20 July, 2012

 

Sigma Pharmaceuticals (Australia) Pty Ltd v Wyeth [2011] FCAFC 132

 

In brief

 

  • Sigma, Alphapharm and Generic Health sought revocation of Wyeth’s patent for an extended release formulation of venlafaxine hydrochloride on the basis that the patent was invalid on a number of grounds. Wyeth cross-claimed alleging that the generics' use of their own extended release formulations of venlafaxine hydrochloride infringed certain claims of its patent.
  • At trial, Jagot J dismissed the applicants' claim for revocation of Wyeth's patent and granted relief on Wyeth's cross-claim for alleged infringement.
  • The Full Court of the Federal Court overturned Jagot J's decision and held that the key claims of Wyeth's patent were invalid because as a result of amendments made during prosecution, they were not fairly based on the priority document or the patent specification, and were thus not novel by reason of a deferred priority date.

 

An update in 1 December 2010 edition of Life Sciences Update reported on the Federal Court decision in Sigma Pharmaceuticals (Australia) Pty Ltd v Wyeth [2010] FCA 1211 which concerned the validity and alleged infringement of Wyeth's Australian Patent No. 2003259586, granted on 11 May 2007, entitled "Extended Release Formulation" (the "Patent") of the compound venlafaxine hydrochloride.

 

In 1999 Wyeth released its extended release dosage form of venlafaxine hydrochloride in Australia, known as Efexor-XR, an anti-depressant. Sigma, Alphapharm and Generic Health obtained registration of extended release formulations of venlafaxine hydrochloride on the Australian Register of Therapeutic Goods, known as Evelexa XR, Enlafax-XR and generichealth XR respectively. The generic companies challenged the validity of the patent on various grounds, including, among others, lack of novelty by reason of deferred priority date and lack of fair basis. Wyeth contended that the applicants' use of their extended release formulations in Australia infringed certain claims of the patent.

 

Wyeth claimed the earliest priority date for the Patent as 25 March 1996, based on US Patent Application No 60/014,006 (the priority document), which is a divisional of the parent application (Australian Patent Application No 65442/00) which is in turn a divisional of a grandparent (Australian Patent Application No 16400/97). Wyeth made substantial amendments to the specification and claims on and after December 2006, after the complete specification was filed and before acceptance.

 

Trial decision

 

At trial, Jagot J dismissed the applicants' claim for revocation of the Patent and granted Wyeth's cross-claim for infringement. In reaching this decision, Jagot J concluded that the priority document disclosed two inventions:

 

  • "an encapsulated formulation"; and
  • "a method for obtaining a certain drug to plasma relationship over time yielding a 'tighter plasma therapeutic control' than multiple daily dosing", eliminating the sharp peaks and troughs in blood plasma level induced by multiple daily dosing and thereby reducing the level of nausea and the incidence of emesis that attended multiple daily dosing.

 

In addition, Jagot J held that when the priority document is read as a whole, the method disclosed was not confined to the particular encapsulated formulations disclosed and that the references in the priority document to the inventor’s failed attempt to prepare an extended release formulation using hydrogel tablet technology did not eliminate the independent disclosure of a method of treatment. Based on this construction of the priority document, Jagot J held that the claims of the amended patent were fairly based on the priority document and, therefore, entitled to the 25 March 1996 priority date.

 

Appeal

 

On appeal, the Full Court (Bennett, Nicholas and Yates JJ) overturned Jagot J's findings as to infringement and invalidity. Although each of the judges delivered separate judgments, all were in agreement that the key claims of the Patent were invalid because they were not fairly based on the priority document or the patent specification. As a result, the priority date of the claims of the amended Patent was shifted from 1996 to 2006 and was, therefore, anticipated by Wyeth's own products released in 1999.

 

The invention as described and claimed in the priority document

 

As a result of the 2006 amendments, there had been substantial changes to the body of the specification, which, importantly, included a deletion of the reference to a particular extended release formulation that provided a therapeutic blood serum level over a 24 hour period, and the addition of statements that the invention was no longer simply the formulation described, which was but one example of a broader invention.

 

The appellants challenged Jagot J's finding that the priority document disclosed two inventions and submitted that the only invention disclosed in the priority document was the encapsulated formulation described. The appellants submitted that the formulation was central to the operation of the method and that the "method" was merely a description of the result of administering a single daily dose of venlafaxine hydrochloride. Wyeth submitted that it had developed a new method of treatment which depended upon the parameters of the blood plasma profile achieved, which was not specific to any particular formulation.

 

The Full Court agreed with the appellants' submissions and held that the patent specification only disclosed an encapsulated formulation that obtained a certain drug to plasma relationship over time, with the methods of treatment described being confined to those which make use of that formulation and was at all times linked to the nature of that formulation. As Bennett J explained, "the formulation achieved is central to the invention and it is the administration of the formulation that achieves the results as set out in the method. The method is dependent on the formulation. It is not a separate and independent invention". Importantly, the Full Court held that the invention was not the discovery of a new method with any formulation, rather, the method disclosed is the use of the invention which is an extended release formulation.

 

 

Claims in the priority document lacked fair basis

 

Another issue before the Full Court on appeal was whether the priority document included a method for using any extended release formulation, included hydrogel tablets. Wyeth pointed to two independent claims in the priority document which, standing alone, pointed to a method unrestricted in formulation, other than a requirement that it be an encapsulated extended release formulation containing venlafaxine hydrochloride as the active ingredient.

 

The Full Court held that properly construed, it simply could not be said that these independent claims encompassed a method for using any extended release formulation, including those produced by hydrogel tablet technology. The body of the patent specification explicitly stated that the need for a different extended release formulation of venlafaxine hydrochloride existed because numerous attempts to produce extended release tablets by known and existing hydrogel technology proved to be "fruitless". The solution to an extended release formulation was to therefore use a different kind of formulation altogether; a spheroid formulation. In light of this, and the fact that the basis proffered for the invention was the impossibility of creating the extended release formulation using hydrogel tablet technology, the Full Court held that read as a whole and in context, the formulation was not unlimited. On this basis in the Full Court's view, it simply could not be said that the priority document disclosed an inventive step that extended to or included hydrogel tablet technology or formulations.

 

The Full Court thus held that a construction of these claims as encompassing any extended release formulation of venlafaxine hydrochloride would result in these claims not being fairly based on the specification of the priority document. A skilled reader reading the whole of the priority document would, therefore, understand that these independent claims were referring to use of an encapsulated extended release formulation and were thereby so limited. This further reinforced the Full Court's finding that Jagot J had erred in concluding that the priority document disclosed two inventions, as it established that the method was thus formulation-dependent and referable only to Wyeth's particular extended release spheroid formulation of venlafaxine hydrochloride.

 

Lack of external fair basis

 

Based on her Honour's conclusions that the priority document disclosed two inventions, Jagot J at first instance had found that the subject matter of the relevant claims of the amended Patent were disclosed in the priority document. On appeal, the appellants argued that the relevant claims of the amended patent claimed matter that was in substance disclosed as a result of the 2006 amendments and that as a result, the priority date of the claims should be deferred to the date of filing of the statement of amendments, which was December 2006.

 

The Full Court held that the test for "in substance disclosed" for external basis under section 114 of the Act is essentially the same as that for fair basis under section 40(3) of the Act. Therefore, the issue fell to be determined in accordance with the principles set out in Lockwood Security Products Pty Ltd v Doric Products Pty Ltd (2004) 217 CLR 274. The question was whether, as a matter of drafting, the claims as appearing in the amended Patent could be said to reflect what was in substance disclosed or stated in the body of the specification of the priority document. Based on their findings as to the invention as disclosed in the priority document, their Honours held that the claims of the amended patent were wider than the invention there disclosed, most importantly because they claimed a method unrestricted to the formulation described, and which included administration of a formulation utilising hydrogel technology. This travelled beyond the disclosure of the priority document, because the priority document excluded a formulation based on hydrogel tablet technology. The claims of the amended patent were, therefore, not fairly based, lacked novelty and were thus liable to be revoked.

 

Lack of internal fair basis

 

Jagot J's characterisation of the invention of the amended patent, as including a method for obtaining a certain drug to plasma relationship over time yielding a tighter plasma therapeutic control, led her Honour to conclude that the relevant claims of the amended patent were fairly based on the description of the invention in the amended patent specification. Having reached this conclusion, her Honour rejected the applicants' contention that consistory style statements in the specification were broader than the disclosure.

 

On appeal, the Full Court cited the "real and reasonably clear disclosure" test as laid down by the High Court in Lockwood (No 1), which established that fair basis requires a real and reasonably clear disclosure in the body of the specification of what is claimed. In Lockwood, the High Court also explained that if there are other matters disclosed in the specification which show that the invention is narrower than the consistory clause suggests, it will not be possible to rely upon such consistory clauses alone as providing fair basis for a claim. On appeal, their Honours held that because the specification contained what was tantamount to a disclaimer of hydrogel tablet technology, each of the relevant claims was too broad and not fairly based upon matter described in the specification.

 

Subsidiary issues

 

Having reached the conclusion that the relevant claims of the patent were invalid for lack of novelty, and lack of fair basis, the Full Court otherwise upheld some of Jagot J's conclusions at first instance with regard to sufficiency of description, false suggestion, clarity, and entitlement.

 

Application for special leave to appeal

 

Wyeth's application to the High Court of Australia for special leave to appeal the Full Court's judgment was refused on 11 May 2012. The High Court was not satisfied that any question of principle in relation to fair basis was presented by the application.

 

Lessons

 

  • This case illustrates the manner in which the Full Court will approach extensive amendments in the prosecution of divisional applications.
  • Patentees cannot set forth one basis for, and description of, an invention and then change the basis, characterisation and description of the invention while seeking to retain the same priority date.
  • The Full Court has reaffirmed that questions of priority and fair basis under Australian law require a real and reasonably clear disclosure of what is claimed in the body of the specification, and that this requires a comparison of the invention as claimed with the invention as disclosed.

 

 

For further information, please contact:
 
Ben Miller, Partner, Ashurst 
ben.miller@ashurst.com
 
Jessie Buchan, Ashurst 
jessie.buchan@ashurst.com
 

 

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