In H Lundbeck A/S v Generics (UK) Ltd and ors [2008] EWCA Civ 311 (10 April 2008), the Court of Appeal handed down an important judgment concerning patent sufficiency. This article reviews the Court’s decision.

BACKGROUND

The patent in dispute (EP (UK) 0 347 066) related to a category of antidepressant generally working as a selective serotonin reuptake inhibitor (SSRI) and was owned by the Danish company H Lundbeck A/S. The drug sold under this patent (called Cipralex) is boasted as being the top selling antidepressant (in terms of volume) in the world.

Before the present patent was filed, Lundbeck had a patent, now expired, for Citalopram, which is also an SSRI. Citalopram is sold in the United Kingdom under the brand name Cipramil; other serotonin inhibitors are fluoxetine (sold as Prozac) and paroxetine (Seroxat). Since the expiry of the Citalopram patent, the drug has been sold by a number of manufacturers in its generic form.

Citalopram is a racemate, consisting of equal numbers of two molecules called enantiomers. In brief, an enantiomer is a molecule that cannot be mapped to its mirror image by rotations and translations alone. The only physical difference between enantiomers is their effect on polarised light, causing rotation of the plane of light either to the left or right. A racemate is an equal mix of left and right-handed enantiomers that has no effect on polarised light. They are conventionally designated (+) and (-). It has been well known for many years that, despite their similarities, two enantiomers may bind to different proteins and produce different biological effects.

An example provided by the Court to illustrate how this works in practice was thalidomide, which consists of a (+) enantiomer, which was effective in preventing morning sickness in pregnant women and, unknown to the consumers, a (-) enantiomer, which was teratogenic and caused severe birth defects. It is now known as one of the best treatments for leprosy.

Separating a racemate into its constituent enantiomers is not a straightforward matter. Because they have the same boiling point, they cannot be separated by conventional means such as fractional distillation or fractional crystallisation. There are indirect methods of coming at the problem and Lundbeck set out to try to find one of them in 1980. This involved a good deal of trial and error and Lundbeck was not successful until 1987.

When they had resolved the racemate, Lundbeck found that the reuptake inhibitory effect was caused entirely by the (+) enantiomer, which is called escitalopram and led to the development of the current antidepressant, Cipralex. In 1989, Lundbeck applied for the patent in suit, EP (UK) 0 347 066, with a priority date of 14 June 1988.

The dispute was commenced by Generics (UK), Arrow Generics and Teva, which market the generic form of citalopram in competition with Lundbeck’s Cipralex. They contended that Lundbeck was simply repatenting its previous invention of citalopram, or the active ingredient in that product, to extend its monopoly for another decade. They claimed revocation of the patent on three grounds:

1. Claims 1 and 3 lack novelty by reason of the disclosure of the racemate in Lundbeck’s patent for citalopram

2. Claims 1, 3 and 6 are invalid for obviousness

3. Claims 1 and 3 are invalid for insufficiency because they claim the enantiomer made by any method, but the specification discloses only two ways of making it

Kitchin J at first instance rejected the first two grounds of attack, but accepted the arguments regarding the lack of sufficiency thereby revoking claims 1 and 3. He upheld claim 6. The parties appealed and cross appealed.

NOVELTY

A patentable invention must be new (Patents Act 1977, Section 1(1)(a)) and an invention is not new if it forms part of the state of the art (Section 2(1)). The state of the art comprises all matter made available to the public before the priority date (Section 2(2)). The claimants relied upon Lundbeck’s U.S. patent for Citalopram as prior art, (U.S. 4,136,193, published 23 January 1979) which disclosed the chemical structure of citalopram and that it was a racemate.

In order to anticipate a patent, the prior art must disclose the claimed invention and (together with common general knowledge) enable the ordinary skilled person to perform it. It is agreed that the prior art did not anticipate the isolated enantiomer. It is settled jurisprudence in the European Patent Office (EPO) that disclosure of a racemate does not in itself amount to disclosure of each of its enantiomers. Therefore, Lord Hoffman was satisfied that the subject patent was novel.

INVENTIVENESS/OBVIOUSNESS

The Claimants’ case at trial was that there were principally two methods or “routes” for resolving the racemate which would have been obvious to a skilled person at the priority date. Diastereomic salts of the amino diol (the last intermediate in the synthesis of citalopram) were resolved it into its enantiomers and then converted into the enantiomers of citalopram by a reaction that preserved their distinctive threedimensional structures. This method was specified in claim 6 of the patent. The specification also disclosed another method which had not been said to be obvious and therefore need not be considered. Kitchin J found that the amino diol route was not obvious.

The judge heard a good deal of evidence on how the skilled person might set about trying to resolve citalopram. The parties agreed that he would initially try to resolve the molecules of the final product. Initially, 13 different possible techniques described in the literature were unearthed at trial and, although Kitchin J found that the skilled person would not have known about all of them, that still left several that he could and might try. In no case was the outcome predictable. Lord Hoffman agreed with Kitchin J that there were “a number of avenues of research” open to the skilled man seeking a solution to the problem and that therefore he would not have taken the diol route unless satisfied there was a “real prospect” that the necessary reaction would work. Experts for the Claimants were not deemed particularly helpful and their evidence was largely rejected. Once their evidence was dismissed, any issue regarding the obviousness of the patent faded away.

SUFFICIENCY

The Court of Appeal then addressed the issue of sufficiency and, in particular, the decision of Biogen v Medeva.

In Biogen v Medeva, the House of Lords considered the sufficiency of a product claim to a DNA molecule that defined the product partly by the way it had been made and partly by its function. The patent claim was held to be a class of products that satisfied the specified conditions, which could have been made by a wide variety of possible processes. The House of Lords held that the law of sufficiency in both the United Kingdom and the EPO, was that a class of products was enabled only if the skilled man could work the invention in respect of ALL members of the class. As the claim under dispute only described one method of making DNA and the patent specification disclosed no general principle, it was insufficient and therefore invalid.

In respect of Lundbeck’s patent for Cipralex, Kitchin J held that claims 1 and 3 were insufficient. His reasoning was that claim 1, being a claim to the (+) enantiomer as a product, was a claim to a monopoly of that product however made. Lundbeck’s inventive idea, however, was not to discover that the enantiomer existed and had a medicinal effect. Everyone knew that the two enantiomers existed and that one or other or both had a medicinal effect. What Lundbeck discovered was one way of making it. But that did not entitle them to a monopoly over every way of making it.

Lord Hoffman was sympathetic with this analysis but could not concur and stated:

“I can understand and sympathise with the judge’s instinctive reaction to the inherent breadth of a product claim… [b]ut in my opinion his reasoning is not justified either by the statute or the authorities. In an ordinary product claim, the product is the invention. It is sufficiently enabled if the specification and common general knowledge enables the skilled person to make it. One method is enough.”

The statutory basis for a claim for revocation on the grounds of insufficiency is Section 72(1)(c):

“[T]he court may revoke a patent [on the ground that] the specification of the patent does not disclose the invention clearly enough and completely enough for it to be performed by a person skilled in the art.”

In order to decide whether the specification is sufficient, it is therefore first necessary to decide what the invention is by reading and construing the claims, in which the inventor identifies what he claims as his invention. Section 60(1) of the Patents Act makes it clear that a claim may be either to a product or a process. In the case of a product claim, performing the invention for the purposes of Section 72(1)(c) means making or otherwise obtaining the product. In the case of a process claim, it means working the process. A product claim is therefore sufficiently enabled if the specification discloses how to make it. There is nothing to say that it must disclose more than one way.

Kitchin J clearly reached his judgment entirely upon the decision of the House of Lords in Biogen v Medeva. Lord Hoffman reviewed the House of Lords decision and ultimately concluded:

“In my opinion, therefore, the decision in Biogen is limited to the form of claim which the House of Lords was there considering and cannot be extended to an ordinary product claim in which the product is not defined by a class of processes of manufacture. It is true that the House in Biogen indorsed the general principle stated by the Board of Appeal in T409/91 Fuel Oils/EXXON [1994] OJ EPO, that ‘the extent of the patent monopoly, as defined by the claims, should correspond to the technical contribution to the art in order for it to be supported or justified’….[w]hen a product claim satisfies the requirements of section 1 of the 1977 Act, the technical contribution to the art is the product and not the process by which it was made, even if that process was the only inventive step.

What the judge has done is to make the requirements for sufficiency under section 72(1)(c) differ according to the nature of the inventive step. If it is to “describe a new and nonobvious compound which has a beneficial effect”, the judge acknowledges … that one way of making it will be sufficient. But the case is otherwise if the inventive step is to find a way of making an obvious compound. In my opinion, however, there is nothing in section 72(1)(c) which connects the requirements of sufficiency to the inventive step. What needs to be disclosed sufficiently to enable it to be performed is the invention as defined in the claim. That remains the same, whatever may have been the inventive step.”

Lastly, Lord Hoffman stated: “Biogen should therefore not be read as casting any doubt upon the proposition that an inventor who finds a way to make a new product is entitled to make a product claim, even if its properties could have been fully specified in advance and the desirability of making it was obvious.”

In a concurring opinion, Lord Justice Jacob agreed that Lundbeck’s appeal should be allowed for the reasons given by Lord Hoffmann. Jacob LJ, however, wanted to provide his own spin on the main points under appeal and in particular on the issue of sufficiency. He stated:

“There is a very short answer to this point [re: sufficiency]. The claim is to the (+) enantiomer. That is novel and nonobvious. If one asks the straightforward question “Does the patent enable the skilled man to make it?” the answer is an equally straightforward: “Yes.” So, in the language of Art 83, the patent discloses ‘the invention in a manner sufficiently clear and complete for it to be carried out.”

COMMENT

It is easy to see why Kitchin J was tempted to follow the Biogen decision straight down the line, especially as this area of law and the subject matter of the Lundbeck patent would not have made it any easier for the judge to see some of the subtleties of the case. He essentially saw one product claim as being very much the same as any other product claim but, that clearly was not the case and was expressly spelled out by Lord Hoffman in his judgment. There have been numerous cases invalidating patents on the grounds of insufficiency—for example, Halliburton Energy Services Inc v Smith International Ltd [2006] EWCA Civ 1715—and this latest decision will undoubtedly attract more scrutiny by patentees on how their “product claims” are drafted. Ordinary product claims will not be affected by the Biogen decision. However, in order to avoid Biogen insufficiency, applicants for products defined by either the process of their manufacture or by their properties must be very aware that sufficiency of the specification will be very much at the heart of the case.