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Clearing the way: the tests for obviousness and insufficiency clarified

20 May 2016

A recent High Court decision explains the tests for obviousness and insufficiency resulting from a “clearing the way” action brought by Actavis against Eli Lilly (Lilly).  Actavis intended to invalidate Lilly’s patent on the basis of a lack of inventive step and insufficiency. Lilly’s patent relates to the second medical use of atomoxetine in the treatment of ADHD, and was the subject of a Supplementary Protection Certificate (SPC) due to expire May 2019. Actavis admitted they had brought the action primarily to “clear the way” before marketing their generic atomoxetine product. In response, Lilly brought a counterclaim for threatened infringement.

At the priority date, the leading treatments for ADHD were central nervous stimulants, such as Ritalin. It was accepted that approximately 25% of patients were non-responders and were treated with tricyclics, known to be noradrenaline re-uptake inhibitors, more commonly used to treat depression but with varied side effects including sudden death. Actavis argued there was a strong motivation to develop alternative treatments at the priority date, whereas Lilly maintained there was a long felt want for alternatives which existed long before the priority date.

Inventive step was attacked on the basis of three prior art documents. Two of the documents reported clinical trials in depressed patients and the other reported a rodent in vivo study. All established atomoxetine as a noradrenaline re-uptake inhibitor.

The judge, Mr Justice Carr, begins the assessment of inventive step with the question “what must be obvious?”, and states that the ‘claimed invention’ must be assessed, not the ‘invention’ as defined by the data in the specification, following Conor v Angiotech where Lord Hoffman stated that “…the invention is the product specified in the claim and the patentee is entitled to have the question of obviousness determined by reference to his claim and not to some vague paraphrase based upon the extent of his disclosure in the description”.

Carr J concluded that atomoxetine was not obvious to use to treat ADHD in light of any of the prior art documents.

Carr J went on to state that even if it was obvious at the priority date to try atomoxetine for the treatment of ADHD, the skilled team would not have had a fair expectation that the drug would be effective, due to the small number of patients, lack of placebo control and the emphasis on treating depression. The skilled clinician would have considered that tricyclics may be effective in treating ADHD due to the mechanism of action, however, the pathology of ADHD was complex which created a background of uncertainty.

Carr J stated that for the purpose of obviousness, the skilled person should be able to make a fair prediction that the alleged invention will succeed.  The question arose as to whether this methodology should also be applied to sufficiency and plausibility.

Actavis argued that the tests are the same, and should be balanced alongside one another.  Lilly disagreed, and stated that plausibility issues only arise when an unduly broad claim scope is contended. In his findings, Carr J emphasised that plausibility is only a threshold test, used to exclude speculative patents based on mere assertion. Carr J concluded that “the standard for assessment of plausibility is not the same as the standard for assessment of expectation of success in the context of obviousness”.

Carr J stated that the specification discloses for the first time that atomoxetine can be used to treat ADHD, and that at the priority date the skilled clinician would recognise that a selective noradrenaline re-uptake inhibitor would reduce side effects. Along with post-published data demonstrating successful administration of atomoxetine, Carr J concluded that the patent was both credible and plausible.

Accordingly, Actavis’ attack on inventive step and insufficiency failed and Lilly successfully counterclaimed for threatened infringement.

In light of this judgement, the ‘squeeze’ between obviousness and insufficiency may be a less preferable option when looking to litigate in the UK pharmaceutical field in future.

 

Katherine Banks
Life Sciences & Chemistry Group

If you require further information on anything covered in this briefing, please contact Katherine Banks (kbanks@withersrogers.com; +44 1926 310700) or your usual contact at the firm.

This publication is a general summary of the law. It should not replace legal advice tailored to your specific circumstances.

© Withers & Rogers LLP, May 2016