INNsight articles by Duncan Curley

Last month, GenericsWeb covered the decision of the UK Court of Appeal of 10 April 2008 in Generics (UK) Limited, Arrow Generics Limited and Teva Pharmaceuticals Limited v H.Lundbeck A/S - “Escitalopram enantiomer patent claims upheld in court”.  The judgment on the validity of Lundbeck’s European Patent (UK) No. 0,347,066 B1 (New enantiomers and their isolation) took a number of people by surprise and it has generated considerable discussion, not just about the UK patent protection to escitalopram but also the possible implications for the validity of other patents claiming enantiomeric forms of important products.  Here is a list of Frequently Asked Questions with the opinions of Dr Duncan Curley of Innovate Legal in response.  
   

1. Why did the generic companies lose on the issues of novelty and lack of inventive step?

A. The case on novelty was difficult, because existing caselaw says that the prior disclosure of a racemate does not equate to a disclosure of its constituent enantiomers.  The case on obviousness was predicated on showing that Lundbeck had patented an obvious route to escitalopram, i.e. a route that was obvious to try.  The generic companies’ expert was unable to persuade the judge that it was obvious to try the route of stereoselective chemical synthesis from an optically active intermediate, as developed by Lundbeck. 

2. The generic companies won at first instance on insufficiency.  What happened on appeal?

A. The generic companies won at first instance when the judge applied a ruling from a House of Lords case called Biogen. The Court of Appeal distinguished escitalopram from the previous decision in Biogen by saying that Biogen was decided on the basis of the particular complicated form of the claim that was in issue in that case. The Court of Appeal held that the ordinary product claims in the escitalopram patent were sufficiently enabled, because there was enough information in the patent specification to enable the skilled person to make the product in question. 

3. What does the UK escitalopram decision mean for enantiomer patents generally?

A. The UK escitalopram decision sets no precedent, as far as enantiomer patents generally are concerned.   It is best thought of as a “one off” decision. 

4. Are there lessons to be learned from the escitalopram case?

A. Yes.  Although the generic companies did not win, they managed to establish with the Court that an enantiomeric form of an active drug molecule was an obviously desirable goal for the skilled person by June 1988.  Judges in the UK are likely to concur with this assessment in further cases where the validity of an enantiomer patent is being challenged.  Note however that for enantiomer patents with a priority date earlier than 1988, it will probably be necessary to supplement the evidence that was before the court in the escitalopram case with pre-1988 evidence about the desirability of isolating enantiomers.
 

5. How should future cases challenging the validity of enantiomer patents be managed?
A.  The critical question for the Court in future cases will be: how easy was it to resolve an active drug molecule into its enantiomers?  If resolution was difficult and required ingenuity (as in the escitalopram case), it may prove tough to make out a case of obviousness.  If resolution was straightforward and it was carried out by standard means, the route to the enantiomer is more likely to be obvious, making any claims to the enantiomer product itself also potentially obvious.  

6. What about escitalopram?  In the UK, the patent expires in 2009 but the SPC will continue until 2014.  Can the validity of the patent be challenged again?

A. Yes, but only by different companies.  The escitalopram patent will receive a “Certificate of Contested Validity”.  This means that if someone else challenges the patent and loses, there will be more stringent costs order made against the losing party (payment of 80-90% of the patentee’s costs, as opposed to 60-70% on an unsuccessful first challenge).

7. Has this ever happened before? 

A. Yes.  In the last five years, a UK judge has reversed himself once on a previous finding of validity, deciding second time around that the same patent was invalid (although it was not a pharmaceutical case).  

8. Could this be done with the escitalopram patent?

A. Possibly.  The case that was run by the generic companies first time around was quite unusual.  There is another possible route to proving obviousness that could be built around the disclosure of citalopram in the prior art.