EU & Competition news

Date:    10 April 2008

Court:   Court of Appeal - England

Background

Escitalopram is an antidepressant of the selective serotonin reuptake inhibitor class. Escitalopram is marketed under the brand name Cipralex by the Danish pharmaceutical company, H. Lundbeck A/S ('Lundbeck'), who successfully found a way to isolate the drug, the (+) enantiomer, from its racemate citalopram.  

Three manufacturers of generic citalopram challenged European Patent (UK) No. 0347066 (the 'Patent') in relation to escitalopram on the grounds of lack of novelty, obviousness and insufficiency. In May 2007, Mr Justice Kitchin in the UK Patents Court rejected the novelty and obviousness challenges, but held that the Patent was invalid for insufficiency, on the basis that the claims of the invention extended beyond its technical teaching. The generic companies appealed against the decisions of Kitchin J regarding novelty and obviousness and Lundbeck appealed against Kitchin J's finding of insufficiency.

On 10 April 2008, the Court of Appeal, in a leading judgment given by Lord Hoffman, (who, was sitting quite unusually, as a Court of Appeal judge) dismissed the appeals of the generic companies but allowed Lundbeck's appeal. In doing so, the Court of Appeal reversed the High Court's finding of invalidity and clarified the principles surrounding insufficiency.

Novelty

The novelty challenge was based on the prior art of Lundbeck's earlier US patent No. 4,136,193 ('193'), which discloses a racemate of the ( + ) and ( - ) enantiomers of citalopram. Claims 1 and 3 of the Patent, entitled “new enantiomers and their isolation”, were directed to the ( + ) enantiomer and salts thereof, and to pharmaceutical compositions comprising the ( + ) enantiomer. The generic companies alleged that claims 1 and 3 not only covered the isolated ( + ) enantiomer, but also the ( + ) enantiomer as an unresolved part of the racemate, and were therefore anticipated by patent 193. 

The Court of Appeal held that Kitchin J was correct to conclude that the context would have made it obvious to the skilled person that the patentee was laying claim to the individual ( + ) enantiomer, and not the ( + ) enantiomer when in the form of the racemate. The claims were therefore not anticipated by the prior art and were considered to be novel.

Obviousness

The generic companies appealed against Kitchin J's finding that the synthetic method for resolving the racemate was not obvious. This method, described in claim 6 of the Patent, involved resolving an intermediate chiral product to produce its enantiomers, from which the pure enantiomers of citalopram could be made. The chiral intermediate had previously been disclosed in Lundbeck's US patent No. 4,650,884 ('884').   However, patent 884 did not disclose how to separate the enantiomers or how one might convert those enantiomers into the pure enantiomers of citalopram.  On the contrary, patent 884 was for a better method of making the racemate. 

Kitchin J found that the reactions necessary in order to convert the chiral intermediate disclosed in patent 884 into the pure enantiomers of citalopram would not have been obvious to the skilled person. Kitchin J also considered that there were a number of avenues of research open to the skilled person seeking a solution to the problem of how to resolve the racemate into its enantiomers, and in no case was the outcome predictable.    Accordingly, Kitchin J concluded that the method described in the claims was not obvious and therefore inventive. 

An appellate court in the UK will not ordinarily reverse a trial judge’s finding on obviousness unless he has made an error of principle. The Court of Appeal concluded that Kitchin J had identified the correct principle with regard to obviousness, namely that it must be considered on the facts of each case, including such matters as the motive to find a solution to the problem the patent addresses, the number and extent of the possible avenues of research, the effort involved in pursuing them and the expectation of success. Kitchin J had then proceeded to apply this principle correctly to the facts of the case.  

Sufficiency

The generic companies alleged that claims 1 and 3 of the Patent were invalid for insufficiency because they claim the ( + ) enantiomer however obtained, but the specification discloses only two ways of making it. It was argued that citalopram was an obvious target for resolution and that Lundbeck's inventive idea was not to discover that the enantiomer existed but to discover how it could be made. This did not entitle Lundbeck to a monopoly over every way of making it. 

Kitchin J agreed and, following the arguments in Biogen v Medeva in the House of Lords, concluded that the claims were so broad that they covered methods for resolving citalopram that were not disclosed in the Patent and were therefore, insufficient and invalid. 

The Court of Appeal found that Kitchin J had erred in his reasoning and in his application of Biogen. Biogen concerned a product claim to a DNA molecule which was defined partly by the way it had been made and partly by what it did. It was a hybrid "product-by-process" claim. As a matter of construction, the House of Lords interpreted the claim as being to a class of products which satisfied the specified conditions. In both the UK and in the European Patent Office ('EPO'), the law of sufficiency requires that a class of products is enabled only if the skilled person can work the invention in respect of all members of the class. In Biogen, the inventor had only disclosed one method of making the DNA molecule. 

Lord Hoffman in the Court of Appeal stated that:

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 was true that the House of Lords in Biogen endorsed the principle stated by the EPO Board of Appeal in T409/91, Fuel oils/EXXON 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.  However, Kitchin J had wrongly treated the relevant "technical contribution to the art" as being the process of making the product, rather than the product itself. Lord Hoffman stated that where a product claim is novel, inventive, capable of industrial application and not in an excluded class, 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.

The Court of Appeal concluded that the Patent was an ordinary product claim, and the product was the invention.  An ordinary product claim is sufficiently enabled if the Patent and common general knowledge enables the skilled person to make it, even if only one method is disclosed.   

Comment

The Court of Appeal have clarified the application of so-called 'Biogen' type insufficiency, emphasising that it should 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 specified in advance and the desirability of making it was obvious. 

It is interesting to note that Lord Hoffman, a member of the House of Lords, also gave the leading opinion in Biogen. It is unusual for a law lord to sit on the Court of Appeal and therefore this judgment, led by Lord Hoffman, is particularly authoritative on the application and the scope of 'Biogen' type insufficiency. 

The Court of Appeal have sought to address the perception that in recent years the UK courts have been 'anti-patents' or have had a tendency invalidate patents on the grounds of insufficiency. The principles in Biogen will continue to apply to those claims which cover a class of products, or product-by-process claims. However, as a result of this case, it will now be harder to invalidate ordinary product claims.