CASELAW-EPO - reviews of EPO Boards of Appeal decisions

T 1654/22 – On the choice of the Closet Prior Art – No pointer needed in the CPA – Prejudice in the patent world

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Patent EP 3 027 186 B1 relates to a process for the preparation of filler compositions comprising hyaluronic acid and mepivacaine hydrochloride, an anaesthetic agent.

Brief outline of the case

The OD found that claim 1 as granted lacked N over claim 36 of D2=WO 2012/104419, the first document cited in the ISR established by the EPO. The same applied to AR 1-8. The patent was maintained according to AR9.

The proprietor and opponents 2 and 3 appealed.

The board held that all the requests on file lacked IS over D2 and revoked the patent.

The discussion is interesting as it deals with the choice of the CPA.

The proprietor’s point of view

For the proprietor, to arrive at a method for providing a hyaluronic acid composition comprising mepivacaine starting from claim 36 of D2, two selections were needed, Furthermore, at the filing date of D2, the skilled person was refrained based on its knowledge to prepare compositions comprising mepivacaine, considering its pKa and the resulting high risk of precipitation. Thus D2 did not disclose clearly and unambiguously a method for providing a hyaluronic acid composition comprising mepivacaine.

Regarding IS, only the examples of D2 comprising lidocaine hydrochloride or bupivacaine could be seen as promising springboards to the invention. Considering the similar physicochemical properties of lidocaine and mepivacaine, the most promising springboard was the embodiment comprising lidocaine hydrochloride.

The proprietor submitted that claim 36 of D2 was not a suitable starting point for the assessment of IS.

This was also the position of the OD.

The opponents’ point of view

The appealed decision identified three possible starting points within the disclosure in D2, namely:

a) claim 36 in combination with the selection of mepivacaine;

b) the examples comprising lidocaine as anaesthetic; and

c) the examples comprising bupivacaine as anaesthetic.

There was however no justification for the OD’s conclusion that embodiment a) was an unrealistic starting point.

The boards decision

D2 belongs to the same field of anaesthetic-containing filler compositions and addresses the same problem of rheological stability upon sterilisation.

The board confirmed the three starting points set out by the opponents.

For the board, on the basis of claim 36 of D2, a method comprising mixing a hyaluronic acid, mepivacaine and an ascorbic acid derivative, and then subjecting the mixture to sterilization by heat, belonged to the state of the art.

There is no requirement in the case law that an embodiment of the state of the art must be exemplified for it to be considered in the assessment of IS.

There is likewise no requirement that the prior art contains any pointer, suggestion or incentive to select a particular embodiment for further development for this embodiment to qualify as a starting point in the problem solution approach. On this point, the board disagreed with the proprietor and the OD.

The criteria developed in the case law are mainly that the starting point, or “closest prior art”, is normally a prior art document disclosing subject-matter conceived for the same purpose or aiming at the same objective as the claimed invention and having the most relevant technical features in common. There is no debate that D2, including any of its embodiments a)-c) identified above, meet these criteria.

But beyond these broad criteria, it is also established case law that, if the skilled person has a choice of several workable routes which might lead to the invention, the rationale of the problem and solution approach requires that the invention be assessed relative to all these possible routes, before an IS can be acknowledged.

Conversely, if the invention is obvious to the skilled person in respect of at least one of these routes, then IS is lacking. If IS is to be denied, the choice of starting point needs no specific justification, because the claimed invention must be non-obvious having regard to any prior art. The board referred to T 261/19, Reasons 2.5 of the; T 1112/19, Reasons 2.1.3; T 574/19, point 2.2.3).

The board further considered that the disclosure in D2 relating to mepivacaine is neither defective nor speculative. Contrary to the proprietor’s view, no prejudice is shown to have existed at the relevant date against the use of mepivacaine in hyaluronic acid compositions.

The sole document on which the appellant – proprietor based this argument is D13, which is a single patent application document originating from opponent 3 and filed after the filing date of the patent in suit.

D13 is thus not suitable for establishing the existence of a prejudice, i.e. a widely held but incorrect opinion of a technical fact, at the relevant date.

The mere fact that the use of mepivacaine is not exemplified does not mean either that D2 is speculative or not enabled in this respect. This is because D2 discloses examples showing the successful use of other anaesthetics, namely bupivacaine, tetracaine and, especially, the closely related lidocaine, whose physicochemical and pharmaceutical properties are very similar to those of mepivacaine.

Considering in particular that the pKa of mepivacaine is barely different from that of lidocaine, the proprietor’s argument regarding the expected unsuitability of mepivacaine for the preparation of hyaluronic acid – anaesthetics compositions due to its pKa and the resulting high risk of precipitation, is not convincing. There is accordingly no reason to regard the mention of mepivacaine in D2 as an unrealistic starting point.

Lastly, even if, at the filing date of the patent, only dermal fillers comprising lidocaine hydrochloride were marketed, the prior art for the assessment of IS is not limited to such marketed products.

For these reasons, the above embodiment a), i.e. the method of claim 36 of D2 as applied to mepivacaine, is taken as starting point for the assessment of IS


The present decision is a good refresher as to the choice of the CPA. No pointer is need in the CPA and if one route, among a plurality of possible routes, shows an obvious way to arrive at the invention, the invention lacks IS.

The present decision is also a good refresher that one single document, and not a  patent document cannot be considered disclosing a prejudice even if difficulties can be expected.

On the procedure

As D2 was in the ISR established by the EPO, and in view of the result of the appeal, it is difficult to understand that this patent was ever granted. Once more the decision of an OD has been set aside by a board.

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