In the recent decision of Apotex Pty Ltd v Warner-Lambert Company LLC (No 2) [2016] FCA 1238, the Federal Court has upheld the validity of Pfizer's patent covering its pain relief drug LYRICA® (pregabalin).

The patent survived attacks on the grounds of false suggestion, utility, and sufficiency. A different result was reached in the corresponding case in the UK – and may have been reached in Australia under the recently introduced "Raising the Bar" reforms (which did not apply to Pfizer's patent). The decision provides guidance as to the application of the principles on the law of sufficiency of description, false suggestion and utility in respect of method of treatment claims.

Pfizer's method of treatment patent

The Federal Court has upheld Australian Standard Patent 714,980, registered in the name of Warner-Lambert Company LLC, which claims a method for treating pain comprising administering a "therapeutically effective" amount of the compound pregabalin (the compound) (marketed by Pfizer under the name LYRICA®) or a pharmaceutically acceptable salt, diastereomer or enantiomer thereof (the patent). Additionally, it was found that generic pharmaceutical companies Apotex and Generic Partners had threatened to infringe the patent.

The description of the invention in the body of the patent contained various examples of the compound being used to treat rats, but no examples or illustration of the use of the compound to treat humans. The patent did not provide detailed guidance as to the amount of the compound to be administered to a human patient, instead simply explaining that the quantity of active compound in a dose may be varied or adjusted from 1 mg to about 300 mg/kg daily (preferably 1mg to 50mg/kg), based on an average 70-kg patient. It was argued that a skilled reader would understand, from the reference to an average 70kg patient, that the dosage range was referable to the treatment of human patients.

The invention: a compound for the treatment of pain

The patent directed that the compound was suitable for treating various types of pain including "neuropathic pain". Neuropathic pain as a category can be further divided into two sub-types - peripheral neuropathic pain, which arises from damage to the primary sensory neurons, and central neuropathic pain, which arises from nerve damage in the spinal cord or brain.

The patent contained a false suggestion, but it was not material

Broadly speaking, a patent is obtained by fraud, false suggestion or misrepresentation1 if it is established that the false suggestion or misrepresentation was a material factor that caused or contributed to the grant of the patent.

Apotex alleged that Pfizer had obtained the patent by the false suggestion or misrepresentation (by implication) that a particular form of the compound had been tested for the treatment of pain as described and claimed in the patent.

On the Court's reading of the patent, it was held that the patent did in fact convey a false suggestion, but that this suggestion was not central to the claimed invention and therefore did not materially contribute to the grant of the patent.

Pfizer's invention was "useful"

Apotex also alleged that the invention was not useful.2

For an invention to be "useful" within the meaning of the Australian Patents Act, it does not need to be useful or desirable in a commercial sense (in the absence of any promise to that effect).

Rather, the question is whether, as a consequence of following the specification, the result claimed is produced.3 In addition, a patent can be useful even if a promised advantage cannot be achieved in all cases or to the same degree in every instance of use.4

The allegations made by Apotex regarding inutility involved two contentions:

  1. The compound was not useful because it was not effective in the treatment of pain that did not involve neuropathic pain or central sensitization (the latter being an important mechanism leading to central neuropathic pain as well as other types of pain); and
  2. all claims which encompassed a certain form of the compound (known as the R-enantiomer) were invalid because that form was "inactive" or "practically inactive" and not useful as a treatment for any type of pain.

With respect to Apotex's first allegation, Nicholas J found that although it was clinically undesirable to use the compound for the treatment of pain not involving a "clinically relevant" amount of central sensitization5, Apotex failed to establish that the therapeutic effect would be non-existent.

On the second allegation, his Honour was not persuaded that the R-enantiomer was not useful as a treatment for any type of pain as, although it was considerably less active than the compound, evidence was presented that this form would be effective if administered in high doses, and that the dosage range provided in the patent contemplated that the dosage may be varied depending on the compound being employed.

The patent taught clinicians how to treat patients without the need for further invention

Sufficiency in australia

The requirement of sufficiency is that the specification "fully describes" the invention. The leading test for sufficiency was propounded by the High Court in Kimberly-Clark Australia Pty Ltd v Arico Trading International Pty Ltd (2001) 207 CLR 1 (Kimberly-Clark):

The question is – will the disclosure enable the addressee of the specification to produce something within each claim without new inventions or additions or prolonged study of matters presenting initial difficulty?

The parties' submissions

  • Apotex asserted that:
    • enablement in relation to rats was not sufficient, given the patent was primarily directed to the treatment of pain in humans; and
    • the patent did not enable a skilled addressee to treat humans without undue burden (e.g. completing clinical trials to ascertain a safe and effective dosage range amongst the largewithin the broad range specified in the patent).
  • Pfizer submitted that the requirements of sufficiency would be met if the patent provided sufficient information to enable the skilled addressee to perform the invention in relation to rats (as a type of mammal).
  • In the alternative, Pfizer submitted that if the patent needed to enable human treatment, a skilled addressee could do so without undue burden.

With respect to Apotex's first argument, Nicholas J said that, whilst it was clear that the claim was expressly directed to the treatment of pain in mammals generally, it would:

  • be a nonsense to say that the invention was sufficiently described if it enabled the skilled addressee to perform the method of the invention on rats (or other mammals) but did not enable it to be performed on humans.

In reaching this conclusion, his Honour distanced himself from Kimberly Clark, saying that the High Court's reasons in that case are not to be construed as if they were statute and could not be sensibly applied in the case before him.

Whilst Apotex's first sufficiency argument was successful, its second was not – Nicholas J accepted that the patent provided sufficient information for a skilled addressee to perform the invention in humans.

In reaching this conclusion, His Honour relevantly explained that:

The description of the invention will not be insufficient merely because the skilled addressee is expected to apply considerable skill, effort and resources to make it work. If 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.

Sufficiency: Australia v the UK

The test for sufficiency in the UK differs from the "pre-Raising the Bar"6 sufficiency law in Australia (that applied to the corresponding Australian Patent referred to above) in that it requires a skilled person to be able to perform the invention across the full scope, rather than merely enable "something"7 within the claim.

By the Raising the Bar amendments (applicable for patent applications where examination was requested after 15 April 2013), Australia’s test for sufficiency is now harmonised with the test in the UK for patent applications where examination was requested after 15 April 2013. As we have reported previously, the explanatory memorandum makes it clear the new provision is intended to be interpreted in a similar manner to the corresponding United Kingdom provision, so this case provides useful guidance as to how you can expect the law to apply here.

Sufficiency in the UK

Sufficiency of description similarly formed part of the attack on the validity of the patent covering the same compound in the UK.8

Claim 1 of the UK patent was a Swiss style claim in the following terms:

Use of pregabalin or a pharmaceutically acceptable salt thereof for the preparation of a pharmaceutical composition for treating pain.

Claim 3 was to the use according to claim 1, where the pain is neuropathic pain.

Given that claim 3 of the UK patent was drafted broadly to cover neuropathic pain, the skilled addressee needed to be given enough information to relieve any pain which fell within this category (that is, both central and peripheral neuropathic pain) in order to satisfy the sufficiency test.

However, the specification was described by Floyd J as justifying only a claim to the treatment of peripheral neuropathic pain - as there was no data in the patent from which a prediction about the efficacy of the drug for treating central neuropathic pain could be made. Consequently, the claims were not enabled across their scope as the specification did not cover all types of neuropathic pain. The patent was held to be invalid for lack of sufficiency.

Infringement

Apotex contended that there had been no threatened infringement of the Swiss style claims9 of the patent as the medicine had been physically produced outside of Australia. However, Nicholas J found that the relevant act of infringement was the exploitation of the medicine in Australia (by importation and sale), not the use of the method outside the patent area, and this view was in-line with a previous decision of the Federal Court.10

Key lessons for patentees

  • The test for sufficiency proposed by Nicholas J for method of treatment claims embodies a "substance over form" approach which pays close attention to whether the patentee has given proper consideration to the public in exchange for the monopoly conferred by the patent.
  • Other recent Australian decisions11 have similarly shown a preference towards a substance-orientated approach, introducing some uncertainty for patentees (and patent challengers) as to the level of disclosure required to support a valid patent in Australia. Although little guidance has been provided, it appears that the requisite level of disclosure will largely be dependent upon the proper identity of the claimed invention and the common general knowledge of the relevant skilled addressee.
  • The corresponding UK decision provides an illustration of how Australian courts may assess the sufficiency of disclosure of method of treatment claims under the Raising the Bar reforms.