Factual and Procedural Background
This opinion concerns the trial of three claims for revocation of European Patent (UK) No 0,347,066 ("The Patent") held by the Defendant ("Lundbeck"), a Danish pharmaceutical company specialising in central nervous system diseases. The Patent, with a priority date of June 1988, relates to escitalopram, an antidepressant drug comprising the pure (+) enantiomer of citalopram. The claims challenged include product, pharmaceutical composition, and method of preparation claims directed at the (+) enantiomer and its synthesis.
The challenges to the Patent are based on prior art relating to citalopram, a racemic mixture antidepressant first synthesised by Lundbeck in 1972 and launched in 1989. The claimants allege invalidity on grounds of lack of novelty over two US patents, obviousness, and insufficiency. Lundbeck counters with arguments including commercial success and unexpected technical benefits of escitalopram. The evidence from the three claims has been consolidated, allowing the court to treat them as a single claim for revocation.
Legal Issues Presented
- Whether claims 1 and 3 of the Patent lack novelty over prior art disclosures of racemic citalopram and related patents.
- Whether claims 1, 3, and 6 are invalid for obviousness in light of prior art patents and common general knowledge.
- Whether claims 1 and 3 are invalid for insufficiency due to over-breadth, claiming an obvious goal rather than a technical contribution.
- The scope and construction of claim 1, specifically whether it covers the isolated (+) enantiomer or also includes the (+) enantiomer within the racemic mixture.
- The relevance and admissibility of evidence relating to the unexpected superior efficacy and commercial success of escitalopram in assessing inventive step.
Arguments of the Parties
The opinion does not contain a detailed account of the parties' legal arguments.
Table of Precedents Cited
| Precedent |
Rule or Principle Cited For |
Application by the Court |
| Catnic Components v Hill and Smith Ltd [1982] RPC 183 |
Definition of the skilled addressee and approach to claim construction. |
Used to identify the skilled addressee as a team with practical knowledge and no inventive capacity. |
| Kirin-Amgen Inc v Hoechst Marion Roussel [2005] UKHL 59; [2005] RPC 9 |
Principles of claim construction and understanding the purpose of a patent specification. |
Applied to construe claim 1 as limited to isolated (+) enantiomer, excluding racemate. |
| Ultraframe v Eurocell Building Plastics [2005] EWCA Civ 761; [2005] RPC 36 |
Interpretation of claim scope in light of specification to avoid covering prior art. |
Supported the conclusion that the Patent claims exclude the racemate as prior art. |
| Beloit Technologies Inc v Valmet Paper Machinery [1995] RPC 705 |
Claim construction and approach to common general knowledge. |
Referenced in support of claim construction and common general knowledge principles. |
| Windsurfing International Inc. v Tabur Marine (Great Britain) Ltd [1985] RPC 59 |
Structured approach to assessing obviousness. |
Applied as the framework for analysing obviousness of the claims. |
| Ferag v Muller Martini [2007] EWCA Civ 15 |
Avoidance of hindsight in obviousness assessment. |
Emphasised the importance of assessing obviousness without knowledge of the invention. |
| Coflexip v Stolt Connex Seaway (unreported, 31 July 2000) |
Use of common general knowledge in obviousness attacks. |
Referenced regarding the nature of common general knowledge evidence. |
| Brugger v Medic-Aid Ltd [1996] RPC 635 |
Obviousness of multiple obvious routes. |
Confirmed that multiple obvious avenues do not negate obviousness. |
| Angiotech Pharmaceuticals v Conor [2007] EWCA Civ 5 |
Doctrine of "obvious to try" in obviousness. |
Clarified the limits of "obvious to try" and its application in patent law. |
| Synthon v Smithkline Beecham [2005] UKHL 59; [2006] RPC 323 |
Requirements for novelty including enabling disclosure. |
Applied to determine that racemate disclosure does not anticipate isolated enantiomer. |
| Hallen v Brabantia [1991] RPC 195 |
Unexpected technical benefits as indication of inventive step. |
Referenced in context of whether unexpected benefits support inventiveness. |
| Richardson-Vicks Inc.'s Patent [1995] RPC 568 |
Limitations on relying on post-patent unexpected benefits for inventive step. |
Applied to exclude reliance on undisclosed surprising benefits in the Patent. |
| Glaxo Group Ltd's Patent [2004] EWHC 477 (Ch); [2004] RPC 43 |
Requirement that unexpected benefits be described in specification to support claims. |
Confirmed that undisclosed benefits cannot support inventive step. |
| Parkes v Cocker (1929) 46 RPC 241 |
Commercial success as secondary evidence of inventiveness. |
Considered in assessing the relevance of escitalopram's commercial success. |
| Biogen v Medeva [1997] RPC 1 |
Principles of sufficiency and over-broad claims covering obvious goals. |
Applied to find claims 1 and 3 invalid for claiming all methods of obtaining (+) enantiomer without enabling all. |
| O'Reilly v Morse (1854) 56 U.S. (15 How.) 62 |
Limits on claiming all means of achieving a result without invention of all means. |
Illustrated the principle that claims must not monopolise all ways of achieving an obvious goal. |
| British United Shoe Machinery Co. Ltd. v. Simon Collier Ltd. (1908) 26 RPC 21 |
Claims must correspond to the technical contribution made. |
Applied to limit claims to the specific inventive method disclosed. |
Court's Reasoning and Analysis
The court examined the Patent’s claims and the prior art, focusing on whether the claims were novel and non-obvious over the racemic citalopram and its known synthesis. It found that claims 1 and 3 are directed to the isolated (+) enantiomer and pharmaceutical compositions containing it, excluding the racemate. This construction was supported by the specification’s focus on isolation and testing of individual enantiomers, and established principles of claim interpretation.
On obviousness, the court applied the Windsurfing structured approach and emphasized the need to avoid hindsight. It identified the inventive concepts as the isolated (+) citalopram (claim 1), its pharmaceutical composition (claim 3), and a method of stereoselective preparation via conversion of the (-) diol intermediate (claim 6).
The court found that the skilled team in 1988 would have had a clear motive to isolate and test individual enantiomers of citalopram, supported by regulatory guidance and industry practice, despite some disagreement among experts about the level of interest at that time.
Regarding methods of resolution, classical approaches using chiral acids, derivatives, and asymmetric synthesis were known but unpredictable. Preparative chiral HPLC was acknowledged as a developing technique but was not routine or widely practiced at the priority date, and the skilled medicinal chemist likely had little familiarity with it for preparative purposes.
The court analyzed the reaction mechanisms for the method of claim 6, particularly the ring closure step. It rejected the argument that Baldwin's Rules clearly favored the SN2 ring closure required, due to differences between saturated and unsaturated systems and the nature of the intermediate. The court concluded that it was not obvious that the stereochemistry could be preserved by this method.
The court considered the extensive research efforts by Lundbeck, which included failed attempts to resolve citalopram and its intermediates by classical and chiral HPLC methods, supporting the non-obviousness of the claimed method.
On the issue of unexpected superior efficacy of escitalopram, the court accepted evidence of enhanced potency and clinical advantages, but ruled that these benefits were not disclosed or foreshadowed in the Patent and thus could not support inventive step.
Commercial success was acknowledged but was attributed to factors including marketing and later-discovered benefits not disclosed in the Patent. The court held that commercial success alone does not establish inventiveness, especially where the invention was already protected and third parties were unable to exploit it.
On insufficiency, the court relied on Biogen v Medeva principles to find that claims 1 and 3 were overbroad, claiming all methods of obtaining the (+) enantiomer without enabling them all. The technical contribution was limited to the specific resolution method via the diol intermediate. Thus, claims covering all methods, including preparative chiral HPLC, were unsupported and insufficient.
Holding and Implications
The court held that claims 1 and 3 of the Patent are invalid for insufficiency because they claim an obvious goal (the isolated (+) enantiomer) without enabling all methods of obtaining it, extending beyond the technical contribution made. In contrast, claim 6 is valid as it is limited to a specific, non-obvious method of stereoselective preparation via the diol intermediate.
The direct effect is that the Patent’s monopoly is confined to the method of claim 6, excluding broader claims to the isolated enantiomer and pharmaceutical compositions containing it. No new precedent is established beyond the application of established principles on claim construction, obviousness, sufficiency, and the limits of relying on post-patent discoveries for inventive step.