The (high) value of second medical use patents: practical example

Previously we reported on the legal background of second medical use claims (for further details please see "The (high) value of second medical use patents: legal background"). This report discusses the commercial value of second medical use claims based on an example from practice.

EP 0 896 538
The following example illustrates existing European Patent Office (EPO) praxis. European Patent (EP) 0 896 538 was granted with a functional definition in Claim 1 as follows: “1. The use of activity lowering effectors of dipeptidyl peptidase IV (DP IV) or DP IV-like enzyme activity for the preparation of a medicament for the oral therapy of diseases, which are based on glucose concentrations in the serum of mammals characteristic of hyperglycemia.” The compound in this second medical use claim was represented by the term 'activity lowering effectors of dipeptidyl peptidase IV (DP IV) or DP IV-like enzyme activity'. 

Several big pharma companies had DP IV inhibitors in clinical development and filed oppositions against this patent, leading to the revocation of EP 0 896 538. The revocation decision was later confirmed by EPO Technical Board of Appeal Decision T1151/04, which can be summarised as follows:

• The granted claims contained no structural limitation of the feature 'activity lowering effectors of dipeptidyl peptidase IV (DP IV) or DP IV-like enzyme activity'.
• Further, the scope of the claims was not limited to substances that were already known at the priority date. Accordingly, the scope of the granted claims included future compounds from which either the structure or the function as DP IV inhibitor was not yet known at the priority date of the patent.
• Thus, it would be an undue burden for a skilled person to investigate an endless number of compounds for:
  • their activity lowering potential towards DP IV; and
  • their treatment efficacy towards hyperglycemia.

The EPO's view is not necessarily shared in other jurisdictions. For example, the German Federal Court of Justice (BGH) ruled on a similar case but reached a different conclusion. Opposition proceedings against German Patent (DE) 196 16 486, whose priority was claimed by EP 0 896 538, limited Claim 1 of the German patent to aminoacyl-thiazolidines and alanyl-pyrrolidines as activity lowering effectors of DP IV. However, the BGH overturned the first-instance decision and found the broad functional term 'inhibitor of the enzyme activity of DP IV' in Claim 1 allowable (File X ZB 8/12). The BGH ruled that the patent applicant could make certain generalisations in the claims provided that it was possible to understand the full scope of the invention. According to the BGH, functional use claims are not precluded from patentability, albeit such claims may cover substances that may be provided only in future, and even if an inventive step is required to provide these substances. Interestingly, after the BGH's ruling the EPO granted EP 1 084 705 on a divisional application of EP 0 896 538, reciting the functional term 'activity-lowering effector of dipeptidyl peptidase IV enzyme activity' in a second medical use claim. Thus, even though the legal certainty for obtaining broad second medical use claims appears to be higher before German patent authorities, some chances still exist to obtain a European patent on a second medical use claim reciting functional features.

Drafting second medical use patents thoroughly
EP 0 896 538 and DE 196 16 486 belong to a patent family in which patents have been granted in, for example, Australia, Canada, China, South Korea, Russia and the United States, most of them with the above-discussed broad functional terms in the claims. This patent family illustrates that broadly defined second medical use claims can be of great value. After several deals, this patent family was purchased (with other assets) by Royalty Pharma for $609 million. Royalty Pharma receives royalties for several medicaments containing DP IV inhibitors, including Trajenta® (Boehringer Ingelheim/Eli Lilly), Onglyza® (Bristol- Myers Squibb/AstraZeneca), Januvia ® (Merck & Co), Nesina® (Takeda), and Galvus®/Eucreas® (Novartis). Only Merck & Co achieved $6 billion in worldwide annual sales for Januvia.