Markush formulae and Art 3(a) of SPC Regulation

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? That was the issue before Arnold J. in his latest judgment considering the SPC Regulation in (1) Sandoz Limited (2) Hexal AG v (1) G.D. Searle LLC (2) Janssen Sciences Ireland UC [2017] EWHC 987 (Pat).  [Surprise! says the IP Kitten - the matter was capable of resolution without a reference to the CJEU...] 

Background

The Claimants 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, and agreed to give the Defendants 30 days' notice before launching their product.  

Formula I

There are a handful of points to note by way of background before delving into the analysis:

1. The Claimants did not put the validity of the patent (as distinct from the SPC) in issue;
2. The claims of the patent are framed by reference to two Markush formulae, formula I and formula II.  Formula II is the same as formula I except that it omits the stereochemistry of the lefthand two carbon atoms of the backbone;
3. The patent specification lists 41 preferred compounds of formula 1 - none of these is darunavir;  
4. The Claimants' expert evidence estimated that there are approximately 100 compounds disclosed in the patent specification - again, none of these is darunavir;
5. Darunavir is a compound represented by formula I and formula II that falls within claims 1, 2, 5,  10 and 11 of the patent;
6. It was common ground that there is no reference to darunavir anywhere in the patent specification.

SPC Regulation and Court's Analysis

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"

Applying the various interpretation options for Article 3(a) currently on the table (pending the resolution of various references to the CJEU), the Court concluded that the SPC did comply with Art 3(a) of the SPC Regulation: 

1. The broadest tenable interpretation of Article 3(a) is that it is sufficient that the product falls within at least one claim of the patent.  If this interpretation is correct, then darunavir is "protected" by the patent.  However, Arnold J once again observed that this interpretation does not appear to be correct because the CJEU has so far held that more is required.

2.  The CJEU held in Case C-322/10 Medeva BV v Comptroller-General of Patents, Designs and Trade Marks [2011] ECR I-12051 that it was necessary for the product to be "specified" or "identified" in the wording of the claims.  The question as to whether a Markush formula was sufficient for this purpose remained open at that time.  Subsequently, the CJEU held in Case C-493/12 Eli Lilly & Co Ltd v Human Genome Sciences Inc [EU: C:2013:835] that Article 3(a) must be interpreted as meaning that it was not necessary for the active ingredient to be identified in the claim by means of a structural formula.  It is sufficient for the active ingredient to be covered by a functional description provided that the claims "relate, implicitly but necessarily and specifically, to the active ingredient".  The judge noted that it is not necessarily an objection that the relevant claim covers a large number of other compounds in addition to the active ingredient question (since if that was so, it would have provided a simple answer in Lilly).

3. Arnold J. reiterated his view (expressed previously in Teva UK Ltd v Gilead Sciences Inc [2017] EWHC 13 (Pat)) that the test in Lilly remains unclear.  However, he was of the view that the light that Lilly sheds on Medeva suggests that it is sufficient for the claim to specify the product by means of a Markush formula, and that darunavir is therefore "protected" by the patent within the meaning of Article 3(a). 

4. The judge also reiterated that a better test would be the one proposed previously by him to the CJEU, namely that "Article 3(a) should be interpreted as meaning that the product is "protected" by the basic patent if (i) the product falls within the scope of the claim when interpreted in accordance with the Extent of Protection Rules and (ii) the product does so because it contains an active ingredient, or a combination of active ingredients, which embodies the inventive advance (or technical contribution) of the patent."  On the facts, the technical contribution of claim 1 of the patent lies in the identification of the compounds covered by claim 1 as having utility as HIV protease inhibitors - and darunavir embodies that inventive advance. 

Observations

Arnold J observed that the Claimants' real objection in this case was that claim 1 was of excessive breadth because it encompassed a vast number of compounds which the skilled person could not make even a tiny fraction of and which it was not plausible would all be efficacious as protease inhibitors.  However, that was an objection to validity on the basis that the claims were obvious on an AgrEvo basis, or alternatively, were insufficient.  On the facts, the Claimants did not put the validity of the patent in issue and it was therefore presumed valid (some of the Claimants' expert evidence was relevant only to sufficiency which was not in issue, and was therefore excluded).

The judge also noted that it is not a function of the patent offices when assessing applications for SPCs to have to consider whether the breadth of the claims of the basic patent is justified.  That would not make for a simple and transparent system, envisaged in paragraph 16 of the European Commission's Explanatory Memorandum proposing the predecessor to the SPC Regulation.  By contrast, paragraph 39 of the Memorandum did envisage SPCs being granted where "a patent protects a series of products based on the same formula".  [Paragraph 39 of the Explanatory Memorandum would appear more illuminative on the question of Markush formulae than Lilly.  However, the Explanatory Memorandum to the Proposal for a European Parliament and Council Regulation (EC), of 11 April 1990, concerning the creation of a supplementary protection certificate for medicinal products is proving difficult to pin down online - any pointers welcome so that I can include a link. UPDATE: Thank you kind reader, please see link here].

For future reference, interested readers may wish to note that the decision is a handy reference guide covering: (a) the background to Markush claims and their development (see paragraphs 12-18); and (b) a review of the current position on possible interpretations of Article 3(a) of the SPC Regulation (see paragraphs 7-11 and 61-65).