A spectrum of specificity - Article 3(a) of SPC Regulation

Formula 1 of EP (UK) 0 810 209

Is a compound that is represented by a Markush formula in a patent claim but not identified elsewhere in the patent specification a product "protected by a basic patent" for the purposes of Article 3(a) of the SPC Regulation?  This issue was considered last year in the first instance decision of (1) Sandoz Limited (2) Hexal AG v (1) G.D. Searle LLC (2) Janssen Sciences Ireland UC [2017] EWHC 987 (Pat). At the time, the IP Kitten noted with surprise that the matter was capable of resolution without a reference to the CJEU (see previous post here).  Well, it now turns out that was a little premature, and a reference from the Court of Appeal in the same case [2018] EWCA Civ 49 is winging its way across the English Channel. 

Background

The Claimants/Appellants sought to revoke SPC/GB07/038 (the SPC) which is due to expire on 23 Feb 2019 for a product described in the SPC as "Darunavir or the pharmaceutically acceptable salt, ester or prodrug thereof".   Darunavir is marketed by Janssen (the exclusive licensee) under the brand Prezista.  Prezista is a protease inhibitor anti-retroviral medication used to treat HIV.  The Claimants aimed to clear the way for their generic darunavir product, on the basis that the SPC is invalid because on a true construction of Article 3(a) of the SPC Regulation, darunavir is not a product "protected" by the patent.  There is no challenge to the validity of the patent itself.  The patent consists of Markush claims.  

Article 3(a) of the SPC Regulation provides as follows: 

"A certificate shall be granted if, in the Member State in which the application referred to in Article 7 is submitted and at the date of that application:
(a) the product is protected by a basic patent in force".

The judge at first instance decided that the SPC complied with each of the various interpretation options for Article 3(a) currently on the table (see further detail of those options in previous post here), and concluded that the SPC did comply with Art 3(a) of the SPC Regulation. 

Issues on appeal

It was common ground that there is no reference to darunavir anywhere in the specification, and that it fell within Markush formulae in the patent. The appellants' evidence was that the closest compound to darunavir disclosed in the patent was "Compound 7", and the difference with darunavir was only in the P1 substituent.  In the case of Compound 7, the P1 substituent is an aralkoxycarbonyl group, whereas for darunavir, the corresponding P1 substituent is a heterocyclyloxycarbonyl group (specifically a fused bis-tetrahydrofuran derivative).  The difference in the two P1 substituents is set out below:

P1 substituent: Compound 7

P1 substituent: Darunavir

The appellants’ evidence was that the heterocyclyloxycarbonyl substituent in darunavir was unusual, did not form part of the common general knowledge available to the skilled team at the priority date, and the structure of the P1 substituent group of darunavir was not published until after the priority date of the patent.  The defendants'/respondents' evidence drew attention to a pre-priority date article which discloses the heterocyclyloxy portion of the P1 group in darunavir (but not the whole P1 group) as an intermediate in a reaction scheme for the synthesis of insect anti-feeding compounds.

The appellants argued that given the large number of compounds covered by the claims and the unusual nature of the P1 substituent of darunavir, Article 3(a) was not satisfied on the facts.  The respondents contended that darunavir was protected by the patent if it is one of the class of products defined and claimed by reference to the Markush formulae in the claims. 

Article 3(a):  a spectrum of specificity

The Court of Appeal reviewed the case law of the CJEU and pending references, focussing on Case C-322/10 Medeva BV v Comptroller-General of Patents, Designs and Trade Marks and Case C-493/12 Eli Lilly & Co Ltd v Human Genome Sciences Inc.  The CJEU articulated for the first time in Eli Lilly that in order to be protected by the basic patent, the claim must relate to the product implicitly, but necessarily and specifically (the "Lilly requirement").   Issues before the Court of Appeal included the following: (a) Is the Lilly requirement limited to functional claims? (b) If it is not so limited and applies to all claims, is it always satisfied by a Markush claim which covers the active ingredient? (c) Is the position unclear necessitating a reference to the CJEU?

Floyd LJ (for a unanimous Court of Appeal) noted that an important point of detail is the time and circumstances in which the national authority has to determine whether a product is protected by a basic patent - this falls to be judged when the product is known and authorised to be placed on the market.  The question remains what is the necessary exercise for determining whether the product is protected by the patent: is the correct approach to ask whether it is clear that the product is claimed as such, or whether the product is one which is sufficiently identified?
The Court of Appeal considered paragraph 43 of the Lilly judgment to try and identify what underlies the specificity requirement. This indicates that one way to prevent the marketing authorisations of third parties from being used as the basis for SPCs is to insist on a high degree of specificity in the basic patent.  The Court of Appeal continued, that if there is a general requirement that the active ingredient which is the subject of the SPC must be identified, the question arises of how specific the claims must be - there is a "spectrum of specificity" indicated by the factual scenarios in the various decided cases and references to the CJEU.  With regard to Markush claims, the judge noted that he would:

"regard it as plain that a Markush claim can in some circumstances amount to a sufficiently precise claim for the purposes of Article 3(a), for example where individual substituents are identified in the specification, or where classes of such substituents are set out, and the skilled person would be able to determine the extent of those classes.  However I do not think one can extract from the reasoning in Eli Lilly the proposition that an active ingredient is adequately identified by a Markush formula however broadly that formula is framed and however obscure the particular substituent required to form the active ingredient the subject of the SPC.  I think it is at least arguable that that substituent must be amongst those which the skilled person would be able to identify based on his common general knowledge at the priority date." (para 106, emphasis added)

The Court of Appeal gave two reasons for this conclusion: First, if the objective is to ensure that the patent proprietor has come close to an actual realisation of the product, then the fact that the relevant substituents cannot be arrived at from a reading of the specification and the CGK may be highly relevant. Secondly, the Bundespatentgericht (German Federal Patents Court) in the pending Sitagliptin reference (Decision 14 W (pat) 12/17 dated 17 October 2017, original here, English translation here) expressed the view that the functional formula in that case, and the Markush formula in the present case are factually indistinguishable for the purposes of Article 3(a) - a view with which the Court of Appeal in the present case disagreed.  This divergence of opinion could lead to conflicting decisions between member states. 
The Court of Appeal expressed concern about the identification test, and expressed agreement with the first instance judge that a far better test would be to ask "whether the product the subject of the SPC embodies the core inventive advance of the basic patent."  However, the Court also recognised that an adoption of the core inventive advance test would present difficulty to patent offices around Europe in its application, and would be a "very long way indeed from the simple, transparent and objective approach foreseen by the Memorandum" to the SPC Regulation (which can be found here). 

Provisional conclusion and reference to the CJEU

Left to his own devices, the judge would have concluded that darunavir was a product protected by the claims of the patent.  In the case of a product with a single active ingredient and a patent with a claim which identifies a number of compounds by means of a Markush formula, all of which embody the core inventive technical advance of the patent, the test should be whether the skilled person, considering the claims of the patent on the one hand and the structure of the product in question on the other, would immediately recognise that the active ingredient in question is one of those specified by the formula.  On the facts of the present case, that test is satisfied, but it is not clear that this is the correct approach in EU law.  (It is worth noting that the core inventive contribution test has also been disapproved by the Bundespatentgericht in its sitagliptin reference, which considers that such a test has a place only in connection with Article 3(c) of the SPC Regulation.)

The Court of Appeal therefore stayed the appeal proceedings and referred the following question to the CJEU:

“Where the sole active ingredient the subject of a supplementary protection certificate issued under [the SPC Regulation] is a member of a class of compounds which fall within a Markush definition in a claim of the patent, all of which class members embody the core inventive technical advance of the patent, is it sufficient for the purposes of Article 3(a) of the SPC Regulation that the compound would, upon examination of its structure, immediately be recognised as one which falls within the class (and therefore would be protected by the patent as a matter of national patent law) or must the specific substituents necessary to form the active ingredient be amongst those which the skilled person could derive, based on their common general knowledge, from a reading of the patent claims?”