claims of the clopidogrel enantiomer patent were invalid for reasons of novelty and obviousness. This is in contrast to the other recent decisions of the Full Court concerning the validity of an enantiomer patent, the escitalopram patent in Lundbeck v Alphapharm2 and the related first instance decision in Alphaphram v Lundbeck.3

Prior patents for the racemate

In Lundbeck v Alphapharm, the Full Court held that the patent for escitalopram was novel over a prior patent which claimed the racemate (the racemate being a mixture consisting of equal amounts of two enantiomers). However in Apotex v Sanofi-Aventis, Justices Bennett and Middleton (with whom Justice Emmett agreed) held that claim 1 of the patent, in so far as it related to the enantiomer, was invalid on the basis of lack of novelty when compared to prior patent for the racemate.

The different outcome can be explained with reference to the prior patents in each case. The prior racemate patents in Apotex v Sanofi-Aventis specifically referred to and expressly claimed the enantiomers in addition to the racemate. Whereas, the prior patent to the racemate in Lundbeck v Alphapharm did not refer to the enantiomers. The Full Court held that the cases could therefore be distinguished and that by expressly claiming the enantiomers in the prior patents, ‘there was a clear direction to the skilled reader to prepare the enantiomers’.4 In making this decision, the court rejected Sanofi’s argument that unless the claimed compound was actually made and the making of it described in the prior publication there could be no anticipation. Justices Bennett and Middleton stated that it could not be correct that the prior publication must, in every case, set out the method of preparation and each step in the preparative process, no matter how routine.

Obviousness

The patents had priority dates of 1987 for clopidogrel and 1988 for escitalopram and in both cases, obviousness was assessed with reference to section 100(1)(e) of the Patents Act 1952 (Cth). It was accepted in both cases that the common general knowledge included a range of techniques for obtaining enantiomers from a racemate.

In Apotex v Sanofi-Aventis, the Full Court held that the prior patents for the racemate were not part of the common general knowledge in Australia at the priority date. The court then had to consider the relevant starting point for the assessment of obviousness. Apotex argued that the correct starting point was the racemate and Sanofi-Aventis argued that the correct starting point was the common general knowledge at the priority date.

Justices Bennett and Middleton (with whom Justice Emmett agreed) held that the question for the court is whether ‘the invention, so far as claimed in the particular claim, is obvious and does not involve an inventive step’5 and this requires that the invention, as described in the specification, be identified. The court held that the invention of the patent was the resolution of the enantiomers of the racemate and therefore, the hypothetical skilled worker, armed with the common general knowledge as at the priority date, would have the racemic mixture as the starting point. In support of this finding, Justices Bennett and Middleton found that the specification ‘made it clear’ that the selection of the racemate to be resolved formed no part of the invention as described and claimed. They emphasised that ‘the base line or starting point may itself be part of the inventive step or inventive process’ but this was not the case here as the selection of the racemate was not claimed to be inventive. On this issue, Justices Bennett and Middleton compared the case to that of Insta v KD Kanopy6 where the claim was to an entire structure or construction which included the subject matter of earlier patents with additional features. In that case the invention was not limited to the introduction of new features.

Given the starting point of the racemate in light the common general knowledge, the Full Court held that the claims to the enantiomer, the method of obtaining the enantiomer and pharmaceutical compositions of the enantiomer were invalid on the basis of obviousness. The Full Court also held that claims in the patent to salts of the enantiomer were invalid on the basis of obviousness. Although there was a choice of salt to be made and this process would involve trial and error, this did not involve an inventive step because ‘trial and error are normal, everyday parts of laboratory work and non-inventive laboratory experiments’.7

This decision can be compared to that in Alphaphram v Lundbeck where the claims were held to be not obviousness. This aspect of the case was not appealed to the Full Court. In that decision, the prior patents to the racemate were held to be part of the common general knowledge. Therefore, the starting point for obviousness in the two decisions was basically the same (the racemate in light of the common general knowledge). However, the claims in Alphaphram v Lundbeck were found to be inventive and not obviousness because the skilled address would not, as a matter of routine, have resolved the racemate into the enantiomers using the route as claimed. That process claimed by Lundbeck was not a common technique for resolving racemates.