Posted on 7/7/2023

Sufficiency of second medical use claims

This decision sheds light on the sufficiency requirement for second medical use claims.

Sufficiency is a critical requirement for the patentability of an invention, which ensures that a patent discloses a claimed invention in a manner clear and complete enough for it to be carried out by a person skilled in the field of the invention.

Second medical use inventions relate to the use of a substance or composition for treatment or diagnosis of a specific disease or condition, even if that substance or composition is already known to treat a different disease or condition. To meet the requirements of sufficiency, second medical use patent claims must go beyond merely suggesting the potential use, and instead disclose the suitability of the substance or composition for the claimed application.

In a recent decision of the European Patent Office (EPO) Boards of Appeal (T1196/21), the Board shed light on the extent of experimental data needed to establish the suitability of a substance or composition for a specific use and to satisfy the condition of sufficiency.


The patent in question (EP 3 016 527), which was granted in 2018, related to a product for use in the treatment of metabolic diseases.

Claim 1 of the patent as granted claimed: A product for use in the treatment of obesity, the metabolic syndrome, type 2 diabetes, cardiovascular diseases, dementia, alzheimers disease and inflammatory bowel disease comprising at least one isolated bacterial strain from the species Prevotellaceae, wherein the strain is selected from the group consisting of Prevotella copri and Prevotella ruminicola.

The patent proprietor filed an appeal against a decision of the Opposition Division. The Opposition Division concluded that the invention as claimed in the main request (patent as granted), as well as in auxiliary requests 1-8, was insufficiently disclosed. The Opposition Division only found the invention to be sufficiently disclosed for the treatment of obesity and type 2 diabetes, and claimed that that the patent did not make it plausible that the composition was suitable for treating the other diseases in claim 1 as granted.

In his appeal, the proprietor contested the Opposition Division’s finding of insufficient disclosure for the invention as claimed in the patent as granted.

Board of Appeal’s Decision

When assessing the facts of the case, the Board explained that according to established case law, achieving the claimed therapeutic effect is a functional technical feature in medical use claims, and for second medical use claims to meet the sufficiency requirement, the therapeutic efficacy of the composition for the claimed therapeutic indication must be credible.

In contrast to the decision of the Opposition Division, the Board of Appeal concluded that experiments described in the opposed patent established the credibility of the claimed product for treating all the diseases in claim 1 of the patent as granted, and not just obesity and type 2 diabetes. Notably, Example 1 of the patent demonstrated that the administration of barley kernel bread instead of white bread to healthy human responders resulted in various positive effects, including decreased postprandial blood glucose, insulin release, and appetite, as well as increased perceived satiety and increased plasma concentration of factors enhancing insulin sensitivity.

Example 2 of the patent revealed that the administration of barley kernel bread increased the level of Prevotella species and succinate, a major metabolite of fermentation by Prevotella species. Furthermore, it showed that the inoculation and colonisation of mice intestines with Prevotella copri improved glucose tolerance and prevented impairment induced by Bacteroidetes thetaiotaomicron.

Additional supporting documents showed that Prevotella strains could decrease postprandial blood glucose levels and improve glucose tolerance, and that a high Prevotella to Bacteroides ratio correlates with a decrease in body weight and fat loss in humans.

Based on the results and their relevance, the Board concluded that the claimed composition was suitable for inducing the therapeutic benefits mentioned in the patent. Moreover, considering the interconnection and comorbidity of the diseases mentioned, the Board found that the evidence presented made it credible that the composition is not only suitable for treating obesity and type 2 diabetes, but could also be effective in treating metabolic syndrome, cardiovascular diseases, dementia, Alzheimer’s disease and inflammatory bowel disease, as claimed.

As such, the Board overruled the decision of the Opposition Division and considered the invention as claimed in the patent as granted to be sufficiently disclosed.


This decision sheds light on the sufficiency requirement for second medical use claims, specifically regarding the “credibility” of therapeutic efficacy. It indicates that it is not necessary to have data relating to tests performed directly on the specific diseases claimed, as long as the patent application as filed contains some data that at least indirectly suggests that the claimed use should work for the diseases claimed.

For further information about patents, please get in touch to speak to one of our patent attorneys.

Wilson Gunn