Full Court dismisses Boehringer appeal on obviousness of veterinary injectable formulation

The Full Court’s decision in Boehringer Ingelheim Animal Health USA Inc., v Intervet International B.V. [2022] FCAFC 88 is a useful analysis of the application of the “Cripps question” in inventive step.¹  This is one of the key tests applied by the Australian Courts in this regard.  While the patent in question relates to a veterinary injection formulation the learnings are equally applicable to patents to pharmaceutical formulations for human treatment.

Key takeaways

The Full Court rejected Boehringer’s submissions that it was improper for the primary judge to consider factors which did not form features of the claims when applying the Cripps question.  In this case, the problem purported to be solved by the invention was relevant to the characterisation of the invention to which the Cripps question was addressed.

The Full Court emphasised that the onus on Boehringer was to establish an error of principle by the primary judge, and rejected arguments that the primary judge gave improper weight to certain evidence.  Finally, the Full Court endorsed the distinction drawn in Aktiebolage Hassle v Alphapharm Pty Ltd (2002) 212 CLR 411 (Alphapharm) between testing required to move from the common general knowledge or relevant prior art to the invention, and confirmatory testing after the invention, accepting that the fact that confirmatory testing may be routine does not necessarily make the steps to reach the invention routine.

Opposition and primary court proceedings

Boehringer initially opposed the grant of Intervet’s patent application AU 2011268899.  The application, which was subject to the Patents Act 1990 (Cth) prior to the reforms in the Intellectual Property Law Amendment (Raising the Bar) Act 2012 (Cth),   was directed to injectable formulations for controlling parasites in animals.   It claimed an injectable formulation comprising two active ingredients, a macrocyclic lactone and levamisole, both of which had previously been used individually for the same purpose.   According to the claims the macrocyclic lactone was in a non-aqueous solvent system comprising oil, and levamisole was a salt in particulate form.

Following rejection of the opposition, Boehringer appealed to the Federal Court in respect of inventive step.  Since such an appeal is a proceeding de novo, involving a rehearing of the case, Boehringer was required to establish that it was clear or practically certain that the patent is invalid.  The appeal was dismissed by the primary judge.

While the primary judge found that it was not inventive to combine the two active ingredients into a single formulation, he did find that they were known to be chemically incompatible, stable under different pH conditions and have very different solubilities in water.  An expert in formulation chemistry called by Boehringer gave evidence that these characteristics would have led him to consider a suspension formulation (as in the claimed invention), to keep the two active ingredients separate from each other.  However the product development expert called by Intervet gave evidence that use of a suspension, wherein the levamisole was in particulate form, could affect its release profile.  The judge accepted it was common general knowledge that the release profile of levamisole was important to its efficacy.

His Honour found that Boehringer had not made out its lack of inventive step case for three reasons: (i) the known chemical incompatibility of the two active ingredients, (ii) the fact that the formulation chemist had not considered the impact on release profile when proposing his formulation approach, and (iii) secondary considerations, in particular the lack of commercially available formulations of levamisole in oily formulations or particulate form and prior unsuccessful attempts at combined formulations.

His Honour considered two prior art documents, concluding they did not help its case.  The first noted the difficulty of formulating these types of active ingredients together.  The primary judge found that Boehringer had led no evidence that this difficulty had been overcome between the date of this patent and the relevant priority date.  The second disclosed a macrocyclic lactone and levamisole formulated in a suspension, but without any discussion of stability issues or any material detail as to the manufacture or practical description of the formulation itself, and no evidence that the formulations exemplified were made or tested.

Appeal – application of Cripps question

The majority of Boehringer’s grounds for appeal related to the primary judge’s application of the Cripps question.  This test is commonly applied as an aid to analysing obviousness, and essentially asks whether the skilled addressee would, in all the circumstances, be directly led as a matter of course to try the claimed invention in the expectation that it might well produce a useful or better alternative.

Boehringer submitted that the primary judge erred by failing to limit his consideration to the invention as claimed (that is, the form and relative quantities of the active ingredients) and taking into account issues of efficacy and the levamisole release rate which did not form part of the integers of claim 1.  Intervet submitted that the problem to be solved was to create a stable formulation with at least some efficacy, and that these considerations were relevant to the characterisation of the invention that the Cripps question addressed, even though these specific features did not appear in the claims.

The Full Court held that the uncertainty as to the effect of using a particulate form on the levamisole release rate would teach away from the claimed formulation, given some meaningful anti-parasitic effect was an essential feature of the nature of the invention and given the known issue of resistance to the active ingredients when used individually.  This conclusion was not affected by the fact that a specified release rate did not expressly form part of the claims, since a formulation within the scope of the claims nevertheless needed to be safe and efficacious.  Boehringer had not established any error of principle on this point.

Moreover, the Cripps question does not involve an assessment of whether any barrier was overcome, and so Boehringer’s submissions on this point were also rejected.  In coming to this conclusion the Full Court also placed significant weight on secondary considerations, that is the prior unsuccessful attempts by Boehringer to overcome the formulation problem.

The fact that the stability of the formulation could be assessed by routine testing did not of itself make the invention obvious.   The Full Court approved the application of Alphapharm, which distinguished between testing and experimentation required to reach the invention and subsequent routine testing and checking.  Consistent with this, the Full Court held that the evidence had not established that any testing which led to the invention was routine.

Conclusion

The Court concluded it was open to the primary judge to reject the obviousness case.

[1] Proposed in Olin Mathieson Chemical Corporation v Biorex Laboratories Ltd [1970] RPC 157

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