Scintilla – a flash, a spark, an iota. Shorthand for creativity and an indicator of inventiveness under Australian law.






Thursday, December 8, 2016

Pregabalin Patent Powers Through

By Lev Gutkin, Lawyer

Pfizer's drug Lyrica (pregabalin) is usually used to treat neuropathic pain, but is no doubt the cause of plenty of headaches for Apotex and Generic Partners, after Nicholas J dismissed their invalidity attack against patent no. 714980 and held that their conduct amounted to threatened infringement.

The patent is in respect of the use of pregabalin, the (S)-enantiomer of 3-aminomethyl-5-methylhexanoic acid (the 3-amino compound), a known anti-seizure drug, for the treatment of pain. Apotex claimed the patent was invalid on the grounds of insufficiency, inutility, false suggestion and because the patentee, Warner-Lambert, was not entitled to the patent.* Other than in relation to the entitlement issue, the pre-Raising-The-Bar provisions of the Patents Act 1990 (Cth) applied.

False Suggestion


The false suggestion attack was based on a number of statements in the patent specification, which Apotex claimed together conveyed the meaning that the racemate of the 3-amino compound had been tested for the treatment of pain in the manner described in the patent. Pfizer agreed that if this meaning was conveyed, it was not true. Justice Nicholas accepted that a false meaning was conveyed, but then said 'it does not follow that this false suggestion materially contributed to the Commissioner’s decision to grant the Patent'. As the link between the false meaning conveyed and the decision to grant being made was not evident, the ground of false suggestion was not established. This decision helpfully confirms that merely pointing to errors (or ambiguities open to erroneous interpretation) in the patent specification will not be enough to make out false suggestion, unless perhaps they go to the heart of the invention, for example where the erroneous statements affect whether the invention is novel or non-obvious.

Utility


Apotex argued that pregabalin was not useful for the treatment of all pain types, for example those not involving 'neuropathic pain or central sensitisation', and so the patent failed for inutility. Justice Nicholas noted that the patent did not contain a promise as to the degree to which the claimed method of treatment will relieve pain, so all that was required for the purposes of utility was that the claimed method of treatment was 'capable of providing some measure of pain relief to a substantial number of patients in need of treatment for pain'. Although it was accepted that pregabalin would provide limited benefit to the pain experienced in certain conditions, such as acute gout, Nicholas J considered that it had not been shown that pregabalin would provide no benefit at all in comparison to a placebo treatment, and so the patent did not fail for inutility. This was because Nicholas J considered that the process of central sensitisation, which pregabalin modulates, played a part in all pain conditions, albeit it may play a relatively minor role in some. Just because in practice pregabalin would not be used to treat particular pain conditions, as other treatments could be used to resolve them, did not mean pregabalin was not useful for the treatment of pain. Utility does not require that the claimed treatment be the gold standard, only that it produce the promised effect to some extent.

Apotex similarly argued that most of the claims of the patent covered the (R)-enantiomer of the 3-amino compound, which would be less effective in the treatment of pain than the racemate or (S)-enantiomer, but Nicholas J held that this did not mean that the '(R)-enantiomer is not useful in the relevant sense'.

Sufficiency 


The patent specification contained data showing the effectiveness of pregabalin in rat studies, but not data separately showing information on human studies. Referring to the test for sufficiency outlined in Kimberly-Clark Australia Pty Ltd v Arico Trading International Pty Ltd, Pfizer sought to argue that it was only required that the skilled addressee be able to produce something within each claim, so the ground of sufficiency would be satisfied if the skilled addressee could use the data provided to treat rats; even if treatment of humans was not enabled. Justice Nicholas did not accept this argument, noting that the claims of the patent were primarily directed to the treatment of humans, and outlining that the Kimberley-Clark test for sufficiency was not appropriate for the assessment of every type of patent claim.

Apotex sought to argue that the patent failed for insufficiency as there was no information on specific dosage regimes, solubility, bioavailability or safety for use in humans. However Nicholas J stated that '[i]f the steps required to be taken to work the invention are readily apparent to the notional skilled addressee, and they are standard or routine steps within the competence of the notional skilled addressee, then the test for sufficiency will be satisfied.' Although it was recognised that the process for proving the safety and efficacy of pregabalin, and obtaining regulatory approval for its use, would be arduous, involving 'complex, time consuming, and expensive work', Nicholas J stated 'that does not mean that the steps involved are not routine for the notional skilled team'. As there was no evidence that the required further testing would present challenges beyond the competence of the 'notional skilled team', the attack on the ground of insufficiency failed.

These findings can be contrasted with the English first instance and appeal decisions on the corresponding UK patent, where a number of claims were found invalid for lack of sufficiency, on the basis that the data provided in the specification was inadequate to make it 'plausible' that pregabalin could be used for the treatment of central neuropathic pain. Australian filers should be mindful that Nicholas J was applying the pre-Raising-The-Bar test for sufficiency and the position may be different for new filings.

The post-Raising-The-Bar provisions require more experimental data to be included in the specification. The Patent Examiners Manual now states: 'where the treatment of a number of different medical conditions is claimed, the description should demonstrate by relevant in vivo or in vitro tests that the specified compounds are indeed effective against each of the claimed conditions'.

Soothing Sore Nerves


This decision is a welcome finding for patentees, given there have been a number of recent decisions finding patents invalid on grounds that are not grounds for revocation in other major filing jurisdictions, as discussed in our previous post. As this judgment by Nicholas J exemplifies, minor inadvertent errors, or mistakes in the drafting of a specification, should not alone invalidate patents for inventions that are clearly novel, non-obvious, and are of undisputable commercial value.


Note: Allens acted for Warner-Lambert in the case. 
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* Generic Partners relied on the same grounds in a similar proceeding. The proceedings were heard together. 

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