SPCs and Markush claims

SPCs and Markush claims

The High Court has upheld the validity of GD Searle’s SPC on Prezista, which is used to treat HIV. The decision will be welcomed by patentees for its positive approach to SPCs based on Markush claims.

Case: Sandoz Ltd and another v GD Searle LLC and another [2017] EWHC 987.

Markush Claims

A “Markush” claim is used to denote a large class of compounds with similar structures. The class of compounds is represented by means of a structural formula consisting of a specified backbone to the compound, with substituents denoted by R groups. These substituents share common properties and structures, which are often defined or identified elsewhere in the patent specification and/or the claims themselves.

Interpretation of Article 3(a)

Under Article 3(a) of the SPC Regulation (469/2009/EC), a supplementary protection certificate (“SPC”) may be granted where a product is “protected by a basic patent” which is in force in the Member State in which the application is submitted at the date of the application.

To date, the correct interpretation of Article 3(a) has been the subject of a number of references to the CJEU, including in the recent case of Teva UK v Gilead Sciences (2017, High Court), for which a ruling is still pending.  However, the Judge, Arnold J, held that this uncertainty did not matter for the purposes of the present case.

Darunavir (“Prezista”)

GD Searle holds an SPC for a product known as “Darunavir”, sold under the brand name “Prezista”, which is used as an anti-retroviral medication to treat HIV. Sandoz sought to challenge the validity of the SPC in the hope of clearing the way for a generic Darunavir product.

Sandoz claimed that, whilst Darunavir fell within the wide breadth of the claims of the basic patent, it was not specifically identified by either name or structure elsewhere in the claims or specification. However, it did fall within 5 of the claims.

Applying the (albeit unclear) test laid down by the CJEU in the Eli Lily case (C-493/12), the High Court confirmed that it was sufficient for the basic patent claim to specify the active ingredient implicitly by means of a functional description (e.g. a Markush formula) which covered it, provided that the claims “relate implicitly but necessarily and specifically to the active ingredient”. 

Interestingly, Arnold J also commented that the real attack by Sandoz should have been aimed, not at the SPC, but at the breadth of the basic patent claims which allowed for protection of Darunavir.  There has been some suggestion that such skirmish tactics confirm a commercial preference by generics to avoid, where possible, the time and costs involved in attacking the patent itself. 

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Charlotte Tillett, Henry Milas

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