08 September 2022

T 2627/17: Divergent outcomes for first and second medical use claims under Article 83 EPC

This recent decision by the European Patent Office (EPO) Boards of Appeal (T 2627/17) highlighted the way in which the ‘sufficiency of disclosure’ requirements under Article 83 EPC can lead to different (and perhaps counterintuitive) outcomes for claims to medical uses in general (so called ‘first medical use’ claims) and for claims to specific medical uses (so called ‘second medical use’ claims). In T 2627/17, the Board held that in vitro data in the patent were supportive of the (broader) first medical use claim, but not the (narrower) second medical use claim.

In overview, the patent relates to compounds for use in the treatment or prevention of diseases or conditions that are estrogen sensitive, estrogen receptor dependent, or estrogen receptor mediated (collectively, such compounds are said to have ‘ER activity’). The patent contained in vitro data demonstrating ER activity of a large number of compounds which fall within the scope of the claims in estrogen-dependent breast cancer cell lines. The patent also contained a discussion linking ER activity with estrogen-dependent cancer therapy.

The patent granted with claims directed to compounds per se, use of the compounds in medicine (first medical use), and use of the compounds in the treatment of a wide range of specific conditions including various types of cancer, alcoholism, arthritis, migraines, dementia, and infertility (second medical uses).

First medical use claim

During the appeal proceedings, the appellant argued that the alleged ER activity was not supported across the wide range of compounds covered by the claims.

The Board disagreed, and referred to T 609/02 (Reason 9), which noted that “for demonstrating sufficient disclosure of a therapeutic application, the patent must provide some information in the form of, for example, experimental tests, to the avail that the claimed compound has a direct effect on a metabolic mechanism specifically involved in the disease, this mechanism being either known from the prior art or demonstrated in the patent per se.” (emphasis added).

Demonstration of ER activity, combined with a discussion linking ER activity with estrogen-dependent cancer therapy, was ultimately held to support the (broad) medical use claim.

Second medical use claim

The appellant argued that the ER activity data in the patent were limited to a specific breast cancer cell line, and that these data did not support each of the specific conditions listed in the second medical use claim.

The patentee (respondent) argued that the patent rendered it plausible that ER activity is involved in each of the conditions listed in the second medical use claim, and that each of those conditions were therefore sufficiently disclosed.

The Board decided that the data, combined with the discussion linking ER activity with existing estrogen-dependent cancer therapies, supported treatment of estrogen-dependent cancers.

Regarding the other conditions listed in the second medical use claim, the Board again pointed to T 609/02 (Reason 9) and noted that in vitro data may support a therapeutic application “if there is a clear and accepted established relationship between the shown physiological activities and the disease” (emphasis added). Without evidence of an established relationship between ER activity and the other conditions listed in the second medical use claim, those other conditions were considered insufficiently disclosed.


T 2627/17 highlights the considerable importance of establishing a relationship between a biological or a physiological activity and a disease or a condition, particularly when supporting data for that disease or condition are unavailable. Patent applications are often filed before robust in vivo (or even in vitro)data are available, and so investing time at the drafting stage to explain why or how a demonstrated biological activity is relevant to a condition, can pay significant dividends.

T 2627/17 contained a further quirk: even though the second medical use claim was considered ‘bad’ for treatment of conditions other than estrogen-dependent cancer, those other conditions were nevertheless covered by the broader scope of the granted first medical use claim and claims to the compounds per se.