In case T1673/11, an EPO Board of Appeal was asked to consider whether a post-grant amendment of a Swiss-style claim into a second medical use claim according to Article 54(5) EPC would constitute added matter according to Article 123(3) EPC, which provides that the claims of a European patent may not be amended in such a way as to extend the protection conferred upon grant.

The patent at issue was granted with the following claim 1:

The use of human acid alpha glucosidase in the manufacture of a medicament for the treatment of infantile Pompe’s disease, wherein the human acid alpha glucosidase is in the 100 to 110 kD form, wherein the medicament is to be administered intravenously, and wherein the treatment is to be continued for at least 4 weeks.

During opposition proceedings, the Opposition Division found the following amended claim 1 to be allowable:

Human acid alpha glucosidase in the 100 to 110 kD form, for use in the treatment of infantile Pompe’s disease, wherein the human acid alpha glucosidase is to be administered intravenously, and wherein the treatment is to be continued for at least 4 weeks.

An appeal was filed by one of the opponents on the basis that the amendment to claim 1 contravened Article 123(3) EPC.

The Board held that the amendments contravened Article 123(3) EPC by extending the scope of protection conferred.

In its decision the Board referred to G2/88, which states that the test to be applied under Article 123(3) EPC is whether the subject matter defined by the claims is more or less narrowly defined as a result of the amendment made. The same test applies to an amendment involving a change of claim category.

In the present case, the amendment resulted in a change of claim category from a purpose-limited process claim (a Swiss-style claim) to a purpose-limited product claim (a second medical use claim according to Article 54(5) EPC). Following on from G2/88 (and also related case T1780/12), the Board reiterated the generally accepted principle that a claim to a particular physical activity (ie process, use etc.) confers less protection than a claim to the physical entity per se.

The proprietor had tried to argue that Article 64(2) EPC, which states that the protection conferred by a claim to a process extends to the products directly obtained by that process, should be taken into account when assessing whether the amendment added matter. According to the proprietor, as a Swiss-style claim is directed to a process of manufacture of a product and this process is not limited by any technical feature, the manufacture could not be limiting on any product obtained by it. Rather, the specific medical use was the limiting feature and this was the same in both the granted and amended claims. However, the Board ruled that even if Article 64(2) EPC were to be taken into account, the two claims still conferred differing amounts of protection.

The Board adopted the position that a medicament containing human acid alpha glucosidase in the 100 to 110 kD form packaged and provided with instructions for use in a treatment other than that of infantile Pompe’s disease was encompassed by the scope of amended claim 1 when the so-packaged medicament is being used for the treatment of infantile Pompe’s disease. This was based on the logic that amended claim 1 is a purpose-limited product claim which confers protection whenever the relevant form of human acid alpha glucosidase is being used for the treatment of infantile Pompe’s disease. In contrast, the Board concluded that the protection conferred by granted claim 1 did not encompass such a use because the direct product of the Swiss-style process claim is a medicament which is packaged and/or provided with instructions for use in the treatment of infantile Pompe’s disease. The patent had therefore been amended so as to extend the protection it conferred and was revoked in its entirety.

Although the Swiss-style claim format is no longer accepted by the EPO for new filings, a number of applications with a filing date (or, if applicable, priority date) prior to 28 January 2011 are still likely to grant with claims in this format. European practitioners should therefore be aware that a change of claim category from a Swiss-style claim into a second medical use claim according to Article 54(5) EPC, in the absence of any other basis, is likely to constitute added matter.