In decision T 1437/21, the Board of Appeal held that documents reporting the successful completion of a clinical trial involving the use of a medicine do not render the invention obvious.


Clinical trials are conducted in public to check the efficacy and risks associated with a drug. Therefore, the results are often publicly accessible in most countries which can be problematic in both pre-grant and post-grant patent proceedings. It is not surprising that such published clinical trial information is frequently cited in patent proceedings before national offices and courts if they are overly positive about the success of the trial. But whether such disclosure relating to a clinical trial can be prejudicial to the patentability of an invention varies from case to case.

European patent EP2981271 was granted to Boehringer Ingelheim with claims directed to a second medical use of empagliflozin in the treatment of type 2 diabetes in a subpopulation of patients with moderate renal impairment. Several oppositions were filed against the patent on the grounds of lack of novelty, inventive step and sufficiency. At first instance, the Opposition Division revoked the patent in view of the patentee’s own documents reporting the successful completion of a clinical trial involving the efficacy of empagliflozin in the treatment of type 2 diabetes mellitus (T2DM) patients with “mild, moderate and severe” renal impairment.


On appeal, the patentee argued that the press releases of clinical trial presented a general disclosure of patients with renal impairment ranging from mild to severe, and that the positive outcome was only related to this patient group in particular. The patentee submitted post-published data demonstrating that treatment was not effective in patients with severe renal impairment.

Overturning the decision of the opposition division, the Board of Appeal maintained the patent as granted.

On novelty, the Board of Appeal agreed with the patentee, noting in its reasoning that while the press releases announced the efficacy of treatment with empagliflozin in the treatment of T2DM patients with mild, moderate, or severe renal impairment as a whole, there was no specific information on the efficacy in each subgroup of patients. Therefore, from these press releases alone, the skilled person could not directly and unambiguously derive the information that said treatment was effective in patients with moderate renal impairment.

Regarding inventive step, after considering the press releases as the closest prior art, the Board of Appeal formulated the objective technical problem as the provision of effective treatment for diabetic patients with moderate renal impairment. The Board found that the information available in the press releases did not provide a reasonable expectation of the efficacy of empagliflozin in the treatment of diabetic patients with moderate renal impairment. It was noted that there was a lack of information on the specific number of patients with moderate renal impairment in the clinical trial and because of the distinctive status of patients with moderate renal impairment, the skilled person’s expectation of efficacy was affected. The information in the press release documents was judged to be ‘purely speculative’.

The Board further observed that the approval of a clinical trial depends on the assessment of the foreseeable risks to the participants in relation to the anticipated benefit in terms of the relevance of the findings and cannot therefore be construed as a positive outcome of the drug.

Notably, the decision diverges from the earlier EPO Board of Appeal decisions (T 239/16, T 1123/16), where it was held that a clinical trial can provide an assumption of a reasonable expectation of success.


This decision has provided a degree of relief to the patentee in that a second medical use claim can be novel and inventive over a successful clinical trial disclosure. The success envisaged in a clinical trial does not always provide a reasonable expectation of success for the proposed treatment, as most compounds fail before being brought to market.

It is worth noting that clinical trial information disclosure can be detrimental and therefore, it is important to carefully ascertain the scope of such information, ideally at the stage of filing a patent application.

For inventive step, it may be worth submitting evidence showing why there was a reasonable expectation of failure of any particular trial, or why the success of the trial was unexpected.

Overall, the European Patent Office seems to have taken a more nuanced approach, however, applicants should bear in mind that any outcome will vary depending on the facts and circumstances of each case.


Sapna Sohal

Technical Assistant
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