Both the patent proprietor and the opponent filed appeals against the decision of the Opposition Division (OD) to maintain the patent in amended form.
Claim 1 of the main request before the Board read:
“1. An intravascular stent (300) having an outer surface (302) and an inner surface (301), the improvement comprising:at least one groove (400) disposed in the inner surface (301) of the stent (300), wherein the at least one groove (400) has a width, a length having a dimension greater than the width, and a depth less than the distance between the inner surface and the outer surface of the stent, the at least one groove (400) promoting migration of endothelial cells onto the inner surface (301) of the stent (300) when the stent (300) is implanted.”
Having found the requests on file to comply with the requirements of A 123(2), the Board considers the sufficiency of disclosure (paragraph [4] of the reasons) :
It has been contested that the disclosure is entirely silent about how the at least one groove has to be configured in order to promote migration of endothelial cells onto the inner surface of the stent when the stent is implanted, a feature which is present in both independent claims according to all requests. This feature relates to the technical problem of increasing the rate and/or speed of migration of these cells onto the inner surface […].
For the assessment of the requirements of A 83 it is not necessary for the Board to determine whether a desired effect, i.e. in the present case the promotion of migration of endothelial cells, has actually been obtained. It is also not the function of the Board to verify if an invention works properly. The disclosure is not required to comprise an explanation of how the desired effect is actually obtained, i.e. an indication of the underlying mechanisms. An invention is in principle sufficiently disclosed if at least one way is clearly indicated enabling the person skilled in the art to carry out the invention, and if the disclosure comprises the necessary technical information that permits the intended result to be achieved at least in some realistic cases (T 487/91 [5]). It should at least be plausible from the disclosure that its teaching does indeed solve the problem it purports to solve (T 1329/04 [12]).
In the Board’s view, this is the case in the situation under consideration here. As convincingly explained by one of the inventors, Mr. J. C. Palmaz, it is perfectly plausible that the edges of a groove influence the otherwise zig-zag type of migration of the endothelial cells on a flat surface such that they are guided by the edges of the groove to follow these edges. Their average velocity vector component along the groove thus increases and their migration rate hence becomes accelerated or “promoted” compared to that on a flat surface. All of the grooves depicted in the drawings clearly exhibit edges, and it is not necessary that the term “edge” as such and the resulting effect of guidance be explicitly mentioned or further described in the patent in order to enable the skilled person to carry out the invention as claimed.
The reference to construing the term “groove”, inter alia, as a “rounded indentation” in column 6, lines 7 to 10 of the specification is to be understood as relating to the U-shaped configuration of the groove shown in Figure 10 which also has edges, thus being in line with the explanation given above. The fact that in paragraphs [0009] and [0022] the expression “It is believed that ...” is used with respect to the property of the groove increasing the rate of migration represents the understanding of the authors, but does not imply a lack of sufficiency of disclosure.
In document D5 […] one of the inventors of the patent in suit (J. C. Palmaz) stated that introducing texture on a stent surface may have a beneficial effect on migration, but referred to this effect as a hypothesis which “has not yet been explored”. However, such a general and open statement does not mean that this effect does not exist or is impossible to achieve. It is per se not suited to raise serious doubts with regard to the sufficiency of the disclosure of the patent in suit.
Moreover, the symposium where the respective presentation was made took place from 15 to 17 October 1997, i.e. several weeks before the priority date of the patent in suit. At least within this period, it is quite possible that the unexplored hypothesis was actually verified.
Furthermore, a researcher familiar with the patenting system, like the above-mentioned co-inventor, is unlikely to take the risk of disclosing the details of a potentially patentable invention at a research conference before protecting it by filing a patent application.
In document D9 it is stated that grooves having a depth of 0.5 microns were found to have no effect on cell proliferation […]. However, this result relates to the proliferation of rat dermal fibroblasts, which are quite different from endothelial cells, which have the capability of forming monolayers. Moreover, these studies were performed on silicon substrates […], a material not normally used on stent surfaces. Accordingly, the teaching of this document does not cast any doubt on the sufficiency of the disclosure of the patent in suit. The introductory statement […] that the fundamental mechanisms of cell control by guidance in response to surface topography were still unknown is, like the sentence referred to in D5, very general and does not call into question the effect as such. The same applies to the statement […] where the influence of micro-geometrical surface patterns on cellular behaviour is referred to as a “hypothesis”.
If, in opposition appeal proceedings, the parties make contrary assertions regarding facts considered an obstacle to patentability, as in the present case, the patentee is given the benefit of the doubt, and the burden of proof lies primarily with the opponent (cf. Case Law of the Boards of Appeal of the EPO, 6th edition 2010, VI.H.5.1.1). The argument that routine in-vitro screening studies would not be sufficient for determining whether the grooves promote endothelialisation, which could only be established by means of in-vivo clinical trials representing an undue burden on the opponent, is not accepted by the Board.
The decision T 63/06 cited by the opponent in this respect is not applicable to the situation under consideration here since, as indicated above, the patentee has in fact presented plausible arguments on how the grooves promote endothelialisation, whereas the opponent has failed to present convincing counter-arguments or evidence raising serious doubts with respect to workability. Under these circumstances it is not justified to shift the burden of proof to the patentee. The evidence provided by the opponent (mainly based on D5 and D9) is not sufficient to call into question the sufficiency of the present disclosure. Such an objection is in principle justified only if there are serious doubts substantiated by verifiable facts (cf. Case Law of the Boards of Appeal of the EPO, 6th edition 2010, VI.H.5.1.1). Neither condition is fulfilled in the present case.
Accordingly, the invention as described in the present patent and defined in the claims according to the various requests is disclosed in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art as required by A 83.
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