Important Case of Inadmissibility of Experimental Evidence Filed After Filing to Support Inventive Step Before the EPO

By: Elsa Benveniste


This year, the Board of Appeal of the European Patent Office (EPO) issued decision T488/16 regarding the revocation of Bristol-Myers Squibb’s (BMS) European Patent EP1 169 038. In this case, the Board considered that the anti-cancer drug dasatinib (Sprycel®) claimed by the European patent lacked inventive step, despite the proprietor’s efforts to prove the contrary based on experimental evidence submitted to the EPO during opposition proceedings.

The European application was directed to a broadly-defined group of compounds, indicated by a general chemical formula. Dasatinib was one of 580 specific compounds disclosed in the application. The application also disclosed a number of possible targets of the claimed compounds, among which was Protein Tyrosine Kinase (PTK), and listed a number of associated specific disorders, including certain types of cancer. Assays for testing the activity of compounds as PTK inhibitors were also disclosed. However, the application did not contain any experimental evidence of PTK inhibitory activity of the compounds, but merely stated that “Compounds described in the following examples have been tested in one or more of these assays and have shown activity”.

During the opposition proceedings, the claims were narrowed to a single claim directed toward the single compound, dasatinib, or salts thereof. The main issue was the lack of inventive step owing to lack of evidence in the application as filed (or of evidence of common general knowledge) which makes “plausible” the activity of dasatinib as PKT inhibitor. The choice of dasatinib was considered to be arbitrary. Moreover, the mere provision of a compound without any evidence of the technical effect or any particular activity thereof was also considered not to solve any technical problem. As a consequence, the compound was found not to involve any inventive step.

In response, the applicant attempted to prove the effect (inhibiting PTK activity) of the claimed compound (dasatinib) based on post-published documents filed during the Examination procedure. While, in many instances, this type of evidence is admitted by the EPO because the plausibility criterium does not come into play, in this case at issue it was not.

According to the Board, it is established jurisprudence of the Boards of Appeal that the assessment of inventive step should made at the effective date of the patent on the basis of the information in the patent, together with the common general knowledge then available to one reasonably skilled in the art. For post-published evidence to be taken into account, it is necessary to establish whether the asserted activity has been made sufficiently plausible for dasatinib at the effective date of the patent (see T1329/04, point 12 of the Reasons).

In the present case, the Board further stated that it could find no evidence that at the filing date of the application, one skilled in the art would have possessed the common general knowledge necessary to make it plausible that compounds described in the application would have had PTK inhibitory activity. As plausibility was not established, the patent proprietor was not allowed to rely on later experimental data to support its arguments in favor of an inventive step. Consequently, the post-publication documents have not be taken into consideration on the grounds that the alleged activity had not been plausible at the effective date of the patent-in-suit and that these documents were the first disclosure that went beyond speculation.

Although it is not always required to include experimental data or results in a European application (see T578/06, point 13 of the Reasons), it is a conditio sine qua non that the application convincingly shows the technical problem underlying the invention was at least plausibly solved by the filing date.

In summary, it appears that the safest approach, taking into account the plausibility criterium set by the EPO, is to make sure that the application-as-filed (especially in pharmaceutical and biotechnological applications and in chemical applications more generally), contains detailed examples showing that the technical problem underlying the invention has been solved for a number of compounds commensurate with the scope of protection defined by the claims. At a minimum, applicants should incorporate in the application, at the time of filing, experimental data showing that a technical effect is achieved at least for the compounds or groups of compounds closest to the compounds which are expected to be commercialized. In the latter case, these compounds or groups of compounds must be clearly and unambiguously disclosed in the application-as-filed so as to comply with the requirement of Art. 123(2) EPC (added subject-matter), which the EPO assesses in a strict manner.

A possible alternative approach could be renouncing the claim to a broad class of compounds in a single application and, rather protecting them in separate applications so as to cover, in each application, carve out a narrower sub-group of the broad class of compounds. In this manner, it might be easier for applicants to make it plausible that the asserted technical effect is achieved for each sub-group of compounds. Depending on the size of the selected subgroups, a few examples might be sufficient for this purpose. At any rate, applicants should be aware of the fact that compliance with the plausibility criterium has to be assessed on a case-by-case basis.