T 0375/13 - "Stable" as parameter

EPO T 375/13

For the decision, click here

Key points

• The OD had deemed the word "stable" in the claim resulted in a lack of sufficiency, the term being an undefined parameter. 
• The Board does not agree. " Even if in most cases a specific condition is not defined of what is meant by a stable pharmaceutical product, the person skilled in the art would not consider the adjective "stable" as so uncommon and ill-defined as to lead to a lack of sufficiency."
• Note that both "uncommon"  and " ill-defined"  are mentioned as criteria. 

Summary of Facts and Submissions

I. The appeal of the patent proprietor (appellant) lies against the decision of the opposition division announced at the oral proceedings on 18 October 2012 to revoke European Patent 1 169 062. The patent was granted on the basis of 9 claims, claim 1 reading as follows: [...]

Reasons for the Decision

Main request - revision of the decision on sufficiency

8. Lack of sufficiency on the basis of the feature "such complex being stable at a temperature of at least 121 °C for a period effective to sterilise the complex" was the main reason for revocation of the patent. 

In particular the opposition division came to the conclusion that the patent lacked sufficiency of disclosure, as the skilled person did not find in the specification which parameter(s) he should measure, how to accomplish the measurement(s) and which standard(s) to apply in order to assess stability. In the present decision only a revision of the appealed decision is accomplished with regard to sufficiency of disclosure, while the further objection based on additional evidence filed by the respondent in appeal will have to be analysed in subsequent opposition proceedings after remittal (see point 9, below).

8.1 The case in which undefined parameters or an undefined condition are used in the the claims and no details of the measuring methods are present in the patent is well known in the jurisprudence of the Boards of Appeal (Case Law of the Boards of Appeal of the EPO, 7th edition 2013, II.C.7.2), which jurisprudence should be taken into account in deciding on the issue. In this respect a central point according to the Board is that the question whether or not the skilled person knows if he is working within or outside of the scope of the claims is as such a matter of clarity of the claims and not of sufficiency of disclosure, particularly if an ambiguity exists at the edges of the claims. On the other side, the presence of an ill-defined parameter may under certain circumstances prevent the skilled person from being able to carry out the invention. Following T 0593/09 of 20 December 2011 (see point 4.1.4), the Board considers that what is decisive for establishing insufficiency is whether the parameter, in the specific case, is so ill-defined that the skilled person is not able, on the basis of the disclosure as a whole and using his common general knowledge, to identify (without undue burden) the technical measures necessary to put the claimed invention into practice.

8.2 In the present case the Board is of the view that the stability condition in claim 1 is not so ill-defined that a person skilled in the art is not in the position to carry out the claimed invention.

8.3 First of all, stability is in itself a fundamental condition of any pharmaceutical product, which, if suitable for the intended use at production, must remain suitable for that use up to the point in which it is employed. Even if in most cases a specific condition is not defined of what is meant by a stable pharmaceutical product, the person skilled in the art would not consider the adjective "stable" as so uncommon and ill-defined as to lead to a lack of sufficiency.

8.4 In the opinion of the Board the specific stability condition in claim 1 of the main request is understood by the skilled person in this light as meaning that the product is able to withstand a sterilisation step at at least 121 °C (the autoclaving defined in the claim) without losing its properties, namely without losing its suitability for the intended purpose. In other words, as the product before sterilisation is suitable for administration by injection (apart from the potential presence of still to be eliminated micro-organisms), it must remain suitable for that use after sterilisation.

8.5 This reading of the claim is in agreement with the disclosure in the patent in suit.

[...]

8.6 In other words, it is indicated in the patent that a material which undergoes such physical changes as mentioned in paragraph [0034] clearly loses its suitability for the intended purpose and cannot be considered as stable and that, while several parameters may be associated to the concept of stability, greater stability is achieved when the material is not altered by the autoclaving step, so that if it is suitable for administration by injection before sterilisation, it remains suitable for that use after sterilisation.

8.7 As the condition of "suitability" for a specific use does not usually give rise to problems of sufficiency, even if normally a specific test with specific conditions is not defined, the same is valid for the present parameter. The limitation given by the condition may be broad and may not have sharply defined limits, but it does not appear to be so uncommon and ill-defined to prevent the skilled person from being able to carry out the invention. On the contrary, even if it is not stated in a conclusive way in the patent which parameters should be measured and which variations should be allowed, some indications are given (see paragraph [0149] and table 9, cited above) of relevant parameters and satisfactory variations, which is more than what is normally present for a "suitability" condition.

8.8 With regard to how a product meeting the stability condition is obtained, the patent gives quite detailed information about the process for obtaining a complex according to the invention with the main process steps being included in claim 1 and it discloses at least one product (example 31) which is obtained according to the sequence of steps in claim 1 (see paragraph [0124] with reference to example 5 in paragraphs [0078] to [0080]), has properties which are unaffected by sterilisation at 121 °C (paragraphs [0147] to [0149] and table 9) and is disclosed as being stable.

8.9 Thus, based on the facts of the decision, it cannot be concluded that the patent does not disclose the invention in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art.