Plausibility at the EPO

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In the recently issued decision T184/16, the BoA reached a patentee favourable decision in confirming that the concepts of ‘plausibility’ and ‘obviousness’ should be evaluated using different tests.

The patent at issue was directed to new chemical entities and, due to an inhibitory activity against SGLT (sodium-dependent glucose transporter), to the use of such compounds in the treatment of various conditions relating to diabetes. Notably, and despite an absence of any biological data in the patent, the BoA acknowledged that the requirements of sufficiency of disclosure (Art. 83 EPC) and inventive step (Art. 56 EPC) were satisfied.

In acknowledging sufficiency of disclosure, the BoA indicated not only that the question of plausibility is key, but also that disclosure of the application as filed must be considered together with common general knowledge and relevant prior art when assessing the plausibility of any claimed technical effect. Specifically, the BoA considered that, based on the contents of a prior art document cited in the background section of the patent, which taught that compounds having the ‘same core structure’ as claimed were SGLT inhibitors, it was plausible that the claimed compounds would also possess SGLT inhibitory activity.

Further, the BoA held that the Appellant had not argued that there is prima facie and serious doubt that the clamed therapeutic effect [i.e. SGLT inhibition] can be obtained, nor was there a priori any indication in the common general knowledge that such an effect could not be obtained. This further evidenced that the claimed therapeutic effect was plausible and, as a consequence, post-published data confirming SGLT2 inhibitory activity for the claimed compounds was taken into consideration and sufficiency of disclosure was thus acknowledged.

Turing to inventive step, and is often the case in EPO proceedings, the formulation of the objective technical problem appeared to be of critical importance. In particular, the BoA held that the claimed compounds and their use in the treatment of SGLT implicated conditions was not obvious in view of the SGLT inhibitory compounds described in the prior art, despite the earlier reliance on the disclosure of these compounds having the ‘same core structure’ to support the plausibility of the compounds as claimed. In reaching this decision the BoA stated that the criteria for plausibility and obviousness differ:

‘…On the one hand, as set out above, for plausibility of a claimed effect to be acknowledged, it is enough if there are no prima facie serious doubts that the effect can be obtained and conversely no a priori reason and indication in the common general knowledge that the effect cannot be obtained. On the other hand, obviousness is decided in the framework of the problem-solution approach, where generally an important consideration is whether the claimed solution is suggested and thus made obvious by the prior art.’

Specifically, and as post-filed data demonstrated that the distinguishing technical feature conferred improved SGLT2 inhibitory activity, the objective technical problem was formulated as the provision of improved SGLT2 inhibition. As the obviousness of this solution was not contested, the BoA concluded that it would not have been obvious to modify the core-structure to arrive at the claimed compounds in the expectation that doing so would result in such a beneficial effect. Accordingly, an inventive step was acknowledged for the claimed compounds and their use in various SGLT implicated diabetic conditions.


In providing guidance as to how plausibility and obviousness are divergently assessed before the EPO, the above decision should be of interest to research and development teams across all technological fields.

It will be of particular interest to those in the medical sector given the suggestion that, provided one can demonstrate that a technical effect disclosed in the application is plausible (based on, amongst others, structural similarity with the prior art), new compound and/or second medical use claims do not necessary need to be accompanied by supporting data in the application as filed. However, in such a scenario, post filing data demonstrating a clear performance improvement over the prior art compounds would most likely be required in order to overcome the traditional “squeeze” type argument, i.e. the invention is either obvious or implausible based on the prior art disclosure.

It remains the case that, wherever possible, exemplification in the form of biological data should be provided when drafting new patent applications. However, this decision suggests that protection in Europe may still be possible even if such data is not available at the time of filing. In particular, if the technical effect is found to be plausible, post filing data can be provided to demonstrate the presence of an inventive step.

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