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Sound plausible? How much data does your patent application really need to include?

15 August 2017

Inventors and applicants are often surprised to learn that the European Patent Convention (EPC) does not formally require a patent application to include experimental data. However, it has long been understood that any technical effect of an invention can only be relied upon to support an inventive step to the extent that the application as filed makes it at least “plausible” that the effect has been achieved (see EPO Technical Board of Appeal Decisions T939/92 and T1329/04). Provided that this initial hurdle can be overcome, an applicant can then submit data from work carried out after the patent application was filed to support their arguments for an inventive step. Historically, however (especially for inventions in the chemical, pharmaceutical and biological fields), it has not been completely clear how much, and indeed if any, experimental data must be included in the application as filed to establish plausibility.

In February 2017, a decision by the EPO in case T 488/16 to revoke the European patent for the anti-cancer drug dasatinib (Sprycel®) caused ripples through the pharmaceutical industry. The reasoning behind this decision has now been published by the EPO and provides some useful guidance as to what is required to establish that a technical effect is plausibly achieved.

The dasatinib application as filed was directed to an extremely broadly defined group of compounds, indicated by a general chemical formula, with 580 specific compounds disclosed as falling within the group, one of which was dasatinib. The application also described a number of protein tyrosine kinases (PTKs) as potential targets of the claimed compounds and listed a number of associated specific disorders, including certain types of cancer. The application as filed described assays for testing the activity of compounds as PTK inhibitors. However, there was no evidence at all in the application that any of the compounds falling within the general chemical formula had any PTK inhibitory activity, other than an assertion that “Compounds described in the following examples have been tested in one or more of these assays and have shown activity.”

The Board of Appeal noted that no values or ranges were provided, nor was any information as to whether the observed activity was suitable for the intended use of the compounds, i.e., in the treatment of the various specific disorders. The Board concluded that in the absence of verifiable technical evidence, the mere statement that compounds had PTK inhibitory activity was not sufficient to render it plausible that the technical problem purported to be solved by the invention (i.e., providing PTK inhibitors to treat associated specific disorders) was actually solved. The very broad definition of the class of compounds was held to make it highly unlikely that all of the compounds falling within that general formula had PTK inhibitory activity. The Board were also of the opinion that there was no evidence that at the filing date of the application, the skilled person would have possessed common general knowledge that would have made 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 work to support their arguments for an inventive step.

Interestingly, the Board explicitly addressed the question of whether it is always necessary for an application to include experimental data. In their view experimental data are not always required. However, they reiterated the requirement that the technical problem underlying the invention must at least be plausibly solved at the filing date of the application. The Board went on to note that for an invention that relies on a technical effect that is not self-evident, predictable or based on a conclusive theoretical concept, at least some technical evidence is required to show that the technical problem has been solved. The Board took pains to emphasise that the issue with the dasatinib application was not an absence of in vivo data or clinical data, but an absence of any verifiable data.

This decision by the Board of Appeal provides greater clarity for applicants, especially those in the chemical, pharmaceutical and biological fields, who are likely to be relying on an unexpected technical effect to solve the problem underlying the invention. This underlines the fact that it is essential for applications relying on a technical effect to include at least some verifiable technical data.

It seems reasonable to conclude that the level of data required will be commensurate with the scope of the claims and how unexpected the technical effect may be. While the Board implied in this decision that in vivo and/or clinical data may not be required, it seems likely that broader claims and/or highly unexpected technical effects will need greater amounts of data to make it plausible that the technical effect is achieved across the scope of the claim.

Our advice continues to be that, wherever possible, applicants should try to delay filing applications until at least in vitro data are available and should take care to present it clearly and completely. This will be important not only for establishing an inventive step during examination of the application but also for defending against any plausibility attack that might be raised during opposition proceedings.


Dr Helen Henderson
Life Sciences & Chemistry Group

If you require further information on anything covered in this briefing, please contact Helen Henderson ( ; +44 207 940 3600) or your usual contact at the firm. This publication is a general summary of the law. It should not replace legal advice tailored to your specific circumstances.

© Withers & Rogers LLP, August 2017