25.01.2024

Plausibility, a (new) condition for patenting inventions?

Law no. 84/1991, in accordance with the European Patent Convention ("EPC"), establishes three basic conditions for patenting an invention: novelty, inventive step and industrial applicability.

Novelty requires that an invention must not be comprised within the state of the art at the filing date of the application, which is made up of all the knowledge which has become available to the public up to that time. The condition of the existence of inventive step is fulfilled when, to a person skilled in the art, the invention does not obviously result from the knowledge contained in the prior art. Industrial applicability exists when the subject matter of the invention can be manufactured or used in any industrial field. Failure to meet any of these three conditions leads either to the rejection of the patent application or, if the patent has already been granted, to its revocation (by OSIM) or annulment (by the court).

The same effect, i.e. the rejection of the patent application or, as the case may be, its revocation or annulment, is given by a finding that the invention is not disclosed in the patent application clearly and completely enough to enable a person skilled in the art to realize it. This requirement concerning the patent application is contained in Article 17 of Law No 84/1991 and Article 83 EPC and is known as "sufficient disclosure " of the invention.

According to the practice of the European Patent Office ("EPO"), in order for the invention to be considered sufficiently disclosed, a detailed description of at least one embodiment of the invention must be provided in the patent application. As such, an attack based on insufficient disclosure requires the existence of serious doubts that the person skilled in the art would be capable of making the invention.

As the Board of Appeal of the EPO pointed out in case T 0500/20, the standard of sufficient disclosure is generally low and can be satisfied by providing in the patent application a single example falling within the scope of the claim. Thus, for most inventions, there is no serious doubt, based on verifiable facts, that the skilled person would be capable of making the invention. However, for some types of inventions, such as those in the pharmaceutical field, there is a greater inherent doubt as to whether this is the case. For example, there is a high level of doubt that a new chemical compound will cure a particular disease, and this is because it is widely known that most chemical compounds do not cure that disease. Consequently, some evidence is needed to establish a level of probability that the new chemical will cure the disease in question.

In the case of a therapeutic use invention (in the pharmaceutical field, we are usually dealing with product inventions - a new chemical substance, or process inventions, therapeutic use - a known chemical substance used in the treatment of a particular disease), this evidence is considered in the context of establishing whether the condition of sufficient disclosure is met. The higher level of doubt underlying therapeutic use inventions finds expression in the plausibility test. Thus, for an invention for therapeutic use to be sufficiently disclosed, there must be sufficient information in the filed application to make the therapeutic use "technically plausible", as held by the EPO Board of Appeal in case T 1599/06. In other words, the applicant must provide sufficient evidence to overcome the high level of inherent doubt that a new medicinal product will have a certain therapeutic effect.

In this context the concept of 'plausibility' has emerged in EPO practice. However, plausibility is not only used in the context of analyzing the sufficiency of the disclosure, but is also relevant, in some situations, when analyzing inventive step, which may give rise to confusion. In any case, it should be borne in mind that the use of the concept in EPO practice is intended to signal the existence of a higher level of doubt about certain types of inventions or about the claimed technical effects of certain types of inventions.

In case T 1616/09, the EPO Board of Appeal pointed out that, for the purposes of Article 83 EPC, the degree of disclosure required to be present in the application for claims relating to novel pharmaceutical compositions (substances) is not the same as that required for claims relating to medical use. Thus, for claims which relate to compositions (substances) it is in principle sufficient that the application provides information enabling the skilled person to produce that composition (substance) and that there is no well-founded doubt that it could indeed be used in therapy. For claims for medical use, on the other hand, it is necessary not only that the composition itself is disclosed in a manner that enables its realization (or this follows from general technical knowledge), but also that its efficacy for the claimed treatment is plausibly disclosed in the application. Thus, if a claim for a medical use is to be accepted as sufficiently disclosed, the application and/or the general technical knowledge must provide some information making it plausible to the person skilled in the art that the claimed substance can be applied for the claimed medical use.

On the other hand, in case T 1437/07, the EPO Board of Appeal held that, merely because a patent discloses an effect which has not actually been achieved, there is no reason - in the absence of convincing evidence that the effect cannot be achieved - to doubt that the effect could be achieved. With regard to the extent to which the therapeutic use proves to be effective, the EPO Board of Appeal ruled in case T 421/14 in which the claims related to a subsequent medical use with the characteristic of frequency of dosing (twice-daily administration for the treatment of multiple sclerosis). The objections raised concerned the credibility of the claimed therapeutic efficacy, as the proprietor relied on data from a clinical trial which showed that only a proportion of patients responded positively to the treatment, so that the existence of a significant sample of patients who did not respond to the treatment was thus confirmed by the inventors' own results. In the opinion of the EPO Board of Appeal, the existence of the segment of patients who did not respond to the treatment is not a reason to consider the disclosure of the invention as insufficient, and the treatment of non-responders in the study should not be excluded or rejected. In other words, the fact that a substantial proportion of patients did not respond to treatment was considered a common phenomenon that did not affect the sufficiency of the disclosure.

In case T 899/14, the EPO Board of Appeal pointed out that it is not sufficient to merely describe a regimen of administration to be followed without any evidence of its therapeutic efficacy. In that case, the patentee relied on some theoretical examples, and the question was therefore whether the information presented in the examples could render the purported efficacy credible or at least establish the initial plausibility. The conclusion was that the examples do not contain any evidence of the efficacy of the treatments defined in the claims, so that neither the application nor the patent at issue provides any theoretical or technical argument that the proposed treatment would be effective.

In the same sense, as regards the evidence used to demonstrate the plausibility of the invention, in case T 609/02, the EPO Board of Appeal accepted as a well-known fact that demonstrating the efficacy of a particular compound as an active ingredient in a pharmaceutical composition requires years and very high costs which will only be incurred by industry if it can benefit from some form of protection. The patent system takes into account the inherent difficulties for a compound to be authorized as a medicinal product, and does not require absolute proof that the compound is approved as a medicinal product before it can be claimed as such in the form of an invention. The EPO Boards of Appeal (T 241/95, T 158/96) have accepted that it is not always necessary for the results of the application of the compound in clinical trials to be reported in order to hold a sufficient disclosure of a therapeutic claim. However, this does not mean that a mere oral statement to the effect that substance X can be used to treat disease Y is sufficient to provide sufficient disclosure of a claim of use in a pharmaceutical product. It is necessary for the patent to provide some information in the form of, for example, experimental tests, to result in the claimed substance having a direct effect on a metabolic mechanism specifically involved in the disease, which mechanism is either known, or prior art, or demonstrated in the patent itself. The presentation of a pharmaceutical effect in vitro (outside a living organism) may be sufficient if, to the person skilled in the art, this observed effect directly and unambiguously reflects a therapeutic application.

Another example of the use of the concept of plausibility can be found in case T 1571/19, where the EPO Board of Appeal analyzed, using the plausibility test, the sufficiency of the disclosure for a therapeutic use claim. The patent at issue claimed the use of a fish food in the treatment of fish diseases. In this case, the person skilled in the art knows that most fish foods do not treat fish diseases. As a result of this finding, it can be considered that there was a high level of doubt as to the efficacy of the proposed patent solution. However, the patent included data relating to a study in which two examples of the claimed compositions were administered to fish. The opponent argued that, although the data showed some beneficial effects to begin with, these were not statistically significant and therefore the claimed therapeutic effect was not plausible. The EPO Board of Appeal, however, considered that the initial beneficial effects observed contributed to an overall picture that made the claimed therapeutic effect credible. For the Board of Appeal, the opponent could not point to evidence of serious doubts about the claimed therapeutic effect in view of the evidence set out in the patent application. Thus, the claims were considered to be sufficiently disclosed in view of the plausible therapeutic effect.

As can be seen from the examples given above, according to EPO practice, if a functional effect of an invention is explicitly mentioned in a claim (e.g. "...in which the medicament treats disease X"), the plausibility evidence will be taken into account in the sufficient disclosure analysis. It should be noted, however, that the plausibility test is not a higher standard for analyzing the sufficient disclosure requirement for (possibly medical) use inventions. The requirement of sufficiency of disclosure, that there be no reasonable doubt that the invention will work, remains the same. What changes for therapeutic-use inventions is only the level of doubt, of skepticism about the invention, and therefore the amount of evidence needed to overcome that doubt.

In contrast, as confirmed by the recent decision of the EPO Grand Board of Appeal in G 2/21, evidence of an unclaimed technical effect only becomes relevant to the inventive step and is not relevant to the sufficiency of the disclosure. Thus, if the functional or technical effect of an invention is not expressed in a claim, but contributes to the problem that the invention is intended to solve (e.g., the functional properties of a new chemical compound), evidence of the effect is considered in the inventive step analysis.

In the same case G 2/21, the Enlarged Board of Appeal of the EPO sought to clarify the legal nature of plausibility, pointing out that the term itself "does not represent a distinct legal concept or a specific requirement of patent law under the EPC". Thus, the Grand Chamber considered plausibility to be nothing more than a "generic word" and instead focused the issue at hand towards what a qualified person would have understood from the application at the time of filing, rather than what would be considered credible.

The Grand Chamber concluded that a technical effect could be relied upon to withhold inventive step if the skilled person, given general technical knowledge and the patent application, would consider the technical effect to be encompassed by the prior art and embodied by the same invention as originally disclosed. An important point to note from this conclusion is that there is no requirement that such a technical effect be explicitly supported by the data in the original application - thus, a technical effect that is supported only by evidence published subsequent to filing may still be sufficient to be considered as encompassed by the teachings of the invention. Thus, the fact that they can rely on published post-filing evidence is particularly welcome news for applicants for whom early filing is a necessity.

In conclusion, plausibility is not a distinct legal concept and thus not a condition of patentability in its own right, enjoying an express legal basis in the EPC or in Romanian law. Both require that an invention be sufficiently disclosed in the application, but do not mention "plausibility" as a component of disclosure. However, plausibility has been and is used in EPO practice in two particular situations, in particular in the case of pharmaceutical inventions, namely either in the analysis of sufficient disclosure for medical use inventions or in the analysis of inventive step for novel product (substance) inventions.

As such, plausibility is not a formal ground for rejection of an application or revocation/cancellation of a patent. Instead, practice has used the concept to assess whether a claimed effect - such as the treatment of a particular disease - is credible to the person skilled in the art on the basis of the patent application as filed and the general technical knowledge in the field.

Plausibility is thus the way in which the EPO expresses a greater degree of doubt about certain types of inventions. If there is more doubt that an invention will work, then the applicant must provide more evidence and information about the invention in order for the patent to be granted. Therefore, plausibility is not a new or additional requirement for patenting, but merely a recognition of the technical challenges and complexity of certain categories of inventions.

An article by Mihai Stănescu, Managing Associate - mstanescu@stoica-asociatii.ro - STOICA & Associates