17 November 2005

Pfizer and Eli Lilly Battle over Viagra

Australia's Full Federal Court handed down Pfizer Overseas Pharmaceuticals v Eli Lilly and Company [2005] FCAFC 224 on 31 October 2005.

Background

Pfizer is the registered patentee of Australian Patent no. 676571, entitled "Pyrazolopyrimidinones for the treatment of impotence". The well-known anti-impotence drug, Viagra, is said to be embodied in the patent. Eli Lilly markets the anti-impotence drug, Cialis, in Australia.

On 17 September 2003, Lilly commenced proceedings in the federal court for the revocation of the patent and sought a declaration that the patent was and always had been invalid. The bases upon which invalidity was alleged included:

1. The invention as claimed in claim 10 did not involve an inventive step.
2. The invention as claimed in claim 10 was not fairly based on the matter described in the specification.
3. The specification as claimed in claim 10 was not novel.
4. The invention as claimed in claim 10 was not sufficiently described.
5. The specification did not describe the best method of performing the invention as claimed in claim 10.
6. The grant of the Patent was obtained by false suggestion or misrepresentation.

Pfizer cross-claimed against Lilly, alleging that Cialis infringed the patent.

Heerey J. of the Federal Court found that claim 10 was invalid because it did not involve an inventive step. He also found that claim 10 was not fairly based on matter disclosed in the complete specification. Otherwise, he rejected the further contentions of Lilly. Pfizer appealed.

The Decision

Their honours, French J. and Lindgren J. held that:

1. The invention as claimed in claim 10 did involve an inventive step.
2. The invention as claimed in claim 10 was not fairly based on the matter described in the specification.
3. The invention as claimed in claim 10 was novel.
4. The invention as claimed in claim 10 was sufficiently described.
5. The specification described the best method of performing the invention as claimed in claim 10.
6. The grant of the patent was not obtained by false suggestion.
7. The Lilly product, Cialis, would have infringed claim 10 if that claim were valid.

Her honour, Crennan J. agreed with these except for point 2 relating to fair basing.

It follows that the appeal was dismissed .

Claim 10

The matter hinged on the construction and scope of claim 10, which is worth setting out here:

'A method of orally treating man to cure or prevent erectile dysfunction in man in need of such treatment, which comprises treatment with an orally effective amount of cGMP PDEv inhibitor, or a pharmaceutically acceptable salt thereof, or a pharmaceutical composition containing either entity.'

This claim was the result of an amendment ordered by Heerey J. on Pfizer's application made on 19 September 2003.

Grounds of the Appeal

Pfizer asserted that Heerey J. erred in finding that:

1. In claim 10, in the context of the patent as a whole, the term 'cGMP PDEv inhibitor' does not connote an inhibitor which is selective for PDEv.
2. Claim 10 was not fairly based on the matter described in the specification of the Patent.
3. Claim 10 of the patent was invalid because it was obvious.

Notice of Contention

Lilly asserted that Heerey J:

1. Should have held that claim 10 of the patent was not novel.
2. Should have held that the date for determining whether the best method known to the patentee of performing the invention is described in the specification of the patent is the date of filing of the complete specification.
3. Should have held that the specification of the patent did not describe the best method known to the patentee of performing the invention claimed in claim 10 of the patent at the relevant date.
4. Erred in his findings as to sufficiency in relation to the relevant date for determining sufficiency, the construction of claim 10, and the test applied to determining sufficiency.
5. Should have held that there was false suggestion made by the patentee which materially contributed to the decision to grant the patent.
6. Should have held that the importation or sale of Cialis by the respondents would not infringe claim 10 of the patent because it does not "cure or prevent" male erectile dysfunction within the meaning of claim 10 of the patent.

Matters of Construction

The constructional debate was narrowly focussed on two questions:

1. Whether the 'cGMP PDEv inhibitor' in claim 10 refers only to inhibitors which are selective for PDEv.
2. Whether the term 'cure or prevent' in claim 10 covers a method of treatment which temporarily overcomes the effects of erectile dysfunction.

In connection with point 1, their honours found on a reading of the specification that it was important that administration of a selective inhibitor would not unduly affect the functioning of smooth muscles in organs other than the penis. Minimising the risk of adverse smooth muscle effects in cardiac, respiratory, bowel and retinal tissue was an important purpose of the invention.

Thus, reading claim 10 in a way that is consistent with the terms of the specification to which reference has been made and the state of common general knowledge at the time and with an eye to its utility yielded the narrower construction advanced by Pfizer.

In connection with point 2, Lilly submitted that use of the expression 'cure or prevent' results in claim 10 extending beyond the functionality of Cialis. Cialis, Lilly submitted, treats male impotence on an ad-hoc basis, whereas the word 'cure' connotes that the man no longer has the problem of impotence.

Their honours looked to the definition of impotence in the specification. They held that impotence as defined in the patent and commonly understood, is an inability to 'perform' from time to time when desired. In their opinion, impotence was not only 'cured or prevented' by a once and for all remedy, but also by the maintenance of an ongoing dosing regimen which is directed to the condition's manifestations from time to time.

Fair Basing

Heerey J. held that claim 10 was not fairly based on the specification. This finding found basis in the generality of claim 10 extending to substances outside the group defined as 'compounds of the invention'.

Their honours noted that the specification opening with a statement that the invention related to the use of a particular set of compounds made it clear that the invention related to a particular class of drugs.They also noted that there were repeated references to the use of a compound of Formula (I). Their honours held that claim 10, read as a whole, travelled well beyond the range of compounds which was disclosed in the body of the specification. Thus, they supported Heerey J. in his finding that claim 10 was not fairly based on the specification.

Lack of Inventive Step

By way of background, an invention would lack an inventive step if the invention would have been obvious to a person skilled in the relevant art in the light of the common general knowledge as it existed in Australia before the priority date of the relevant claim.

Their honours cited the well known Minnesota Mining and Manufacturing Co v Beiersdorf (Australia) Ltd (1980) 144 CLR 253 and noted that common general knowledge forms the background knowledge and experience which is available to all in the trade.

Their honours reinforced the position of the High Court that a claimed invention is not obvious if the steps that led to it would have been seen by a person skilled in the art as 'worth while to try' in the light of the common general knowledge at the priority date. Rather, the question is whether the notional research group would, at the relevant date, in all the circumstances, directly be led, as a matter of course, to the invention.

Heerey J, their honours noted, came close to adopting the 'worthwhile to try' approach eschewed by the high court. Furthermore, their honours held that there were too many uncertainties in the evidence of experiments carried out to hold that the person skilled in the art (notional research group) would be led to the invention claimed in claim 10, as a matter of course.

Of interest is the claim by Pfizer that some of the expert witnesses presented by Lilly did not qualify as representative of persons skilled in the art, being from foreign countries. Their honours did not accept this argument and held that that kind of approach would place the fields of pharmacology, medicinal chemistry and urology in Australia in a rather unreal state of isolation from the rest of the world.

Novelty

By way of background, any document that was publicly available before the priority date of the claim would destroy the novelty of that claim. The test in Australia is known as the 'reverse infringement test' as set out in Meyers Taylor Pty Ltd v Vicarr Industries Ltd (1977) 137 CLR 228. Their honours cited the case with approval: '...generally one can ask oneself whether the alleged anticipation would, if the patent were valid, constitute an infringement.'

Citing a number of old British cases (something which is really unnecessary, given our mature source of judicial precedent), their honours noted that if a prior publication is to destroy novelty, it must give a direction, or make a recommendation, or suggestion which will result, if the skilled reader follows it, in the claimed invention.

Their honours had regard to the generality of the discussion in the prior art references cited by Lilly and to the brevity of their references to the use of PDEv inhibitors. They held that it could not be said on any test that the invention as claimed in claim 10 was lacking in novelty.

Sufficiency of Description

Section 40(2)(a) of the Act requires that a complete specification 'describe the invention fully including the best method known to the applicant of performing the invention'.

Their honours noted that the complete specification is the whole document and includes the claims. Thus, the claims can dispel any uncertainty or ambiguity in the description.

The accepted test formulated by the High Court for sufficiency 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?' ( Kimberly-Clark Australia Pty Ltd v Arico Trading International Pty Ltd (2001) 207 CLR 1 )

Furthermore, in Lockwood Security Products Pty Ltd v Doric Products Pty Ltd (2004) 212 ALR 1 it was held that it is enough that the disclosure enables the addressee 'to produce something within each claim without new inventions or additions or prolonged study of matters presenting additional difficulty.'

It was not disputed that a range of tests would have to be performed before any compound was administered to a human to determine whether it was efficacious. Lilly therefore submitted that a considerable investment in time and resources were required before any compound could be tested. By forcing the selection of compound, Lilly held that the 'initial difficulty' of Kimberly-Clark was presented.

Heerey J. had held, as a question of fact, that patents incorporated by reference into the patent contained sufficient instructions.He found that there were a number of specifically identified compounds which could be tested and screened by a skilled addressee. This was not challenged by Lilly. Relying on this, their honours held that there was more than adequate basis for Heerey J to decide that the complete specification was sufficient.

Best Method

As set out above, section 40(2)(a) sets out that the complete specification must describe the best method known to the applicant of performing the invention.

The active ingredient of Viagra is sildenafil monocitrate. This was added to the specification as a result of an amendment subsequent to filing the original international patent application.

Lilly submitted that the 'best method' must be included in the complete specification at the 'filing date' and no later. Pfizer submitted that the date for compliance with the 'best method' requirement is either the date of grant of the patent or the date of commencement of legal proceedings.

Heerey J. held that the date is the date of grant. In support of this, he considered the definition of 'complete specification' as set out in Schedule I of the Patents Act: 'Complete specification means...a specification filed in respect of a complete patent application or, if the specification has been amended, the complete specification as amended'. He saw no reason why the definition did not apply to section 40(2)(a) (supra).

Their honours emphasized that it is indeed the case that the disclosure of the best method must be made in the specification as filed. However, they held that one has to look at the Act's regime for providing for amendment of a complete specification, coupled with the definition of a complete specification. In the examination process, in opposition proceedings and in revocation proceedings it is the specification as amended that must be regarded in order to determine compliance with section 40(2)(a). Furthermore, section 104(1) entitles a patentee to request an amendment of the complete specification for the purpose of removing a lawful ground of objection to it. If the best method is not described, there is a lawful ground of objection. It follows that their honours supported Heerey J.

False Suggestion

Lilly's case for false suggestion depended upon a statement in which it was asserted that patient studies had confirmed that one of the especially preferred compounds induced penile erection in males. Lilly submitted that this assertion was calculated to give the false impression that one of the specified compounds identified earlier has been tested and worked. Lilly held that that the assertion was referring to a salt and not to one of the free amines as described in the specification.

Heerey J. held that a person of ordinary skill in the art would not draw a distinction between a compound in its freebase form and the same compound in its salt form. He based this on the evidence of one of the expert witnesses.

Their honours supported Heerey J. when considering cross-examination evidence of one of the witnesses.

Conclusion

In summary, Pfizer succeeded in demonstrating error on the part of Heerey J. regarding his finding of lack of inventive step. However it did not succeed in its challenge to the lack of fair basis finding concerning claim 10.

Bazpat has raised the issue of fair basis in previous posts. This case again emphasizes the need for practitioners always to ensure as close a correlation as possible between the claims and the specification. Also for those considering inventive step, this case indicates the difficulties associated with proving the deficiency of that quality.

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