T 1422/12 – Change Of Character

This is an examination appeal.

Claim 1 of the request on file read:

A crystalline form of Tigecycline characterized by a powder XRD pattern having peaks at 6.8, 9.5, 9.8, 12.1, 12.6, 18.1, 20.2, 21.6, 23.3, and 26.8 ± 0.2 degrees 2-theta.

The Board made a noteworthy statement on the choice of the objective technical problem:

[2.1] The sole issue arising from this appeal is the inventiveness of the subject-matter of the claims of the main request on file.

[2.2] The Board considers, in agreement with the Examining Division (ED) and the appellant, that the closest prior art is document D2, more particularly, the product of Example 8 thereof, which is a solid form of tigecycline. According to the appellant […], repetition of Example 8 of document D2 resulted in amorphous tigecycline. A further repetition of the process of Example 8 performed by the appellant, the experimental details of which were provided in Annex B of letter dated 8 March 2013, confirmed said conclusion. With regard to the appellant’s submission to the ED in the letter dated 22 March 2010 that a repetition of the procedure of this example resulted in a crystalline form of tigecycline, the appellant subsequently provided the full experimental protocol which resulted in this assertion, namely Annex A accompanying its letter dated 8 March 2013. Said procedure was, however, not a true repetition of the prior art, since the requirements that the pH of the mixture obtained [… in] Example 8 of document D2 was adjusted to 7.2 to 7.4 and that the solution was stirred in a chill room overnight […], were not fulfilled. This divergence from the prior art procedure could have influenced the nature of the final product, such that this “repetition” is to be disregarded when assessing the nature of the product of Example 8 of document D2. Further confirmation that the product of Example 8 of document D2 is amorphous is also provided in the form of the declaration D5 submitted by one of the inventors cited in document D1 before the USPTO. The Board is thus convinced that the tigecycline product of Example 8 of document D2 is an amorphous material.

[2.3] In view of this state of the art, the appellant submitted that the problem underlying the present application is the provision of tigecycline which is more stable with respect to epimerisation.

[2.3.1] In the decision under appeal, the ED did not accept the formulation of the technical problem as the provision of tigecycline in more thermodynamically stable form, since there was no indication in the application as filed that this was indeed the problem which the invention attempted to solve. The reference in paragraph [0010] of the application to the chemical and physical stability of crystalline solids was very general and belonged merely to the background of the invention and thus could not form a basis for formulating the problem.

[2.3.2] According to the well established case law of the Boards of Appeal, the technical problem has to be determined on the basis of objectively established facts, since for the determination of the objective technical problem, only the effect actually achieved vis-à-vis the closest prior art should be taken into account (see T 13/84 [headnote 1; 10-11] and T 39/93 [5.3.1-4]). In this connection, any effects may be taken into account, so long as they concern the same field of use and do not change the character of the invention (see T 440/91 [4.1-2]).

[2.3.3] In the present case, it is indicated in the application in suit […] that the present invention relates to crystalline forms of tigecycline, tigecycline being a tetracycline antibiotic already marketed as lyophilised powder or cake for intravenous injection, namely in the amorphous form. The section concerning the background of the invention […] relates to improving the performance characteristics of pharmaceutical products, including tigecycline.

The formulation of the technical problem to be solved as the provision of tigecycline which is more stable with respect to epimerisation, said reduction in epimerisation resulting in improved biological activity, thus falls within the framework of the invention as disclosed in the application in suit, namely the performance characteristics of the antibiotic, tigecycline, regardless of whether these characteristics are relevant to handling, storage or formulation and/or to its pharmaceutical properties. That the more specific problem of improved stability with respect to epimerisation is not mentioned in the application as originally filed is irrelevant (see T 39/93 [5.3.5]), since improvement of stability by avoidance of epimerisation, and, as a consequence, improved biological activity, is clearly recognisable by the skilled person as a desirable effect for a tetracycline antibiotic.

As a consequence, the Board does not agree with the conclusions of the ED regarding the formulation of the technical problem and thus allows the definition given under point [2.3] above.

The Board finally issued an order to grant a patent.

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